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Sample records for volatile spoilage metabolites

  1. Volatile Metabolites

    Directory of Open Access Journals (Sweden)

    Daryl D. Rowan

    2011-11-01

    Full Text Available Volatile organic compounds (volatiles comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites.

  2. Antimicrobial packaging to retard the growth of spoilage bacteria and to reduce the release of volatile metabolites in meat stored under vacuum at 1°C.

    Science.gov (United States)

    Ferrocino, Ilario; La Storia, Antonietta; Torrieri, Elena; Musso, Salvatore Spagna; Mauriello, Gianluigi; Villani, Francesco; Ercolini, Danilo

    2013-01-01

    A nisin-EDTA solution was used for activation of the internal surface of plastic bags that were used to store beef chops at 1°C after vacuum packaging. The aim of the work was to evaluate the effect of the antimicrobial packaging on beef during storage. Volatile compounds and microbial populations were monitored after 0, 9, 20, 36, and 46 days of storage. The active packaging retarded the growth of lactic acid bacteria. Brochothrix thermosphacta was unable to grow for the whole storage time in treated samples, while the levels of Carnobacterium spp. in treated samples were below the detection limit for the first 9 days and reached loads below 5 Log CFU/cm(2) after 46 days. On the other hand, Enterobacteriaceae and Pseudomonas spp. were not affected by the use of the antimicrobial packaging and grew in all of the samples, with final populations of about 4 Log CFU/cm(2). Carnobacterium divergens was identified by PCR-denaturing gradient gel electrophoresis analysis of DNA extracted from beef after 36 days of storage. During beef storage, alcohols, aldehydes, ketones, and carboxylic acids were detected in the headspace of beef samples by solid-phase microextraction-gas chromatography-mass spectrometry analysis. The microbial metabolic activity was affected by the use of the antimicrobial film from the beginning up to 36 days with a maximum in the differences of volatile metabolites in samples analyzed at 20 days. The volatiles were also determined by electronic nose, allowing differentiation based on the time of storage and not on the type of packaging. The active packaging reduces the loads of spoilage microbial populations and the release of metabolites in the headspace of beef with a probable positive impact on meat quality.

  3. Volatile components associated with bacterial spoilage of tropical prawns

    DEFF Research Database (Denmark)

    Chinivasagam, H.N.; Bremner, Allan; Wood, A.F.

    1998-01-01

    Analysis of headspace volatiles by gas chromatography/mass spectrometry from king (Penaeus plebejus), banana (P. merguiensis), tiger (P. esculentus/semisulcatus) and greasy (Metapenaeus bennettae) prawns stored in ice or ice slurry, which is effectively an environment of low oxygen tension......, whereas sulphides and amines occurred whether the predominant spoilage organism was Ps.fragi or Shewanella putrefaciens. The free amino acid profiles of banana and king prawns were high in arginine (12-14%) and low in cysteine (0.1-0.17%) and methionine (0.1-0.2%). Filter sterilised raw banana prawn broth...

  4. Volatile metabolites from actinomycetes

    DEFF Research Database (Denmark)

    Scholler, C.E.G.; Gurtler, H.; Pedersen, R.

    2002-01-01

    Twenty-six Streptomyces spp. were screened for their volatile production capacity on yeast starch agar. The volatile organic compounds (VOCs) were concentrated on a porous polymer throughout an 8-day growth period. VOCs were analyzed by gas chromatography with flame ionization detection and ident...

  5. Volatile components associated with bacterial spoilage of tropical prawns

    DEFF Research Database (Denmark)

    Chinivasagam, H.N.; Bremner, Allan; Wood, A.F.

    1998-01-01

    , whereas sulphides and amines occurred whether the predominant spoilage organism was Ps.fragi or Shewanella putrefaciens. The free amino acid profiles of banana and king prawns were high in arginine (12-14%) and low in cysteine (0.1-0.17%) and methionine (0.1-0.2%). Filter sterilised raw banana prawn broth...... inoculated with a total of 15 cultures of Ps. fragi and S. putrefaciens and incubated for two weeks at 5°C, showed the presence of 17 major compounds in the headspace volatiles analysed using gas chromatography/mass spectrometry (GC/MS). These were mainly amines, sulphides, ketones and esters. Principal...... Component Analysis of the results for the comparative levels of the volatiles produced by pure cultures, inoculated into sterile prawn broth, indicated three subgroupings of the organisms; I, Ps. fragi from a particular geographic location; II, S. putrefaciens from another geographic location; and III...

  6. Volatile organic compounds and Photobacterium phosphoreum associated with spoilage of modified-atmosphere-packaged raw pork

    DEFF Research Database (Denmark)

    Nieminen, Timo T.; Dalgaard, Paw; Björkroth, Johanna

    2016-01-01

    Accumulation of volatile organic compounds was monitored in association with sensory quality, bacterial concentrations and culture-independent microbial community analyses in raw pork loin and pork collar during storage under high-oxygen modified atmosphere at +4°C. Of the 48 volatile compounds....... According to the culture-dependent and culture-independent characterization of bacterial communities, Brochothrix thermosphacta, lactic acid bacteria (Carnobacterium, Lactobacillus, Lactococcus, Leuconostoc, Weissella) and Photobacterium spp. predominated in pork samples. Photobacterium spp., typically...... not associated with spoilage of meat, were detected also in 8 of the 11 retail packages of pork investigated subsequently. Eleven isolates from the pork samples were shown to belong to Photobacterium phosphoreum by phenotypic tests and sequencing of the 16S rRNA and gyrB gene fragments. Off-odors in pork samples...

  7. Rapid Detection of Meat Spoilage by Measuring Volatile Organic Compounds by Using Proton Transfer Reaction Mass Spectrometry

    OpenAIRE

    Mayr, D; Margesin, R.; Klingsbichel, E.; E. Hartungen; Jenewein, D.; Schinner, F.; Märk, T.D.

    2003-01-01

    The evolution of the microbial spoilage population for air- and vacuum-packaged meat (beef and pork) stored at 4°C was investigated over 11 days. We monitored the viable counts (mesophilic total aerobic bacteria, Pseudomonas spp., Enterobacteriaceae, lactic acid bacteria, and Enterococcus spp.) by the microbiological standard technique and by measuring the emission of volatile organic compounds (VOCs) with the recently developed proton transfer reaction mass spectrometry system. Storage time,...

  8. Detection of mastitis pathogens by analysis of volatile bacterial metabolites

    NARCIS (Netherlands)

    Hettinga, K.A.; Valenberg, van H.J.F.; Lam, T.J.G.M.; Hooijdonk, van A.C.M.

    2008-01-01

    The ability to detect mastitis pathogens based on their volatile metabolites was studied. Milk samples from cows with clinical mastitis, caused by Staphylococcus aureus, coagulase-negative staphylococci, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli were collected. In

  9. Rapid detection of meat spoilage by measuring volatile organic compounds by using proton transfer reaction mass spectrometry.

    Science.gov (United States)

    Mayr, D; Margesin, R; Klingsbichel, E; Hartungen, E; Jenewein, D; Schinner, F; Märk, T D

    2003-08-01

    The evolution of the microbial spoilage population for air- and vacuum-packaged meat (beef and pork) stored at 4 degrees C was investigated over 11 days. We monitored the viable counts (mesophilic total aerobic bacteria, Pseudomonas spp., Enterobacteriaceae, lactic acid bacteria, and Enterococcus spp.) by the microbiological standard technique and by measuring the emission of volatile organic compounds (VOCs) with the recently developed proton transfer reaction mass spectrometry system. Storage time, packaging type, and meat type had statistically significant (P meat. We found statistically significant strong correlations (up to 99%) between some of the VOCs and the bacterial contamination. The concentrations of these VOCs increased linearly with the bacterial numbers. This study is a first step toward replacing the time-consuming plate counting by fast headspace air measurements, where the bacterial spoilage can be determined within minutes instead of days.

  10. Volatile chemical spoilage indexes of raw Atlantic salmon (salmo salar)stored under aerobic condition in relation to microbiological and sensory shelf lives

    Science.gov (United States)

    The purpose of this investigation was to identify and quantify the volatile chemical spoilage indexes (CSIs) for raw Atlantic salmon (Salmo salar) fillets stored under aerobic storage conditions at 4, 10 and 21 degrees C in relation to the determined microbial and sensory shelf lives. The volatile o...

  11. Significance of volatile compounds produced by spoilage bacteria in vacuum-packed cold-smoked salmon ( Salmo salar ) analyzed by GC-MS and multivariate regression

    DEFF Research Database (Denmark)

    Jørgensen, Lasse Vigel; Huss, Hans Henrik; Dalgaard, Paw

    2001-01-01

    Changes were studied in the concentration of 38 volatile compounds during chilled storage at 5 degreesC of six lots of commercially produced vacuum-packed cold-smoked salmon and sterile cold-smoked salmon. The majority of volatile compounds produced during spoilage of cold-smoked salmon were......, 1- penten-3-ol, and 1-propanol. The potency and importance of these compounds was confirmed by gas chromatography- olfactometry. The present study provides valuable information on the bacterial reactions responsible for spoilage off-flavors of cold-smoked salmon, which can be used to develop...

  12. Identification and Quantification of Volatile Chemical Spoilage Indexes Associated with Bacterial Growth Dynamics in Aerobically Stored Chicken.

    Science.gov (United States)

    Mikš-Krajnik, Marta; Yoon, Yong-Jin; Ukuku, Dike O; Yuk, Hyun-Gyun

    2016-08-01

    Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 °C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H2 S producing bacteria were characterized based on maximum growth rates (μmax ), maximal microbial concentration (Nmax ) and at the moment of microbial shelf life (Svalues ), calculated from Gompertz-fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest μmax . The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC-MS in spoiled chicken samples, ethanol (EtOH), 1-butanol-3-methyl (1But-3M), and acetic acid (C2 ) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But-3M and C2 was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But-3M, and C2 ) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But-3M, and C2 as rapid evaluation for poultry quality testing using SPME-GC-MS.

  13. Characterisation of volatile compounds produced by bacteria isolated from the spoilage flora of cold-smoked salmon.

    Science.gov (United States)

    Joffraud, J J; Leroi, F; Roy, C; Berdagué, J L

    2001-06-15

    This study investigated the volatile compounds produced by bacteria belonging to nine different bacterial groups: Lactobacillus sake, L. farciminis, L. alimentarius, Carnobacterium piscicola, Aeromonas sp., Shewanella putrefaciens, Brochothrix thermosphacta, Photobacterium phosphoreum and Enterobacteriaceae isolated from cold-smoked salmon. Each bacterial group was represented by several strains. In addition, combinations of the groups were examined as well. Sterile blocks of cold-smoked salmon were inoculated, vacuum-packed and stored at 6 degrees C. After 40 days of storage at 6 degrees C, aerobic viable count and pH were recorded, the volatile fraction of the samples was analysed by gas chromatography-mass spectrometry (GC-MS), and spoilage was assessed by sensory evaluation. Among the 81 volatile compounds identified by GC-MS, 30 appeared to be released as a result of bacterial metabolism. Some of the effects of inoculated bacterial strains on the composition of the volatile fraction seemed to be characteristic of certain bacterial species. Sensory analysis showed relationships between bacteria, the composition of the volatile fraction and the organoleptic quality of smoked salmon.

  14. Relationships between methane emission of Holstein Friesian dairy cows and fatty acids, volatile metabolites and non-volatile metabolites in milk

    NARCIS (Netherlands)

    Gastelen, van S.; Antunes-Fernandes, E.C.; Hettinga, K.A.; Dijkstra, Jan

    2017-01-01

    This study investigated the relationships between methane (CH4) emission and fatty acids, volatile metabolites (V) and non-volatile metabolites (NV) in milk of dairy cows. Data from an experiment with 32 multiparous dairy cows and four diets were used. All diets had a roughage : concentrate ratio of

  15. Volatile organic metabolites identify patients with breast cancer, cyclomastopathy, and mammary gland fibroma.

    Science.gov (United States)

    Wang, Changsong; Sun, Bo; Guo, Lei; Wang, Xiaoyang; Ke, Chaofu; Liu, Shanshan; Zhao, Wei; Luo, Suqi; Guo, Zhigang; Zhang, Yang; Xu, Guowang; Li, Enyou

    2014-06-20

    The association between cancer and volatile organic metabolites in exhaled breaths has attracted increasing attention from researchers. The present study reports on a systematic study of gas profiles of metabolites in human exhaled breath by pattern recognition methods. Exhaled breath was collected from 85 patients with histologically confirmed breast disease (including 39 individuals with infiltrating ductal carcinoma, 25 individuals with cyclomastopathy and from 21 individuals with mammary gland fibroma) and 45 healthy volunteers. Principal component analysis and partial least squares discriminant analysis were used to process the final data. The volatile organic metabolites exhibited significant differences between breast cancer and normal controls, breast cancer and cyclomastopathy, and breast cancer and mammary gland fibroma; 21, 6, and 8 characteristic metabolites played decisive roles in sample classification, respectively (P fibroma patients, and patients with cyclomastopathy (P < 0.05). The identified three volatile organic metabolites associated with breast cancer may serve as novel diagnostic biomarkers.

  16. Severe drought stress is affecting selected primary metabolites, polyphenols, and volatile metabolites in grapevine leaves (Vitis vinifera cv. Pinot noir).

    Science.gov (United States)

    Griesser, Michaela; Weingart, Georg; Schoedl-Hummel, Katharina; Neumann, Nora; Becker, Manuel; Varmuza, Kurt; Liebner, Falk; Schuhmacher, Rainer; Forneck, Astrid

    2015-03-01

    Extreme weather conditions with prolonged dry periods and high temperatures as well as heavy rain events can severely influence grapevine physiology and grape quality. The present study evaluates the effects of severe drought stress on selected primary metabolites, polyphenols and volatile metabolites in grapevine leaves. Among the 11 primary metabolites, 13 polyphenols and 95 volatiles which were analyzed, a significant discrimination between control and stressed plants of 7 primary metabolites, 11 polyphenols and 46 volatile metabolites was observed. As single parameters are usually not specific enough for the discrimination of control and stressed plants, an unsupervised (PCA) and a supervised (PLS-DA) multivariate approach were applied to combine results from different metabolic groups. In a first step a selection of five metabolites, namely citric acid, glyceric acid, ribose, phenylacetaldehyde and 2-methylbutanal were used to establish a calibration model using PLS regression to predict the leaf water potential. The model was strong enough to assign a high number of plants correctly with a correlation of 0.83. The PLS-DA provides an interesting approach to combine data sets and to provide tools for the specific evaluation of physiological plant stresses.

  17. Spoilage of light (PSE-like) and dark turkey meat under aerobic or modified atmosphere package: microbial indicators and their relationship with total volatile basic nitrogen.

    Science.gov (United States)

    Fraqueza, M J; Ferreira, M C; Barreto, A S

    2008-01-01

    1. The aim of this work was to evaluate the shelf life of turkey meat from different colour categories (Pale, Soft and Exudative (PSE)-like), intermediate and dark), packaged under aerobic or modified atmosphere (MAP) conditions; also to establish a relationship between microbial quality and total volatile basic nitrogen (TVB-N), evaluating its capacity for shelf life determination. 2. Breasts were selected according to luminance (L*) and pH(24): L >/= 51 and pH 5.8 for dark colour. Sliced meat was packaged under aerobic or MAP conditions with 50% N(2) and 50% CO(2), then stored in the dark at 0 +/- 1 degrees C for periods of 12 or 25 d. Meat under aerobic conditions was evaluated for microbiological characteristics and TVB-N on d 0, 5 and 12. This evaluation was extended to include d 19 and 25 when samples were under MAP conditions. 3. The dark meat group after 12 d of storage in aerobiosis presented significantly higher plate counts of aerobic mesophilic, psychrotrophic micro-organisms and higher TVB-N than other meat colour categories. The shelf life of turkey meat under MAP was one week longer for intermediate and light colour meat (20 d) than for dark meat. TVB-N values of 20 to 30 mg NH(3)/100 g turkey meat correspond to advanced spoilage stages. We proposed 14 mg NH(3)/100 g as the limit of freshness acceptability for turkey meat. 4. TVB-N was an indicator of turkey meat microbial spoilage but was not a suitable early predictor for microbial spoilage and in particular for turkey meat stored under MAP conditions because counts of micro-organisms were moderately correlated (Pseudomonas spp. and Enterobacteriaceae) with this index, as they were inhibited by MAP gas mixture and storage temperature used in the present study.

  18. The Ecological Role of Volatile and Soluble Secondary Metabolites Produced by Soil Bacteria.

    Science.gov (United States)

    Tyc, Olaf; Song, Chunxu; Dickschat, Jeroen S; Vos, Michiel; Garbeva, Paolina

    2016-12-27

    The rich diversity of secondary metabolites produced by soil bacteria has been appreciated for over a century, and advances in chemical analysis and genome sequencing continue to greatly advance our understanding of this biochemical complexity. However, we are just at the beginning of understanding the physicochemical properties of bacterial metabolites, the factors that govern their production and ecological roles. Interspecific interactions and competitor sensing are among the main biotic factors affecting the production of bacterial secondary metabolites. Many soil bacteria produce both volatile and soluble compounds. In contrast to soluble compounds, volatile organic compounds can diffuse easily through air- and gas-filled pores in the soil and likely play an important role in long-distance microbial interactions. In this review we provide an overview of the most important soluble and volatile classes of secondary metabolites produced by soil bacteria, their ecological roles, and their possible synergistic effects.

  19. Volatile metabolites from some gram-negative bacteria

    DEFF Research Database (Denmark)

    Schöller, Charlotte; Molin, Søren; Wilkins, Ken

    1997-01-01

    A survey of volatile organic compounds (VOCs) excreted from various Gram-negative bacteria (Pseudomonas spp., Serratia spp. and Enterobacter spp.) was carried out. Compounds were identified by gas chromatography-mass spectrometry. VOCs identified included dimethyl disulphide, dimethyl trisulphide...

  20. Detection of Volatile Metabolites of Garlic in Human Breast Milk.

    Science.gov (United States)

    Scheffler, Laura; Sauermann, Yvonne; Zeh, Gina; Hauf, Katharina; Heinlein, Anja; Sharapa, Constanze; Buettner, Andrea

    2016-06-06

    The odor of human breast milk after ingestion of raw garlic at food-relevant concentrations by breastfeeding mothers was investigated for the first time chemo-analytically using gas chromatography-mass spectrometry/olfactometry (GC-MS/O), as well as sensorially using a trained human sensory panel. Sensory evaluation revealed a clear garlic/cabbage-like odor that appeared in breast milk about 2.5 h after consumption of garlic. GC-MS/O analyses confirmed the occurrence of garlic-derived metabolites in breast milk, namely allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO) and allyl methyl sulfone (AMSO₂). Of these, only AMS had a garlic-like odor whereas the other two metabolites were odorless. This demonstrates that the odor change in human milk is not related to a direct transfer of garlic odorants, as is currently believed, but rather derives from a single metabolite. The formation of these metabolites is not fully understood, but AMSO and AMSO₂ are most likely formed by the oxidation of AMS in the human body. The excretion rates of these metabolites into breast milk were strongly time-dependent with large inter-individual differences.

  1. Detection of Volatile Metabolites of Garlic in Human Breast Milk

    Directory of Open Access Journals (Sweden)

    Laura Scheffler

    2016-06-01

    Full Text Available The odor of human breast milk after ingestion of raw garlic at food-relevant concentrations by breastfeeding mothers was investigated for the first time chemo-analytically using gas chromatography−mass spectrometry/olfactometry (GC-MS/O, as well as sensorially using a trained human sensory panel. Sensory evaluation revealed a clear garlic/cabbage-like odor that appeared in breast milk about 2.5 h after consumption of garlic. GC-MS/O analyses confirmed the occurrence of garlic-derived metabolites in breast milk, namely allyl methyl sulfide (AMS, allyl methyl sulfoxide (AMSO and allyl methyl sulfone (AMSO2. Of these, only AMS had a garlic-like odor whereas the other two metabolites were odorless. This demonstrates that the odor change in human milk is not related to a direct transfer of garlic odorants, as is currently believed, but rather derives from a single metabolite. The formation of these metabolites is not fully understood, but AMSO and AMSO2 are most likely formed by the oxidation of AMS in the human body. The excretion rates of these metabolites into breast milk were strongly time-dependent with large inter-individual differences.

  2. Grains colonised by moulds: fungal identification and headspace analysis of produced volatile metabolites

    Directory of Open Access Journals (Sweden)

    Maria Paola Tampieri

    2010-01-01

    Full Text Available The aim of this work was to verify if the headspace analysis of fungal volatile compounds produced by some species of Fusarium can be used as a marker of mould presence on maize. Eight samples of maize (four yellow maize from North Italy and four white maize from Hungary, naturally contaminated by Fusarium and positive for the presence of fumonisins, were analyzed to detect moisture content, Aw, volatile metabolites and an enumeration of viable moulds was performed by means of a colony count technique. Headspace samples were analysed using a gas-chromatograph equipped with a capillary column TR-WAX to detect volatile metabolites of moulds. Furthermore macro and microscopic examination of the colonies was performed in order to distinguish, according to their morphology, the genera of the prevalent present moulds. Prevalent mould of eight samples was Fusarium, but other fungi, like Aspergillus, Penicillum and Mucoraceae, were observed. The metabolites produced by F.graminearum and F. moniliforme were Isobutyl-acetate, 3-Methyl-1-butanol and, only at 8 days, 3-Octanone. The incubation time can affect off flavour production in consequence of the presence of other moulds. Further studies on maize samples under different conditions are needed in order to establish the presence of moulds using the count technique and through the identification of volatile compounds.

  3. In vitro antifungal activity of bacteria against Mycosphaerella fijiensis mediated by diffused and volatile metabolites

    Directory of Open Access Journals (Sweden)

    Mileidy Cruz-Martín

    2012-07-01

    Full Text Available Antagonistic microorganisms do not have a unique mode of action. Multiplicity of these is an important feature for selection as biological control agents. Black Sigatoka is considered the foliar disease with most economic impact for the banana industry worldwide. New strategies to control it are required to reduce the use of fungicides. That is why an increasing interest to find biological alternatives, such as the use of antagonistic bacteria, has risen. Assays wer e carr ied ou t to determine whether in v it r o ant if ungal ac ti vity of 20 bacterial str ai ns against My cosphaer ella fijiensis was caused by metabolites diffused into the culture medium or volatile. Results demonstrated that 80.0% of bacterial strains tested showed in vitro antifungal activity by diffused metabolites in the culture medium and 60.0% by producing volatile metabolites. The 55.0% of strains showed both mechanisms. This feature makes these bacteria the best candidate for its selection as biological control agent. Keywords: antagonistic, biocontrol, volatile compounds, diffused metabolites.

  4. Involvement of a volatile metabolite during phosphoramide mustard-induced ovotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Madden, Jill A. [Department of Animal Science, Iowa State University, Ames, IA 50011 (United States); Hoyer, Patricia B. [Department of Physiology, University of Arizona, Tucson, AZ 85724 (United States); Devine, Patrick J. [INRS—Institut Armand-Frappier Research Centre, University of Quebec, Laval, QC H7V 1B7 (Canada); Keating, Aileen F., E-mail: akeating@iastate.edu [Department of Animal Science, Iowa State University, Ames, IA 50011 (United States); Department of Physiology, University of Arizona, Tucson, AZ 85724 (United States)

    2014-05-15

    The finite ovarian follicle reserve can be negatively impacted by exposure to chemicals including the anti-neoplastic agent, cyclophosphamide (CPA). CPA requires bioactivation to phosphoramide mustard (PM) to elicit its therapeutic effects however; in addition to being the tumor-targeting metabolite, PM is also ovotoxic. In addition, PM can break down to a cytotoxic, volatile metabolite, chloroethylaziridine (CEZ). The aim of this study was initially to characterize PM-induced ovotoxicity in growing follicles. Using PND4 Fisher 344 rats, ovaries were cultured for 4 days before being exposed once to PM (10 or 30 μM). Following eight additional days in culture, relative to control (1% DMSO), PM had no impact on primordial, small primary or large primary follicle number, but both PM concentrations induced secondary follicle depletion (P < 0.05). Interestingly, a reduction in follicle number in the control-treated ovaries was observed. Thus, the involvement of a volatile, cytotoxic PM metabolite (VC) in PM-induced ovotoxicity was explored in cultured rat ovaries, with control ovaries physically separated from PM-treated ovaries during culture. Direct PM (60 μM) exposure destroyed all stage follicles after 4 days (P < 0.05). VC from nearby wells depleted primordial follicles after 4 days (P < 0.05), temporarily reduced secondary follicle number after 2 days, and did not impact other stage follicles at any other time point. VC was determined to spontaneously liberate from PM, which could contribute to degradation of PM during storage. Taken together, this study demonstrates that PM and VC are ovotoxicants, with different follicular targets, and that the VC may be a major player during PM-induced ovotoxicity observed in cancer survivors. - Highlights: • PM depletes all stage ovarian follicles in a temporal pattern. • A volatile ovotoxic compound is liberated from PM. • The volatile metabolite depletes primordial follicles.

  5. Highly sensitive electromembrane extraction for the determination of volatile organic compound metabolites in dried urine spot.

    Science.gov (United States)

    Suh, Joon Hyuk; Eom, Han Young; Kim, Unyong; Kim, Junghyun; Cho, Hyun-Deok; Kang, Wonjae; Kim, Da Som; Han, Sang Beom

    2015-10-16

    Electromembrane extraction coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for determination of ten volatile organic compound metabolites in dried urine spot samples. The dried urine spot approach is a convenient and economical sampling method, wherein urine is spotted onto a filter paper and dried. This method requires only a small amount of sample, but the analysis sometimes suffers from low sensitivity, which can lead to analytical problems in the detection of minor components in samples. The newly developed dried urine spot analysis using electromembrane extraction exhibited improved sensitivity and extraction, and enrichment of the sample was rapidly achieved in one step by applying an electric field. Aliquots of urine were spotted onto Bond Elut DMS cards and dried at room temperature. After drying, the punched out dried urine spot was eluted with water. Volatile organic compound metabolites were extracted from the sample through a supported liquid membrane into an alkaline acceptor solution inside the lumen of a hollow fiber with the help of an electric potential. The optimum extraction conditions were determined by using design of experiments (fractional factorial design and response surface methodology). Satisfactory sensitivity was achieved and the limits of quantification (LOQ) obtained were lower than the regulatory threshold limits. The method was validated by assessing the linearity, precision, accuracy, recovery, reproducibility, stability, and matrix effects. The results were acceptable, and the developed method was successfully applied to biological exposure monitoring of volatile organic compound metabolites in fifty human urine samples.

  6. Detection of rare species of volatile organic selenium metabolites in male golden hamster urine.

    Science.gov (United States)

    Kwak, Jae; Ohrnberger, Sarah A; Valencak, Teresa G

    2016-07-01

    Selenium has been considered as an essential trace element in mammals and its intake comes mainly from food. Mammals can metabolize both inorganic and organic species, and urinary excretion is the primary elimination route of selenium. Selenosugars and trimethylselenonium ion have been identified as major urinary metabolites. Other metabolites have been reported, but they were detected in some studies and not in others. Still, a large portion of the ingested selenium eliminated from the body is unknown. Volatile selenium species may account for a certain portion of the unknown species since they can easily be lost during sample analyses. While we analyzed male golden hamster urine in search of potential volatile pheromone(s), four volatile selenium compounds were detected. They were dimethyl selenenylsulfide, dimethyl diselenide, dimethyl bis(thio)selenide, and dimethyl selenodisulfide. When the urine samples were aged and dried for 48 h, dimethyl selenodisulfide tended to increase, while others decreased. The increase might be due to the formation of dimethyl selenodisulfide via reaction of dimethyl diselenide and dimethyl trisulfide whose concentration increased as urine aged. To our knowledge, dimethyl bis(thio)selenide and dimethyl selenodisulfide have never been demonstrated in urine. It remains to be determined whether these species are common metabolites in other animals or hamster-specific.

  7. Identification of Volatile Metabolites from Fungal Endophytes with Biocontrol Potential towards Fusarium oxysporum F. sp. cubense Race 4

    Directory of Open Access Journals (Sweden)

    A. S. Y. Ting

    2010-01-01

    Full Text Available Problem statement: Fungal endophytes are widely studied for their potential as biocontrol agents towards fungal pathogens. In vitro assessments usually reveal their antibiosis and mycoparasitism nature, but little is understood regarding their production of volatile metabolites as mechanisms of antagonism. Approach: This study explored the potential of fungal endophytes in controlling the pathogen responsible for Fusarium wilt disease. Nine fungal endophytes were tested for their ability to inhibit the growth of the pathogenic Fusarium oxysporum F. sp. cubense race 4 (FocR4 via production of volatile inhibitory metabolites. The type of volatile metabolites produced were subsequently characterized and identified using the Gas-Chromatography Mass-Spectrophotometry (GCMS. Results: Eight of the isolates (BTF05, BTF07, BTF08, BTF15, BTF21, WAA03, WAA02, MIF01 showed positive results with percentages of inhibition varying from 1.43-31.43% while one isolate (ALF01, showed negative result (0% inhibition. Volatile profiles showed that these fungal endophytes produced between 15-47 volatile metabolites per isolate. However, the more volatile metabolites produced by a single endophyte does not indicate better biocontrol potential. Isolate BTF05 produced 47 different volatile metabolites, but has only 8.57% inhibition, compared to isolate BTF21 with 15 metabolites but a percentage of 11.43% inhibition. The potency of the volatile metabolites produced may also influenced the biocontrol potential of the fungal endophytes as some isolates such as BTF08 and MIF01 have only two to three known inhibitory metabolites but have higher PIDG values at 31.43 and 11.43%, respectively. Contrary, isolates WAA02 and WAA03 which has five to six metabolites but PIDG values of less than 3%. Conclusion: Fungal endophytes have the ability to produce several types of volatile metabolites to inhibit the growth of FocR4. These volatile inhibitory metabolites can be further

  8. Application of head-space solid-phase microextraction for the analysis of volatile metabolites emitted by Penicillium species

    DEFF Research Database (Denmark)

    Nilsson, Torben; Larsen, Thomas Ostenfeld; Montanarella, Luca

    1996-01-01

    Head-space solid-phase microextraction (HS-SPME) has been used to collect volatile organic compounds (VOCs) emitted from fungi of the genus Penicillium. Gas chromatography combined with mass spectrometry (GC-MS) was employed for the analysis of the profiles of volatile metabolites characteristic ...

  9. Influence of different salting processes on the evolution of the volatile metabolites of vacuum-packed fillets of farmed and wild sea bass (Dicentrarchus labrax) stored under refrigeration conditions: a study by SPME-GC/MS.

    Science.gov (United States)

    Vidal, Natalia P; Manzanos, María J; Goicoechea, Encarnación; Guillén, María D

    2017-02-01

    Fish shelf-life extension is a topic of great interest. In this study the behaviour of salted and unsalted farmed and wild European sea bass (Dicentrarchus labrax) fillets during storage was analysed through the evolution of their volatile metabolites. Farmed and wild sea bass fillets were brine-salted for 15 or 75 min, or dry-salted, vacuum-packed and stored at 4 °C for up to 1 month, and their headspaces were studied by Solid Phase Micro extraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). At the same storage time, unsalted wild fillets contained, in general, a higher number and abundance of volatile compounds coming from microbiological or endogenous enzymatic activity than unsalted farmed ones. The more intense the salting, the lower the number and abundance of microbiological spoilage metabolites, especially in wild samples. The appearance of oxidation metabolites only in dry-salted wild samples evidences that this kind of salting provokes a certain oxidation in these samples. The better performance of farmed than wild fillets suggests that salted farmed fillets, vacuum-packed and stored under refrigeration conditions, could be a successful alternative to diversify the presence of sea bass in the market. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  10. Multi-Capillary Column-Ion Mobility Spectrometry of Volatile Metabolites Emitted by Saccharomyces Cerevisiae

    Directory of Open Access Journals (Sweden)

    Christoph Halbfeld

    2014-09-01

    Full Text Available Volatile organic compounds (VOCs produced during microbial fermentations determine the flavor of fermented food and are of interest for the production of fragrances or food additives. However, the microbial synthesis of these compounds from simple carbon sources has not been well investigated so far. Here, we analyzed the headspace over glucose minimal salt medium cultures of Saccharomyces cerevisiae using multi-capillary column-ion mobility spectrometry (MCC-IMS. The high sensitivity and fast data acquisition of the MCC-IMS enabled online analysis of the fermentation off-gas and 19 specific signals were determined. To four of these volatile compounds, we could assign the metabolites ethanol, 2-pentanone, isobutyric acid, and 2,3-hexanedione by MCC-IMS measurements of pure standards and cross validation with thermal desorption–gas chromatography-mass spectrometry measurements. Despite the huge biochemical knowledge of the biochemistry of the model organism S. cerevisiae, only the biosynthetic pathways for ethanol and isobutyric acid are fully understood, demonstrating the considerable lack of research of volatile metabolites. As monitoring of VOCs produced during microbial fermentations can give valuable insight into the metabolic state of the organism, fast and non-invasive MCC-IMS analyses provide valuable data for process control.

  11. Molecular analysis of volatile metabolites released specifically by staphylococcus aureus and pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Filipiak Wojciech

    2012-06-01

    Full Text Available Abstract Background The routinely used microbiological diagnosis of ventilator associated pneumonia (VAP is time consuming and often requires invasive methods for collection of human specimens (e.g. bronchoscopy. Therefore, it is of utmost interest to develop a non-invasive method for the early detection of bacterial infection in ventilated patients, preferably allowing the identification of the specific pathogens. The present work is an attempt to identify pathogen-derived volatile biomarkers in breath that can be used for early and non- invasive diagnosis of ventilator associated pneumonia (VAP. For this purpose, in vitro experiments with bacteria most frequently found in VAP patients, i.e. Staphylococcus aureus and Pseudomonas aeruginosa, were performed to investigate the release or consumption of volatile organic compounds (VOCs. Results Headspace samples were collected and preconcentrated on multibed sorption tubes at different time points and subsequently analyzed with gas chromatography mass spectrometry (GC-MS. As many as 32 and 37 volatile metabolites were released by S. aureus and P. aeruginosa, respectively. Distinct differences in the bacteria-specific VOC profiles were found, especially with regard to aldehydes (e.g. acetaldehyde, 3-methylbutanal, which were taken up only by P. aeruginosa but released by S. aureus. Differences in concentration profiles were also found for acids (e.g. isovaleric acid, ketones (e.g. acetoin, 2-nonanone, hydrocarbons (e.g. 2-butene, 1,10-undecadiene, alcohols (e.g. 2-methyl-1-propanol, 2-butanol, esters (e.g. ethyl formate, methyl 2-methylbutyrate, volatile sulfur compounds (VSCs, e.g. dimethylsulfide and volatile nitrogen compounds (VNCs, e.g. 3-methylpyrrole. Importantly, a significant VOC release was found already 1.5 hours after culture start, corresponding to cell numbers of ~8*106 [CFUs/ml]. Conclusions The results obtained provide strong evidence that the detection and perhaps even

  12. Detection of Volatile Metabolites Derived from Garlic (Allium sativum in Human Urine

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    Laura Scheffler

    2016-12-01

    Full Text Available The metabolism and excretion of flavor constituents of garlic, a common plant used in flavoring foods and attributed with several health benefits, in humans is not fully understood. Likewise, the physiologically active principles of garlic have not been fully clarified to date. It is possible that not only the parent compounds present in garlic but also its metabolites are responsible for the specific physiological properties of garlic, including its influence on the characteristic body odor signature of humans after garlic consumption. Accordingly, the aim of this study was to investigate potential garlic-derived metabolites in human urine. To this aim, 14 sets of urine samples were obtained from 12 volunteers, whereby each set comprised one sample that was collected prior to consumption of food-relevant concentrations of garlic, followed by five to eight subsequent samples after garlic consumption that covered a time interval of up to 26 h. The samples were analyzed chemo-analytically using gas chromatography-mass spectrometry/olfactometry (GC-MS/O, as well as sensorially by a trained human panel. The analyses revealed three different garlic-derived metabolites in urine, namely allyl methyl sulfide (AMS, allyl methyl sulfoxide (AMSO and allyl methyl sulfone (AMSO2, confirming our previous findings on human milk metabolite composition. The excretion rates of these metabolites into urine were strongly time-dependent with distinct inter-individual differences. These findings indicate that the volatile odorant fraction of garlic is heavily biotransformed in humans, opening up a window into substance circulation within the human body with potential wider ramifications in view of physiological effects of this aromatic plant that is appreciated by humans in their daily diet.

  13. Detection of Volatile Metabolites Derived from Garlic (Allium sativum) in Human Urine

    Science.gov (United States)

    Scheffler, Laura; Sauermann, Yvonne; Heinlein, Anja; Sharapa, Constanze; Buettner, Andrea

    2016-01-01

    The metabolism and excretion of flavor constituents of garlic, a common plant used in flavoring foods and attributed with several health benefits, in humans is not fully understood. Likewise, the physiologically active principles of garlic have not been fully clarified to date. It is possible that not only the parent compounds present in garlic but also its metabolites are responsible for the specific physiological properties of garlic, including its influence on the characteristic body odor signature of humans after garlic consumption. Accordingly, the aim of this study was to investigate potential garlic-derived metabolites in human urine. To this aim, 14 sets of urine samples were obtained from 12 volunteers, whereby each set comprised one sample that was collected prior to consumption of food-relevant concentrations of garlic, followed by five to eight subsequent samples after garlic consumption that covered a time interval of up to 26 h. The samples were analyzed chemo-analytically using gas chromatography-mass spectrometry/olfactometry (GC-MS/O), as well as sensorially by a trained human panel. The analyses revealed three different garlic-derived metabolites in urine, namely allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO) and allyl methyl sulfone (AMSO2), confirming our previous findings on human milk metabolite composition. The excretion rates of these metabolites into urine were strongly time-dependent with distinct inter-individual differences. These findings indicate that the volatile odorant fraction of garlic is heavily biotransformed in humans, opening up a window into substance circulation within the human body with potential wider ramifications in view of physiological effects of this aromatic plant that is appreciated by humans in their daily diet. PMID:27916960

  14. Food spoilage - interactions between food spoilage bacteria

    DEFF Research Database (Denmark)

    Gram, Lone; Flodgaard, Lars; Rasch, Maria

    2002-01-01

    the actual specific spoilage organism. Whilst the chemical and physical parameters are the main determining factors for selection of spoilage microorganisms, a level of refinement may be found in some products in which the interactive behavior of microorganisms may contribute to their growth and/or spoilage...... activity. This review gives three such examples. We describe the competitive advantage of Pseudomonas spp. due to the production of iron-chelating siderophores, the generation of substrates for spoilage reactions by one organism from another microorganism (so-called metabiosis) and the up...

  15. Fungal volatile compounds induce production of the secondary metabolite Sodorifen in Serratia plymuthica PRI-2C.

    Science.gov (United States)

    Schmidt, Ruth; Jager, Victor de; Zühlke, Daniela; Wolff, Christian; Bernhardt, Jörg; Cankar, Katarina; Beekwilder, Jules; Ijcken, Wilfred van; Sleutels, Frank; Boer, Wietse de; Riedel, Katharina; Garbeva, Paolina

    2017-04-13

    The ability of bacteria and fungi to communicate with each other is a remarkable aspect of the microbial world. It is recognized that volatile organic compounds (VOCs) act as communication signals, however the molecular responses by bacteria to fungal VOCs remain unknown. Here we perform transcriptomics and proteomics analyses of Serratia plymuthica PRI-2C exposed to VOCs emitted by the fungal pathogen Fusarium culmorum. We find that the bacterium responds to fungal VOCs with changes in gene and protein expression related to motility, signal transduction, energy metabolism, cell envelope biogenesis, and secondary metabolite production. Metabolomic analysis of the bacterium exposed to the fungal VOCs, gene cluster comparison, and heterologous co-expression of a terpene synthase and a methyltransferase revealed the production of the unusual terpene sodorifen in response to fungal VOCs. These results strongly suggest that VOCs are not only a metabolic waste but important compounds in the long-distance communication between fungi and bacteria.

  16. Contribution of volatiles to the antifungal effect of Lactobacillus paracasei in defined medium and yogurt

    DEFF Research Database (Denmark)

    Aunsbjerg, Stina Dissing; Honoré, Anders Hans; Marcussen, J.

    2015-01-01

    Lactic acid bacteria with antifungal properties can be used to control spoilage of food and feed. Previously, most of the identified metabolites have been isolated from cell-free fermentate of lactic acid bacteria with methods suboptimal for detecting possible contribution from volatiles to the a...... the contribution of diacetyl in the antifungal effect of L. paracasei DGCC 2132 and indicate that the importance of volatiles may have been previously underestimated....

  17. Volatile Metabolites Emission by In Vivo Microalgae—An Overlooked Opportunity?

    Science.gov (United States)

    Achyuthan, Komandoor E.; Harper, Jason C.; Manginell, Ronald P.; Moorman, Matthew W.

    2017-01-01

    Fragrances and malodors are ubiquitous in the environment, arising from natural and artificial processes, by the generation of volatile organic compounds (VOCs). Although VOCs constitute only a fraction of the metabolites produced by an organism, the detection of VOCs has a broad range of civilian, industrial, military, medical, and national security applications. The VOC metabolic profile of an organism has been referred to as its ‘volatilome’ (or ‘volatome’) and the study of volatilome/volatome is characterized as ‘volatilomics’, a relatively new category in the ‘omics’ arena. There is considerable literature on VOCs extracted destructively from microalgae for applications such as food, natural products chemistry, and biofuels. VOC emissions from living (in vivo) microalgae too are being increasingly appreciated as potential real-time indicators of the organism’s state of health (SoH) along with their contributions to the environment and ecology. This review summarizes VOC emissions from in vivo microalgae; tools and techniques for the collection, storage, transport, detection, and pattern analysis of VOC emissions; linking certain VOCs to biosynthetic/metabolic pathways; and the role of VOCs in microalgae growth, infochemical activities, predator-prey interactions, and general SoH. PMID:28788107

  18. Influence of mineral salts upon activity of Trichoderma harzianum non-volatile metabolites on Armillaria spp. rhizomorphs

    Directory of Open Access Journals (Sweden)

    Krystyna Przybył

    2011-01-01

    Full Text Available Effect of non-volatile metabolites of Trichoderma harzianum together with certain salts containing Mg++, Fe+++, Mn++, Cu++, Al+++, Ca++, K++, Na+, PO4--- and SO3--- on the production and length of rhizomorphs of Armillaria borealis, A. gallica and A. ostoyae was studied. In pure medium, T. harzianum exhibited stimulating effect on rhizomorphs of A. borealis (both number and length and A. ostoyae (only initiation. Cu++ salt totaly inhibited the initiation of rhizomorphs of Armillaria borealis, A. gallica and A. ostoyae. Effect of other compounds on the activity of T. harzianum depended on Armillaria species. The majority of chemical compounds tested supressed the activity of non-volatile metabolites of T. harzianum. Evident stimulating effect was observed under influence of sulphate salts consisting Al++ and Fe+++ on the rhizomorph number of A. borealis and A. gallica, respectively.

  19. Influence of carbon and nitrogen source on production of volatile fragrance and flavour metabolites by the yeast Kluyveromyces marxianus.

    Science.gov (United States)

    Gethins, Loughlin; Guneser, Onur; Demirkol, Aslı; Rea, Mary C; Stanton, Catherine; Ross, R Paul; Yuceer, Yonca; Morrissey, John P

    2015-01-01

    The yeast Kluyveromyces marxianus produces a range of volatile molecules with applications as fragrances or flavours. The purpose of this study was to establish how nutritional conditions influence the production of these metabolites. Four strains were grown on synthetic media, using a variety of carbon and nitrogen sources and volatile metabolites analysed using gas chromatography-mass spectrometry (GC-MS). The nitrogen source had pronounced effects on metabolite production: levels of the fusel alcohols 2-phenylethanol and isoamyl alcohol were highest when yeast extract was the nitrogen source, and ammonium had a strong repressing effect on production of 2-phenylethyl acetate. In contrast, the nitrogen source did not affect production of isoamyl acetate or ethyl acetate, indicating that more than one alcohol acetyl transferase activity is present in K. marxianus. Production of all acetate esters was low when cells were growing on lactose (as opposed to glucose or fructose), with a lower intracellular pool of acetyl CoA being one explanation for this observation. Bioinformatic and phylogenetic analysis of the known yeast alcohol acetyl transferases ATF1 and ATF2 suggests that the ancestral protein Atf2p may not be involved in synthesis of volatile acetate esters in K. marxianus, and raises interesting questions as to what other genes encode this activity in non-Saccharomyces yeasts. Identification of all the genes involved in ester synthesis will be important for development of the K. marxianus platform for flavour and fragrance production.

  20. Dynamic headspace analysis of volatile metabolites from the reductive dehalogenation of trichloro- and tetrachloroethanes by hepatic microsomes.

    Science.gov (United States)

    Thompson, J A; Ho, B; Mastovich, S L

    1985-03-01

    A dynamic headspace technique was developed to facilitate the identification and quantitation of low levels of volatile metabolites produced in vitro by subcellular preparations. The method is complementary to commonly used static headspace and solvent-extraction techniques, and involves purging the compounds from microsomal suspensions with an inert gas, trapping them on a short column of adsorbant resin, and transferring the metabolites to a gas chromatograph. An apparatus was designed to facilitate the incubations and isolations of volatile compounds. Recoveries of several chlorinated hydrocarbons with boiling points in the range 12 to 186 degrees C were 85% or higher, and the recovery of vinyl chloride (boiling point -13 degrees C) was 25%. The quantitative precision of the method was determined and calibration curves were established for each metabolite, demonstrating that no discrimination occurred over a wide range of concentrations. This technique was employed to investigate the reductive metabolism of 1,1,1-trichloroethane, 1,1,2-trichloroethane, and 1,1,2,2-tetrachloroethane by rat liver microsomes. The metabolites from these substrates were 1,1-dichloroethane, vinyl chloride, and 1,2-dichloroethylene, respectively. These conversions were NADPH-dependent, occurred only under anaerobic conditions, and indicate that chloroethanes with relatively low electron affinities can be reduced slowly by microsomal cytochrome P-450. The rates of formation of vinyl chloride, 1,1-dichloroethane, and 1,2-dichloroethylene with 1.0 mM substrate were 12.5 +/- 2.0, 122 +/- 14, and 147 +/- 12 pmol/min/mg of protein, respectively. The results show that there are distinct advantages of the purge/trap method over the static headspace method for studying volatile metabolites when high sensitivity is required.

  1. 2-Aminoacetophenone Is the Main Volatile Phase I Skatole Metabolite in Pietrain × Baden-Württemberg Hybrid Type Boars.

    Science.gov (United States)

    Gerlach, Christoph; Elsinghorst, Paul W; Schmarr, Hans-Georg; Wüst, Matthias

    2016-02-10

    Skatole metabolites have been considered as putative contributors to boar taint. Recently, 2-aminoacetophenone, a volatile phase I skatole metabolite, was identified in back fat samples from boars of Pietrain × Baden-Württemberg hybrid type. This paper addresses the question of the physiological origin of the observed 2-aminoacetophenone in these pigs. Microsomal fractions from nine boars were isolated, and formation of skatole metabolites was subsequently analyzed by stable-isotope dilution analysis (SIDA) using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS). Significant breed-related differences in phase I skatole metabolism were observed, explaining the high levels of 2-aminoacetophenone in Pietrain × Baden-Württemberg hybrid type boars.

  2. Simultaneous determination of six mercapturic acid metabolites of volatile organic compounds in human urine.

    Science.gov (United States)

    Ding, Yan S; Blount, Benjamin C; Valentin-Blasini, Liza; Applewhite, Heather S; Xia, Yang; Watson, Clifford H; Ashley, David L

    2009-06-01

    The widespread exposure to potentially harmful volatile organic compounds (VOCs) merits the development of practical and accurate exposure assessment methods. Measuring the urinary concentrations of VOC mercapturic acid (MA) metabolites provides noninvasive and selective information about recent exposure to certain VOCs. We developed a liquid chromatography-tandem mass spectrometry method for quantifying urinary levels of six MAs: N-acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA), N-acetyl-S-(3-hydroxypropyl)-L-cysteine (HPMA), N-acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine (MHBMA), N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), N-acetyl-S-(2-hydroxyethyl)-L-cysteine (HEMA), and N-acetyl-S-(phenyl)-L-cysteine (PMA). The method provides good accuracy (102% mean accuracy) and high precision (3.5% mean precision). The sensitivity (limits of detection of 0.01-0.20 microg/L) and wide dynamic detection range (0.025-500 microg/L) make this method suitable for assessing VOC exposure of minimally exposed populations and those with significant exposures, such as cigarette smokers. We used this method to quantify MA levels in urine collected from smokers and nonsmokers. Median levels of creatinine-corrected CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA among nonsmokers (n = 59) were 38.1, 24.3, 21.3, 104.7, 0.9, and 0.5 microg/g creatinine, respectively. Among smokers (n = 61), median levels of CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA were 214.4, 839.7, 10.2, 509.7, 2.2, and 0.9 microg/g creatinine, respectively. All VOC MAs measured were higher among smokers than among nonsmokers, with the exception of MHBMA.

  3. Meat spoilage during distribution.

    Science.gov (United States)

    Nychas, George-John E; Skandamis, Panos N; Tassou, Chrysoula C; Koutsoumanis, Konstantinos P

    2008-01-01

    Meat spoilage during distribution can be considered as an ecological phenomenon that encompasses the changes of the available substrata (e.g., low molecular compounds), during the prevailing of a particular microbial association, the so-called specific spoilage organisms (SSO). In fact, spoilage of meat depends on an even smaller fraction of SSO, called ephemeral spoilage organisms (ESO). These ESO are the consequence of factors that dynamically persist or imposed during, e.g., processing, transportation and storage in the market. Meanwhile spoilage is a subjective judgment by the consumer, which may be influenced by cultural and economic considerations and background as well as by the sensory acuity of the individual and the intensity of the change. Indeed, when spoilage progresses, most consumers would agree that gross discoloration, strong off-odors, and the development of slime would constitute the main qualitative criteria for meat rejection. On the other hand, meat industry needs rapid analytical methods or tools for quantification of these indicators to determine the type of processing needed for their raw material and to predict remaining shelf life of their products. The need of an objective evaluation of meat spoilage is of great importance. The use of metabolomics as a potential tool for the evaluation of meat spoilage can be of great importance. The microbial association of meat should be monitored in parallel with the estimation of changes occurring in the production and/or assimilation of certain compounds would allow us to evaluate spoilage found or produced during the storage of meat under different temperatures as well as packaging conditions.

  4. Target identification of volatile metabolites to allow the differentiation of lactic acid bacteria by gas chromatography-ion mobility spectrometry.

    Science.gov (United States)

    Gallegos, Janneth; Arce, Cristina; Jordano, Rafael; Arce, Lourdes; Medina, Luis M

    2017-04-01

    The purpose of this work was to study the potential of gas chromatography-ion mobility spectrometry (GC-IMS) to differentiate lactic acid bacteria (LAB) through target identification and fingerprints of volatile metabolites. The LAB selected were used as reference strains for their influence in the flavour of cheese. The four strains of LAB can be distinguished by the fingerprints generated by the volatile organic compounds (VOCs) emitted. 2-butanone, 2-pentanone, 2-heptanone and 3-methyl-1-butanol were identified as relevant VOCs for Lactobacillus casei and Lactobacillus paracasei subsp. paracasei. 2-Butanone and 3-methyl-1-butanol were identified in Lactococcus lactis subsp. lactis and Lactococcus cremoris subsp. cremoris. The IMS signals monitoring during a 24-30h period showed the growth of the LAB in vitro. The results demonstrated that GC-IMS is a useful technology for bacteria recognition and also for screening the aromatic potential of new isolates of LAB.

  5. Real time monitoring of population dynamics in concurrent bacterial growth using SIFT-MS quantification of volatile metabolites.

    Science.gov (United States)

    Sovová, Kristýna; Čepl, Jaroslav; Markoš, Anton; Španěl, Patrik

    2013-09-07

    Population dynamics of three different bacterial species, Serratia rubidaea (R), Serratia marcescens (F) and Escherichia coli (Ec), growing in single or mixed populations in liquid media, was monitored by real time headspace quantification of volatile compounds using selected ion flow tube mass spectrometry, SIFT-MS. The three bacterial species interact with each other in a competitive fashion in a way similar to the game "rock-paper-scissors" (R-Ec-F). The concentrations of volatile metabolites (ammonia, ethanol, acetaldehyde, propanol, acetoin, acetone and acetic acid) were measured in the headspace of the individual species and of their mixtures continuously for 24 hour periods. The results demonstrate that dynamics in bacterial cultures can be monitored using SIFT-MS in real time.

  6. Investigation of spoilage in saveloy samples inoculated with four potential spoilage bacteria

    DEFF Research Database (Denmark)

    Holm, Esben Skibsted; Schäfer, A.; Koch, A.G.

    2013-01-01

    Sliced saveloy samples were inoculated with monocultures of four potential spoilage bacteria and studied during a four week storage period. The objective was to investigate the resulting changes in the composition of Volatile Organic Compounds (VOCs) and the sensory quality of the product. Based...... on the sensory scores and the VOC composition Brochothrix thermosphacta, Chryseomonas luteola and Carnobacterium maltaromaticum were found to have a high spoilage potential in saveloy samples subjected to consumer simulated storage during the fourth week. Inoculation with Leuconostoc carnosum only resulted...... in a low level of spoilage. The sensory changes in the saveloy samples were modeled based on the VOC composition using Partial Least Squares Regression. The changes in the six sensory descriptors were closely related to the amount of diacetyl, acetoin, 2- and 3-methylbutanol, 2- and 3-methylbutanal and 2...

  7. Spoilage of light (PSE-like) and dark turkey meat under aerobic or modified atmosphere package: microbial indicators and their relationship with total volatile basic nitrogen

    OpenAIRE

    Fraqueza, Maria João Ramos; Ferreira, Marilia Catarina; Barreto, António Salvador

    2008-01-01

    Abstract 1. The aim of this work was to evaluate the shelf life of turkey meat from different colour categories (light (PSE-like), intermediate and dark), packaged under aerobic or modified atmosphere (MAP) conditions; also to establish a relationship between microbial quality and total volatile basic nitrogen (TVB-N), evaluating its capacity for shelf life determination. Breasts were selected according to Luminance (L*) and pH24: L ? 51 and pH < 5.8 for light colour, 43 < L < 51 f...

  8. Gene-Metabolite Networks of Volatile Metabolism in Airen and Tempranillo Grape Cultivars Revealed a Distinct Mechanism of Aroma Bouquet Production

    Science.gov (United States)

    Rambla, José L.; Trapero-Mozos, Almudena; Diretto, Gianfranco; Rubio-Moraga, Angela; Granell, Antonio; Gómez-Gómez, Lourdes; Ahrazem, Oussama

    2016-01-01

    Volatile compounds are the major determinants of aroma and flavor in both grapes and wine. In this study, we investigated the emission of volatile and non-volatile compounds during berry maturation in two grape varieties (Airén and Tempranillo) throughout 2010 and 2011. HS-SPME coupled to gas chromatography and mass spectrometry was applied for the identification and relative quantitation of these compounds. Principal component analysis was performed to search for variability between the two cultivars and evolution during 10 developmental stages. Results showed that there are distinct differences in volatile compounds between cultivars throughout fruit development. Early stages were characterized in both cultivars by higher levels of some apocarotenoids such as β-cyclocitral or β-ionone, terpenoids (E)-linalool oxide and (Z)-linalool oxide and several furans, while the final stages were characterized by the highest amounts of ethanol, benzenoid phenylacetaldehyde and 2-phenylethanol, branched-amino acid-derived 3-methylbutanol and 2-methylbutanol, and a large number of lipid derivatives. Additionally, we measured the levels of the different classes of volatile precursors by using liquid chromatography coupled to high resolution mass spectrometry. In both varieties, higher levels of carotenoid compounds were detected in the earlier stages, zeaxanthin and α-carotene were only detected in Airén while neoxanthin was found only in Tempranillo; more variable trends were observed in the case of the other volatile precursors. Furthermore, we monitored the expression of homolog genes of a set of transcripts potentially involved in the biosynthesis of these metabolites, such as some glycosyl hydrolases family 1, lipoxygenases, alcohol dehydrogenases hydroperoxide lyases, O-methyltransferases and carotenoid cleavage dioxygenases during the defined developmental stages. Finally, based on Pearson correlation analyses, we explored the metabolite-metabolite fluctuations

  9. Evaluation of volatile metabolites as markers in Lycopersicon esculentum L. cultivars discrimination by multivariate analysis of headspace solid phase microextraction and mass spectrometry data.

    Science.gov (United States)

    Figueira, José; Câmara, Hugo; Pereira, Jorge; Câmara, José S

    2014-02-15

    To gain insights on the effects of cultivar on the volatile metabolomic expression of different tomato (Lycopersicon esculentum L.) cultivars--Plum, Campari, Grape, Cherry and Regional, cultivated under similar edafoclimatic conditions, and to identify the most discriminate volatile marker metabolites related to the cultivar, the chromatographic profiles resulting from headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-qMS) analysis, combined with multivariate analysis were investigated. The data set composed by the 77 volatile metabolites identified in the target tomato cultivars, 5 of which (2,2,6-trimethylcyclohexanone, 2-methyl-6-methyleneoctan-2-ol, 4-octadecyl-morpholine, (Z)-methyl-3-hexenoate and 3-octanone) are reported for the first time in tomato volatile metabolomic composition, was evaluated by chemometrics. Firstly, principal component analysis was carried out in order to visualise data trends and clusters, and then, linear discriminant analysis in order to detect the set of volatile metabolites able to differentiate groups according to tomato cultivars. The results obtained revealed a perfect discrimination between the different Lycopersicon esculentum L. cultivars considered. The assignment success rate was 100% in classification and 80% in prediction ability by using "leave-one-out" cross-validation procedure. The volatile profile was able to differentiate all five cultivars and revealed complex interactions between them including the participation in the same biosynthetic pathway. The volatile metabolomic platform for tomato samples obtained by HS-SPME/GC-qMS here described, and the interrelationship detected among the volatile metabolites can be used as a roadmap for biotechnological applications, namely to improve tomato aroma and their acceptance in the final consumer, and for traceability studies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Moulds in food spoilage

    DEFF Research Database (Denmark)

    Filtenborg, Ole; Frisvad, Jens Christian; Thrane, Ulf

    1996-01-01

    There is an increasing knowledge and understanding of the role played by moulds in food spoilage. Especially the discovery of mycotoxin production in foods has highligh-ted the importance of moulds in food quality. It is, however, only within the last 5-10 years that major progresses have been made...... towards the prevention of spoilage caused by moulds. This is due to recent international agreements on taxonomy and analytical methods for foodborne moulds, which has led to the discovery, that a specific, very limited funga (=mycobiota) is responsible for the spoilage of each kind of food. This is called...... the associated or critical funga and has been shown to consist of less than 10 species. In this paper the associated funga is described for the following foods: Citrus and pomaceous fruits, potato and yam tubers, onions, rye, wheat, rye bread, cheese and fermented sausages and whenever possible the selective...

  11. Multi-Capillary Column-Ion Mobility Spectrometry of Volatile Metabolites Emitted by Saccharomyces Cerevisiae

    OpenAIRE

    Christoph Halbfeld; Ebert, Birgitta E.; Blank, Lars M.

    2014-01-01

    Volatile organic compounds (VOCs) produced during microbial fermentations determine the flavor of fermented food and are of interest for the production of fragrances or food additives. However, the microbial synthesis of these compounds from simple carbon sources has not been well investigated so far. Here, we analyzed the headspace over glucose minimal salt medium cultures of Saccharomyces cerevisiae using multi-capillary column-ion mobility spectrometry (MCC-IMS). The high sensitivity and f...

  12. Spoilage fungi and their mycotoxins in commercially marketed chestnuts

    DEFF Research Database (Denmark)

    Overy, David Patrick; Seifert, K.A.; Savard, M.E.

    2003-01-01

    A nationwide survey was carried out to assess mould spoilage of Castanea sativa nuts sold in Canadian grocery stores in 1998-99. Morphological and cultural characters, along with secondary metabolite profiles derived from thin-layer chromatography, were used to sort and identify fungi cultured fr...

  13. Detection of volatile metabolites of moulds isolated from a contaminated library.

    Science.gov (United States)

    Micheluz, Anna; Manente, Sabrina; Rovea, Manuela; Slanzi, Debora; Varese, Giovanna Cristina; Ravagnan, Giampietro; Formenton, Gianmaria

    2016-09-01

    The principal fungal species isolated from a contaminated library environment were tested for their microbial volatile organic compound (MVOC) production ability. Aspergillus creber, A. penicillioides, Cladosporium cladosporioides, Eurotium chevalieri, E. halophilicum, Penicillium brevicompactum and P. chrysogenum were cultivated on suitable culture media inside sample bottles specifically designed and created for direct MVOC injection to a GC-MS instrument. The fungal emissions were monitored over several weeks to detect changes with the aging of the colonies, monitored also by respirometric tests. A total of 55 different MVOCs were detected and isopropyl alcohol, 3-methyl-1-butanol and 2-butanone were the principal compounds in common between the selected fungal species. Moreover, 2,4-dimethylheptane, 1,4-pentadiene, styrene, ethanol, 2-methyl-1-butanol, acetone, furan and 2-methylfuran were the most detected compounds. For the first time, the MVOC production for particular fungal species was detected. The species A. creber, which belongs to the recently revised group Aspergillus section Versicolores, was characterized by the production of ethanol, furan and 1,4-pentadiene. For the xerophilic fungus E. halophilicum, specific production of acetone, 2-butanone and 1,4-pentadiene was detected, supported also by respirometric data. The results demonstrated the potential use of this method for the detection of fungal contamination phenomena inside Cultural Heritage's preservation environments. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Volatile metabolites produced from agro-industrial wastes by Na-alginate entrapped Kluyveromyces marxianus

    Directory of Open Access Journals (Sweden)

    Onur Güneşer

    Full Text Available Abstract The aim of this study was to evaluate the effects of alginate entrapment on fermentation metabolites of Kluyveromyces marxianus grown in agrowastes that served as the liquid culture media. K. marxianus cells entrapped in Na-alginate were prepared using the traditional liquid-droplet-forming method. Whey and pomaces from processed tomatoes, peppers, and grapes were used as the culture media. The changes in the concentrations of sugar, alcohol, organic acids, and flavor compounds were analyzed using gas chromatography-mass spectrometry (GC-MS and high pressure liquid chromatography (HPLC. Both free and entrapped, K. marxianus were used individually to metabolize sugars, organic acids, alcohols, and flavor compounds in the tomato, pepper, grape, and acid whey based media. Marked changes in the fermentation behaviors of entrapped and free K. marxianus were observed in each culture. A 1.45-log increase was observed in the cell numbers of free K. marxianus during fermentation. On the contrary, the cell numbers of entrapped K. marxianus remained the same. Both free and entrapped K. marxianus brought about the fermentation of sugars such as glucose, fructose, and lactose in the agrowaste cultures. The highest volume of ethanol was produced by K. marxianus in the whey based media. The concentrations of flavor compounds such as ethyl acetate, isoamyl alcohol, isoamyl acetate, 2-phenylethyl isobutyrate, phenylethyl acetate, and phenylethyl alcohol were higher in fermented agrowaste based media compared to the control.

  15. Analysis of Volatile Metabolites Released by Staphylococcus Aureus using Gas Chromatography-Mass Spectrometry and Determination of its Antifungal Activity

    Directory of Open Access Journals (Sweden)

    Hayfaa Hussein Jaddoa

    2016-08-01

    Full Text Available Bacterial volatile organic compounds (VOCs have been considered as sensitive and specific biomarkers for bacterial detection in human specimens and culture media. The possibility of using VOCs markers as one of the largest groups of bacterial metabolites would open a new frontier for developing more efficient techniques in the diagnosis of bacterial infections. The aims of this research were analysis of the bioactive chemical products and evaluation of antibacterial and antifungal activity. Bioactives (chemical compounds often referred to as secondary metabolites were analyzed using gas chromatography-mass spectroscopy (GC-MS techniques, then the in vitro antibacterial and antifungal activity of the methanolic extract was evaluated. Thirty five bioactive compounds were identified in the methanolic extract of Staphylococcus aureus. GC-MS analysis of Staphylococcus aureus revealed the existence of the: Hexanoic acid , 2-methyl, 12,15-Octadecadiynoic acid , methyl ester, 1-Aminononadecane ,N-trifluoroacetyl-, N-[3-[N-Aziridyl]propylidene]hexylamine, N-(2,5-Dicyano-3,4-dihydro-2H-pyrrol-2-yl-acetamide, 3-Cyclohex-3-enyl-propionic acid, 1-Methyl-4-[nitromethyl]-4-piperidinol, 3-Azonia-5-hexyn-1-ol , N,N-dimethyl-O-acetyl-,bromide, 1-Hexadecanol -2-methyl-, 1-Propyl-3,6-diazahomoadamantan, 9-Borabicyclo[3.3.1]nonane , 9-mercapto-, Benzyl methyl ketone, L-Aspartic acid ,N-glycyl-, Aminoacetamide , N-methyl-N-[4-(1-pyrrolidinyl-2-butynyl]-, Tertbutyloxyformamide , N-methyl-N-[4-(1-pyrrolidinyl-2-butyn, 5,7-Dodecadiyn-1,12-diol, Deoxyspergualin, D-Streptamine , O-6-deoxy-α-D-glucopyranosyl-(1-4, dl-Citrulline, N-[3-Diethylaminopropyl]-4-oxo-1,2,3,4,5,6,7,8-octahydroqui, N-Propionyl-D-glucoseamine, Cystine, 3,4-Dihydrocoumarin ,6-fluoro-4,4-dimethyl-, 4-(2,5-Dihydro-3-methoxyphenylbutylamine, 3-methoxy-2-(1-methylethyl-5-(2-methylpropylpyrazine, Uric acid, Thiocyanic acid 4-methoxy-2,6-dimethyl-3-pyridyl ester, 12-Dimethylamino-10-oxododecanoic acid

  16. Spoilage of lightly salted lumpfish (Cyclopterus lumpus) roe at 5°C

    DEFF Research Database (Denmark)

    Basby, Merethe; Jeppesen, V.F.; Huss, Hans Henrik

    1998-01-01

    sulphury, sour odors. The microflora consisted of lactic acid bacteria, Enterobacteriaceae and Vibrio spp. Concentration of lactic acid, acetic acid, trimethylamine and total volatile bases were unrelated to spoilage odors. Volatile sulfur compounds (H2S, probably CS2, CH3SH and CH3CH2SH or CH3SCH3...

  17. Effects of feeding metabolite combinations produced by Lactobacillus plantarum on growth performance, faecal microbial population, small intestine villus height and faecal volatile fatty acids in broilers.

    Science.gov (United States)

    Thanh, N T; Loh, T C; Foo, H L; Hair-Bejo, M; Azhar, B K

    2009-05-01

    1. Four combinations of metabolites produced from strains of Lactobacillus plantarum were used to study the performance of broiler chickens. 2. A total of 432 male Ross broilers were raised from one-day-old to 42 d of age in deep litter pens (12 birds/pen). These birds were divided into 6 groups and fed on different diets: (i) standard maize-soybean-based diet (negative control); (ii) standard maize-soybean-based diet + Neomycin and Oxytetracycline (positive control); (iii) standard maize-soybean-based diet + 0.3% metabolite combination of Lactobacillus plantarum RS5, RI11, RG14 and RG11 strains (com3456); (iv) standard maize-soybean-based diet + 0.3% metabolite combination of L. plantarum TL1, RI11 and RG11 (Com246); (v) standard maize-soybean-based diet + 0.3% metabolite combination of L. plantarum TL1, RG14 and RG11 (Com256) and (vi) standard maize-soybean-based diet + 0.3% metabolite combination of L. plantarum TL1, RS5, RG14 and RG11 (Com2356). 3. Higher final body weight, weight gain, average daily gain and lower feed conversion ratio were found in all 4 treated groups. 4. The addition of a metabolite combination supplementation also increased faecal lactic acid bacteria population, small intestine villus height and faecal volatile fatty acids and faecal Enterobacteriaceae population.

  18. Effectiveness of different solid-phase microextraction fibres for differentiation of selected Madeira island fruits based on their volatile metabolite profile--identification of novel compounds.

    Science.gov (United States)

    Pereira, João; Pereira, Jorge; Câmara, José S

    2011-01-15

    A headspace solid-phase microextraction (HS-SPME) procedure based on five commercialised fibres (85 μm polyacrylate - PA, 100 μm polydimethylsiloxane - PDMS, 65 μm polydimethylsiloxane/divinylbenzene - PDMS/DVB, 70 μm carbowax/divinylbenzene - CW/DVB and 85 μm carboxen/polydimethylsiloxane - CAR/PDMS) is presented for the characterization of the volatile metabolite profile of four selected Madeira island fruit species, lemon (Citrus limon), kiwi (Actinidia deliciosa), papaya (Carica papaya L.) and Chickasaw plum (Prunus angustifolia). The isolation of metabolites was followed by thermal desorption gas chromatography-quadrupole mass spectrometry (GC-qMS) methodology. The performance of the target fibres was evaluated and compared. The SPME fibre coated with CW/DVB afforded the highest extraction efficiency in kiwi and papaya pulps, while in lemon and plum the same was achieved with PMDS/DVB fibre. This procedure allowed for the identification of 80 compounds, 41 in kiwi, 24 in plums, 23 in papaya and 20 in lemon. Considering the best extraction conditions, the most abundant volatiles identified in kiwi were the intense aldehydes and ethyl esters such as (E)-2-hexenal and ethyl butyrate, while in Chicasaw plum predominate 2-hexenal, 2-methyl-4-pentenal, hexanal, (Z)-3-hexenol and cyclohexylene oxide. The major compounds identified in the papaya pulp were benzyl isothiocyanate, linalool oxide, furfural, hydroxypropanone, linalool and acetic acid. Finally, lemon was shown to be the most divergent of the four fruits, being its aroma profile composed almost exclusively by terpens, namely limonene, γ-terpinene, o-cymene and α-terpinolene. Thirty two volatiles were identified for the first time in the fruit or close related species analysed and 14 volatiles are reported as novel volatile metabolites in fruits. This includes 5 new compounds in kiwi (2-cyclohexene-1,4-dione, furyl hydroxymethyl ketone, 4-hydroxydihydro-2(3H)-furanone, 5-acetoxymethyl-2-furaldehyde and

  19. Lactic acid bacteria and their controversial role in fresh meat spoilage.

    Science.gov (United States)

    Pothakos, Vasileios; Devlieghere, Frank; Villani, Francesco; Björkroth, Johanna; Ercolini, Danilo

    2015-11-01

    Lactic acid bacteria (LAB) constitute a heterogeneous group that has been widely associated with fresh meat and cooked meat products. They represent a controversial cohort of microbial species that either contribute to spoilage through generation of offensive metabolites and the subsequent organoleptic downgrading of meat or serve as bioprotective agents with strains of certain species causing unperceivable or no alterations. Therefore, significant distinction among biotypes is substantiated by studies determining spoilage potential as a strain-specific trait corroborating the need to revisit the concept of spoilage.

  20. Microbiological Spoilage of Cereal Products

    Science.gov (United States)

    Cook, Frederick K.; Johnson, Billie L.

    A wide range of cereal products, including bakery items, refrigerated dough, fresh pasta products, dried cereal products, snack foods, and bakery mixes, are manufactured for food consumption. These products are subject to physical, chemical, and microbiological spoilage that affects the taste, aroma, leavening, appearance, and overall quality of the end consumer product. Microorganisms are ubiquitous in nature and have the potential for causing food spoilage and foodborne disease. However, compared to other categories of food products, bakery products rarely cause food poisoning. The heat that is applied during baking or frying usually eliminates pathogenic and spoilage microorganisms, and low moisture contributes to product stability. Nevertheless, microbiological spoilage of these products occurs, resulting in substantial economic losses.

  1. Metabolite profiling of the ripening of Mangoes Mangifera indica L. cv. 'Tommy Atkins' by real-time measurement of volatile organic compounds.

    Science.gov (United States)

    White, Iain R; Blake, Robert S; Taylor, Andrew J; Monks, Paul S

    Real-time profiling of mango ripening based on proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) of small molecular weight volatile organic compounds (VOCs), is demonstrated using headspace measurements of 'Tommy Atkins' mangoes. VOC metabolites produced during the ripening process were sampled directly, which enabled simultaneous and rapid detection of a wide range of compounds. Headspace measurements of 'Keitt' mangoes were also conducted for comparison. A principle component analysis of the results indicated that several mass channels were not only key to the ripening process but could also be used to distinguish between mango cultivars. The identities of 22 of these channels, tentatively speciated using contemporaneous GC-MS measurements of sorbent tubes, are rationalized through examination of the biochemical pathways that produce volatile flavour components. Results are discussed with relevance to the potential of headspace analysers and electronic noses in future fruit ripening and quality studies.

  2. Plant volatiles.

    Science.gov (United States)

    Baldwin, Ian T

    2010-05-11

    Plant volatiles are the metabolites that plants release into the air. The quantities released are not trivial. Almost one-fifth of the atmospheric CO2 fixed by land plants is released back into the air each day as volatiles. Plants are champion synthetic chemists; they take advantage of their anabolic prowess to produce volatiles, which they use to protect themselves against biotic and abiotic stresses and to provide information - and potentially disinformation - to mutualists and competitors alike. As transferors of information, volatiles have provided plants with solutions to the challenges associated with being rooted in the ground and immobile.

  3. Volatile metabolites associated with one aflatoxigenic and one nontoxigenic Aspergillus flavus strain grown on two different substrates

    Directory of Open Access Journals (Sweden)

    Z. Jurjevic

    2009-01-01

    Full Text Available Aflatoxigenic and non-toxigenic Aspergillus flavus strains were grown on corn and on peanut substrates. Microbial volatile organic compounds (MVOCS were collected by trapping headspace volatiles using thermal desorption tubes (TDT packed with Tenax® TA and Carbotrap™ B. Samples were collected at various fungal growth stages. Trapped compounds were thermally desorbed from the adsorbent tubes, separated by gas chromatography, and identified by mass spectrometry. The fungal stage did not have many differences in the MVOCs but the concentrations of some volatiles changed over time depending on the substrate. Volatiles that were associated with both the aflatoxigenic A. flavus strain and the nontoxigenic strain on both substrates included: ethanol, 1-propanol, butanal, 2-methyl-1-propanol, 3-methylfuran, ethyl acetate, 1-butanol, 3-methylbutanal, 3-methyl-1-butanol, propanoic acid-2-methyl-ethyl-ester, 2-methyl-1-butanol, 1-pentanol, 2-pentanol, 3-methyl-3-buten-1-ol, benzaldehyde, 3-octanone, 2-ethyl-1-hexanol and octane. Volatiles that were associated only with the aflatoxigenic A. flavus strain included: dimethyl disulfide and nonanal. Volatiles that were associated only with the nontoxigenic A. fl avus strain included: hexanal, 1-hexanol, 1-octene-3-ol, 1-octen-3-one and 2-pentyl furan.

  4. Fish spoilage bacteria - problems and solutions

    DEFF Research Database (Denmark)

    Gram, Lone; Dalgaard, Paw

    2002-01-01

    Microorganisms are the major cause of spoilage of most seafood products. However, only a few members of the microbial community, the specific spoilage organisms (SSOs), give rise to the offensive off-flavours associated with seafood spoilage. Combining microbial ecology, molecular techniques, ana...

  5. Urinary metabolites of a polycyclic aromatic hydrocarbon and volatile organic compounds in relation to lung cancer development in lifelong never smokers in the Shanghai Cohort Study.

    Science.gov (United States)

    Yuan, Jian-Min; Butler, Lesley M; Gao, Yu-Tang; Murphy, Sharon E; Carmella, Steven G; Wang, Renwei; Nelson, Heather H; Hecht, Stephen S

    2014-02-01

    Exposures to polycyclic aromatic hydrocarbons (PAHs) from various environmental and occupational sources are considered a primary risk factor for lung cancer among lifelong never smokers, based largely on results from epidemiologic studies utilizing self-reported exposure information. Prospective, biomarker-based human studies on the role of PAH and other airborne carcinogens in the development of lung cancer among lifelong non-smokers have been lacking. We prospectively investigated levels of urinary metabolites of a PAH and volatile organic compounds in relation to lung cancer risk in a nested case-control study of 82 cases and 83 controls among lifelong never smokers of the Shanghai Cohort Study, a prospective cohort of 18 244 Chinese men aged 45-64 years at enrollment. We quantified three PAH metabolites: r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene (PheT), 3-hydroxyphenanthrene (3-OH-Phe) and total hydroxyphenanthrenes (total OH-Phe, the sum of 1-, 2-, 3- and 4-OH-Phe), as well as metabolites of the volatile organic compounds acrolein (3-hydroxypropyl mercapturic acid), benzene (S-phenyl mercapturic acid), crotonaldehyde (3-hydroxy-1-methylpropylmercapturic acid) and ethylene oxide (2-hydroxyethyl mercapturic acid). Urinary cotinine was also quantified to confirm non-smoking status. Compared with the lowest quartile, odds ratios (95% confidence intervals) for lung cancer risk for the highest quartile levels of PheT, 3-OH-Phe and total OH-Phe were 2.98 (1.13-7.87), 3.10 (1.12-7.75) and 2.59 (1.01-6.65) (all P trend risk. This study demonstrates a potentially important role of exposure to PAH in the development of lung cancer among lifelong never smokers.

  6. Development of urine standard reference materials for metabolites of organic chemicals including polycyclic aromatic hydrocarbons, phthalates, phenols, parabens, and volatile organic compounds

    Science.gov (United States)

    Schantz, Michele M.; Benner, Bruce A.; Heckert, N. Alan; Sander, Lane C.; Sharpless, Katherine E.; Vander Pol, Stacy S.; Vasquez, Y.; Villegas, M.; Wise, Stephen A.; Alwis, K. Udeni; Blount, Benjamin C.; Calafat, Antonia M.; Li, Zheng; Silva, Manori J.; Ye, Xiaoyun; Gaudreau, Éric; Patterson, Donald G.; Sjödin, Andreas

    2016-01-01

    Two new Standard Reference Materials (SRMs), SRM 3672 Organic Contaminants in Smokers’ Urine (Frozen) and SRM 3673 Organic Contaminants in Non-Smokers’ Urine (Frozen), have been developed in support of studies for assessment of human exposure to select organic environmental contaminants. Collaborations among three organizations resulted in certified values for 11 hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and reference values for 11 phthalate metabolites, 8 environmental phenols and parabens, and 24 volatile organic compound (VOC) metabolites. Reference values are also available for creatinine and the free forms of caffeine, theobromine, ibuprofen, nicotine, cotinine, and 3-hydroxycotinine. These are the first urine Certified Reference Materials characterized for metabolites of organic environmental contaminants. Noteworthy, the mass fractions of the environmental organic contaminants in the two SRMs are within the ranges reported in population survey studies such as the National Health and Nutrition Examination Survey (NHANES) and the Canadian Health Measures Survey (CHMS). These SRMs will be useful as quality control samples for ensuring compatibility of results among population survey studies and will fill a void to assess the accuracy of analytical methods used in studies monitoring human exposure to these organic environmental contaminants. PMID:25651899

  7. Development of urine standard reference materials for metabolites of organic chemicals including polycyclic aromatic hydrocarbons, phthalates, phenols, parabens, and volatile organic compounds.

    Science.gov (United States)

    Schantz, Michele M; Benner, Bruce A; Heckert, N Alan; Sander, Lane C; Sharpless, Katherine E; Vander Pol, Stacy S; Vasquez, Y; Villegas, M; Wise, Stephen A; Alwis, K Udeni; Blount, Benjamin C; Calafat, Antonia M; Li, Zheng; Silva, Manori J; Ye, Xiaoyun; Gaudreau, Éric; Patterson, Donald G; Sjödin, Andreas

    2015-04-01

    Two new Standard Reference Materials (SRMs), SRM 3672 Organic Contaminants in Smokers' Urine (Frozen) and SRM 3673 Organic Contaminants in Non-Smokers' Urine (Frozen), have been developed in support of studies for assessment of human exposure to select organic environmental contaminants. Collaborations among three organizations resulted in certified values for 11 hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and reference values for 11 phthalate metabolites, 8 environmental phenols and parabens, and 24 volatile organic compound (VOC) metabolites. Reference values are also available for creatinine and the free forms of caffeine, theobromine, ibuprofen, nicotine, cotinine, and 3-hydroxycotinine. These are the first urine Certified Reference Materials characterized for metabolites of organic environmental contaminants. Noteworthy, the mass fractions of the environmental organic contaminants in the two SRMs are within the ranges reported in population survey studies such as the National Health and Nutrition Examination Survey (NHANES) and the Canadian Health Measures Survey (CHMS). These SRMs will be useful as quality control samples for ensuring compatibility of results among population survey studies and will fill a void to assess the accuracy of analytical methods used in studies monitoring human exposure to these organic environmental contaminants.

  8. Microbiological Spoilage of Fruits and Vegetables

    Science.gov (United States)

    Barth, Margaret; Hankinson, Thomas R.; Zhuang, Hong; Breidt, Frederick

    Consumption of fruit and vegetable products has dramatically increased in the United States by more than 30% during the past few decades. It is also estimated that about 20% of all fruits and vegetables produced is lost each year due to spoilage. The focus of this chapter is to provide a general background on microbiological spoilage of fruit and vegetable products that are organized in three categories: fresh whole fruits and vegetables, fresh-cut fruits and vegetables, and fermented or acidified vegetable products. This chapter will address characteristics of spoilage microorganisms associated with each of these fruit and vegetable categories including spoilage mechanisms, spoilage defects, prevention and control of spoilage, and methods for detecting spoilage microorganisms.

  9. Combined transcript and metabolite analysis reveals genes involved in spider mite induced volatile formation in cucumber plants

    NARCIS (Netherlands)

    Mercke, P.; Kappers, I.F.; Verstappen, F.W.A.; Vorst, O.F.J.; Dicke, M.; Bouwmeester, H.J.

    2004-01-01

    Many plants have an indirect defense against herbivores by emitting volatiles that attract carnivorous enemies of the herbivores. In cucumber (Cucumis sativus) the production of carnivore attractants can be induced by herbivory or jasmonic acid spraying. From the leaves of cucumber plants with and

  10. HS-SPME-GC×GC-qMS volatile metabolite profiling of Chrysolina herbacea frass and Mentha spp. leaves.

    Science.gov (United States)

    Cordero, Chiara; Zebelo, Simon Atsbaha; Gnavi, Giorgio; Griglione, Alessandra; Bicchi, Carlo; Maffei, Massimo E; Rubiolo, Patrizia

    2012-02-01

    Headspace solid-phase microextraction (HS-SPME) comprehensive two-dimensional (2D) gas chromatography combined with quadrupole-mass spectrometry (GC×GC-qMS) with dedicated comparative data elaboration was applied to separate chemical patterns arising from the interaction between some Mentha species and the herbivore Chrysolina herbacea, also known as the mint bug. Upon feeding on different Mentha species (Mentha spicata L., Mentha × piperita L. and Mentha longifolia L.), C. herbacea produced frass (faeces) which were characterized by a typical volatile fraction. HS-SPME GC×GC-qMS analysis of the complex volatile fraction of both mint leaf and C. herbacea frass was submitted to advanced fingerprinting analysis of 2D chromatographic data. 1,8-Cineole, found in the leaves of all the Mentha species examined, was oxidized, and C. herbacea frass yielded high rates of several hydroxy-1,8-cineoles, including 2α-hydroxy-, 3α-hydroxy-, 3β-hydroxy- and 9-hydroxy-1,8-cineole. Upon insect feeding, several unknown oxidized monoterpenes, a p-menthane diol and three unknown phenylpropanoids were also detected in the frass volatiles. In M. longifolia, the occurrence of the monoterpene piperitenone oxide was found to be toxic and associated with insect death. The results of this work show that high throughput techniques such as HS-SPME and GC×GC-qMS fingerprint analysis are ideal tools to analyze complex volatile matrices, and provide a sensitive method for the direct comparison and chemical visualization of plant and insect emitted volatile components.

  11. Dynamic headspace solid-phase microextraction combined with one-dimensional gas chromatography-mass spectrometry as a powerful tool to differentiate banana cultivars based on their volatile metabolite profile.

    Science.gov (United States)

    Pontes, Marisela; Pereira, Jorge; Câmara, José S

    2012-10-15

    In this study the effect of the cultivar on the volatile profile of five different banana varieties was evaluated and determined by dynamic headspace solid-phase microextraction (dHS-SPME) combined with one-dimensional gas chromatography-mass spectrometry (1D-GC-qMS). This approach allowed the definition of a volatile metabolite profile to each banana variety and can be used as pertinent criteria of differentiation. The investigated banana varieties (Dwarf Cavendish, Prata, Maçã, Ouro and Platano) have certified botanical origin and belong to the Musaceae family, the most common genomic group cultivated in Madeira Island (Portugal). The influence of dHS-SPME experimental factors, namely, fibre coating, extraction time and extraction temperature, on the equilibrium headspace analysis was investigated and optimised using univariate optimisation design. A total of 68 volatile organic metabolites (VOMs) were tentatively identified and used to profile the volatile composition in different banana cultivars, thus emphasising the sensitivity and applicability of SPME for establishment of the volatile metabolomic pattern of plant secondary metabolites. Ethyl esters were found to comprise the largest chemical class accounting 80.9%, 86.5%, 51.2%, 90.1% and 6.1% of total peak area for Dwarf Cavendish, Prata, Ouro, Maçã and Platano volatile fraction, respectively. Gas chromatographic peak areas were submitted to multivariate statistical analysis (principal component and stepwise linear discriminant analysis) in order to visualise clusters within samples and to detect the volatile metabolites able to differentiate banana cultivars. The application of the multivariate analysis on the VOMs data set resulted in predictive abilities of 90% as evaluated by the cross-validation procedure.

  12. 高山被孢霉挥发性次生代谢产物分析%Analysis for the Volatile Secondary Metabolites of Mortierella alpina

    Institute of Scientific and Technical Information of China (English)

    刘欣; 马小琛; 黄和; 于文涛; 纪晓俊; 彭超; 高振

    2009-01-01

    [Objective] The study was to investigate the volatile components of secondary metabolites from M.alpine producing arachidonic acid and explore the changes in its metabolic pathway. [Method] The air above M.alpine broth was extracted by solid-phase microextraction(SPME) during the post-exponential phase of growth and analyzed by GC-MS. [Result] 13 compounds were identified, 12 of which were sesquiterpenes with C15H24 formula and accounting for 99.62% of the complete compounds. Thujopsene-(12), α-Guaiene and Aristolene were three most sesquiterpenes accounting for 10.66%, 33.69% and 34.85% of total content respectively. It can be sufficiently certified that sesquiterpene metabolic pathway existing in M.alpine. [Conclusion] Metabolic flux of sesquiterpene pathway increased to improve its mass accumulation, because one or several key enzyme genes mutation in isoprene or sesquiterpene pathway enhanced their activities during induction of mutation from initial strain.

  13. Contribution of volatiles to the antifungal effect of Lactobacillus paracasei in defined medium and yogurt.

    Science.gov (United States)

    Aunsbjerg, S D; Honoré, A H; Marcussen, J; Ebrahimi, P; Vogensen, F K; Benfeldt, C; Skov, T; Knøchel, S

    2015-02-02

    Lactic acid bacteria with antifungal properties can be used to control spoilage of food and feed. Previously, most of the identified metabolites have been isolated from cell-free fermentate of lactic acid bacteria with methods suboptimal for detecting possible contribution from volatiles to the antifungal activity. The role of volatile compounds in the antifungal activity of Lactobacillus paracasei DGCC 2132 in a chemically defined interaction medium (CDIM) and yogurt was therefore investigated with a sampling technique minimizing volatile loss. Diacetyl was identified as the major volatile produced by L. paracasei DGCC 2132 in CDIM. When the strain was added to a yogurt medium diacetyl as well as other volatiles also increased but the metabolome was more complex. Removal of L. paracasei DGCC 2132 cells from CDIM fermentate resulted in loss of both volatiles, including diacetyl, and the antifungal activity towards two strains of Penicillium spp. When adding diacetyl to CDIM or yogurt without L. paracasei DGCC 2132, marked inhibition was observed. Besides diacetyl, the antifungal properties of acetoin were examined, but no antifungal activity was observed. Overall, the results demonstrate the contribution of diacetyl in the antifungal effect of L. paracasei DGCC 2132 and indicate that the importance of volatiles may have been previously underestimated.

  14. [Study of the effect of volatile metabolites of Trichoderma hamatum on the growth of phytopathogenic soilborne fungi.].

    Science.gov (United States)

    Dal Bello, G M; Mónaco, C I; Cháves, A R

    1997-09-01

    Volatile compounds produced by Trichoderma hamatum were tested for their capacity to suppress in vitro the growth of Alternaria citri, Bipolaris cynodontis, Bipolaris sorokiniana, Curvularia brachyspora, Curvularia lunata, Curvularia oryzae-sativae, Drechslera tritici-repentis, Rhizoctonia solani, Sclerotinia minor and Sclerotium rolfsii. The organisms were cultured in an apparatus made with two Erlenmeyer flasks assembled by their top parts. With the aid of the gas chromatographic technique the variation of carbon dioxide, oxygen and ethylene in the internal system was determined. Acetaldehyde and ethanol were not found. Due to the respiratory metabolism of T. hamatum the carbon dioxide level progressively increased while the oxygen content decreased. Ethylene production was low and after three days remained constant. Excepting C. oryzae-sativae and B. cynodontis the other species showed changes in the growth and development. These results suggest the inhibitory volatiles of T. hamatum as one possible mechanism of biological control.

  15. Evaluation of non-volatile metabolites in beer stored at high temperature and utility as an accelerated method to predict flavour stability.

    Science.gov (United States)

    Heuberger, Adam L; Broeckling, Corey D; Sedin, Dana; Holbrook, Christian; Barr, Lindsay; Kirkpatrick, Kaylyn; Prenni, Jessica E

    2016-06-01

    Flavour stability is vital to the brewing industry as beer is often stored for an extended time under variable conditions. Developing an accelerated model to evaluate brewing techniques that affect flavour stability is an important area of research. Here, we performed metabolomics on non-volatile compounds in beer stored at 37 °C between 1 and 14 days for two beer types: an amber ale and an India pale ale. The experiment determined high temperature to influence non-volatile metabolites, including the purine 5-methylthioadenosine (5-MTA). In a second experiment, three brewing techniques were evaluated for improved flavour stability: use of antioxidant crowns, chelation of pro-oxidants, and varying plant content in hops. Sensory analysis determined the hop method was associated with improved flavour stability, and this was consistent with reduced 5-MTA at both regular and high temperature storage. Future studies are warranted to understand the influence of 5-MTA on flavour and aging within different beer types. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Estimation of bacteriological spoilage of pork cutlets by electronic nose.

    Science.gov (United States)

    Horváth, Kinga M; Seregély, Zs; Dalmadi, I; Andrássy, Eva; Farkas, J

    2007-06-01

    The utility of chemosensor array (EN) signals of head-space volatiles of aerobically stored pork cutlets as a non-invasive technique for monitoring their microbiological load was studied during storage at 4, 8 and 12 degrees C, respectively. The bacteriological quality of the meat samples was determined by standard total aerobic plate counts (TAPC) and colony count of selectively estimated Pseudomonas (PS) spp., the predominant aerobic spoilage bacteria. Statistical analysis of the electronic nose measurements were principal component analysis (PCA), and canonical discriminant analysis (CDA). Partial least squares (PLS) regression was used to model correlation between microbial loads and EN signal responses, the degree of bacteriological spoilage, independently of the temperature of the refrigerated storage. Sensor selection techniques were applied to reduce the dimensionality and more robust calibration models were computed by determining few individual sensors having the smallest cross correlations and highest correlations with the reference data. Correlations between the predicted and "real" values were given on cross-validated data from both data reduced models and for full calibrations using the 23 sensor elements. At the same time, sensorial quality of the raw cutlets was noted subjectively on faultiness of the odour and colour, and drip formation of the samples. These preliminary studies indicated that the electronic nose technique has a potential to detect bacteriological spoilage earlier or at the same time as olfactory quality deterioration.

  17. Solving Microbial Spoilage Problems in Processed Foods

    Science.gov (United States)

    Clavero, Rocelle

    This chapter surveys common microbial food spoilage processes. The chapter is organized by food products and includes sections addressing spoilage in meat, poultry, fish; dairy products (milk, butter, cheese); beverage products; bakery products; canned foods; fruit and confectionery products; and emulsions. It addresses the isolation and identification of spoilage organisms and provides several case studies as examples. It introduces various organisms responsible for spoilage including Gram-positive lactic acid bacteria, Gram-negative aerobic bacteria, yeasts, molds, and fungal contaminants. Throughout the chapter, attention is given to when, where, and how spoilage organisms enter the food processing chain. Troubleshooting techniques are suggested. The effect (or lack of effect) of heating, dehydration, pH change, cooling, and sealing on various organisms is explained throughout. The chapter contains four tables that connect specific organisms to various spoilage manifestations in a variety of food products.

  18. Electrophysiology and behavior feedback of diamondback moth, Plutella xylostella, to volatile secondary metabolites emitted by Chinese cabbage

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The volatiles, absorbed by Porapak Q and eluted by hexane, from Chinese cabbage, Brassica campestris chinesis (L.) Makino. var. communis Tsen et Lee, have been identified as allyl isothiocyanate, Z-3-hexenyl acetate, 3,7-dimethyl-1,3,6-octatriene, 2,5-hexanediol, Z-3-hexen-1-ol, nonanol, (-myrcene, (-pinene, E-2-hexen-1-ol, D-limonene, Z-3-hexenyl propanoate, linalool, geraniol, E-4-hexen-1-ol, Z-3-hexenyl isovalerate, (-terpinene, (-caryophyllene, 3-carene and (-caryophyllene, by their mass spectra and retention times in comparison with authentic samples. The first five chemicals are the main components. All components can elicite electroantennogram (EAG) responses of diamondback moth (DBM), Plutella xylostella, in which allyl isothiocyanate and C6 alcohols and esters, i.e. Z-3-hexen-1-ol, E-2-hexen-1-ol, E-4-hexen-1-ol, Z-3-hexenyl isovalerate and 2,5-hexanediol elicite stronger EAG responses than other components, and EAG responses of female moths to them are slightly larger than those of male moths. However, EAG responses elicited by terpenes are smaller, and EAG responses from females to terpenes are smaller than those from males, but ((myrcene can evoke stronger EAG responses from both females and males. Volatiles from intact Chinese cabbage, allyl isothiocyanate, 2,5-hexanediol and Z-3-hexenyl isovalerate intensely cause DBM directional flying and landing in wind tunnel, in which volatiles from intact Chinese cabbage have the strongest activity, and the next is allyl isothiocyanate. Allyl isothiocyanate is more attractive to females than to males a bit. As for (-terpinene and other subordinate components, EAG and wind tunnel test make sure they have weak activity.

  19. Fish spoilage bacteria - problems and solutions

    DEFF Research Database (Denmark)

    Gram, Lone; Dalgaard, Paw

    2002-01-01

    Microorganisms are the major cause of spoilage of most seafood products. However, only a few members of the microbial community, the specific spoilage organisms (SSOs), give rise to the offensive off-flavours associated with seafood spoilage. Combining microbial ecology, molecular techniques, ana......, analytical chemistry, sensory analysis and mathematical modelling allows us to characterise the SSOs and to develop methods to determine, predict and extend the shelf life of products....

  20. In vitro and in situ growth characteristics and behaviour of spoilage organisms associated with anaerobically stored cooked meat products.

    Science.gov (United States)

    Vermeiren, L; Devlieghere, F; De Graef, V; Debevere, J

    2005-01-01

    Understanding spoilage caused by different types of spoilage organisms, associated with vacuum-packaged sliced cooked meat products (CMP). First, strains were characterized in a broth at 7 degrees C under anaerobic conditions to compare their growth rate, acidifying character and metabolite production under conditions simulating refrigerated vacuum-packaged conditions. Brochotrix thermosphacta grew faster than the lactic acid bacteria (LAB). Within the group of the LAB, all strains grew fast except Leuconostoc mesenteroides subsp. dextranicum and Leuconostoc carnosum. Secondly, the organisms were inoculated on a model cooked ham to better understand the relationship between spoilage, microbial growth, pH, metabolite production and accompanying sensory changes. Most rapidly growing strains were Leuc. mesenteroides subsp. mesenteroides followed by B. thermosphacta, while Leuc. mesenteroides subsp. dextranicum and Leuc. carnosum grew very slowly compared with the other LAB. Brochotrix thermosphacta caused sensory deviations at a lower cell number compared with the LAB. The related pH changes, metabolite production and sensory perception are presented. In this pure culture study, B. thermosphacta and Leuc. mesenteroides subsp. mesenteroides had the highest potential to cause rapid spoilage on CMP. A systematic study on the behaviour of spoilage organisms on a model cooked ham to establish the relationship between microbial growth, pH, metabolite formation and organoleptic deviations.

  1. Can volatile organic metabolites be used to simultaneously assess microbial and mite contamination level in cereal grains and coffee beans?

    Science.gov (United States)

    Salvador, Angelo C; Baptista, Inês; Barros, António S; Gomes, Newton C M; Cunha, Angela; Almeida, Adelaide; Rocha, Silvia M

    2013-01-01

    A novel approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-ToFMS) was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts), and mite contamination (ca. 70 min versus ca. 24 h). A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice), oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts) was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC-ToFMS. Principal Component Analysis (PCA) was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC-ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans.

  2. Can volatile organic metabolites be used to simultaneously assess microbial and mite contamination level in cereal grains and coffee beans?

    Directory of Open Access Journals (Sweden)

    Angelo C Salvador

    Full Text Available A novel approach based on headspace solid-phase microextraction (HS-SPME combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-ToFMS was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts, and mite contamination (ca. 70 min versus ca. 24 h. A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice, oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC-ToFMS. Principal Component Analysis (PCA was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC-ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans.

  3. VOC-based metabolic profiling for food spoilage detection with the application to detecting Salmonella typhimurium-contaminated pork.

    Science.gov (United States)

    Xu, Yun; Cheung, William; Winder, Catherine L; Goodacre, Royston

    2010-07-01

    In this study, we investigated the feasibility of using a novel volatile organic compound (VOC)-based metabolic profiling approach with a newly devised chemometrics methodology which combined rapid multivariate analysis on total ion currents with in-depth peak deconvolution on selected regions to characterise the spoilage progress of pork. We also tested if such approach possessed enough discriminatory information to differentiate natural spoiled pork from pork contaminated with Salmonella typhimurium, a food poisoning pathogen commonly recovered from pork products. Spoilage was monitored in this study over a 72-h period at 0-, 24-, 48- and 72-h time points after the artificial contamination with the salmonellae. At each time point, the VOCs from six individual pork chops were collected for spoiled vs. contaminated meat. Analysis of the VOCs was performed by gas chromatography/mass spectrometry (GC/MS). The data generated by GC/MS analysis were initially subjected to multivariate analysis using principal component analysis (PCA) and multi-block PCA. The loading plots were then used to identify regions in the chromatograms which appeared important to the separation shown in the PCA/multi-block PCA scores plot. Peak deconvolution was then performed only on those regions using a modified hierarchical multivariate curve resolution procedure for curve resolution to generate a concentration profiles matrix C and the corresponding pure spectra matrix S. Following this, the pure mass spectra (S) of the peaks in those region were exported to NIST 02 mass library for chemical identification. A clear separation between the two types of samples was observed from the PCA models, and after deconvolution and univariate analysis using N-way ANOVA, a total of 16 significant metabolites were identified which showed difference between natural spoiled pork and those contaminated with S. typhimurium.

  4. Microbiological spoilage of fish and fish products

    DEFF Research Database (Denmark)

    Gram, Lone; Huss, Hans Henrik

    1996-01-01

    Spoilage of fresh and lightly preserved fish products is caused by microbial action. This paper reviews the current knowledge in terms of the microbiology of fish and fish products with particular emphasis on identification of specific spoilage bacteria and the qualitative and quantitative...

  5. Feeding of different levels of metabolite combinations produced by Lactobacillus plantarum on growth performance, fecal microflora, volatile fatty acids and villi height in broilers.

    Science.gov (United States)

    Loh, Teck C; Thanh, Nguyen T; Foo, Hooi L; Hair-Bejo, Mohd; Azhar, Bin K

    2010-04-01

    The effects of feeding different dosages of metabolite combination of L. plantarum RS5, RI11, RG14 and RG11 strains (Com3456) on the performance of broiler chickens was studied. A total of 504 male Ross broilers were grouped into 7 treatments and offered different diets: (i) standard corn-soybean based diet (negative control); (ii) standard corn-soybean based diet +100 ppm neomycin and oxytetracycline (positive control); (iii) standard corn-soybean based diet + 0.1% metabolite combination of L. plantarum RS5, RI11, RG14 and RG11 strains (Com3456); (iv) standard corn-soybean based diet + 0.2% of Com3456; (v) standard corn-soybean based diet + 0.3% of Com3456 (vi) standard corn-soybean based diet + 0.4% of Com3456 and (vii) standard corn-soybean based diet + 0.5% of Com3456. Supplementation of Com3456 with different dosages improved growth performance, reduced Enterobacteriaceae and increased lactic acid bacteria count, and increased villi height of small intestine and fecal volatile fatty acid concentration. Treatment with 0.4% and 0.2% Com3456 had the best results, especially in terms of growth performance, feed conversion ratio and villi height among other dosages. However, the dosage of 0.2% was recommended due to its lower concentration yielding a similar effect as 0.4% supplementation. These results indicate that 0.2% is an optimum level to be included in the diets of broiler in order to replace antibiotic growth promoters.

  6. Influence of geosmin-producing Streptomyces on the growth and volatile metabolites of yeasts during chinese liquor fermentation.

    Science.gov (United States)

    Du, Hai; Lu, Hu; Xu, Yan

    2015-01-14

    Diverse Streptomyces species act as geosmin producers in the Chinese liquor-making process, causing an earthy, off-odor containment. Through microbiological and metabolite analyses, this paper investigates the influence of several geosmin-producing Streptomyces on the microbial community of a brewing system. The antifungal activity against functional liquor-brewing microbes was assayed by an agar diffusion method. Several Streptomyces, most notably Streptomyces sampsonii QC-2, inhibited the growth of the brewing functional yeasts and molds in pure culture. In a simulated coculture, Streptomyces spp. reduced the flavor compounds (alcohols and esters) contributed by yeasts. Nine components in Streptomyces sampsonii QC-2 broth were detected by ultraperformance liquid chromatography coupled with photo diode array (UPLC–PDA), with characteristic ultraviolet absorptions at 360, 380, and 400 nm. The main products of Streptomyces sampsonii QC-2 were identified by ultraperformance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF–MS/MS), and confirmed by standard mass spectrometry. The antifungal active components were revealed as a series of heptaene macrolide antibiotics.

  7. Pitfalls in the analysis of volatile breath biomarkers: suggested solutions and SIFT-MS quantification of single metabolites.

    Science.gov (United States)

    Smith, David; Spanel, Patrik

    2015-04-01

    The experimental challenges presented by the analysis of trace volatile organic compounds (VOCs) in exhaled breath with the objective of identifying reliable biomarkers are brought into focus. It is stressed that positive identification and accurate quantification of the VOCs are imperative if they are to be considered as discreet biomarkers. Breath sampling procedures are discussed and it is suggested that for accurate quantification on-line real time sampling and analysis is desirable. Whilst recognizing such real time analysis is not always possible and sample collection is often required, objective recognition of the pitfalls involved in this is essential. It is also emphasized that mouth-exhaled breath is always contaminated to some degree by orally generated compounds and so, when possible, analysis of nose-exhaled breath should be performed. Some difficulties in breath analysis are mitigated by the choice of analytical instrumentation used, but no single instrument can provide solutions to all the analytical challenges. Analysis and interpretation of breath analysis data, however acquired, needs to be treated circumspectly. In particular, the excessive use of statistics to treat imperfect mass spectrometry/mobility spectra should be avoided, since it can result in unjustifiable conclusions. It is should be understood that recognition of combinations of VOCs in breath that, for example, apparently describe particular cancer states, will not be taken seriously until they are replicated in other laboratories and clinics. Finally, the inhibiting notion that single biomarkers of infection and disease will not be identified and utilized clinically should be dispelled by the exemplary and widely used single biomarkers NO and H2 and now, as indicated by recent selected ion flow tube mass spectroscopy (SIFT-MS) results, triatomic hydrogen cyanide and perhaps pentane and acetic acid. Hopefully, these discoveries will provide encouragement to research workers to be

  8. A chromatographic approach to distinguish Gram-positive from Gram-negative bacteria using exogenous volatile organic compound metabolites.

    Science.gov (United States)

    Ramírez-Guízar, Susana; Sykes, Hannah; Perry, John D; Schwalbe, Edward C; Stanforth, Stephen P; Perez-Perez, Ma Cristina I; Dean, John R

    2017-06-09

    This paper utilized L-alanine aminopeptidase activity as a useful approach to distinguish between Gram-negative and Gram-positive bacteria. This was done using two enzyme substrates, specifically 2-amino-N-phenylpropanamide and 2-amino-N-(4-methylphenyl)propanamide which liberated the volatile compounds aniline and p-toluidine, respectively. Two complementary analytical techniques have been used to identify and quantify the VOCs, specifically static headspace multicapillary column gas chromatography ion mobility spectrometry (SHS-MCC-GC-IMS) and headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS). Superior limits of detection were obtained using HS-SPME-GC-MS, typically by a factor of x6 such that the LOD for aniline was 0.02μg/mL and 0.01μg/mL for p-toluidine. In addition, it was also possible to determine indole interference-free by HS-SPME-GC-MS at an LOD of 0.01μg/mL. The approach was applied to a range of selected bacteria: 15 Gram-negative and 7 Gram-positive bacteria. Use of pattern recognition, in the form of Principal Component Analysis, confirmed that it is possible to differentiate between Gram-positive and Gram-negative bacteria using the enzyme generated VOCs, aniline and p-toluidine. The exception was Stenotrophomonas maltophilia which showed negligible VOC concentrations for both aniline and p-toluidine, irrespective of the analytical techniques used and hence was not characteristic of the other Gram-negative bacteria investigated. The developed methodology has the potential to be applied for clinical and food applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Microbiological Spoilage of Meat and Poultry Products

    Science.gov (United States)

    Cerveny, John; Meyer, Joseph D.; Hall, Paul A.

    Humankind has consumed animal protein since the dawn of its existence. The archaeological record shows evidence of animal protein consumption as early as 12,500 BC (Mann, 2005). Raw meat and poultry are highly perishable commodities subject to various types of spoilage depending on handling and storage conditions. Because of this high potential for spoilage, the historical record reveals that early civilizations used techniques such as salting, smoking, and drying to preserve meat (Mack, 2001; Bailey, 1986). Today, more than ever, because of the globalization of the food supply, and increasing demands from exacting consumers, the control of meat and poultry spoilage is essential.

  10. Beer spoilage bacteria and hop resistance

    NARCIS (Netherlands)

    Sakamoto, K; Konings, WN

    2003-01-01

    For brewing industry, beer spoilage bacteria have been problematic for centuries. They include some lactic acid bacteria such as Lactobacillus brevis, Lactobacillus lindneri and Pediococcus damnosus, and some Gram-negative bacteria such as Pectinatus cerevisiiphilus, Pectinatus frisingensis and

  11. Spoilage microorganisms in milk and dairy products

    Directory of Open Access Journals (Sweden)

    Andrea Skelin

    2007-12-01

    Full Text Available Spoilage microorganisms cause changes of primary characteristics and properties of milk and dairy products. The product defects depends on the specific species and number of microorganisms involved in pre- and post- technological processing. Most often, these changes are related to single undesirable sensory characteristic, smell, flavour or conistency. However, in the case of heavier microbial contamination all these undesirable characteristics can occur simultaneously. Besides, even small changes caused by presence of spoilage microorganisms lead to decreased quality of milk and various dairy products. Despite of the importance for the overall quality, the control of spoilage microorganisms for dairy industry is not obligated and therefore, only a few producers control them. Therefore, the present study describes the undesirable effect of spoilage microorganisms on quality of raw, pasteurized and sterilized milk, fermented milk, butter, sour cream and cheeses with the intention to emphasize the importance and significance of their control in the dairy industry.

  12. Beer spoilage bacteria and hop resistance

    NARCIS (Netherlands)

    Sakamoto, K; Konings, WN

    2003-01-01

    For brewing industry, beer spoilage bacteria have been problematic for centuries. They include some lactic acid bacteria such as Lactobacillus brevis, Lactobacillus lindneri and Pediococcus damnosus, and some Gram-negative bacteria such as Pectinatus cerevisiiphilus, Pectinatus frisingensis and Mega

  13. Spoilage fungi and their mycotoxins in commercially marketed chestnuts.

    Science.gov (United States)

    Overy, David P; Seifert, Keith A; Savard, Marc E; Frisvad, Jens C

    2003-11-15

    A nationwide survey was carried out to assess mould spoilage of Castanea sativa nuts sold in Canadian grocery stores in 1998-99. Morphological and cultural characters, along with secondary metabolite profiles derived from thin-layer chromatography, were used to sort and identify fungi cultured from nut tissue. Three mycotoxigenic fungi dominated (Penicillium crustosum, Penicillium glabrum/spinulosum and Penicillium discolor) and were isolated at frequencies of 67.1%, 18.6% and 17.7%, respectively, from a total sample size of 350 nuts. Another mycotoxin producer, Aspergillus ochraceus was also isolated, but at a much lower frequency. HPLC and diode array detection were used to confirm the suspected presence of the mycotoxins penitrem A, chaetoglobosin A and C, emodin and ochratoxin A in extracts prepared from naturally infected nut tissue. To the best of our knowledge, this is the first time emodin has been found in a naturally contaminated food source.

  14. Microbiological Spoilage of Canned Foods

    Science.gov (United States)

    Evancho, George M.; Tortorelli, Suzanne; Scott, Virginia N.

    Nicolas Appert (1749-1841) developed the first commercial process that kept foods from spoiling in response to an offer from the French government for a method of preserving food for use by the army and navy. Appert, a confectioner and chef, began to experiment in his workshop in Massy, near Paris, but since little was known about bacteriology and the causes of spoilage (Louis Pasteur had yet to formulate the germ theory), much of his work involved trial and error. In 1810, after years of experimenting, he was awarded the prize of 12,000 francs for his method of preservation, which involved cooking foods in sealed jars at high temperatures. He described his method of preserving food in a book published in 1811, "L'Art De Conserver, Pendant Plusiers Annes, Toutes les Substances Animales et Végétales," which translated means "The Art of Preserving All Kinds of Animal and Vegetable Substances for Several Years." He later built a bottling factory and began to produce preserved foods for the people of France and is credited with being the "Father of Canning."

  15. Effect of Initial Headspace O2 Level on the Growth and Volatile Metabolite Production of Leuconostoc Mesenteriodes and the Microbial and Sensorial Quality of Modified Atmosphere Packaged Par-Fried French Fries.

    Science.gov (United States)

    Samapundo, Simbarashe; Mujuru, Felix Mugove; de Baenst, Ilse; Denon, Quenten; Devlieghere, Frank

    2016-02-01

    This study evaluated the effect of residual O2 level (0% to 5%) on microbial growth and volatile metabolite production on par-fried French fries packaged in a modified atmosphere with 60% CO2 (rest N2 ) at 4 °C. The results obtained showed that the initial headspace (IH) O2 level had an effect on growth of Leuconostoc mesenteroides on French fry simulation agar, whereby growth was slightly faster under 5% O2 . In terms of quantity, ethanol, 2-methyl-1-propanol, and dimethyl disulphide were the most significant volatile metabolites produced by L. mesenteroides. The production of ethanol by L. mesenteroides was highest on simulation agar packaged under low IH O2 levels (0% to 1%), indicating that the fermentative metabolism was induced under these conditions. In agreement with the results observed on the simulation medium, growth of native lactic acid bacteria was faster under an IH O2 level of 5%. In addition, ethanol, 2-methyl-1-propanol, and dimethyl disulphide were also quantitatively the most important volatile metabolites. However, in contrast, greater quantities of ethanol and dimethyl disulphide were produced on par-fried French fries packaged under 5% O2 . This was attributed to the limited growth of the native flora on the par-fried French fries under residual O2 levels of 0% and 1%. Although some significant differences (P < 0.05) occurred between the French fries packaged in 0%, 1%, and 5 % residual O2 during storage, all products were considered to be acceptable for consumption. The results of this study can be used to optimize the shelf-life of packaged chill stored potato products.

  16. Comparison of different extraction methods for the analysis of volatile secondary metabolites of Lippia alba (Mill.) N.E. Brown, grown in Colombia, and evaluation of its in vitro antioxidant activity.

    Science.gov (United States)

    Stashenko, Elena E; Jaramillo, Beatriz E; Martínez, Jairo René

    2004-01-30

    Hydrodistillation (HD), simultaneous distillation solvent extraction (SDE), microwave-assisted hydrodistillation (MWHD), and supercritical fluid (CO2) extraction (SFE) were employed to isolate volatile secondary metabolites from fresh leaves and stems of Colombian Lippia alba (Mill.) N.E. Brown. Kovàts indices, mass spectra or standard compounds were used to identify around 40 components in the various volatile fractions. Carvone (40-57%) was the most abundant component, followed by limonene (24-37%), bicyclosesquiphellandrene (5-22%), piperitenone (1-2%), piperitone (ca. 1.0%), and beta-bourbonene (0.6-1.5%), in the HD, SDE, MWHD, and SFE volatile fractions. Static headspace (S-HS), simultaneous purge and trap in solvent (CH2Cl2) (P&T), and headspace solid-phase microextraction (HS-SPME) were used to sample volatiles from fresh L. alba stems and leaves. The main components isolated from the headspace of the fresh plant material were limonene (27-77%), carvone (14-30%), piperitone (0.3-0.5%), piperitenone (ca. 0.4%), and beta-bourbonene (0.5-6.5%). The in vitro antioxidant activity of L. alba essential oil, obtained by hydrodistillation was evaluated by determination of hexanal, the main carbonyl compound released by linoleic acid subjected to peroxidation (1 mm Fe2+, 37 degrees C, 12 h), and by quantification of this acid as its methyl ester. Under the same conditions, L. alba HD-essential oil and Vitamin E exhibited similar antioxidant effects.

  17. Undergraduate Laboratory Exercises Specific to Food Spoilage Microbiology

    Science.gov (United States)

    Snyder, Abigail B.; Worobo, Randy W.; Orta-Ramirez, Alicia

    2016-01-01

    Food spoilage has an enormous economic impact, and microbial food spoilage plays a significant role in food waste and loss; subsequently, an equally significant portion of undergraduate food microbiology instruction should be dedicated to spoilage microbiology. Here, we describe a set of undergraduate microbiology laboratory exercises that focus…

  18. Fish Spoilage Mechanisms and Preservation Techniques: Review

    Directory of Open Access Journals (Sweden)

    Abdel E. Ghaly

    2010-01-01

    Full Text Available Problem statement: Spoilage of food products is due to chemical, enzymatic or microbial activities One-fourth of the worlds food supply and 30% of landed fish are lost through microbial activity alone. With the ever growing world population and the need to store and transport the food from one place to another where it is needed, food preservation becomes necessary in order to increase its shelf life and maintain its nutritional value, texture and flavor. The freshness and quality of fish have always gained the attention by Food Regulatory Agencies and Food Processing Industry. Proper handling, pretreatment and preservation techniques can improve the quality fish and fish products and increase their shelf life. Methodology: Historically salting, drying, smoking, fermentation and canning were the methods to prevent fish spoilage and extend its shelf life. In response to consumer demand for texture, appearance and taste, new methods were developed including: Cooling, freezing and chemical preservation. A comprehensive review of the literature on the subject of fish spoilage and modern preservation techniques was carried out. Conclusion: Fish spoilage results from three basic mechanisms: Enzymatic autolysis, oxidation, microbial growth. Low temperature storage and chemical techniques for controlling water activity, enzymatic, oxidative and microbial spoilage are the most common in the industry today. A process involving the addition of an EDTA (1 mM-TBHQ (0.02% combination and ascorbic acid and storage at refrigerated temperatures (5°C in darkness can be the most positive for controlling the spoilage of fish and fish product. The suggested process would address antimicrobial activity as well as destructive oxidation of the desired lipids and fats. However, more efforts are required to understand the role of proximate composition of fish, post harvest history, environmental conditions, initial microbial load, type and nature of bacteria and their

  19. Monitoring of microbial metabolites and bacterial diversity in beef stored under different packaging conditions.

    Science.gov (United States)

    Ercolini, Danilo; Ferrocino, Ilario; Nasi, Antonella; Ndagijimana, Maurice; Vernocchi, Pamela; La Storia, Antonietta; Laghi, Luca; Mauriello, Gianluigi; Guerzoni, M Elisabetta; Villani, Francesco

    2011-10-01

    Beef chops were stored at 4°C under different conditions: in air (A), modified-atmosphere packaging (MAP), vacuum packaging (V), or bacteriocin-activated antimicrobial packaging (AV). After 0 to 45 days of storage, analyses were performed to determine loads of spoilage microorganisms, microbial metabolites (by solid-phase microextraction [SPME]-gas chromatography [GC]-mass spectrometry [MS] and proton nuclear magnetic resonance [(1)H NMR]), and microbial diversity (by PCR-denaturing gradient gel electrophoresis [DGGE] and pyrosequencing). The microbiological shelf life of meat increased with increasing selectivity of storage conditions. Culture-independent analysis by pyrosequencing of DNA extracted directly from meat showed that Brochothrix thermosphacta dominated during the early stages of storage in A and MAP, while Pseudomonas spp. took over during further storage in A. Many different bacteria, several of which are usually associated with soil rather than meat, were identified in V and AV; however, lactic acid bacteria (LAB) dominated during the late phases of storage, and Carnobacterium divergens was the most frequent microorganism in AV. Among the volatile metabolites, butanoic acid was associated with the growth of LAB under V and AV storage conditions, while acetoin was related to the other spoilage microbial groups and storage conditions. (1)H NMR analysis showed that storage in air was associated with decreases in lactate, glycogen, IMP, and ADP levels and with selective increases in levels of 3-methylindole, betaine, creatine, and other amino acids. The meat microbiota is significantly affected by storage conditions, and its changes during storage determine complex shifts in the metabolites produced, with a potential impact on meat quality.

  20. Using an electronic nose for determining the spoilage of vacuum-packaged beef.

    Science.gov (United States)

    Blixt, Y; Borch, E

    1999-02-02

    The use of an electronic nose in the quantitative determination of the degree of spoilage of vacuum-packaged beef was evaluated. Beef from four different slaughterhouses was sliced, vacuum-packaged and stored at 4 degrees C for 8 weeks. Samples were withdrawn for bacterial (aerobic bacteria, lactic acid bacteria, Brochothrix thermosphacta, Pseudomonas and Enterobacteriaceae) and sensorial analyses and analysis of the volatile compounds during the storage period. A trained panel was used for the sensorial evaluations. The volatile compounds were analysed using an electronic nose containing a sensory array composed of 10 metal oxide semiconductor field-effect transistors, four Tagushi type sensors and one CO2-sensitive sensor. Four of the 15 sensors were excluded due to lack of response or overloading. Partial least-squares regression was used to define the mathematical relationships between the degree of spoilage of vacuum-packaged beef, as determined by the sensory panel, and the signal magnitudes of the sensors of the electronic nose. The mathematical models were validated after 6 months using a new set of samples. The stability of the sensors during this period was examined and it was shown that the sensitivity of five of the 11 sensors used had changed. Using the six remaining sensors, the signal patterns obtained from the meat from the different slaughterhouses did not change over a period of 6 months. It was shown that the degree of spoilage, as calculated using a model based on two Tagushi sensors, correlated well with the degree of spoilage determined by the sensory panel (r2 = 0.94).

  1. 海水鱼优势腐败菌腐败能力分析%Analysis on spoilage ability of dominant spoilage bacteria from marine fish

    Institute of Scientific and Technical Information of China (English)

    许振伟; 李学英; 杨宪时; 郭全友; 姜朝军

    2011-01-01

    研究大黄鱼和大菱鲆无菌鱼块接种优势腐败菌后5℃贮藏中的感官、腐败产物和腐败菌的变化,以生长动力学参数和腐败产物的产量因子(YTvBn/CFU和YTMA/CFU)为指标,探讨两种冷藏海水鱼优势腐败菌希瓦氏菌和假单胞菌的腐败能力.结果表明,大菱鲆鱼块接种腐败希瓦氏菌和恶臭假单胞菌的货架期分别为60,72 h,货架期终点时的TVBN含量分别为35.48,37.56 mg/100 g,腐败菌菌数分别为8.14,8.32lg (CFU/g),产量因子YTVBN/CFU分别为1.86×10-7,1.35×10-7 mg TVBN/CFU.大黄鱼鱼块接种腐败希瓦氏菌和荧光假单胞菌的货架期分别为162,174 h,货架期终点时的TVBN含量分别为31.74,39.01 mg/100 g,腐败菌菌数分别为8.71,8.91lg(CFU/g),产量因子YTVBN/CFU分别为4.49×10-8,3.72×10-8 mg TVBN/CFU.大黄鱼鱼块的货架期比大菱鲆的明显长,接种假单胞菌的两种鱼块的货架期比接种希瓦氏菌的稍长.两种海水鱼低温有氧贮剂优势腐败菌希瓦氏菌和假单胞菌都有很强的腐败能力.%Sensory, metabolites, change of spoilage bacteria, grow dynamics parameter and the yield factor of metabolites (Ytvhn/cfu and Wma/cfu) were investigated and compared for sterile Pitudosciaena crocea and Scophthatmus maximus blocks inoculated spoilage bacteria stored at 5 ℃ aerobically. Spoilage ability of two dominant spoilage bacte-ria Sinuanella and Pseudomonas spp. From two marine fish cold storage were analyzed. The results demonstrate that shelf life was 60 h and 72 hfor Scophthalmus maximus blocks inoculated Siewanella putrefitciens and Pseudomonas puiida, respectively. TVBN was 35. 48 mg/100 g and 37. 56 mg/100 mg, counts of spoilage bacteria were 8. 14 lg(CFU/g)and 8. 32 lg (CFU/g), YTVBN/CFU was 1. 86 X 10~7 mg TVBN/CFU and 1. 35× 10-7 mg TVBN/CFU. Shelf life was 162 h and 174 h for Pseudosciaena crocea blocks inoculated Shewanella putrefaciens and Pseudomonas fluorescent , respectively. TVBN were 31. 74 mg/100 g and

  2. The influence of different preservation methods on spoilage bacteria populations inoculated in morcilla de Burgos during anaerobic cold storage.

    Science.gov (United States)

    Diez, Ana M; Jaime, Isabel; Rovira, Jordi

    2009-06-30

    Blood sausage is a widely consumed traditional product that would benefit from an extended shelf life. The two main spoilage bacteria in vacuum-packaged morcilla de Burgos are Weissella viridescens and Leuconostoc mesenteroides. This study examines the way in which three preservation treatments--organic acid salts (OAS), high-pressure processing (HPP) and pasteurization--influence these bacterial populations and their spoilage behaviour. HPP and pasteurization treatments were found to inhibit growth of the inoculated species and delay sensory spoilage of the product. In both treatments, L. mesenteroides was observed to have a longer recovery time; even so, once its growth started, it grew faster than W. viridescens. This longer recovery time might be due to metabolic modification following treatment, which would affect the production of metabolites such as acetic acid and some aldehydes. W. viridescens was the first strain to recover from the two treatments. It preserved its spoilage behaviour and even increased the production of certain compounds such as acetoin or ethanol. The extended product shelf life following HPP and pasteurization treatments might be due to a combination of various factors such as the fall in both microbial populations, as well as the delay in spoilage caused by damage to L. mesenteroides cells, as this strain is the fastest-acting, most intensive spoilage microorganism. It was observed that the addition of organic salts neither diminished nor delayed the growth of the two inoculated species. Nevertheless, the results also indicate that this treatment inhibits the metabolic activity of L. mesenteroides, resulting once again in an extended product shelf life.

  3. Noninvasive Qualitative and Quantitative Assessment of Spoilage Attributes of Chilled Pork Using Hyperspectral Scattering Technique.

    Science.gov (United States)

    Zhang, Leilei; Peng, Yankun

    2016-08-01

    The objective of this research was to develop a rapid noninvasive method for quantitative and qualitative determination of chilled pork spoilage. Microbiological, physicochemical, and organoleptic characteristics such as the total viable count (TVC), Pseudomonas spp., total volatile basic-nitrogen (TVB-N), pH value, and color parameter L* were determined to appraise pork quality. The hyperspectral scattering characteristics from 54 meat samples were fitted by four-parameter modified Gompertz function accurately. Support vector machines (SVM) was applied to establish quantitative prediction model between scattering fitting parameters and reference values. In addition, partial least squares discriminant analysis (PLS-DA) and Bayesian analysis were utilized as supervised and unsupervised techniques for the qualitative identification of meat spoilage. All stored chilled meat samples were classified into three grades: "fresh," "semi-fresh," and "spoiled." Bayesian classification model was superior to PLS-DA with overall classification accuracy of 92.86%. The results demonstrated that hyperspectral scattering technique combined with SVM and Bayesian possessed a powerful capability for meat spoilage assessment rapidly and noninvasively. © The Author(s) 2016.

  4. Identification of dominant spoilage bacteria isolated from leg of chilled chicken and study on its spoilage capability%冷鲜鸡腿肉中优势腐败菌的分离鉴定及腐败能力研究

    Institute of Scientific and Technical Information of China (English)

    高磊; 谢晶; 叶藻; 张宁; 汪逸麟; 高忱岳阳

    2015-01-01

    为了有针对性地控制冷鲜鸡中微生物污染,用平板划线分离和感官评价方法对变质冷鲜鸡中的优势腐败菌进行分离筛选.再将传统的微生物生理生化鉴定方法与16S rDNA序列分析方法相结合,通过构建系统发育树,对分离筛选出的进行鉴定.最后将各优势腐败菌重新接种至灭菌肉块于4℃贮藏,分别在第1、2、4、6、8天测定各组接种肉块的菌落总数和挥发性盐基氮(TVB-N),并以TVB-N产量因子(YTVB-N)探讨各优势腐败菌的腐败能力.结果表明:经选择性培养基划线分离和感官评价方法,接种肉块共筛选得到5株优势腐败菌即J3、S1、M3、V1和J1,鉴定结果分别为:Pseudomonas pseudoalcaligenes、Brochothrix thermosphacta、Staphylococcus saprophyticus、Achromobacter xylosoxidans、Serratia grimesii.进一步研究其腐败特性,接种优势腐败菌的肉块在4℃贮藏过程中,通过计算YTVB-N发现:J3的腐败能力最强,而V1的腐败能力相对较弱.%In order to control microbial contaminant of chilled chicken in targeted way,dominant spoilage bacteria isolated from deteriorated chilled chicken leg were screened using selective medium and sensory evaluation.Using the structure of phylogenetic tree,they were identified by traditional physio-biochemical tests combining with 16S rDNA sequence analysis.The sterilized chicken legs were stored at 4 ℃ after inoculated with each identified strain.The bacterial population and total volatile basic nitrogen (TVB-N) value in the 1 st,2nd,4th,6th and 8th day were determined respectively.YTVB-N,the yield factor of microbial metabolites,was selected to evaluate the spoilage capability of strains.The results showed that five strains of dominant spoilage bacteria,designated as J3,S1,M3,V1 and J1,were obtained and identified as Pseudomonas pseudoalcaligenes,Brochothrix thermosphacta,Staphylococcus saprophyticus,Achromobacter xylosoxidans,and Serratia grimesii,respectively.By calculating

  5. Xanthine oxidase biosensor for monitoring meat spoilage

    Science.gov (United States)

    Vanegas, D. C.; Gomes, C.; McLamore, E. S.

    2014-05-01

    In this study, we have designed an electrochemical biosensor for real-time detection of specific biomarkers of bacterial metabolism related to meat spoilage (hypoxanthine and xanthine). The selective biosensor was developed by assembling a `sandwich' of nanomaterials and enzymes on a platinum-iridium electrode (1.6 mm tip diameter). The materials deposited on the sensor tip include amorphous platinum nanoclusters (i.e. Pt black), reduced graphene oxide, nanoceria, and xanthine oxidase. Xanthine oxidase was encapsulated in laponite hydrogel and used for the biorecognition of hypoxanthine and xanthine (two molecules involved in the rotting of meat by spoilage microorganisms). The developed biosensor demonstrated good electrochemical performance toward xanthine with sensitivity of 2.14 +/- 1.48 μA/mM, response time of 5.2 +/- 1.5 sec, lower detection limit of 150 +/- 39 nM, and retained at least 88% of its activity after 7 days of continuous use.

  6. In situ control of food spoilage fungus using Lactobacillus acidophilus NCDC 291.

    Science.gov (United States)

    Garcha, Seema; Natt, Navdeep Kaur

    2012-10-01

    A challenge for food industry today is to produce minimally processed food, without use of chemical preservatives and little compromise on nutritional status. Lactobacillus acidophilus NCDC 291 can be directly added to food where it enhances shelf life by competing with other microflora (both bacterial and fungal) for food and also by production of antimicrobial metabolites as bacteriocins. Comprehensive studies have demonstrated the in vitro activity of bacteriocins. However their role in preventing fresh food spoilage needs more elucidation. The present study was conducted to evaluate the efficacy of the whole cells of this organism as biopreservative agent against fungi. Four most commonly occurring spoilage fungi were isolated and were identified as Fusarium, Alternaria, Penicillium and Aspergillus. Growth of all of them was inhibited in in vitro studies, (approximately 33-43% decrease in mycelial dry weight basis between test and control). In situ biopreservation of Indian cheese and raw poultry meat was attempted and the colony count of Alternaria was significantly (p < 0.05, Bonferroni Holm) reduced in presence of L. acidophilus. Dip and Keep approach of preservation for Mangifera and Momordica were carried out in which microbial spoilage was not observed up to 6 days.

  7. Quorum sensing signals affect spoilage of refrigerated large yellow croaker (Pseudosciaena crocea) by Shewanella baltica.

    Science.gov (United States)

    Zhu, Junli; Zhao, Aifei; Feng, Lifang; Gao, Haichun

    2016-01-18

    In this work we investigated the specific spoilage organism (SSO) of large yellow croaker (Pseudosciaena crocea) stored at 4°C and role of quorum sensing (QS) system of SSO isolated from the spoiled fish. According to microbial count and 16S rRNA gene of the isolated pure strains, Shewanella, mainly Shewanella baltica and Shewanella putrefaciens, was predominant genera at the end of shelf-life of P. crocea. Among Shewanella isolates, S.baltica02 was demonstrated as SSO in spoilage potential characteristics by inoculation into sterile fish juice using sensory and chemical analyses. Autoinducer 2 and two cyclic dipeptides (DKPs) including cyclo-(l-Pro-l-Leu) and cyclo-(l-Pro-l-Phe), no any AHLs, were detected in cell-free S. baltica culture. Interestingly, S.baltica02 had the highest QS activity among three spoilers of S. baltica. The production of biofilm, trimethylamines (TMA) and putrescine in these spoilers significantly increased in the presence of cyclo-(l-Pro-l-Leu), rather than cyclo-(l-Pro-l-Phe) and 4,5-dihydroxy-2,3-pentanedione (the AI-2 precursor, DPD). In accordance with the effect of signal molecules on the spoilage phenotype, exposure to exogenous cyclo-(l-Pro-l-Leu) was also showed to up-regulate the transcription levels of luxR, torA and ODC, and no effect of luxS indicated that S. baltica could sense cyclo-(l-Pro-l-Leu). In the fish homogenate, exogenous cyclo-(l-Pro-l-Leu) shortened lag phase durations and enhanced growth rates of the dominant bacteria, H2S producing bacteria, under refrigerated storage, while exogenous DPD retarded growth of competing bacteria, such as Enterobacteriaceae. Meanwhile, cyclo-(l-Pro-l-Leu) also promoted the accumulation of metabolites on the spoilage process of homogenate. S.baltica02 luxS mutant preliminarily proved that AI-2 might not play a signaling role in the spoilage. The present study suggested that the spoilage potential of S. baltica in P. crocea might be regulated by DKP-based quorum sensing.

  8. Fish Spoilage Mechanisms and Preservation Techniques: Review

    OpenAIRE

    Abdel E. Ghaly; Dave, D; Budge, S; M. S. Brooks

    2010-01-01

    Problem statement: Spoilage of food products is due to chemical, enzymatic or microbial activities One-fourth of the worlds food supply and 30% of landed fish are lost through microbial activity alone. With the ever growing world population and the need to store and transport the food from one place to another where it is needed, food preservation becomes necessary in order to increase its shelf life and maintain its nutritional value, texture and flavor. The freshness and quality of fish hav...

  9. Microbiological Spoilage of High-Sugar Products

    Science.gov (United States)

    Thompson, Sterling

    The high-sugar products discussed in this chapter are referred to as chocolate, sugar confectionery (non-chocolate), liquid sugars, sugar syrups, and honey. Products grouped in the sugar confectionery category include hard candy, soft/gummy candy, caramel, toffee, licorice, marzipan, creams, jellies, and nougats. A common intrinsic parameter associated with high-sugar products is their low water activity (a w), which is known to inhibit the growth of most spoilage and pathogenic bacteria. However, spoilage can occur as a result of the growth of osmophilic yeasts and xerophilic molds (Von Richter, 1912; Anand & Brown, 1968; Brown, 1976). The a w range for high-sugar products is between 0.20 and 0.80 (Banwart, 1979; Richardson, 1987; Lenovich & Konkel, 1992; ICMSF, 1998; Jay, Loessner, & Golden, 2005). Spoilage of products, such as chocolate-covered cherries, results from the presence of yeasts in the liquid sugar brine or the cherry. Generally, the spoiled product will develop leakers. The chocolate covering the cherry would not likely be a source of yeast contamination.

  10. Characterization of volatile metabolites associated with confinement odour during the shelf-life of vacuum packed lamb meat under different storage conditions.

    Science.gov (United States)

    Reis, Marlon M; Reis, Mariza G; Mills, John; Ross, Colleen; Brightwell, Gale

    2016-03-01

    Confinement odour was investigated. Volatiles were extracted directly from the pack, using solid phase microextraction and analysed by gas chromatography-mass spectrometry. Sensory evaluation and microbiological analysis of the meat surface were also performed. Commercial samples of vacuum packed lamb legs (n=85), from two meat processing plants, were kept for 7weeks at -1.5°C then at different regimes of temperature (-1.5 to +4°C) until 11, 12 or 13weeks. Persistent odour was observed in 66% of samples, confinement odour in 24% and no odour in 11%. Volatiles associated with confinement odour (3-methyl-butanal, 3-hydroxy-2-butanone and sulphur dioxide) corresponded with end/sub products of glucose fermentation and catabolism of amino acids by bacteria (all bacteria naturally found in meat and do not represent a risk to health). Confinement odour could indicate a stage at which the environment for bacteria growth is becoming favourable for the production of volatiles with strong odours that are noticed by the consumer.

  11. Beer spoilage bacteria and hop resistance.

    Science.gov (United States)

    Sakamoto, Kanta; Konings, Wil N

    2003-12-31

    For brewing industry, beer spoilage bacteria have been problematic for centuries. They include some lactic acid bacteria such as Lactobacillus brevis, Lactobacillus lindneri and Pediococcus damnosus, and some Gram-negative bacteria such as Pectinatus cerevisiiphilus, Pectinatus frisingensis and Megasphaera cerevisiae. They can spoil beer by turbidity, acidity and the production of unfavorable smell such as diacetyl or hydrogen sulfide. For the microbiological control, many advanced biotechnological techniques such as immunoassay and polymerase chain reaction (PCR) have been applied in place of the conventional and time-consuming method of incubation on culture media. Subsequently, a method is needed to determine whether the detected bacterium is capable of growing in beer or not. In lactic acid bacteria, hop resistance is crucial for their ability to grow in beer. Hop compounds, mainly iso-alpha-acids in beer, have antibacterial activity against Gram-positive bacteria. They act as ionophores which dissipate the pH gradient across the cytoplasmic membrane and reduce the proton motive force (pmf). Consequently, the pmf-dependent nutrient uptake is hampered, resulting in cell death. The hop-resistance mechanisms in lactic acid bacteria have been investigated. HorA was found to excrete hop compounds in an ATP-dependent manner from the cell membrane to outer medium. Additionally, increased proton pumping by the membrane bound H(+)-ATPase contributes to hop resistance. To energize such ATP-dependent transporters hop-resistant cells contain larger ATP pools than hop-sensitive cells. Furthermore, a pmf-dependent hop transporter was recently presented. Understanding the hop-resistance mechanisms has enabled the development of rapid methods to discriminate beer spoilage strains from nonspoilers. The horA-PCR method has been applied for bacterial control in breweries. Also, a discrimination method was developed based on ATP pool measurement in lactobacillus cells. However

  12. Antifungal activity of essential oils evaluated by two different application techniques against rye bread spoilage fungi

    DEFF Research Database (Denmark)

    Suhr, Karin Isabel; Nielsen, Per Væggemose

    2003-01-01

    Aims: To study how antifungal activity of natural essential oils depends on the assay method used.Methods and Results: Oils of bay, cinnamon leaf, clove, lemongrass, mustard, orange, sage, thyme and two rosemary oils were tested by two methods: (1) a rye bread-based agar medium was supplemented...... with 100 and 250 mu l l(-1) essential oil and (2) real rye bread was exposed to 136 and 272 mu l l(-1) volatile oil in air. Rye bread spoilage fungi were used for testing. Method 1 proved thyme oil to be the overall best growth inhibitor, followed by clove and cinnamon. On the contrary, orange, sage...... and rosemary oils had very limited effects. Mustard and lemongrass were the most effective oils by the volatile method, and orange, sage and one rosemary showed some effects. Oil compositions were analysed by gas chromatography-mass spectrography.Conclusions: Antifungal effects of the essential oils depended...

  13. Preventing spoilage of poultry meat: focus on spoilage microorganisms and their control

    Science.gov (United States)

    The shelf-life of fresh poultry meat is determined by the level of contamination of processed meat by spoilage microorganisms, storage temperature and storage atmosphere. This chapter looks at the various ways by which to extend the shelf-life of poultry meat: vacuum and modified atmosphere packagin...

  14. Clostridium botulinum Toxin Production in Relation to Spoilage of Atlantic Salmon (Salmo salar) Packaged in Films of Varying Oxygen Permeabilities and with Different Atmospheres.

    Science.gov (United States)

    Erickson, Marilyn C; Ma, Li M; Doyle, Michael P

    2015-11-01

    Shelf life of fish packaged under modified atmosphere (MA) is extended, but within the United States, commercial application of MA with impermeable packaging films is restricted due to concerns that botulinum toxin production would precede spoilage when contaminated fish are held at abusive storage temperatures. Use of semipermeable packaging films has been advocated; however, previous studies are inconclusive in determining the oxygen transmission rate (OTR) of a film that is needed to achieve an acceptable margin of safety (i.e., toxin production occurs only after spoilage). This study was conducted to determine the influence of OTR (target OTRs of 3 to 15,000) on the development of spoilage volatiles and toxin in salmon inoculated with type E Clostridium botulinum and subjected to air, vacuum, or 75:25 CO2:N2 MA and storage temperatures of 4, 8, 12, or 16°C. The most dominant headspace volatile peak that was produced during spoilage of samples at 4, 8 or 12°C was a peak, having a Kovats retention index (KI) of 753, and at which external standards of 2- or 3-methyl 1-butanol also eluted. Under anaerobic conditions, both the aerobic microbial populations and the size of the KI 753 spoilage peak were less in inoculated samples compared with uninoculated samples. C. botulinum-inoculated samples that were stored at 12 or 16°C under conditions favorable for anaerobic growth were also characterized by a KI 688 peak. Using a previously developed model that related the percentage of elderly consumers who would prepare a sample having the KI 753 spoilage peak of a specific size, it was determined that for salmon packaged with 3 or 3,000 OTR films under any atmosphere and stored at 12 or 16°C, 2 to 61% of the consumers could potentially prepare toxin-contaminated samples. Hence, when abusive storage conditions are suspected, the fish should not be consumed.

  15. Impact of thermal and nonthermal processing technologies on unfermented apple cider aroma volatiles.

    Science.gov (United States)

    Azhu Valappil, Zareena; Fan, Xuetong; Zhang, Howard Q; Rouseff, Russell L

    2009-02-11

    Aroma composition and microbial quality of identical lots of apple cider treated by pulsed electric field (PEF), ultraviolet irradiation (UV), or thermal pasteurization stored at 4 degrees C were compared at 0 and 4 weeks. Conditions were optimized to achieve identical 5 log reductions in Escherichia coli K12 for each treatment. PEF and thermal pasteurization maintained acceptable microbial quality for 4 weeks, but UV samples fermented after 2 weeks. Twenty-eight volatiles were quantified using gas chromatography-mass spectrometry (GC-MS) and odor activity values (OAV) determined. OAVs of 69:hexyl acetate, 41:hexanal, 25:2-methylbutyl acetate, 23:2-methyl ethyl butyrate, and 14:2-(E)-hexenal were observed for the control cider. Significant differences (p ciders only after 4 weeks of storage. Thermal samples lost 30% of the major ester and aldehyde volatiles during storage with significant decreases (p cider, hexanal and 2-(E)-hexenal were completely lost after 4 weeks of storage. Microbial spoilage in UV cider after 4 weeks of storage was chemically confirmed by the detection of the microbial metabolite 1,3-pentadiene. PEF cider lost cider.

  16. Antifungal Activity of Selected Lactic Acid Bacteria and Propionic Acid Bacteria against Dairy-Associated Spoilage Fungi

    DEFF Research Database (Denmark)

    Aunsbjerg, Stina Dissing

    for prolonging shelf-life of food without the addition of specific preservatives. Increased interest in the use of these bacteria for biopreservation has led to identification of a range of potent strains, and in addition, isolation and identification of various antifungal metabolites produced by these cultures......Bacterial cultures of lactic and propionic acid bacteria are widely used in fermented products including dairy products. Spoilage fungi may constitute a quality and safety issue in these products. The antifungal properties of some lactic and propionic acid bacteria make them potential candidates...... defined interaction medium (CDIM) was developed allowing growth of protective Lb. paracasei and P. freudenreichii subsp. shermaniii as well as the spoilage fungi, Penicillium spp., Rhodotorula mucilaginosa and Debaryomyces hansenii isolated from fermented dairy products. Lb. paracasei and P...

  17. Mesophilic and psychrotrophic bacteria from meat and their spoilage potential in vitro and in beef.

    Science.gov (United States)

    Ercolini, Danilo; Russo, Federica; Nasi, Antonella; Ferranti, Pasquale; Villani, Francesco

    2009-04-01

    Mesophilic and psychrotrophic populations from refrigerated meat were identified in this study, and the spoilage potential of microbial isolates in packaged beef was evaluated by analyzing the release of volatile organic compounds (VOC) by gas chromatography-mass spectrometry (GC/MS). Fifty mesophilic and twenty-nine psychrotrophic isolates were analyzed by random amplified polymorphic DNA-PCR, and representative strains were identified by 16S rRNA gene sequencing. Carnobacterium maltaromaticum and C. divergens were the species most frequently found in both mesophilic and psychrotrophic populations. Acinetobacter baumannii, Buttiauxella spp. and Serratia spp. were identified among the mesophilic isolates, while Pseudomonas spp. were commonly identified among the psychrotrophs. The isolates were further characterized for their growth at different temperatures and their proteolytic activity in vitro on meat proteins extracts at 7 degrees C. Selected proteolytic strains of Serratia proteamaculans, Pseudomonas fragi, and C. maltaromaticum were used to examine their spoilage potential in situ. Single strains of these species and mixtures of these strains were used to contaminate beef chops that were packed and stored at 7 degrees C. At time intervals up to 1 month, viable counts were determined, and VOC were identified by GC/MS. Generally, the VOC concentrations went to increase during the storage of the contaminated meats, and the profiles of the analyzed meat changed dramatically depending on the contaminating microbial species. About 100 volatiles were identified in the different contaminated samples. Among the detected volatiles, some specific molecules were identified only when the meat was contaminated by a specific microbial species. Compounds such as 2-ethyl-1-hexanol, 2-buten-1-ol, 2-hexyl-1-octanol, 2-nonanone, and 2-ethylhexanal were detectable only for C. maltaromaticum, which also produced the highest number of aldehydes, lactones, and sulfur compounds. The

  18. Differences in microbial metabolites in urine headspace of subjects with Immune Thrombocytopenia (ITP) detected by volatile organic compound (VOC) analysis and metabolomics.

    Science.gov (United States)

    Batty, Claire A; Cauchi, Michael; Hunter, J O; Woolner, Jenny; Baglin, Trevor; Turner, Claire

    2016-10-01

    ITP is an organ-specific autoimmune disorder characterised by a low platelet count whose cause is uncertain. A possible factor is food intolerance, although much of the information linking this with ITP is anecdotal. The role of food intolerance in ITP was studied by replacing a normal diet with an elemental diet (E028), but this did not increase platelet counts. Clear differences, however, were apparent between the volatile organic compounds (VOCs) in the urine headspace of patients with ITP and those present in healthy volunteers, which leads to speculation that abnormal metabolic activity of the intestinal microbiome may be a factor causing ITP. However, further work is needed to confirm this. There were also differences between the VOCs of patients on a normal diet and those on the elemental diet, and in this case, the VOCs involved are very likely to be of bacterial origin, as their production is affected by dietary manipulation. Many of these VOCs are known to be toxic.

  19. Using Multispectral Imaging for Spoilage Detection of Pork Meat

    DEFF Research Database (Denmark)

    Dissing, Bjørn Skovlund; Papadopoulou, Olga S.; Tassou, Chrysoula

    2013-01-01

    The quality of stored minced pork meat was monitored using a rapid multispectral imaging device to quantify the degree of spoilage. Bacterial counts of a total of 155 meat samples stored for up to 580 h have been measured using conventional laboratory methods. Meat samples were maintained under two...... different storage conditions: aerobic and modified atmosphere packages as well as under different temperatures. Besides bacterial counts, a sensory panel has judged the spoilage degree of all meat samples into one of three classes. Results showed that the multispectral imaging device was able to classify 76...... for the detection of spoilage degree in minced pork meat....

  20. Recycled palm oil spoilage: Correlation between physicochemical properties and oleophilicity

    Science.gov (United States)

    Kadir, Ili Afiqa Ab; Zubairi, Saiful Irwan; Jurid, Lailatul Syema

    2016-11-01

    Palm oil is widely used for domestic and commercial frying due to its techno-economic advantages as compared to other vegetable oils. However, if the oil is used beyond its recommended usage cycle, it might lead to oil spoilage. Therefore this study focuses on the comprehensive analysis of chemical and physical properties of recycled palm oil. Recycled palm oil was prepared by frying potato strips up to 4 batches; 5 cycles for each batch) was carried out with potato (g)-to-oil (ml) ratio of 3/20 prior to physico-chemical analysis (moisture content, color measurement, viscosity, density and iodine value. From 5 tests used to indicate physico-chemical properties of recycled palm oil, only color measurement, viscosity and IV shows results accordingly to theories. Whereas moisture content and density were not comply to theories. With increasing frying times, recycled palm oil color has been darker due to chemical reaction that occurs during frying. The trend line illustrates that with increasing frying times, recycled palm oil lightness decreases. It also means that its color has been darker. Meanwhile, b* rate increase indicating that recycled palm oil show tendency towards green color. Whereas, a* rate decreased, showing low tendency towards red color. Viscosity and moisture content increase with frying cycle. This situation occurred might be due to formation of hydrolysis products which are volatile while frying process. But the remaining non-volatile compounds among the hydrolysis products might also accumulate in palm oil and thus affect the total oil/fat chemical changes. Meanwhile the density of palm oil was quite constant at 0.15 g/cm3 except for cycle 2 with 0.17 g/cm3. The result obtained from this experiment were comply with previous study that stated frying batch number is a significant variable (a = 0.05) affecting the density of oil only after 20 frying batch. The contact angle of recycled palm oil on PHBV thin film was more than 90 °. Hence it shows

  1. Psychrotrophic Clostridia Causing Spoilage in Cooked Meat and Poultry Products

    National Research Council Canada - National Science Library

    Kalinowski, Robin M; Tompkin, R. Bruce

    1999-01-01

    ...°C or below, and typically given use by dates of greater than 50 days. While of rare, sporadic occurrence, an unpleasant spoilage characterized by strong H2S odor and gas production has been observed in these products...

  2. 18 Evaluation of Microbial Spoilage of Some Aquacultured Fresh ...

    African Journals Online (AJOL)

    `123456789jkl''''#

    sp., and four fungi species namely; Aspergillis niger, Geotrichum sp., Rhizopus sp. and ... pathogens in the fresh fish samples could pose a potential public health threat especially to consumers. It is ..... the spoilage of certain sea foods. Journal ...

  3. RAPD analysis : a rapid technique for differentation of spoilage yeasts

    NARCIS (Netherlands)

    Baleiras Couto, M.M.; Vossen, J.M.B.M. van der; Hofstra, H.; Huis in 't Veld, J.H.J.

    1994-01-01

    Techniques for the identification of the spoilage yeasts Saccharomyces cerevisiae and members of the Zygosaccharomyces genus from food and beverages sources were evaluated. The use of identification systems based on physiological characteristics resulted often in incomplete identification or misiden

  4. 水产食品特定腐败菌与货架期的预测和延长%Specific spoilage organisms from aquatic product and prediction & prolongation of the shelf life

    Institute of Scientific and Technical Information of China (English)

    杨宪时; 许钟; 肖琳琳

    2004-01-01

    Fresh fish and lightly preserved fish products are welcome by the global market, however, they are also among the most perishable food products. The research on specific spoilage organisms (SSO) reveals the spoilage process of aquatic product. This paper reviews the current knowledge (past ten years) on SSO of fresh fish and lightly preserved fish products with particular emphasis on characteristics of SSO and how to apply this concept to determine, predict and extend the shelf life of aquatic product. During storage, the microflora changes owing to different abilities of the microorganisms to tolerate the preservation conditions. SSO is defined as special microorganisms which can increase rapidly during preservation and has the ability to produce off- odours and off- flavours associated with spoilage, and spoilage metabolites. Identification of an SSO relies on comparison of the sensory and chemical characteristics of spoiled product with those of isolates from the spoilage microflora. Generally, the SSO of fresh fish may be a single species or genus, but the ones of lightly preserved fish products will be more complex. One exciting area for use of SSO aims to obtain quantitative knowledge about probable behavior of SSO and their function during the progression of spoilage. Thus mathematical models on the growth of SSO are established to evaluate the quality lost degree of product, which provide a sound information for the rational development of devices to monitor loss of products shelf life. Models for the growth of Pseudomonas spp, S. putrefaciens, P. phosphoreum have been established, and validated for shelf life prediction of seafood successfully. Another application field of SSO intends to develop the techniques to prolong the shelf life of food products by inhibiting SSO targetedly. Targeted inhibition of spoilage bacteria during preservation reduces their growth and results in a significant extension of shelf life in despite of the activity of non

  5. Meat Spoilage Mechanisms and Preservation Techniques: A Critical Review

    OpenAIRE

    D. Dave; Abdel E. Ghaly

    2011-01-01

    Problem statement: Extremely perishable meat provides favorable growth condition for various microorganisms. Meat is also very much susceptible to spoilage due to chemical and enzymatic activities. The breakdown of fat, protein and carbohydrates of meat results in the development of off-odors, off-flavor and slim formation which make the meat objectionable for human consumption. It is, therefore, necessary to control meat spoilage in order to increase its shelf life and maintain its nutrition...

  6. Microbiological Spoilage of Spices, Nuts, Cocoa, and Coffee

    Science.gov (United States)

    Pinkas, Joan M.; Battista, Karen; Morille-Hinds, Theodora

    Spices, nuts, cocoa, and coffee are raw materials that may be used alone or as ingredients in the manufacture of processed food products. The control of microbiological spoilage of these raw materials at the ingredient stage will enable the food processor to better assure the production of high-quality foods with an acceptable shelf life. While this chapter is limited to four materials, many of the spoilage control procedures recommended can also be applied to other raw materials of a similar nature.

  7. Biogenic amines in fish: roles in intoxication, spoilage, and nitrosamine formation--a review.

    Science.gov (United States)

    Al Bulushi, Ismail; Poole, Susan; Deeth, Hilton C; Dykes, Gary A

    2009-04-01

    Biogenic amines are non-volatile amines formed by decarboxylation of amino acids. Although many biogenic amines have been found in fish, only histamine, cadaverine, and putrescine have been found to be significant in fish safety and quality determination. Despite a widely reported association between histamine and scombroid food poisoning, histamine alone appears to be insufficient to cause food toxicity. Putrescine and cadaverine have been suggested to potentiate histamine toxicity. With respect to spoilage on the other hand, only cadaverine has been found to be a useful index of the initial stage of fish decomposition. The relationship between biogenic amines, sensory evaluation, and trimethylamine during spoilage are influenced by bacterial composition and free amino acid content. A mesophilic bacterial count of log 6-7 cfu/g has been found to be associated with 5 mg histamine/100 g fish, the Food and Drug Administration (FDA) maximum allowable histamine level. In vitro studies have shown the involvement of cadaverine and putrescine in the formation of nitrosamines, nitrosopiperidine (NPIP), and nitrosopyrrolidine (NPYR), respectively. In addition, impure salt, high temperature, and low pH enhance nitrosamine formation, whereas pure sodium chloride inhibits their formation. Understanding the relationships between biogenic amines and their involvement in the formation of nitrosamines could explain the mechanism of scombroid poisoning and assure the safety of many fish products.

  8. The involvement of bacterial quorum sensing in the spoilage of refrigerated Litopenaeus vannamei.

    Science.gov (United States)

    Zhu, Suqin; Wu, Haohao; Zeng, Mingyong; Liu, Zunying; Wang, Ying

    2015-01-02

    Quorum-sensing signals in refrigerated shrimp (Litopenaeus vannamei) undergoing spoilage were examined using bioreporter assays, thin-layer chromatography and gas chromatography-mass spectrometry, and the results revealed the presence of three types of autoinducers including acetylated homoserine lactones (AHLs) (i.e., N-hexanoyl-homoserine lactone, N-oxohexanoyl-homoserine lactone and N-octanoyl-homoserine lactone), autoinducer-2, and cyclic dipeptides (i.e., cyclo-(L-Pro-L-Leu), cyclo-(L-Leu-L-Leu) and cyclo-(L-Pro-L-Phe)). Autoinducer-2, rather than any AHL, was detected in extracts from pure cultures of the specific spoilage organisms (SSO), i.e., Shewanella putrefaciens (SS01) and Shewanella baltica (SA02). As for the cyclic peptides, only SA02 was determined to produce cyclo-(L-Pro-L-Leu). According to the transcription levels of LuxR (the master quorum-sensing regulator) in the SSO in response to exogenous autoinducers, the SSO could sense AHLs and cyclo-(L-Leu-L-Leu), rather than autoinducer-2, cyclo-(L-Leu-L-Leu) and cyclo-(L-Pro-L-Phe). In accordance with the results of LuxR expression, the production of biofilm matrixes and extracellular proteases in the SSO was regulated by exogenous AHLs and cyclo-(L-Pro-L-Leu), rather than 4,5-dihydroxy-2,3-pentanedione (the autoinducer-2 precursor), cyclo-(L-Leu-L-Leu) and cyclo-(L-Pro-L-Phe). Exogenous N-hexanoyl-homoserine lactone and cyclo-(L-Pro-L-Leu) increased the growth rates and population percentages of the SSO in shrimp samples under refrigerated storage, and interestingly, exogenous 4,5-dihydroxy-2,3-pentanedione also increased the population percentages of the SSO in vivo by inhibiting the growth of the competing bacteria. However, according to the levels of TVB-N and the volatile organic components in the shrimp samples, exogenous 4,5-dihydroxy-2,3-pentanedione did not accelerate the shrimp spoilage process as N-hexanoyl-homoserine lactone and cyclo-(L-Pro-L-Leu) did. In summary, our results suggest that

  9. Fast and simple screening for the simultaneous analysis of seven metabolites derived from five volatile organic compounds in human urine using on-line solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Chiang, Wen-Chieh; Chen, Chao-Yu; Lee, Ting-Chen; Lee, Hui-Ling; Lin, Yu-Wen

    2015-01-01

    Recently, the International Agency for Research on cancer classified outdoor air pollution and particulate matter from outdoor air pollution as carcinogenic to humans (IARC Group 1), based on sufficient evidence of carcinogenicity in humans and experimental animals and strong mechanistic evidence. In particular, a wide variety of volatile organic compounds (VOCs) are volatized or released into the atmosphere and can become ubiquitous, as they originate from many different natural and anthropogenic sources, such as paints, pesticides, vehicle exhausts, cooking fumes, and tobacco smoke. Humans may be exposed to VOCs through inhalation, ingestion, or dermal contact, which may increase the risk of leukemia, birth defects, neurocognitive impairment, and cancer. Therefore, the focus of this study was the development of a simple, effective and rapid sample preparation method for the simultaneous determination of seven metabolites (6 mercaptic acids+t,t-muconic acid) derived from five VOCs (acrylamide, 1,3-butadiene, acrylonitrile, benzene, and xylene) in human urine by using automated on-line solid-phase extraction (SPE) coupled with liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). An aliquot of each diluted urinary sample was directly injected into an autosampler through a trap column to reduce contamination, and then the retained target compounds were eluted by back-flush mode into an analytical column for separation. Negative electrospray ionization tandem mass spectrometry was utilized for quantification. The coefficients of correlation (r(2)) for the calibration curves were greater than 0.995. Reproducibility was assessed by the precision and accuracy of intra-day and inter-day precision, which showed results for coefficient of variation (CV) that were low 0.9 to 6.6% and 3.7 to 8.5%, respectively, and results for recovery that ranged from 90.8 to 108.9% and 92.1 to 107.7%, respectively. The limits of detection (LOD) and limits of

  10. Volatility Discovery

    DEFF Research Database (Denmark)

    Dias, Gustavo Fruet; Scherrer, Cristina; Papailias, Fotis

    The price discovery literature investigates how homogenous securities traded on different markets incorporate information into prices. We take this literature one step further and investigate how these markets contribute to stochastic volatility (volatility discovery). We formally show...... that the realized measures from homogenous securities share a fractional stochastic trend, which is a combination of the price and volatility discovery measures. Furthermore, we show that volatility discovery is associated with the way that market participants process information arrival (market sensitivity...

  11. Low-Temperature Production of Urocanic Acid by Spoilage Bacteria Isolated from Mahimahi (Coryphaena hippurus).

    Science.gov (United States)

    Baranowski, J D

    1985-08-01

    Urocanic acid production was studied in 166 bacterial cultures isolated from mahimahi which had been stored for 14 days on ice in seawater. After 4 days of incubation at 10 degrees C in histidine-supplemented Trypticase soy broth (BBL Microbiology Systems, Cockeysville, Md.), urocanic acid was measured by thin-layer chromatography. Fifty-eight of the cultures were positive for urocanic acid, with the eight most active isolates producing ca. 10 mg/100 ml. These observations, coupled with a report that urocanic acid may be the predominant histidine metabolite in fish held at low temperatures, all suggest that urocanic acid may be a useful alternative to histamine as a spoilage index in scombroid and other fish that are rich in endogenous histidine.

  12. Characterization of the bacterial spoilage flora in marinated pork products.

    Science.gov (United States)

    Schirmer, B C; Heir, E; Langsrud, S

    2009-06-01

    To investigate the microbiota in marinated, vacuum-packed pork and to characterize isolated bacteria with regard to their spoilage potential. Laboratory marinated pork meat and commercial products from three Norwegian producers were examined. Lactic acid bacteria dominated in all products at the expiration date. The flora in marinated products was similar only for products from the same plant. Strains of Lactobacillus algidus, Lactobacillus sakei, Lactobacillus curvatus, Carnobacterium divergens, Carnobacterium maltaromaticum, Leuconostoc mesenteroides, Leuconostoc carnosum and Leuconostoc sp. were isolated and tested for their spoilage potential. Samples inoculated with Lact. algidus or Leuc. mesenteroides were rated as most unpleasant by randomly selected people. A sensory panel scored samples with Lact. algidus highest for sour and intense odour. Lactobacillus algidus was found in products from two out of three production plants. Culture-independent DNA isolation confirmed that cultivation on Blood agar at 20 degrees C yielded a representative picture of the total flora in marinated flintsteak. Lactobacillus algidus may be an important, but underestimated, spoilage organism that needs to be focused on more when spoilage of vacuum-packed meat is considered. Routine microbial testing may have to be revised in order to detect spoilage LAB that are unable to grow under currently used conditions.

  13. Bacterial spoilage of meat and cured meat products.

    Science.gov (United States)

    Borch, E; Kant-Muermans, M L; Blixt, Y

    1996-11-01

    The influence of environmental factors (product composition and storage conditions) on the selection, growth rate and metabolic activity of the bacterial flora is presented for meat (pork and beef) and cooked, cured meat products. The predominant bacteria associated with spoilage of refrigerated beef and pork, are Brochothrix thermosphacta, Carnobacterium spp., Enterobacteriaceae, Lactobacillus spp., Leuconostoc spp., Pseudomonas spp. and Shewanella putrefaciens. The main defects in meat are off-odours and off-flavours, but discolouration and gas production also occur. Bacteria associated with the spoilage of refrigerated meat products, causing defects such as sour off-flavours, discolouration, gas production, slime production and decrease in pH, consist of B. thermosphacta, Carnobacterium spp. Luctobacillus spp. Leuconostoc spp. and Weissella spp. Analysis of spoilage as measured by bacterial and chemical indicators is discussed. It is concluded that a multivariate approach based on spectra of chemical compounds, may be helpful in order to analyse spoilage, at least for spoilage caused by lactic acid bacteria. The consequences of bacteria bacteria interactions should be evaluated more.

  14. Development and validation of a colorimetric sensor array for fish spoilage monitoring

    DEFF Research Database (Denmark)

    Morsy, Mohamed K.; Zor, Kinga; Kostesha, Natalie;

    2016-01-01

    Given the need for non-destructive methods and sensors for food spoilage monitoring, we have evaluated sixteen chemo-sensitive compounds incorporated in an array for colorimetric detection of typical spoilage compounds (trimethylamine, dimethylamine, cadaverine, putrescine) and characterized...

  15. Interactions between nitric oxide and ethylene in monomeric G-protein activation in relation to food spoilage

    DEFF Research Database (Denmark)

    Hall, M A; moshkov, moshkov; Novikova, G

    2014-01-01

    and it is notable that many are dependent on the production of volatile signals or signals which have volatile derivatives. Ethylene (ET) has long been recognized as an important regulator of development, stress responses, senescence and food spoilage. Our work has focused on the gaseous signal nitric oxide (NO......) and how it interacts with established stress signalling pathways and in particular, those regulated by ET. Using laser photoacoustic detection (LPAD) we have established that NO production overlaps with that of ethylene during plant responses to disease. To examine the interaction of NO and ET signalling...... approach and 2D-electrophoresis (2DE) a series of GTP binding proteins which were activated by both ethylene and SNP were detected and some that exhibited specific activation patterns in response to both signals. These observations underline the close relationship between ET and NO signalling cascades...

  16. Bioactive proteins against pathogenic and spoilage bacteria

    Directory of Open Access Journals (Sweden)

    Mahmoud Z. Sitohy

    2014-10-01

    Full Text Available Background: It is likely that both human nutrition and the nutrition of livestock are benefited by the presence of bioactive proteins within their respective diet regimes. Bioactive proteins have been defined as specific protein fragments that positively impact bodily functions or conditions and may, ultimately, influence overall human health. The ingestion of bioactive proteins may have an effect on the major body systems—namely, the cardiovascular, digestive, immune and nervous systems. According to their functional properties, bioactive proteins may be classified as antimicrobial, antithrombotic, antihypertensive, opioid, immune-modulatory, mineral binding and anti-oxidative. There are many examples of biologically active food proteins and active peptides that can be obtained from various food protein sources. They have a physiological significance beyond the pure nutritional requirements; in other wordsthey have the acquisition of nitrogen for normal growth and maintenance. Objective: This study aims to specify and characterize the extent and mode of action of bioactive proteins in their native form, (glycinin, glycinin basic sub-unit and β-conglycinin against specific main pathogens (Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis. We will be using standard media while identifying the main constituents responsible for this action. Methods: Glycinin, basic sub-unit and β-conglycinin were isolated from soybean protein and tested for their antimicrobial action against pathogenic and spoilage bacteria, They were thencompared to the properties of penicillin. Methylated soybean protein and also methylated chickpea protein (MSP and MCP, with isoelectric points around pI 8, were prepared by esterifying. 83 % of their free carboxyl groups and their interactions with Gram positive and Gram negative bacteria were examined. Results: The three divisions of cationic proteins exhibited antibacterial

  17. Virtual volatility

    Science.gov (United States)

    Silva, A. Christian; Prange, Richard E.

    2007-03-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation strategy.

  18. Virtual volatility

    OpenAIRE

    A. Christian Silva; Prange, Richard E.

    2006-01-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation st...

  19. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  20. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  1. Metabolic strategies of beer spoilage lactic acid bacteria in beer.

    Science.gov (United States)

    Geissler, Andreas J; Behr, Jürgen; von Kamp, Kristina; Vogel, Rudi F

    2016-01-04

    Beer contains only limited amounts of readily fermentable carbohydrates and amino acids. Beer spoilage lactic acid bacteria (LAB) have to come up with metabolic strategies in order to deal with selective nutrient content, high energy demand of hop tolerance mechanisms and a low pH. The metabolism of 26 LAB strains of 6 species and varying spoilage potentialwas investigated in order to define and compare their metabolic capabilities using multivariate statistics and outline possible metabolic strategies. Metabolic capabilities of beer spoilage LAB regarding carbohydrate and amino acids did not correlate with spoilage potential, but with fermentation type (heterofermentative/homofermentative) and species. A shift to mixed acid fermentation by homofermentative (hof) Pediococcus claussenii and Lactobacillus backii was observed as a specific feature of their growth in beer. For heterofermentative (hef) LAB a mostly versatile carbohydrate metabolism could be demonstrated, supplementing the known relevance of organic acids for their growth in beer. For hef LAB a distinct amino acid metabolism, resulting in biogenic amine production, was observed, presumably contributing to energy supply and pH homeostasis.

  2. Bacterial spoilage of meat and cured meat products

    NARCIS (Netherlands)

    Borch, E.; Kant-Muermans, M.L.T.; Blixt, Y.

    1996-01-01

    The influence of environmental factors (product composition and storage conditions) on the selection, growth rate and metabolic activity of the bacterial flora is presented for meat (pork and beef) and cooked, cured meat products. The predominant bacteria associated with spoilage of refrigerated

  3. Bacterial spoilage of meat and cured meat products

    NARCIS (Netherlands)

    Borch, E.; Kant-Muermans, M.L.T.; Blixt, Y.

    1996-01-01

    The influence of environmental factors (product composition and storage conditions) on the selection, growth rate and metabolic activity of the bacterial flora is presented for meat (pork and beef) and cooked, cured meat products. The predominant bacteria associated with spoilage of refrigerated bee

  4. Meat Spoilage Mechanisms and Preservation Techniques: A Critical Review

    Directory of Open Access Journals (Sweden)

    D. Dave

    2011-01-01

    Full Text Available Problem statement: Extremely perishable meat provides favorable growth condition for various microorganisms. Meat is also very much susceptible to spoilage due to chemical and enzymatic activities. The breakdown of fat, protein and carbohydrates of meat results in the development of off-odors, off-flavor and slim formation which make the meat objectionable for human consumption. It is, therefore, necessary to control meat spoilage in order to increase its shelf life and maintain its nutritional value, texture and flavor. Approach: A comprehensive literature review was performed on the spoliage mechanisms of meat and meat products and preservation techniques. Results: Historical data reveals that salting, drying, smoking, fermentation and canning were the traditional methods used to prevent meat spoilage and extend its shelf life. However, in order to prevent wholesomeness, appearance, composition, tenderness, flavor, juiciness and nutritive value, new methods were developed. These included: cooling, freezing and chemical preservation. Wide range of physical and chemical reactions and actions of microorganisms or enzymes are responsible for the meat spoilage. Microbial growth, oxidation and enzymatic autolysis are three basic mechanisms responsible for spoilage of meat. Microbial growth and metabolism depends on various factors including: pre-slaughter husbandry practices, age of the animal at the time of slaughtering, handling during slaughtering, evisceration and processing, temperature controls during slaughtering, processing and distribution, preservation methods, type of packaging and handling and storage by consumer. Microbial spoilage causes pH change, slime formation, structural components degradation, off odors and appearance change. Autoxidation of lipids and the production of free radicals are natural processes which affect fatty acids and lead to oxidative deterioration of meat and off-flavour development. Lipid hydrolysis can take

  5. Acetic acid bacteria spoilage of bottled red wine -- a review.

    Science.gov (United States)

    Bartowsky, Eveline J; Henschke, Paul A

    2008-06-30

    Acetic acid bacteria (AAB) are ubiquitous organisms that are well adapted to sugar and ethanol rich environments. This family of Gram-positive bacteria are well known for their ability to produce acetic acid, the main constituent in vinegar. The oxidation of ethanol through acetaldehyde to acetic acid is well understood and characterised. AAB form part of the complex natural microbial flora of grapes and wine, however their presence is less desirable than the lactic acid bacteria and yeast. Even though AAB were described by Pasteur in the 1850s, wine associated AAB are still difficult to cultivate on artificial laboratory media and until more recently, their taxonomy has not been well characterised. Wine is at most risk of spoilage during production and the presence of these strictly aerobic bacteria in grape must and during wine maturation can be controlled by eliminating, or at least limiting oxygen, an essential growth factor. However, a new risk, spoilage of wine by AAB after packaging, has only recently been reported. As wine is not always sterile filtered prior to bottling, especially red wine, it often has a small resident bacterial population (bacteria. This spoilage is evident as a distinct deposit of bacterial biofilm in the neck of the bottle at the interface of the wine and the headspace of air, and is accompanied with vinegar, sherry, bruised apple, nutty, and solvent like off-aromas, depending on the degree of spoilage. This review focuses on the wine associated AAB species, the aroma and flavour changes in wine due to AAB metabolism, discusses the importance of oxygen ingress into the bottle and presents a hypothesis for the mechanism of spoilage of bottled red wine.

  6. Characterization and control of Mucor circinelloides spoilage in yogurt.

    Science.gov (United States)

    Snyder, Abigail B; Churey, John J; Worobo, Randy W

    2016-07-02

    Consumer confidence in the food industry is severely affected by large-scale spoilage incidents. However, relatively little research exists on spoilage potential of members of the fungal subphylum Mucormycotina (e.g. Mucor), which includes dimorphic spoilage organisms that can switch between a yeast-like and hyphal phase depending on environmental conditions. The presence of Mucor circinelloides in yogurt may not cause spoilage, but growth and subsequent changes in quality (e.g. container bloating) can cause spoilage if not controlled. The purpose of this study was to evaluate the effects on M. circinelloides of pasteurization regimen, natamycin concentrations, and storage temperature in yogurt production, as measured by fungal proliferation and carbon dioxide production. A strain of M. circinelloides isolated from commercially spoiled yogurt showed greater yogurt-spoilage potential than clinical isolates and other industrial strains. D-values and z-values were determined for the spoilage isolate in milk as an evaluation of the fungus' ability to survive pasteurization. Natamycin was added to yogurt at 0, 5, 10, 15, and 20ppm (μg/ml) to determine its ability to inhibit M. circinelloides over the course of month-long challenge studies at 4°C, 15°C, and 25°C. Survivors were recovered on acidified PDA and carbon dioxide levels were recorded. The D-values at 54°C, 56°C, and 58°C for hyphae/sporangiospores were (in min) 38.31±0.02, 10.17±0.28, and 1.94±0.53, respectively, which yielded a z-value of 3.09°C. The D-values at 51°C, 53°C, and 55°C for yeast-like cells were (in min) 14.25±0.12, 6.87±1.19, and 2.44±0.35, respectively, which yielded a z-value of 0.34°C. These results indicated that M. circinelloides would not survive fluid milk pasteurization if contamination occurred prior to thermal treatment. CO2 production was only observed when M. circinelloides was incubated under low-oxygen conditions, and occurred only at temperatures above 4

  7. Chasing volatility

    DEFF Research Database (Denmark)

    Caporin, Massimiliano; Rossi, Eduardo; Santucci de Magistris, Paolo

    The realized volatility of financial returns is characterized by persistence and occurrence of unpreditable large increments. To capture those features, we introduce the Multiplicative Error Model with jumps (MEM-J). When a jump component is included in the multiplicative specification, the condi...... models, the introduction of the jump component provides a sensible improvement in the fit, as well as for in-sample and out-of-sample volatility tail forecasts....

  8. Volatility Risk

    OpenAIRE

    Zhiguang Wang

    2009-01-01

    Classical capital asset pricing theory tells us that riskaverse investors would require higher returns to compensate for higher risk on an investment. One type of risk is price (return) risk, which reflects uncertainty in the price level and is measured by the volatility (standard deviation) of asset returns. Volatility itself is also known to be random and hence is perceived as another type of risk. Investors can bear price risk in exchange for a higher return. But are investors willing to p...

  9. Spoilage potential of psychrotrophic lactic acid bacteria (LAB) species: Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, on sweet bell pepper (SBP) simulation medium under different gas compositions.

    Science.gov (United States)

    Pothakos, Vasileios; Nyambi, Clarice; Zhang, Bao-Yu; Papastergiadis, Antonios; De Meulenaer, Bruno; Devlieghere, Frank

    2014-05-16

    Sweet bell peppers are a significant constituent of retail, chilled-stored and packaged food products like fresh salads, marinades and ready-to-eat (RTE) meals. Previously, through general screening of the Belgian market and by means of source tracking analysis in a plant manufacturing minimally processed, vegetable salads the susceptibility of fresh-cut sweet bell peppers to lactic acid bacterium (LAB) contamination was substantiated. The determination of the metabolic profiles of Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, two major psychrotrophic, spoilage-related LAB species, on sweet bell pepper (SBP) simulation medium under different packaging conditions - 1.) vacuum: 100% N2, 2.) air: 21% O2, 79% N2, 3.) MAP1: 30% CO2, 70% N2 and 4.) MAP2: 50% O2, 50% CO2 - facilitated a better understanding of the spoilage potential of these microbes as well as the presumptive contribution of O2 in the spectrum of produced volatile organic compounds (VOCs) associated with poor organoleptic properties of food products. Generally, none of the applied gas compositions inhibited the growth of the 4 L. gelidum subsp. gasicomitatum isolates, however the presence of O2 resulted in buttery off-odors by inducing primarily the accumulation of diacetyl and pungent "vinegar" smell due to acetic acid. The 3 tested isolates of L. piscium varied greatly among their growth dynamics and inhibition at MAP2. They exhibited either weak spoilage profile or very offensive metabolism confirming significant intraspecies diversity.

  10. A generic model for spoilage of acidic emulsified foods: combining physicochemical data, diversity and levels of specific spoilage organisms.

    Science.gov (United States)

    Manios, Stavros G; Lambert, Ronald J W; Skandamis, Panagiotis N

    2014-01-17

    The spoilage pattern of three emulsified, vegetable-based spreads of low pH (3.90-4.15) adjusted with acetic acid was characterized by correlating the growth of spoilage flora with the organoleptic and physicochemical changes, as well as the changes in the species composition of the dominant microflora during storage under isothermal conditions. In a further step, a generic (hereafter called 'unified') model was developed to describe the maximum specific growth rate of the specific spoilage organisms (SSOs) in all acetic acid acidified products, including literature data and additional in-house data from similar products, as a function of the storage temperature, pH (3.61-4.25) and initial concentration of the undissociated acetic acid in each product. The predictions of the unified model were compared with those of product-specific models, with temperature as the sole predictor variable. Two independent batches of commercially prepared pepper- (PS), fava beans- (FS) and eggplant-based (ES) spreads were stored at 4, 7, 10, 12, 15, 18, 20 and 25°C. The growth of lactic acid bacteria (SSOs; LAB) was correlated with changes in pH, titratable acidity and organic acids concentration, as well as sensory characteristics, in order to define the shelf-life of the products. Isolates from each spread and storage temperature were grouped with SDS-PAGE and were identified with 16S rRNA, determining the association between spoilage and species diversity. Product-specific models were developed using the square root model, while a polynomial and the Ratkowsky model were used for the development of the unified model. Products with lower pH and/or higher acetic acid content showed higher microbial stability. Lactobacillus plantarum or Lactobacillus brevis dominated the LAB association in all three spreads, although their relative percentage at the beginning of storage varied significantly. These facultative or obligate hetero-fermentative bacteria increased lactic acid and

  11. Multi spectral imaging analysis for meat spoilage discrimination

    DEFF Research Database (Denmark)

    Christiansen, Asger Nyman; Carstensen, Jens Michael; Papadopoulou, Olga

    with corresponding sensory data would be of great interest. The purpose of this research was to produce a method capable of quantifying and/or predicting the spoilage status (e.g. express in TVC counts as well as on sensory evaluation) using a multi spectral image of a meat sample and thereby avoid any time...... classification methods: Naive Bayes Classifier as a reference model, Canonical Discriminant Analysis (CDA) and Support Vector Classification (SVC). As the final step, generalization of the models was performed using k-fold validation (k=10). Results showed that image analysis provided good discrimination of meat...... samples. In the case where all data were taken together the misclassification error amounted to 16%. When spoilage status was based on visual sensory data, the model produced a MER of 22% for the combined dataset. These results suggest that it is feasible to employ a multi spectral image...

  12. Diversity of Leuconostoc gasicomitatum associated with meat spoilage.

    Science.gov (United States)

    Vihavainen, Elina J; Björkroth, K Johanna

    2009-11-30

    Leuconostoc gasicomitatum isolates (n=384) associated with spoilage of meat and vegetable-based foods were characterised by pulsed-field gel electrophoresis (PFGE) typing. Our aim was to evaluate the diversity and distribution of spoilage-associated L. gasicomitatum isolates from meat products, and to determine whether the PFGE genotypes are specific to product, producer, or isolation year (1997-2007). PFGE typing differentiated the isolates into 68 genotypes, and revealed that none one of the 54 genotypes associated with meat products was recovered from vegetable-based foods. Generally, the meat-derived genotypes were not specific to meat animal species, and many genotypes included isolates from products of different types or processors, as well as isolates collected in different years. Furthermore, certain genotypes were repeatedly identified from products of the same processing plant suggesting that the processing environment may have an impact on L. gasicomitatum contamination of meat products.

  13. Identification of beer spoilage microorganisms using the MALDI Biotyper platform.

    Science.gov (United States)

    Turvey, Michelle Elizabeth; Weiland, Florian; Meneses, Jon; Sterenberg, Nick; Hoffmann, Peter

    2016-03-01

    Beer spoilage microorganisms present a major risk for the brewing industry and can lead to cost-intensive recall of contaminated products and damage to brand reputation. The applicability of molecular profiling using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) in combination with Biotyper software was investigated for the identification of beer spoilage microorganisms from routine brewery quality control samples. Reference mass spectrum profiles for three of the most common bacterial beer spoilage microorganisms (Lactobacillus lindneri, Lactobacillus brevis and Pediococcus damnosus), four commercially available brewing yeast strains (top- and bottom-fermenting) and Dekkera/Brettanomyces bruxellensis wild yeast were established, incorporated into the Biotyper reference library and validated by successful identification after inoculation into beer. Each bacterial species could be accurately identified and distinguished from one another and from over 5600 other microorganisms present in the Biotyper database. In addition, wild yeast contaminations were rapidly detected and distinguished from top- and bottom-fermenting brewing strains. The applicability and integration of mass spectrometry profiling using the Biotyper platform into existing brewery quality assurance practices within industry were assessed by analysing routine microbiology control samples from a local brewery, where contaminating microorganisms could be reliably identified. Brewery-isolated microorganisms not present in the Biotyper database were further analysed for identification using LC-MS/MS methods. This renders the Biotyper platform a promising candidate for biological quality control testing within the brewing industry as a more rapid, high-throughput and cost-effective technology that can be tailored for the detection of brewery-specific spoilage organisms from the local environment.

  14. Effect of Carbon Dioxide on Growth of Meat Spoilage Bacteria

    OpenAIRE

    Gill, C O; Tan, K.H.

    1980-01-01

    The ability of CO2 to inhibit respiration and growth of representative strains of seven species of meat spoilage bacteria was examined. Enterobacter and Microbacterium thermosphactum were unaffected by CO2. Both respiration and growth of the other species were inhibited. With four of the species (fluorescent and nonfluorescent Pseudomonas, Alteromonas putrefaciens, and Yersinia enterocolitica), the inhibition pattern in a complex medium was similar, and inhibition was incomplete and reached a...

  15. Identification of meat spoilage gene biomarkers in Pseudomonas putida using gene profiling

    OpenAIRE

    Mohareb, Fady R; Iriondo, Maite; Doulgeraki, Agapi I.; Van Hoek, Angela; Aarts, Henk; Cauchi, Michael; Nychas, George-John E.

    2015-01-01

    While current food science research mainly focuses on microbial changes in food products that lead to foodborne illnesses, meat spoilage remains as an unsolved problem for the meat industry. This can result in important economic losses, food waste and loss of consumer confidence in the meat market. Gram-negative bacteria involved in meat spoilage are aerobes or facultative anaerobes. These represent the group with the greatest meat spoilage potential, where Pseudomonas tend to dominate the mi...

  16. Identification of meat spoilage gene biomarkers in Pseudomonas putida using gene profiling

    OpenAIRE

    Mohareb, Fady R.; Iriondo, Maite; Doulgeraki, Agapi I.; Hoek, Angela van; Aarts, Henk; Cauchi, Michael; Nychas, George-John E.

    2015-01-01

    While current food science research mainly focuses on microbial changes in food products that lead to foodborne illnesses, meat spoilage remains as an unsolved problem for the meat industry. This can result in important economic losses, food waste and loss of consumer confidence in the meat market. Gram-negative bacteria involved in meat spoilage are aerobes or facultative anaerobes. These represent the group with the greatest meat spoilage potential, where Pseudomonas tend to dominate the mi...

  17. Antifungal Activity of Selected Lactic Acid Bacteria and Propionic Acid Bacteria against Dairy-Associated Spoilage Fungi

    DEFF Research Database (Denmark)

    Aunsbjerg, Stina Dissing

    Bacterial cultures of lactic and propionic acid bacteria are widely used in fermented products including dairy products. Spoilage fungi may constitute a quality and safety issue in these products. The antifungal properties of some lactic and propionic acid bacteria make them potential candidates...... diacetyl and lactic acid, 6 antifungal hydroxy acids were identified. Of these, 3 have previously been reported from antifungal lactic acid bacteria, whereas the other 3 hydroxy acids have not previously been reported produced by antifungal lactic acid bacteria....... factors thereby facilitating development of new protective cultures. The aim of the current thesis was to determine and study metabolites involved in antifungal activity of protective Lactobacillus paracasei and Propionibacterium freudenreichii subsp. shermanii. This involved development of a suitable...

  18. Morphine metabolites

    DEFF Research Database (Denmark)

    Christrup, Lona Louring

    1997-01-01

    , morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) are the major metabolites of morphine. The metabolism of morphine occurs not only in the liver, but may also take place in the brain and the kidneys. The glucuronides are mainly eliminated via bile and urine. Glucuronides as a rule...

  19. Significance of heme-based respiration in meat spoilage caused by Leuconostoc gasicomitatum.

    Science.gov (United States)

    Jääskeläinen, Elina; Johansson, Per; Kostiainen, Olli; Nieminen, Timo; Schmidt, Georg; Somervuo, Panu; Mohsina, Marzia; Vanninen, Paula; Auvinen, Petri; Björkroth, Johanna

    2013-02-01

    Leuconostoc gasicomitatum is a psychrotrophic lactic acid bacterium (LAB) which causes spoilage in cold-stored modified-atmosphere-packaged (MAP) meat products. In addition to the fermentative metabolism, L. gasicomitatum is able to respire when exogenous heme and oxygen are available. In this study, we investigated the respiration effects on growth rate, biomass, gene expression, and volatile organic compound (VOC) production in laboratory media and pork loin. The meat samples were evaluated by a sensory panel every second or third day for 29 days. We observed that functional respiration increased the growth (rate and yield) of L. gasicomitatum in laboratory media with added heme and in situ meat with endogenous heme. Respiration increased enormously (up to 2,600-fold) the accumulation of acetoin and diacetyl, which are buttery off-odor compounds in meat. Our transcriptome analyses showed that the gene expression patterns were quite similar, irrespective of whether respiration was turned off by excluding heme from the medium or mutating the cydB gene, which is essential in the respiratory chain. The respiration-based growth of L. gasicomitatum in meat was obtained in terms of population development and subsequent development of sensory characteristics. Respiration is thus a key factor explaining why L. gasicomitatum is so well adapted in high-oxygen packed meat.

  20. On-site monitoring of fish spoilage using vanadium pentoxide xerogel modified interdigitated gold electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Helali, S.; Abdelghani, A. [Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST (Tunisia); Jaffrezic-Renault, N. [Laboratoire de Sciences Analytiques, Universite de Claude Bernard, Lyon (France); Trikalitis, P.N. [Department of Chemistry, University of Crete, 71 003, Heraklion Crete (Greece); Efstathiou, C.E. [Department of Chemistry, University of Athens, 157 71, Athens (Greece); Prodromidis, M.I., E-mail: mprodrom@cc.uoi.g [Department of Chemistry, University of Ioannina, 45 110, Ioannina (Greece)

    2010-05-30

    The development of a vanadium pentoxide xerogel (VXG)-based sensor for the detection of volatile inorganic (ammonia) and organic (dimethylamine, etc.) amines is described. The xerogel film was deposited on interdigitated gold electrodes by dip-coating using an aqueous solution of VXG. The morphology of the sensing layer, its interaction with ammonia, which was used as a model analyte throughout this work, as well as the regeneration of the surface of the sensor electrodes with vapors of HCl were examined with scanning electron microscopy and FTIR spectroscopy. Signal changes, due to changes of the RC-product of the electrochemical cell (Au-VXG-Au), as a result of its interactions with ammonia vapors, were probed with a portable, homemade charge meter, the Multipulser. Exposing the sensor electrodes to various concentrations of ammonia vapors resulted in proportional changes in the signal output. Finally, the proposed sensors were successfully used for on-site, real-time monitoring of fish spoilage in ambient conditions.

  1. Genome Survey Sequencing of the Wine Spoilage Yeast Dekkera (Brettanomyces) bruxellensis▿ †

    Science.gov (United States)

    Woolfit, Megan; Rozpędowska, Elżbieta; Piškur, Jure; Wolfe, Kenneth H.

    2007-01-01

    The hemiascomycete yeast Dekkera bruxellensis, also known as Brettanomyces bruxellensis, is a major cause of wine spoilage worldwide. Wines infected with D. bruxellensis develop distinctive, unpleasant aromas due to volatile phenols produced by this species, which is highly ethanol tolerant and facultatively anaerobic. Despite its importance, however, D. bruxellensis has been poorly genetically characterized until now. We performed genome survey sequencing of a wine strain of D. bruxellensis to obtain 0.4× coverage of the genome. We identified approximately 3,000 genes, whose products averaged 49% amino acid identity to their Saccharomyces cerevisiae orthologs, with similar intron contents. Maximum likelihood phylogenetic analyses suggest that the relationship between D. bruxellensis, S. cerevisiae, and Candida albicans is close to a trichotomy. The estimated rate of chromosomal rearrangement in D. bruxellensis is slower than that calculated for C. albicans, while its rate of amino acid evolution is somewhat higher. The proteome of D. bruxellensis is enriched for transporters and genes involved in nitrogen and lipid metabolism, among other functions, which may reflect adaptations to its low-nutrient, high-ethanol niche. We also identified an adenyl deaminase gene that has high similarity to a gene in bacteria of the Burkholderia cepacia species complex and appears to be the result of horizontal gene transfer. These data provide a resource for further analyses of the population genetics and evolution of D. bruxellensis and of the genetic bases of its physiological capabilities. PMID:17277171

  2. Genome survey sequencing of the wine spoilage yeast Dekkera (Brettanomyces) bruxellensis.

    Science.gov (United States)

    Woolfit, Megan; Rozpedowska, Elzbieta; Piskur, Jure; Wolfe, Kenneth H

    2007-04-01

    The hemiascomycete yeast Dekkera bruxellensis, also known as Brettanomyces bruxellensis, is a major cause of wine spoilage worldwide. Wines infected with D. bruxellensis develop distinctive, unpleasant aromas due to volatile phenols produced by this species, which is highly ethanol tolerant and facultatively anaerobic. Despite its importance, however, D. bruxellensis has been poorly genetically characterized until now. We performed genome survey sequencing of a wine strain of D. bruxellensis to obtain 0.4x coverage of the genome. We identified approximately 3,000 genes, whose products averaged 49% amino acid identity to their Saccharomyces cerevisiae orthologs, with similar intron contents. Maximum likelihood phylogenetic analyses suggest that the relationship between D. bruxellensis, S. cerevisiae, and Candida albicans is close to a trichotomy. The estimated rate of chromosomal rearrangement in D. bruxellensis is slower than that calculated for C. albicans, while its rate of amino acid evolution is somewhat higher. The proteome of D. bruxellensis is enriched for transporters and genes involved in nitrogen and lipid metabolism, among other functions, which may reflect adaptations to its low-nutrient, high-ethanol niche. We also identified an adenyl deaminase gene that has high similarity to a gene in bacteria of the Burkholderia cepacia species complex and appears to be the result of horizontal gene transfer. These data provide a resource for further analyses of the population genetics and evolution of D. bruxellensis and of the genetic bases of its physiological capabilities.

  3. Astaxanthin from psychrotrophic Sphingomonas faeni exhibits antagonism against food-spoilage bacteria at low temperatures.

    Science.gov (United States)

    Mageswari, Anbazhagan; Subramanian, Parthiban; Srinivasan, Ramachandran; Karthikeyan, Sivashanmugam; Gothandam, Kodiveri Muthukaliannan

    2015-10-01

    Food production and processing industry holds a perpetual relationship with microorganisms and their by-products. In the present study, we aimed to identify beneficial cold-adapted bacteria devoid of any food spoilage properties and study their antagonism against common food-borne pathogens at low temperature conditions. Ten isolates were obtained on selective isolation at 5 °C, which were spread across genera Pseudomonas, Sphingomonas, Psychrobacter, Leuconostoc, Rhodococcus, and Arthrobacter. Methanol extracts of strains were found to contain several bioactive metabolites. Among the studied isolates, methanol extracts of S. faeni ISY and Rhodococcus fascians CS4 were found to show antagonism against growth of Escherichia coli, Proteus mirabilis, Enterobacter aerogenes, Listeria monocytogenes and Vibrio fischeri at refrigeration temperatures. Characterization of the abundant yellow pigment in methanol extracts of S. faeni ISY through UV-Vis spectrophotometry, high performance liquid chromatography (HPLC) and mass spectrometry (LC-MS) revealed the presence of astaxanthin, which, owing to its presence in very large amounts and evidenced to be responsible for antagonistic activity of the solvent extract.

  4. Prediction of spoilage of tropical shrimp (Penaeus notialis) under dynamic temperature regimes

    NARCIS (Netherlands)

    Dabade, D.S.; Azokpota, P.; Nout, M.J.R.; Hounhouigan, D.J.; Zwietering, M.H.; Besten, den H.M.W.

    2015-01-01

    The spoilage activity of Pseudomonas psychrophila and Carnobacterium maltaromaticum, two tropical shrimp (Penaeus notialis) spoilage organisms, was assessed in cooked shrimps stored at 0 to 28 °C. Microbiological, chemical and sensory analyses were performed during storage. P. psychrophila had a hig

  5. Draft Genome Sequence of the Beer Spoilage Bacterium Megasphaera cerevisiae Strain PAT 1T

    OpenAIRE

    Kutumbaka, Kirthi K.; Pasmowitz, Joshua; Mategko, James; Reyes, Dindo; Friedrich, Alex; Han, Sukkyun; Martens-Habbena, Willm; Neal-McKinney, Jason; Janagama, Harish K.; Nadala, Cesar; Samadpour, Mansour

    2015-01-01

    The genus Megasphaera harbors important spoilage organisms that cause beer spoilage by producing off flavors, undesirable aroma, and turbidity. Megasphaera cerevisiae is mainly found in nonpasteurized low-alcohol beer. In this study, we report the draft genome of the type strain of the genus, M. cerevisiae strain PAT 1T.

  6. Lactobacilli and tartrazine as causative agents of a red colored spoilage in cucumber pickle products

    Science.gov (United States)

    The cucumber pickling industry has sporadically experienced spoilage outbreaks in fermented cucumber products characterized by development of red color on the surface of the cucumbers. Lactobacillus casei and Lactobacillus paracasei were isolated from two outbreaks of this spoilage which occurred a...

  7. Metabolic footprinting of Lactobacillus buchneri strain LA1147 during anaerobic spoilage of fermented cucumbers

    Science.gov (United States)

    Lactobacillus buchneri has recently been associated with anaerobic spoilage of fermented cucumbers due to its ability to metabolize lactic acid into acetic acid and 1,2-propanediol. However, we have limited knowledge of other chemical components in fermented cucumber that may be related to spoilage ...

  8. Diversity of spoilage fungi associated with various French dairy products.

    Science.gov (United States)

    Garnier, Lucille; Valence, Florence; Pawtowski, Audrey; Auhustsinava-Galerne, Lizaveta; Frotté, Nicolas; Baroncelli, Riccardo; Deniel, Franck; Coton, Emmanuel; Mounier, Jérôme

    2017-01-16

    Yeasts and molds are responsible for dairy product spoilage, resulting in significant food waste and economic losses. Yet, few studies have investigated the diversity of spoilage fungi encountered in dairy products. In the present study, 175 isolates corresponding to 105 from various spoiled dairy products and 70 originating from dairy production environments, were identified using sequencing of the ITS region, the partial β-tubulin, calmodulin and/or EFα genes, and the D1-D2 domain of the 26S rRNA gene for filamentous fungi and yeasts, respectively. Among the 41 species found in spoiled products, Penicillium commune and Penicillium bialowiezense were the most common filamentous fungi, representing around 10% each of total isolates while Meyerozyma guilliermondii and Trichosporon asahii were the most common yeasts (4.8% each of total isolates). Several species (e.g. Penicillium antarcticum, Penicillium salamii and Cladosporium phyllophilum) were identified for the first time in dairy products or their environment. In addition, numerous species were identified in both spoiled products and their corresponding dairy production environment suggesting that the latter acts as a primary source of contamination. Secondly, the resistance to chemical preservatives (sodium benzoate, calcium propionate, potassium sorbate and natamycin) of 10 fungal isolates representative of the observed biodiversity was also evaluated. Independently of the fungal species, natamycin had the lowest minimum inhibitory concentration (expressed in gram of preservative/l), followed by potassium sorbate, sodium benzoate and calcium propionate. In the tested conditions, Cladosporium halotolerans and Didymella pinodella were the most sensitive fungi while Yarrowia lipolytica and Candida parapsilosis were the most resistant towards the tested preservatives. This study provides interesting information on the occurrence of fungal contaminants in dairy products and environments that may help developing

  9. Spoilage evaluation, shelf-life prediction, and potential spoilage organisms of tropical brackish water shrimp (Penaeus notialis) at different storage temperatures

    NARCIS (Netherlands)

    Dabade, D.S.; Besten, den H.M.W.; Azokpota, P.; Nout, M.J.R.; Hounhouigan, D.J.; Zwietering, M.H.

    2015-01-01

    Maintaining the freshness of shrimp is a concern to shrimp stakeholders. To improve shrimp quality management, it is of importance to evaluate shrimp spoilage characteristics. Therefore, microbiological, sensory, and chemical changes of naturally contaminated tropical brackish water shrimp (Penaeus

  10. Modeling and predicting spoilage of cooked, cured meat products by multivariate analysis.

    Science.gov (United States)

    Mataragas, Marios; Skandamis, Panagiotis; Nychas, George-John E; Drosinos, Eleftherios H

    2007-11-01

    A cooked, cured meat product is a perishable product spoiled mainly by lactic acid bacteria (LAB). LAB cause discoloration, slime formation, off-odors and off-flavors as the result of their metabolic activity producing various products. These microbial products in conjunction with the microbial population could be used to assess the degree of spoilage of this type of product. The spoilage evaluation was achieved by following a multivariate approach. Cluster analysis, principal component analysis and partial least square regression were employed to associate spoilage with microbiological and physicochemical parameters. The developed model was capable of giving accurate predictions of spoilage describing the spoilage associations. The study might contribute to the improvement of quality assurance systems of meat enterprises.

  11. Behaviour of Brochothrix thermosphacta in presence of other meat spoilage microbial groups.

    Science.gov (United States)

    Russo, F; Ercolini, D; Mauriello, G; Villani, F

    2006-12-01

    The microbial flora of fresh meat stored aerobically at 5 degrees C up to spoilage was enumerated and collected in order to have mixed spoilage bacterial groups to be used in competition tests against Brochothrix thermosphacta. The bacterial groups collected as bulk colonies were identified by PCR-DGGE followed by partial 16S rDNA sequencing. The predominant bacteria associated with the spoilage of the refrigerated beef were B. thermosphacta, Pseudomonas spp, Enterobacteriaceae and lactic acid bacteria (LAB). The interactions between B. thermosphacta and the other spoilage microbial groups were studied in vitro at 5 degrees C. The results showed that a decrease of the growth of B. thermosphacta was evidenced in presence of LAB at 5 degrees C while the bacterium is the dominant organism when inoculated with mixtures of Pseudomonas spp., LAB and Enterobacteriaceae. A better understanding of bacterial meat spoilage interactions may lead to improved quality of fresh meat stored in refrigerated conditions.

  12. Survey of volatile oxylipins and their biosynthetic precursors in bryophytes.

    Science.gov (United States)

    Croisier, Emmanuel; Rempt, Martin; Pohnert, Georg

    2010-04-01

    Oxylipins are metabolites which are derived from the oxidative fragmentation of polyunsaturated fatty acids. These metabolites play central roles in plant hormonal regulation and defense. Here we survey the production of volatile oxylipins in bryophytes and report the production of a high structural variety of C5, C6, C8 and C9 volatiles of mosses. In liverworts and hornworts oxylipin production was not as pronounced as in the 23 screened mosses. A biosynthetic investigation revealed that both, C18 and C20 fatty acids serve as precursors for the volatile oxylipins that are mainly produced after mechanical wounding of the green tissue of mosses.

  13. Psychrotrophic clostridia causing spoilage in cooked meat and poultry products.

    Science.gov (United States)

    Kalinowski, R M; Tompkin, R B

    1999-07-01

    Certain types of commercially produced noncured turkey breast and roast beef are precooked in situ, stored at 4 degrees C or below, and typically given use by dates of greater than 50 days. While of rare, sporadic occurrence, an unpleasant spoilage characterized by strong H2S odor and gas production has been observed in these products. This spoilage is due to the growth of psychrotrophic anaerobic sporeformers. Isolates from roast beef resemble Clostridium laramie while isolates from uncured turkey have been designated C. ctm for cooked turkey meat. The turkey breast isolates were characterized by temperature growth ranges, carbohydrate fermentations, and other biochemical reactions. Growth of all isolates was inhibited in broth media by 3.0% NaCl, 100 ppm nitrite, 2.0% sodium lactate, or 0.2% sodium diacetate. Inoculated studies were performed with three isolates in cooked turkey product. All three isolates grew and spoiled product at 10 and 3.3 degrees C, and one isolate grew at 0.5 and -3 degrees C. Some differences in growth were observed with the lactate and diacetate treatments in turkey meat among the three isolates. One isolate appeared to utilize the lactate, two were inhibited. Overall, 0.1% diacetate consistently delayed growth, although to different degrees, for all isolates.

  14. Analysis of Listeria using exogenous volatile organic compound metabolites and their detection by static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS).

    Science.gov (United States)

    Taylor, Carl; Lough, Fraser; Stanforth, Stephen P; Schwalbe, Edward C; Fowlis, Ian A; Dean, John R

    2017-07-01

    Listeria monocytogenes is a Gram-positive bacterium and an opportunistic food-borne pathogen which poses significant risk to the immune-compromised and pregnant due to the increased likelihood of acquiring infection and potential transmission of infection to the unborn child. Conventional methods of analysis suffer from either long turn-around times or lack the ability to discriminate between Listeria spp. reliably. This paper investigates an alternative method of detecting Listeria spp. using two novel enzyme substrates that liberate exogenous volatile organic compounds in the presence of α-mannosidase and D-alanyl aminopeptidase. The discriminating capabilities of this approach for identifying L. monocytogenes from other species of Listeria are investigated. The liberated volatile organic compounds (VOCs) are detected using an automated analytical technique based on static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS). The results obtained by SHS-MCC-GC-IMS are compared with those obtained by the more conventional analytical technique of headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results found that it was possible to differentiate between L. monocytogenes and L. ivanovii, based on their VOC response from α-mannosidase activity.

  15. Pricing Volatility Referenced Assets

    Directory of Open Access Journals (Sweden)

    Alan De Genaro Dario

    2006-12-01

    Full Text Available Volatility swaps are contingent claims on future realized volatility. Variance swaps are similar instruments on future realized variance, the square of future realized volatility. Unlike a plain vanilla option, whose volatility exposure is contaminated by its asset price dependence, volatility and variance swaps provide a pure exposure to volatility alone. This article discusses the risk-neutral valuation of volatility and variance swaps based on the framework outlined in the Heston (1993 stochastic volatility model. Additionally, the Heston (1993 model is calibrated for foreign currency options traded at BMF and its parameters are used to price swaps on volatility and variance of the BRL / USD exchange rate.

  16. Involvement of Acylated Homoserine Lactones (AHLs) of Aeromonas sobria in Spoilage of Refrigerated Turbot (Scophthalmus maximus L.).

    Science.gov (United States)

    Li, Tingting; Cui, Fangchao; Bai, Fengling; Zhao, Guohua; Li, Jianrong

    2016-07-13

    One quorum sensing strain was isolated from spoiled turbot. The species was determined by 16S rRNA gene analysis and classical tests, named Aeromonas sobria AS7. Quorum-sensing (QS) signals (N-acyl homoserine lactones (AHLs)) were detected by report strains and their structures were further determined by GC-MS. The activity changes of AHLs on strain growth stage as well as the influence of different culture conditions on secretion activity of AHLs were studied by the punch method. The result indicated that strain AS7 could induce report strains to produce typical phenotypic response. N-butanoyl-dl-homoserine lactone (C₄-HSL), N-hexanoyl-dl-homoserine lactone (C₆-HSL), N-octanoyl-dl-homoserine lactone (C₈-HSL), N-decanoyl-dl-homoserine lactone (C10-HSL), N-dodecanoyl-dl-homoserine lactone (C12-HSL) could be detected. The activities of AHLs were density-dependent and the max secretion level was at pH 8, sucrose culture, 1% NaCl and 32 h, respectively. The production of siderophore in strain AS7 was regulated by exogenous C₈-HSL, rather than C₆-HSL. Exogenous C₄-HSL and C₈-HSL accelerated the growth rate and population density of AS7 in turbot samples under refrigerated storage. However, according to the total viable counts and total volatile basic nitrogen (TVB-N) values of the fish samples, exogenous C₆-HSL did not cause spoilage of the turbot fillets. In conclusion, our results suggested that QS was involved in the spoilage of refrigerated turbot.

  17. Past and Future of Non-Saccharomyces Yeasts: From Spoilage Microorganisms to Biotechnological Tools for Improving Wine Aroma Complexity

    Science.gov (United States)

    Padilla, Beatriz; Gil, José V.; Manzanares, Paloma

    2016-01-01

    It is well established that non-Saccharomyces wine yeasts, considered in the past as undesired or spoilage yeasts, can enhance the analytical composition, and aroma profile of the wine. The contribution of non-Saccharomyces yeasts, including the ability to secret enzymes and produce secondary metabolites, glycerol and ethanol, release of mannoproteins or contributions to color stability, is species- and strain-specific, pointing out the key importance of a clever strain selection. The use of mixed starters of selected non-Saccharomyces yeasts with strains of Saccharomyces cerevisiae represents an alternative to both spontaneous and inoculated wine fermentations, taking advantage of the potential positive role that non-Saccharomyces wine yeast species play in the organoleptic characteristics of wine. In this context mixed starters can meet the growing demand for new and improved wine yeast strains adapted to different types and styles of wine. With the aim of presenting old and new evidences on the potential of non-Saccharomyces yeasts to address this market trend, we mainly review the studies focused on non-Saccharomyces strain selection and design of mixed starters directed to improve primary and secondary aroma of wines. The ability of non-Saccharomyces wine yeasts to produce enzymes and metabolites of oenological relevance is also discussed. PMID:27065975

  18. Advances in the control of wine spoilage by Zygosaccharomyces and Dekkera/Brettanomyces.

    Science.gov (United States)

    Zuehlke, J M; Petrova, B; Edwards, C G

    2013-01-01

    Understanding the characteristics of yeast spoilage, as well as the available control technologies, is vital to producing consistent, high-quality wine. Zygosaccharomyces bailii contamination may result in refermentation and CO2 production in sweet wines or grape juice concentrate, whereas Brettanomyces bruxellensis spoilage often contributes off-odors and flavors to red wines. Early detection of these yeasts by selective/differential media or genetic methods is important to minimize potential spoilage. More established methods of microbial control include sulfur dioxide, dimethyl dicarbonate, and filtration. Current research is focused on the use of chitosan, pulsed electric fields, low electric current, and ultrasonics as means to protect wine quality.

  19. Multi spectral imaging analysis for meat spoilage discrimination

    DEFF Research Database (Denmark)

    Christiansen, Asger Nyman; Carstensen, Jens Michael; Papadopoulou, Olga

    ) was performed in parallel with videometer image snapshots and sensory analysis. Odour and colour characteristics of meat were determined by a test panel and attributed into three pre-characterized quality classes, namely Fresh; Semi Fresh and Spoiled during the days of its shelf life. So far, different...... classification methods: Naive Bayes Classifier as a reference model, Canonical Discriminant Analysis (CDA) and Support Vector Classification (SVC). As the final step, generalization of the models was performed using k-fold validation (k=10). Results showed that image analysis provided good discrimination of meat...... samples regarding the spoilage process as evaluated from sensory as well as from microbiological data. The support vector classification (SVC) model outperformed other models. Specifically, the misclassification error rate (MER), derived from odour characteristics, was 18% for both aerobic and MAP meat...

  20. Effect of weak acid preservatives on growth of bakery product spoilage fungi at different water activities and pH values.

    Science.gov (United States)

    Suhr, K I; Nielsen, P V

    2004-08-15

    Inhibition of spoilage organisms from bakery products by weak acid preservatives in concentrations of 0%, 0.003%, 0.03% and 0.3% (w/v) was investigated experimentally on a substrate media with water activity (a(w)) and pH ranging from sourdough-fermented acidic rye bread to alkaline intermediate moisture sponge cake types (a(w) 0.80-0.95, pH 4.7-7.4). Initially, rye bread conditions (a(w) 0.94-0.97 and pH 4.4-4.8) in combination with calcium propionate were investigated. Results showed that the highest concentration of propionate (0.3%) at all conditions apart from high a(w) (0.97) and high pH (4.8) totally inhibited fungal growth for a 2-week period, with the exception of Penicillium roqueforti, Penicillium commune and Eurotium rubrum. Characteristically for the major spoiler of rye bread, P. roqueforti, all three isolates tested were stimulated by propionate and the stimulation was significantly enhanced at high water activity levels. The effect of propionate on production of secondary metabolites (mycophenolic acid, rugulovasine, echinulin, flavoglaucin) was also studied, and variable or isolate dependent results were found. Subsequently, a screening experiment representing a wider range of bakery products was conducted using calcium propionate, potassium sorbate and sodium benzoate. The obtained data was modelled using survival analysis to determine 'spoilage-free time' for the fungi. At the low a(w) level (0.80) only Eurotium species grew within the test period of 30 days. Higher water activity levels as well as higher pH values decreased spoilage-free times of the fungi. The preservative calcium propionate was less effective than potassium sorbate and sodium benzoate.

  1. Modelling the effect of ethanol on growth rate of food spoilage moulds

    NARCIS (Netherlands)

    Dantigny, P.; Guilmart, A.; Radoi, F.; Bensoussan, M.; Zwietering, M.H.

    2005-01-01

    The effect of ethanol (E) on the radial growth rate (¿) of food spoilage moulds (Aspergillus candidus, Aspergillus flavus, Aspergillus niger, Cladosporium cladosporioides, Eurotium herbariorum, Mucor circinelloides, Mucor racemosus, Paecilomyces variotii, Penicillium chrysogenum, Penicillium digitat

  2. Lactobacilli and tartrazine as causative agents of red-color spoilage in cucumber pickle products.

    Science.gov (United States)

    Pérez-Díaz, I M; Kelling, R E; Hale, S; Breidt, F; McFeeters, R F

    2007-09-01

    The cucumber pickling industry has sporadically experienced spoilage outbreaks in pickled cucumber products characterized by development of red color on the surface of the fruits. Lactobacillus casei and Lactobacillus paracasei were isolated from 2 outbreaks of this spoilage that occurred about 15 y apart during the last 3 decades. Both organisms were shown to produce this spoilage when inoculated into pickled cucumbers while concomitantly degrading the azo dye tartrazine (FD&C yellow nr 5). This food dye is used as a yellow coloring in the brine cover solutions of commercial pickled cucumber products. The red color does not occur in the absence of tartrazine, nor when turmeric is used as a yellow coloring in the pickles. Addition of sodium benzoate to the brine cover solutions of a pickled cucumber product, more specifically hamburger dill pickles, prevented growth of these lactic acid bacteria and the development of the red spoilage.

  3. Heat inactivation of wine spoilage yeast Dekkera bruxellensis by hot water treatment

    National Research Council Canada - National Science Library

    Fabrizio, V; Vigentini, I; Parisi, N; Picozzi, C; Compagno, C; Foschino, R

    2015-01-01

    Significance and Impact of the Study: Brettanomyces/Dekkera bruxellensis is the main yeast involved in red wine spoilage that occurs during ageing in barrel, generating considerable economic losses...

  4. Adhesive Property of Bacteria and Its Relationship to Microbial Spoilage of Shrimp.

    Science.gov (United States)

    1983-01-04

    Pseudomonas and Staphylococcus spp.) tend to be found in greater proportions and, hence, contribute more to the spoilage of shrimp. Accession For...on the meat surface. They also showed the adhesion process of Pseudomonas fragi when it came in contact with the beef stew meat . Thirdly, they...to indicate that Moraxella spp. would grow readily on shrimp and are a major contrib- utor to seafood spoilage . Staphylococcus spp. and Pseudomonas

  5. Evaluation and Comparison of Lactic Strains Isolated from Traditional Iranian Dairy Products (Richal Shiri with Armenian Dairy Products on Control of Food Spoilage Agents

    Directory of Open Access Journals (Sweden)

    F Karimpour

    2016-10-01

    Full Text Available Abstract Background & aim: Some bacterial metabolites isolated from fermentative products have antibacterial properties against food spoilage bacteria. The aim of this study was to evaluate the antibacterial properties of the isolated strains of traditional Armenian dairy products including cheese and traditional yogurts (Matson and Richal  shiri as a traditional dairy products from Iran. Material and method: In the present experimental study, bacterial strains were isolated, and subsequently the antibacterial activity of supernatants of strains on several types of spoilages bacteria such as Salmonella  was assessed. In addition, isolated strains from Rachel shiri showed  a good  antibacterial properties against Salmonella typhimurium. Results: The isolated strains were significantly reduced food contamination and increased the shelf -life. Furthermore, isolated strains from Richal shiri showed a good antibacterial properties against Salmonella typhimurium Conclusion: LAB strains isolated with appropriate inhibition, fermented power as a natural preservative and pragmatic as new products may be used in the dairy industry.

  6. Reducing Salt in Raw Pork Sausages Increases Spoilage and Correlates with Reduced Bacterial Diversity.

    Science.gov (United States)

    Fougy, Lysiane; Desmonts, Marie-Hélène; Coeuret, Gwendoline; Fassel, Christine; Hamon, Erwann; Hézard, Bernard; Champomier-Vergès, Marie-Christine; Chaillou, Stéphane

    2016-07-01

    Raw sausages are perishable foodstuffs; reducing their salt content raises questions about a possible increased spoilage of these products. In this study, we evaluated the influence of salt reduction (from 2.0% to 1.5% [wt/wt]), in combination with two types of packaging (modified atmosphere [50% mix of CO2-N2] and vacuum packaging), on the onset of spoilage and on the diversity of spoilage-associated bacteria. After 21 days of storage at 8°C, spoilage was easily observed, characterized by noticeable graying of the products and the production of gas and off-odors defined as rancid, sulfurous, or sour. At least one of these types of spoilage occurred in each sample, and the global spoilage intensity was more pronounced in samples stored under modified atmosphere than under vacuum packaging and in samples with the lower salt content. Metagenetic 16S rRNA pyrosequencing revealed that vacuum-packaged samples contained a higher total bacterial richness (n = 69 operational taxonomic units [OTUs]) than samples under the other packaging condition (n = 46 OTUs). The core community was composed of 6 OTUs (Lactobacillus sakei, Lactococcus piscium, Carnobacterium divergens, Carnobacterium maltaromaticum, Serratia proteamaculans, and Brochothrix thermosphacta), whereas 13 OTUs taxonomically assigned to the Enterobacteriaceae, Enterococcaceae, and Leuconostocaceae families comprised a less-abundant subpopulation. This subdominant community was significantly more abundant when 2.0% salt and vacuum packaging were used, and this correlated with a lower degree of spoilage. Our results demonstrate that salt reduction, particularly when it is combined with CO2-enriched packaging, promotes faster spoilage of raw sausages by lowering the overall bacterial diversity (both richness and evenness). Our study takes place in the context of raw meat product manufacturing and is linked to a requirement for salt reduction. Health guidelines are calling for a reduction in dietary salt intake

  7. 常温条件下白鱼中特定腐败菌的鉴定%Identification of Specific Spoilage Organisms in Whitefish at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    夏秀东; 刘小莉; 王英; 李莹; 黄自苏; 贾洋洋; 董明盛; 周剑忠

    2016-01-01

    通过分析常温条件下无菌白鱼鱼块(CK)以及接种不同腐败菌的无菌白鱼鱼块的感官评价、挥发性盐基氮(total volatile base nitrogen,TVBN)值、腐败菌生长动态以及pH值的变化,以腐败菌的生长动力学参数和TVBN产量因子(YTVBN/CFU)为定量指标,鉴定了常温条件下导致白鱼腐败的特定腐败菌(specific spoilage organism,SSO)。结果表明,在CK和接种葡萄球菌wf-1(Staphylococcus sp.wf-1)、摩根氏菌wf-1(Morganella sp.wf-1)、摩根氏菌wf-2(Morganellasp.wf-2)、变形杆菌wf-1(Proteus sp.wf-1)、变形杆菌wf-2(Proteus sp.wf-2)和变形杆菌wf-3(Proteussp.wf-3)的无菌白鱼鱼块中,以接种Morganellasp.wf-1的无菌白鱼鱼块达到感官拒绝点的时间最短,为15.16 h,此时鱼块的TVNB含量和菌落总数分别为29.98 mg/100 g和7.53(lg(CFU/g))。对这些腐败菌的生长动力学参数和YTVBN/CFU分析发现,Morganellasp.wf-1在无菌白鱼鱼块上的生长延滞期最短,为2.60 h;最大比生长速率最大,为0.3046 h-1;YTVBN/CFU最大,为6.27×10-9 mg TVBN/CFU。所有白鱼鱼块均出现pH值先下降后上升的过程,其中接种Morganellasp.wf-1和Morganellasp.wf-2的无菌鱼块在8~48 h之间的pH值远远高于CK和接种其他腐败菌的无菌白鱼鱼块。结合实验数据和SSO的概念,最终确定Morganella sp.wf-1为常温条件下导致白鱼腐败的SSO。%Sensory quality, total volatile base nitrogen (TVBN) value, the growth of spoilage bacteria and pH in sterile whitefish blocks (as control, CK) and those inoculated with different spoilage bacteria were analyzed, and growth kinetic parameters of spoilage bacteria and the yield factor for TVBN production (YTVBN/CFU) were used for quantitative measurements of microbial spoilage to identify the specific spoilage organism (SSO) of whitefish at room temperature. The results showed that the whitefish blocks inoculated

  8. [Fungal spoilage of foods and its risk assessment].

    Science.gov (United States)

    Udagawa, Shun-ichi

    2005-01-01

    From the second half of the 1990s, an increased regard has been given to the fungal spoilage of foods as follows: 1) post-harvest diseases and losses of fruits and vegetables, 2) deterioration of low water activity foods by xerophilic fungi, 3) contamination of psychrotolerant or psychrophilic fungi on foodstuffs and processed foods during storage and distribution at low temperature, and 4) spoilage of heat processed foods and soft drinks by heat-resistant fungi. In accordance with an international concern about food safety, mycotoxin contamination of foods has gained much global attention in recent times owing to its potential health hazards. The evaluation of mycotoxin hazards is principally based on the determination of a no-observed effect level (NOEL) in long-term toxicological studies, and the application of a safety factor (usually 100). In addition to hazard assessment, data on the natural occurrence of mycotoxins in various commodities and food intake data are needed to enable exposure assessment. Thus risk assessment of mycotoxins is, in fact, the product of hazard assessment and exposure assessment. In 1997, the FAO/WHO Joint Expert Committee on Food Additives (JECFA) considered estimates of the carcinogenic potency of aflatoxins and the potential risks associated with their intake. Recently the Codex Alimentarius Commission (Codex) has established standards for aflatoxin M1 in milk and for patulin in apple juice. The Codex is an international organization, supported by FAO/WHO, aiming at facilitating world trade and protecting the health of the consumer by developing international standards for food and feeds. Apart from aflatoxins, the JECFA has measured a provisional tolerable daily intake (TDI) for ochratoxin A, patulin, deoxynivalenol, T-2/HT-2 toxins, zearalenone and fumonisins. In 2001, the mycotoxins evaluated or re-evaluated at the JECFA meeting included ochratoxin A, deoxynivalenol, T-2/HT-2 toxins, fumonisins, and aflatoxin M1. In Japan

  9. Spoilage potential of Pseudomonas species isolated from goat milk.

    Science.gov (United States)

    Scatamburlo, T M; Yamazi, A K; Cavicchioli, V Q; Pieri, F A; Nero, L A

    2015-02-01

    Pseudomonas spp. are usually associated with spoilage microflora of dairy products due to their proteolytic potential. This is of particular concern for protein-based products, such as goat milk cheeses and fermented milks. Therefore, the goal of the present study was to characterize the proteolytic activity of Pseudomonas spp. isolated from goat milk. Goat milk samples (n=61) were obtained directly from bulk tanks on dairy goat farms (n=12), and subjected to a modified International Organization for Standardization (ISO) protocol to determine the number and proteolytic activity of Pseudomonas spp. Isolates (n=82) were obtained, identified by PCR, and subjected to pulsed-field gel electrophoresis with XbaI macro-restriction. Then, the isolates were subjected to PCR to detect the alkaline protease gene (apr), and phenotypic tests were performed to check proteolytic activity at 7°C, 25°C, and 35°C. Mean Pseudomonas spp. counts ranged from 2.9 to 4.8 log cfu/mL, and proteolytic Pseudomonas spp. counts ranged from 1.9 to 4.6 log cfu/mL. All isolates were confirmed to be Pseudomonas spp., and 41 were identified as Pseudomonas fluorescens, which clustered into 5 groups sharing approximately 82% similarity. Thirty-six isolates (46.9%) were positive for the apr gene; and 57 (69.5%) isolates presented proteolytic activity at 7°C, 82 (100%) at 25°C, and 64 (78%) at 35°C. The isolates were distributed ubiquitously in the goat farms, and no relationship among isolates was observed when the goat farms, presence of apr, pulsotypes, and proteolytic activity were taken into account. We demonstrated proteolytic activity of Pseudomonas spp. present in goat milk by phenotypic and genotypic tests and indicated their spoilage potential at distinct temperatures. Based on these findings and the ubiquity of Pseudomonas spp. in goat farm environments, proper monitoring and control of Pseudomonas spp. during production are critical.

  10. Draft genome sequence and annotation of Lactobacillus acetotolerans BM-LA14527, a beer-spoilage bacteria.

    Science.gov (United States)

    Liu, Junyan; Li, Lin; Peters, Brian M; Li, Bing; Deng, Yang; Xu, Zhenbo; Shirtliff, Mark E

    2016-09-01

    Lactobacillus acetotolerans is a hard-to-culture beer-spoilage bacterium capable of entering into the viable putative nonculturable (VPNC) state. As part of an initial strategy to investigate the phenotypic behavior of L. acetotolerans, draft genome sequencing was performed. Results demonstrated a total of 1824 predicted annotated genes, with several potential VPNC- and beer-spoilage-associated genes identified. Importantly, this is the first genome sequence of L. acetotolerans as beer-spoilage bacteria and it may aid in further analysis of L. acetotolerans and other beer-spoilage bacteria, with direct implications for food safety control in the beer brewing industry.

  11. Empirical prediction of net portal appearance of volatile fatty acids, glucose, and their secondary metabolites (beta-hydroxybutyrate, lactate) from dietary characteristics in ruminants: A meta-analysis approach.

    Science.gov (United States)

    Loncke, C; Ortigues-Marty, I; Vernet, J; Lapierre, H; Sauvant, D; Nozière, P

    2009-01-01

    The current trend in energy feeding systems for ruminants toward a nutrient-based system requires dietary energy supply to be determined in terms of amount and nature of absorbed energy-yielding nutrients. The objective of this study was to establish response equations on the net portal appearance (NPA) of VFA and glucose, and their secondary metabolites beta-hydroxybutyrate (BHBA) and lactate, to changes in intake level and chemical dietary characteristics based on the Institut National de la Recherche Agronomique Feed Evaluation System for Ruminants. Meta-analyses were applied on published data compiled from the FLORA database, which pools the results on net splanchnic nutrient fluxes in multi-catheterized ruminants from international publications. For each nutrient, several prediction variables were tested. We obtained robust models for intakes up to 30 g of DM x d(-1) x kg of BW(-1) and diets containing less than 70 g of concentrate per 100 g of DM. These models were designed to predict the NPA (mmol x h(-1) x kg of BW(-1)) of total VFA based on the amount of ruminally fermented OM (RfOM) intake [adjusted R(2) (R(2)(adj)) = 0.95; residual means square errors (RMSE) = 0.24], to predict VFA profile (mol/100 mol of total VFA) based on type of RfOM intake (acetate: R(2)(adj) = 0.85, RMSE = 2.2; propionate: R(2)(adj) = 0.76, RMSE = 2.2; butyrate: R(2)(adj) = 0.76, RMSE = 1.09), and to predict the NPA (mmol x h(-1) x kg of BW(-1)) of glucose based on the starch digested in the small intestine independent of ruminant species, and while presenting no interfering factors on the residuals and individual slopes. The model predicting the NPA (mmol x h(-1) x kg of BW(-1)) of BHBA based on the amount of RfOM intake (R(2)(adj) = 0.91; RMSE = 0.036) was species-dependent, and the model predicting NPA (mmol x h(-1) x kg of BW(-1)) of lactate based on starch digested in the rumen (R(2)(adj) = 0.77; RMSE = 0.042) presented a wide dispersion. However, the NPA (mmol x h(-1) x kg of

  12. Prediction of Mold Spoilage for Soy/Polyethylene Composite Fibers

    Directory of Open Access Journals (Sweden)

    Chinmay Naphade

    2015-01-01

    Full Text Available Mold spoilage was determined over 109 days on soy/PE fibers held under controlled temperatures (T ranging from 10°C to 40°C and water activities (aw from 0.11 to 0.98. Water activities were created in sealed containers using saturated salt solutions and placed in temperature-controlled incubators. Soy/PE fibers that were held at 0.823 aw or higher exhibited mold growth at all temperatures. As postulated, increased water activity (greater than 0.89 and temperature (higher than 25°C accelerated mold growth on soy/PE fibers. A slower mold growth was observed on soy/PE fibers that were held at 0.87 aw and 10°C. A Weibull model was employed to fit the observed logarithmic values of T, aw, and an interaction term log⁡T×log⁡aw and was chosen as the final model as it gave the best fit to the raw mold growth data. These growth models predict the expected mold-free storage period of soy/PE fibers when exposed to various environmental temperatures and humidities.

  13. Yeasts in table olive processing: desirable or spoilage microorganisms?

    Science.gov (United States)

    Arroyo-López, F N; Romero-Gil, V; Bautista-Gallego, J; Rodríguez-Gómez, F; Jiménez-Díaz, R; García-García, P; Querol, A; Garrido-Fernández, A

    2012-11-01

    Yeasts are unicellular eukaryotic microorganisms isolated from many foods, and are commonly found in table olive processing where they can play a double role. On one hand, these microorganisms can produce spoilage of fruits due to the production of bad odours and flavours, the accumulation of CO(2) leading to swollen containers, the clouding of brines, the softening of fruits and the degradation of lactic acid, which is especially harmful during table olive storage and packaging. But on the other hand, fortunately, yeasts also possess desirable biochemical activities (lipase, esterase, β-glucosidase, catalase, production of killer factors, etc.) with important technological applications in this fermented vegetable. Recently, the probiotic potential of olive yeasts has begun to be evaluated because many species are able to resist the passage through the gastrointestinal tract and show beneficial effects on the host. In this way, yeasts may improve consumers' health by decreasing cholesterol levels, inhibiting pathogens, degrading non assimilated compounds, producing antioxidants and vitamins, adhering to intestinal cells or by maintaining epithelial barrier integrity. Many yeast species, usually also found in table olive processing, such as Wicherhamomyces anomalus, Saccharomyces cerevisiae, Pichia membranifaciens and Kluyveromyces lactis, have been reported to exhibit some of these properties. Thus, the selection of the most appropriate strains to be used as starters, alone or in combination with lactic acid bacteria, is a promising research line to develop in a near future which might improve the added value of the commercialized product.

  14. Ancient Item Spoilage Ritual Used in Nomadic Burial Rite

    Directory of Open Access Journals (Sweden)

    Beisenov Arman Z.

    2017-07-01

    Full Text Available The article considers the findings of items in ancient burials which were intentionally spoiled prior to deposition in graves. This tradition was widely spread both in terms of chronology and geography, and therefore cannot be attributed to any individual cultures or regions. The authors present new information on the ritual obtained during an investigation of Borsyk burial mound of the Middle Sarmatian period located in West Kazakhstan. The central grave of barrow 6 contained a heavily damaged bronze cauldron. The grave was looted in antiquity. Individual scattered bones of a human skeleton and minor gold foil adornments from the ceremonial dress of a nobleman were discovered in the grave. The authors suggest that the cauldron was intentionally deformed by the participants of an ancient mortuary and memorial ritual. According to the principal hypothesis concerning the essence of this ritual, spoilage of the items was related to the idea of assign the items with “different” and “transcendent” properties, which resulted from the necessity of burying the owner. Cauldrons played an important role in the life of steppe leaders. The authors assume a sacral nature of the use of cauldrons in the culture of steppe peoples associated with feasts, battles, and sacred hunting. Perhaps, there was a tradition of burying cauldrons together with their owners after spoiling the items in view of the concept of the other world and the role of a heroic leader therein.

  15. Ecophysiology of ochratoxigenic Aspergillus ochraceus and Penicillium verrucosum isolates. Predictive models for fungal spoilage prevention - a review.

    Science.gov (United States)

    Pardo, E; Marín, S; Ramos, A J; Sanchis, V

    2006-04-01

    Ochratoxin A (OTA) is a secondary metabolite produced by several species of Aspergillus and Penicillium; among them Aspergillus ochraceus and Penicillium verrucosum are two ochratoxigenic species capable of growing in different climates and thus contamination of food crops with OTA can occur worldwide. OTA can be found in a wide range of foods such as cereals, coffee, cocoa, spices, beer, wine, dried vine fruit, grapes and meat products. OTA is toxic to animals, it presents neurotoxic, immunotoxic and nephrotoxic effects. It has been implicated in a human kidney disorder known as Balkan Endemic Nephropathy. This review focuses on the ecophysiology of ochratoxin-producing Aspergillus ochraceus and Penicillium verrucosum, the effect of environmental factors on their germination, mycelial growth, and OTA production. Knowledge of environmental conditions required for sucessive stages of fungal development represent the first step towards preventing mycotoxin formation. Predictive models for different stages of fungal development are presented, which allow prediction of the time before spoilage as a function of the abiotic factors. Finally, the implications of these studies in management of barley, coffee and grapes are described. This can help to identify the critical control points in their production, storage and distribution processes.

  16. Bacillus subtilis Biosensor Engineered To Assess Meat Spoilage

    NARCIS (Netherlands)

    Daszczuk, Alicja; Dessalegne, Yonathan; Drenth, Ismael; Hendriks, Elbrich; Jo, Emeraldo; van Lente, Tom; Oldebesten, Arjan; Parrish, Jonathon; Poljakova, Wlada; Purwanto, Annisa A.; van Raaphorst, Renske; Boonstra, Mirjam; van Heel, Auke; Herber, Martijn; van der Meulen, Sjoerd; Siebring, Jeroen; Sorg, Robin A.; Heinemann, Matthias; Kuipers, Oscar P.; Veening, Jan-Willem

    2014-01-01

    Here, we developed a cell-based biosensor that can assess meat freshness using the Gram-positive model bacterium Bacillus subtilis as a chassis. Using transcriptome analysis, we identified promoters that are specifically activated by volatiles released from spoiled meat. The most strongly activated

  17. Efficacy of lactoferricin B in controlling ready-to-eat vegetable spoilage caused by Pseudomonas spp.

    Science.gov (United States)

    Federico, Baruzzi; Pinto, Loris; Quintieri, Laura; Carito, Antonia; Calabrese, Nicola; Caputo, Leonardo

    2015-12-23

    The microbial content of plant tissues has been reported to cause the spoilage of ca. 30% of chlorine-disinfected fresh vegetables during cold storage. The aim of this work was to evaluate the efficacy of antimicrobial peptides in controlling microbial vegetable spoilage under cold storage conditions. A total of 48 bacterial isolates were collected from ready-to-eat (RTE) vegetables and identified as belonging to Acinetobacter calcoaceticus, Aeromonas media, Pseudomonas cichorii, Pseudomonas fluorescens, Pseudomonas jessenii, Pseudomonas koreensis, Pseudomonas putida, Pseudomonas simiae and Pseudomonas viridiflava species. Reddish or brownish pigmentation was found when Pseudomonas strains were inoculated in wounds on leaves of Iceberg and Trocadero lettuce and escarole chicory throughout cold storage. Bovine lactoferrin (BLF) and its hydrolysates (LFHs) produced by pepsin, papain and rennin, were assayed in vitro against four Pseudomonas spp. strains selected for their heavy spoiling ability. As the pepsin-LFH showed the strongest antimicrobial effect, subsequent experiments were carried out using the peptide lactoferricin B (LfcinB), well known to be responsible for its antimicrobial activity. LfcinB significantly reduced (P ≤ 0.05) spoilage by a mean of 36% caused by three out of four inoculated spoiler pseudomonads on RTE lettuce leaves after six days of cold storage. The reduction in the extent of spoilage was unrelated to viable cell density in the inoculated wounds. This is the first paper providing direct evidence regarding the application of an antimicrobial peptide to control microbial spoilage affecting RTE leafy vegetables during cold storage.

  18. Changes of Bacterial Diversity Depend on the Spoilage of Fresh Vegetables

    Directory of Open Access Journals (Sweden)

    Dong Hwan Lee

    2011-04-01

    Full Text Available Almost 10~30% of vegetables were discarded by the spoilage from farms to tables. After harvest, vegetables are often spoiled by a wide variety of microorganisms including many bacterial and fungal species. This investigation was conducted to extent the knowledge of relationship the spoilage of vegetables and the diversity of microbes. The total aerobic bacterial numbers in fresh lettuce, perilla leaf, and chicory were 2.6~2.7×106, 4.6×105, 1.2×106 CFU/g of fresh weight, respectively. The most common bacterial species were Pseudomonas spp., Alysiella spp., and Burkholderia spp., and other 18 more genera were involved in. After one week of incubation of those vegetables at 28℃, the microbial diversity had been changed. The total aerobic bacterial numbers increased to 1.1~4.6×108, 4.9×107, and 7.6×108 CFU/g of fresh weight for lettuce, perilla leaf, and chicory that is about 102 times increased bacterial numbers than that before spoilage. However, the diversity of microbes isolated had been simplified and fewer bacterial species had been isolated. The most bacterial population (~48% was taken up by Pseudomonas spp., and followed by Arthrobacter spp. and Bacillus spp. The spoilage activity of individual bacterial isolates had been tested using axenic lettuce plants. Among tested isolates, Pseudomonas fluorescence and Pantoea agglomerans caused severe spoilage on lettuce.

  19. Volatile Organic Compounds (VOCs)

    Science.gov (United States)

    ... Contact Us Share Volatile Organic Compounds' Impact on Indoor Air Quality On this page: Introduction Sources Health Effects Levels in Homes Steps to Reduce Exposure Standards or Guidelines Additional Resources Introduction Volatile organic compounds ( ...

  20. Implementation of multivariate techniques for the selection of volatile compounds as indicators of sensory quality of raw beef.

    Science.gov (United States)

    Saraiva, Cristina; Oliveira, I; Silva, J A; Martins, C; Ventanas, J; García, C

    2015-06-01

    This study was performed in order to select volatile compounds to predict the off-odour and overall assessment of raw beef's freshness Maronesa breed, using multivariate analysis. M. longissimus dorsi packed in vacuum and MAP (70 % O2/20 % CO2/10 % N2) stored at 4 ºC were examined for off-odour perception as well as the overall assessment of freshness at 10 and 21 days post mortem. The results achieved in this study demonstrated that the selected volatile compounds could be considered as volatile indicators of beef spoilage, enclosing information for discrimination of Maronesa beef samples in sensory classes of odour corresponding to unspoiled and spoiled levels. Fifty-four volatile compounds were detected. A significant increase of aldehydes, ketones and alcohols were observed during storage in MAP. 2 and 3-methylbutanal, 2 and 3-methylbutanol, 1-pentanol, 1-hexanol, 2,3-octanedione, 3,5-octanedione, octanal and nonanal were suggested as indicators of beef spoilage. 3-methylpentane was considered as a marker in the first stages of spoilage in beef, decreasing during storage. Data were examined using PCR and PLSR models for different optimal subsets of volatile compounds. The simplicity and usefulness of the technique in using 0/1 data in preserving high levels of accuracy was also prevalent. The powerful analytical methodologies for reducing variables and the choice of optimal subsets could be advantageous in both basic research and the routine quality control of chilled beef.

  1. Microbial community analysis of food-spoilage bacteria in commercial custard creams using culture-dependent and independent methods.

    Science.gov (United States)

    Arakawa, K; Kawai, Y; Iioka, H; Tanioka, M; Nishimura, J; Kitazawa, H; Tsurumi, K; Saito, T

    2008-08-01

    Custard cream is made from highly nutritive raw materials such as milk and sugar and is easily spoiled by the multiplication of specific microbial contaminants or residents. However, this spoilage microbial community has not been studied. We determined the spoilage microbiota in commercial custard creams using culture-dependent and independent methods. Using the culture-dependent analysis with various agar media, 185 bacterial colonies and 43 eukaryal colonies were isolated from 7 commercial custard cream products. All bacterial isolates were morphologically, physiologically, and genetically identified as bacilli, staphylococci, lactic acid bacteria, and psychrotrophic gram-negative rods. Using culture-independent molecular analysis, the PCR-denaturing gradient gel electrophoresis technique, spoilage of the commercial custard creams was found to be caused by bacilli, staphylococci, lactic acid bacteria, psychrotrophic gram-negative rods, Anoxybacillus sp., Caurobacter sp., and Streptococcus sp. bacteria. The detected spoilage bacteria were the same species as previously detected in spoiled milk products and shown in other reports, suggesting that spoilage bacteria in a raw material easily grow in processed foods made from milk. We determined the spoilage microbial communities in commercial custard creams, and these are the first data concerning spoilage microbiota in nonfermented processed foods using a culture-independent analysis. Our study will be useful for the manufacture and safe preservation of dairy products because the first step toward safe food preservation by food manufacturers is to understand the spoilage microbiota in a target food to select optimal preservatives and to reduce the use of food additives.

  2. Metabolism of lactic acid in fermented cucumbers by Lactobacillus buchneri and related species, potential spoilage organisms in reduced salt fermentations

    Science.gov (United States)

    Recent evidence suggests that Lactobacillus buchneri may play an important role in spoilage-associated secondary fermentation of cucumbers. Lactic acid degradation during fermented cucumber spoilage is influenced by sodium chloride (NaCl) concentration, pH, and presence of oxygen. Objectives were to...

  3. Introduction to the Microbiological Spoilage of Foods and Beverages

    Science.gov (United States)

    Sperber, William H.

    Though direct evidence of ancient food-handling practices is difficult to obtain and examine, it seems safe to assume that over the span of several million years, prehistoric humans struggled to maintain an adequate food supply. Their daily food needed to be hunted or harvested and consumed before it spoiled and became unfit to eat. Freshly killed animals, for example, could not have been kept for very long periods of time. Moreover, many early humans were nomadic, continually searching for food. We can imagine that, with an unreliable food supply, their lives must have often been literally "feast or famine." Yet, our ancestors gradually learned by accident, or by trial and error, simple techniques that could extend the storage time of their food (Block, 1991). Their brain capacity was similar to that of modern humans; therefore, some of them were likely early scientists and technologists. They would have learned that primitive cereal grains, nuts and berries, etc. could be stored in covered vessels to keep them dry and safer from mold spoilage. Animal products could be kept in cool places or dried and smoked over a fire, as the controlled use of fire by humans is thought to have begun about 400,000 years ago. Quite likely, naturally desiccated or fermented foods were also noticed and produced routinely to provide a more stable supply of edible food. Along with the development of agricultural practices for crop and animal production, the "simple" food-handling practices developed during the relatively countless millennia of prehistory paved the way for human civilizations.

  4. Reducing the Bloater Spoilage During Lactic Fermentation of Moroccan Green Olives

    Directory of Open Access Journals (Sweden)

    Zahra Lamzira

    2005-01-01

    Full Text Available The process of natural lactic fermentation of green olives is too long and usually associated with several types of olive deteriorations, mainly the »bloater spoilage«. The control of pH and salt level in brine, a practice mostly used in the olive industry, is not sufficient to avoid these problems. The main objective of this work is the control of the fermentationprocess in order to reduce the duration of the process and the olive spoilage incidence.Therefore, some Moroccan green olives were alkali-treated and brined at 5 % NaCl. The controlled fermentation was carried out by adjusting pH, by inoculation with Lactobacillus plantarum I159 and the addition of potassium sorbate (0.05 % brine. The results showed arapid development of lactic fermentation with a remarkable reduction in »bloater spoilage «, without affecting the organoleptic properties, colour and texture of the final product.

  5. Occurrence and growth of yeasts in processed meat products - implications for potential spoilage

    DEFF Research Database (Denmark)

    Nielsen, Dennis Sandris; Jacobsen, Tomas; Jespersen, Lene

    2008-01-01

    Spoilage of meat products is in general attributed to bacteria but new processing and storage techniques inhibiting growth of bacteria may provide opportunities for yeasts to dominate the microflora and cause spoilage of the product. With the aim of obtaining a deeper understanding of the potential...... role of yeast in spoilage of five different processed meat products (bacon, ham, salami and two different liver patés), yeasts were isolated, enumerated and identified during processing, in the final product and in the final product at the end of shelf life. Yeasts were isolated along the bacon...... of the processed meat products. The yeast microflora was complex with 4-12 different species isolated from the different production sites. In general, Candida zeylanoides, Debaryomyces hansenii and the newly described Candida alimentaria were found to be the dominant yeast species. In addition, three putatively...

  6. Growth and volatile compound production by Brettanomyces/Dekkera bruxellensis in red wine.

    Science.gov (United States)

    Romano, A; Perello, M C; de Revel, G; Lonvaud-Funel, A

    2008-06-01

    Brettanomyces/Dekkera bruxellensis is a particularly troublesome wine spoilage yeast. This work was aimed at characterizing its behaviour in terms of growth and volatile compound production in red wine. Sterile red wines were inoculated with 5 x 10(3) viable cells ml(-1) of three B. bruxellensis strains and growth and volatile phenol production were followed for 1 month by means of plate counts and gas chromatography-mass spectrometry (GC-MS) respectively. Maximum population levels generally attained 10(6)-10(7) colony forming units (CFU) ml(-1) and volatile phenol concentrations ranged from 500 to 4000 microg l(-1). Brettanomyces bruxellensis multiplication was also accompanied by the production of organic acids (from C(2) to C(10)), short chain acid ethyl-esters and the 'mousy off-flavour' component 2-acetyl-tetrahydropyridine. Different kinds of 'Brett character' characterized by distinct metabolic and sensory profiles can arise in wine depending on the contaminating strain, wine pH and sugar content and the winemaking stage at which contamination occurs. We identified new chemical markers that indicate wine defects caused by B. bruxellensis. Further insight was provided into the role of some environmental conditions in promoting wine spoilage.

  7. Effect of sublethal preculturing on the survival of probiotics and metabolite formation in set-yoghurt.

    Science.gov (United States)

    Settachaimongkon, Sarn; van Valenberg, Hein J F; Winata, Vera; Wang, Xiaoxi; Nout, M J Robert; van Hooijdonk, Toon C M; Zwietering, Marcel H; Smid, Eddy J

    2015-08-01

    The objective of this study was to investigate the effect of preculturing of Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB12 under sublethal stress conditions on their survival and metabolite formation in set-yoghurt. Prior to co-cultivation with yoghurt starters in milk, the two probiotic strains were precultured under sublethal stress conditions (combinations of elevated NaCl and low pH) in a batch fermentor. The activity of sublethally precultured probiotics was evaluated during fermentation and refrigerated storage by monitoring bacterial population dynamics, milk acidification and changes in volatile and non-volatile metabolite profiles of set-yoghurt. The results demonstrated adaptive stress responses of the two probiotic strains resulting in their viability improvement without adverse influence on milk acidification. A complementary metabolomic approach using SPME-GC/MS and (1)H-NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Principal component analysis revealed substantial impact of the activity of sublethally precultured probiotics on metabolite formation demonstrated by distinctive volatile and non-volatile metabolite profiles of set-yoghurt. Changes in relative abundance of various aroma compounds suggest that incorporation of stress-adapted probiotics considerably influences the organoleptic quality of product. This study provides new information on the application of stress-adapted probiotics in an actual food-carrier environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Identification of geosmin as a volatile metabolite of Penicillium expansum.

    OpenAIRE

    Mattheis, J P; Roberts, R. G.

    1992-01-01

    Cultures of Penicillium expansum produce a musty, earthy odor. Geosmin [1,10-trans-dimethyl-trans(9)-decalol] was identified by gas chromatography-mass spectrometry from headspace samples of P. expansum cultures. Olfactory comparison of P. expansum cultures with a geosmin standard indicated geosmin is the primary component of the odor associated with P. expansum.

  9. Volatile metabolites profiling of a Chinese mangrove endophytic ...

    African Journals Online (AJOL)

    ufuoma

    humans as novel physiological agents (Xu, 2011a; Zhang et al., 2006). ... analysis has become established in many laboratories involved in fungal ... tor in the electron impact mode (70 eV). .... daily life in foods and pharmaceutical agents against ... activity of propolis collected by three different races of honeybees in.

  10. Photocatalytic disinfection of spoilage bacteria Pseudomonas fluorescens and Macrococcus caseolyticus by nano-TiO2

    Science.gov (United States)

    Photocatalytic disinfection of spoilage bacteria gram-negative (G-) P. fluorescens and gram-positive (G+) M. caseolyticus by nano-TiO2 under different experimental conditions and the disinfection mechanism were investigated. The experimental conditions included the initial bacterial populations, nan...

  11. Amplicon sequencing for the quantification of spoilage microbiota in complex foods including bacterial spores

    NARCIS (Netherlands)

    Boer, de P.; Caspers, M.; Sanders, J.W.; Kemperman, R.; Wijman, J.; Lommerse, G.; Roeselers, G.; Montijn, R.; Abee, T.; Kort, R.

    2015-01-01

    Background
    Spoilage of food products is frequently caused by bacterial spores and lactic acid bacteria. Identification of these organisms by classic cultivation methods is limited by their ability to form colonies on nutrient agar plates. In this study, we adapted and optimized 16S rRNA amplicon

  12. Involvement of bacterial quorum-sensing signals in spoilage of bean sprouts

    DEFF Research Database (Denmark)

    Rasch, Maria; Andersen, Jens Bo; Nielsen, Kristian Fog

    2005-01-01

    sprouts. Thin-layer chromatography and liquid chromatography-high-resolution mass spectrometry revealed the presence of N-3-oxo-hexanoyl-l-homoserine lactone in spoiled bean sprouts and in extracts from pure cultures of bacteria. During normal spoilage, the pH of the sprouts increased due to proteolytic...

  13. Classification of photobacteria associated with spoilage of fish products by numerical taxanomy and pyrolysis mass spectrometry

    DEFF Research Database (Denmark)

    Dalgaard, Paw; Manfio, G.P.; Goodfellow, M.

    1997-01-01

    sub-groups. One sub-group of psychrotolerant P. phosphoreum strains, which was selected in modified atmosphere packed fish stored at low temperature, was also highlighted using each of the methods. The importance of classifying food spoilage bacteria has been shown and a simple key generated...

  14. Amplicon sequencing for the quantification of spoilage microbiota in complex foods including bacterial spores

    NARCIS (Netherlands)

    Boer, de P.; Caspers, M.; Sanders, J.W.; Kemperman, R.; Wijman, J.; Lommerse, G.; Roeselers, G.; Montijn, R.; Abee, T.; Kort, R.

    2015-01-01

    Background
    Spoilage of food products is frequently caused by bacterial spores and lactic acid bacteria. Identification of these organisms by classic cultivation methods is limited by their ability to form colonies on nutrient agar plates. In this study, we adapted and optimized 16S rRNA amplicon

  15. Spoilage of sous vide cooked salmon (Salmo salar) stored under refrigeration.

    Science.gov (United States)

    Díaz, P; Garrido, M D; Bañón, S

    2011-02-01

    The spoilage of Sous Vide 'SV' cooked salmon stored under refrigeration was studied. Samples were packaged under vacuum in polyamide-polypropylene pouches, cooked at an oven temperature/time of 80 (°)C/45 min, quickly chilled at 3 (°)C and stored at 2 (°)C for 0, 5 or 10 weeks for catering use. Microbial (aerobic and anaerobic psychrotrophs, lactic acid bacteria, molds and yeasts and Enterobacteriaceae), physical-chemical (pH, water activity, TBARS, acidity, L*a*b* color, texture profile analysis and shear force) and sensory (appearance, odor, flavor, texture and overall quality) parameters were determined. SV processing prevented the growth of aerobic and anaerobic psychrotrophs, lactic acid bacteria, molds and yeasts and Enterobacteriaceae. There were no relevant changes in pH, water activity, TBARS, CIELab color associated with cooked salmon spoilage. Instrumental texture data were contradictory. Slight decrease in lactic acid levels was found. In contrast, the SV cooked salmon suffered considerable sensory deterioration during its refrigerated storage, consisting of severe losses of cooked salmon odor and flavor, slight rancidity, discoloration associated with white precipitation, and moderates softness, and loss of chewiness and juiciness. No acidification, putrefaction or relevant rancidity was detected. The sensory spoilage preceded microbiological and physical-chemical spoilage, suggesting that microbiological quality alone may overestimate the shelf life of SV cooked salmon.

  16. The influence of substrate on siderophore production by fish spoilage bacteria

    DEFF Research Database (Denmark)

    Gram, Lone

    1996-01-01

    Siderophore production of fish spoilage bacteria (5 isolates of Shewanella putrefaciens and 5 of Pseudomonas sp.) was determined in fish extract, Tris-succinate medium, a liquid medium of the Chrome-Azurol-S (CAS) agar and in M9 medium supplemented with glucose and casamino acids (M9GC). One Pseu...

  17. The fungal flora of loganberries in relation to storage and spoilage.

    Science.gov (United States)

    Davis, R P; Dennis, C

    1977-03-01

    Botrytis cinerea, Cladosporium spp., Penicillium spp., Aureobasidium pullulans, Mucor mucedo, Phoma state of Didymella applanata, Cryptococcus laurentii var. laurentii, C. albidus var. albidus, Candida sake and Sporobolomyces roseus were consistently present on freshly harvested loganberries. Botrytis cinerea was the main spoilage organism with Mucor mucedo of minor importance. The importance of benomyl-resistant strains of B. cinerea is discussed.

  18. Characterisation of biofilms formed by Lactobacillus plantarum WCFS1 and food spoilage isolates.

    Science.gov (United States)

    Fernández Ramírez, Mónica D; Smid, Eddy J; Abee, Tjakko; Nierop Groot, Masja N

    2015-08-17

    Lactobacillus plantarum has been associated with food spoilage in a wide range of products and the biofilm growth mode has been implicated as a possible source of contamination. In this study we analysed the biofilm forming capacity of L. plantarum WCFS1 and six food spoilage isolates. Biofilm formation as quantified by crystal violet staining and colony forming units was largely affected by the medium composition, growth temperature and maturation time and by strain specific features. All strains showed highest biofilm formation in Brain Heart Infusion medium supplemented with manganese and glucose. For L. plantarum biofilms the crystal violet (CV) assay, that is routinely used to quantify total biofilm formation, correlates poorly with the number of culturable cells in the biofilm. This can in part be explained by cell death and lysis resulting in CV stainable material, conceivably extracellular DNA (eDNA), contributing to the extracellular matrix. The strain to strain variation may in part be explained by differences in levels of eDNA, likely as result of differences in lysis behaviour. In line with this, biofilms of all strains tested, except for one spoilage isolate, were sensitive to DNase treatment. In addition, biofilms were highly sensitive to treatment with Proteinase K suggesting a role for proteins and/or proteinaceous material in surface colonisation. This study shows the impact of a range of environmental factors and enzyme treatments on biofilm formation capacity for selected L. plantarum isolates associated with food spoilage, and may provide clues for disinfection strategies in food industry.

  19. Emerging Equity Market Volatility

    OpenAIRE

    Geert Bekaert; Harvey, Campbell R.

    1995-01-01

    Returns in emerging capital markets are very different from returns in developed markets. While most previous research has focused on average returns, we analyze the volatility of the returns in emerging equity markets. We characterize the time-series of volatility in emerging markets and explore the distributional foundations of the variance process. Of particular interest is evidence of asymmetries in volatility and the evolution of the variance process after periods of capital market refor...

  20. Volatility in Equilibrium

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Sizova, Natalia; Tauchen, George

    Stock market volatility clusters in time, carries a risk premium, is fractionally inte- grated, and exhibits asymmetric leverage effects relative to returns. This paper develops a first internally consistent equilibrium based explanation for these longstanding empirical facts. The model is cast......, and the dynamic cross-correlations of the volatility measures with the returns calculated from actual high-frequency intra-day data on the S&P 500 aggregate market and VIX volatility indexes....

  1. Volatile-mediated interactions between phylogenetically different soil bacteria

    Directory of Open Access Journals (Sweden)

    Paolina eGarbeva

    2014-06-01

    Full Text Available There is increasing evidence that organic volatiles play an important role in interactions between micro-organisms in the porous soil matrix. Here we report that volatile compounds emitted by different soil bacteria can affect the growth, antibiotic production and gene expression of the soil bacterium Pseudomonas fluorescens Pf0-1. We applied a novel cultivation approach that mimics the natural nutritional heterogeneity in soil in which P. fluorescens grown on nutrient-limited agar was exposed to volatiles produced by 4 phylogenetically different bacterial isolates (Collimonas pratensis, Serratia plymuthica, Paenibacillus sp. and Pedobacter sp. growing in sand containing artificial root exudates. Contrary to our expectation, the produced volatiles stimulated rather than inhibited the growth of P. fluorescens. A genome-wide, microarray-based analysis revealed that volatiles of all 4 bacterial strains affected gene expression of P. fluorescens, but with a different pattern of gene expression for each strain. Based on the annotation of the differently expressed genes, bacterial volatiles appear to induce a chemotactic motility response in P. fluorescens, but also an oxidative stress response. A more detailed study revealed that volatiles produced by C. pratensis triggered, antimicrobial secondary metabolite production in P. fluorescens. Our results indicate that bacterial volatiles can have an important role in communication, trophic - and antagonistic interactions within the soil bacterial community.

  2. PCR detection of psychrophilic Clostridium spp. causing 'blown pack' spoilage of vacuum-packed chilled meats.

    Science.gov (United States)

    Broda, D M; Boerema, J A; Bell, R G

    2003-01-01

    To develop a practical molecular procedure that directly, without isolation, and specifically detects the presence of clostridia which cause 'blown pack' spoilage of vacuum-packed meat. Primer sets and PCR amplification procedures were developed that detect the presence of 16S rDNA gene and/or 16S-23S rDNA internal transcribed spacer fragments of 'blown pack' causing clostridia in meat. The specificity of the developed procedures was evaluated with DNA obtained from close phylogenetic neighbours of 'blown pack' causing clostridia, food clostridia and common meat spoilage microorganisms. The sensitivity of detection was assessed in non-enriched and low-temperature-enriched beef mince inoculated with serially diluted pure cultures of Clostridium estertheticum DSMZ 8809T and Cl. gasigenes DB1AT. The efficacy of detection procedures was evaluated for naturally contaminated vacuum-packed meat samples. Three primer sets, 16SE, 16SDB and EISR, produced amplicons of the expected size with DNA templates from target clostridia, but failed to yield PCR products with DNAs from any other microorganisms tested. With 16SE and 16SDB primers, minimum levels of detection were 104 CFU g(-1) for non-enriched, and 102 CFU g(-1) for enriched meat samples. Based on the established specificity of these primers, as well as DNA sequencing of amplicons, Cl. gasigenes was confirmed as the causative agent of 'blown pack' spoilage in two packs, and Cl. estertheticum as the causative agent in the third. The developed method can be used for rapid detection of 'blown pack' causing clostridia in commercial blown packs, or following low temperature enrichment, for detection of these microorganisms in meat containing as few as 100 clostridial cells per gram. The paper reports practical procedures that can be used for rapid confirmation of the causative agents of clostridial 'blown pack' spoilage in commercial spoiled packs, or for detection of psychrophilic clostridia in epidemiological trace back of

  3. Changes in the spoilage-related microbiota of beef during refrigerated storage under different packaging conditions.

    Science.gov (United States)

    Ercolini, Danilo; Russo, Federica; Torrieri, Elena; Masi, Paolo; Villani, Francesco

    2006-07-01

    The microbial spoilage of beef was monitored during storage at 5 degrees C under three different conditions of modified-atmosphere packaging (MAP): (i) air (MAP1), (ii) 60% O2 and 40% CO2 (MAP2), and (iii) 20% O2 and 40% CO2 (MAP3). Pseudomonas, Enterobacteriaceae, Brochothrix thermosphacta, and lactic acid bacteria were monitored by viable counts and PCR-denaturing gradient gel electrophoresis (DGGE) analysis during 14 days of storage. Moreover, headspace gas composition, weight loss, and beef color change were also determined at each sampling time. Overall, MAP2 was shown to have the best protective effect, keeping the microbial loads and color change to acceptable levels in the first 7 days of refrigerated storage. The microbial colonies from the plate counts of each microbial group were identified by PCR-DGGE of the variable V6-V8 region of the 16S rRNA gene. Thirteen different genera and at least 17 different species were identified after sequencing of DGGE fragments that showed a wide diversity of spoilage-related bacteria taking turns during beef storage in the function of the packaging conditions. The countable species for each spoilage-related microbial group were different according to packaging conditions and times of storage. In fact, the DGGE profiles displayed significant changes during time and depending on the initial atmosphere used. The spoilage occurred between 7 and 14 days of storage, and the microbial species found in the spoiled meat varied according to the packaging conditions. Rahnella aquatilis, Rahnella spp., Pseudomonas spp., and Carnobacterium divergens were identified as acting during beef storage in air (MAP1). Pseudomonas spp. and Lactobacillus sakei were found in beef stored under MAP conditions with high oxygen content (MAP2), while Rahnella spp. and L. sakei were the main species found during storage using MAP3. The identification of the spoilage-related microbiota by molecular methods can help in the effective establishment of

  4. Low-cost chemiresistive sensor for volatile amines based on a 2D network of a zinc(II) Schiff-base complex

    Science.gov (United States)

    Mirabella, S.; Oliveri, I. P.; Ruffino, F.; Maccarrone, G.; Di Bella, S.

    2016-10-01

    A marked chemiresistive behavior is revealed in a nanostructured material obtained by spin-coating a solution of a bis(salycilaldiminato)Zn(II) Schiff-base (ZnSB) complex. The resulting submicron 2D network exhibits reversible changes in absorbance and resistance under the cycles of absorption and desorption of a volatile amine. These results are explained in terms of a Lewis donor-acceptor interaction between the ZnSB (acceptor) and the chemisorbed amine (donor). The 2D network of ZnSB was employed as a sensing element to fabricate a low-cost device for the volatile amines detection, showing promising results for food spoilage detection.

  5. Analysis of Growth Inhibition and Metabolism of Hydroxycinnamic Acids by Brewing and Spoilage Strains of Brettanomyces Yeast

    Science.gov (United States)

    Lentz, Michael; Harris, Chad

    2015-01-01

    Brettanomyces yeasts are well-known as spoilage organisms in both the wine and beer industries, but also contribute important desirable characters to certain beer styles. These properties are mediated in large part by Brettanomyces’ metabolism of hydroxycinnamic acids (HCAs) present in beverage raw materials. Here we compare growth inhibition by, and metabolism of, HCAs among commercial brewing strains and spoilage strains of B. bruxellensis and B. anomalus. These properties vary widely among the different strains tested and between the HCAs analyzed. Brewing strains showed more efficient metabolism of ferulic acid over p-coumaric acid, a trait not shared among the spoilage strains. PMID:28231223

  6. Analysis of Growth Inhibition and Metabolism of Hydroxycinnamic Acids by Brewing and Spoilage Strains of Brettanomyces Yeast

    Directory of Open Access Journals (Sweden)

    Michael Lentz

    2015-10-01

    Full Text Available Brettanomyces yeasts are well-known as spoilage organisms in both the wine and beer industries, but also contribute important desirable characters to certain beer styles. These properties are mediated in large part by Brettanomyces’ metabolism of hydroxycinnamic acids (HCAs present in beverage raw materials. Here we compare growth inhibition by, and metabolism of, HCAs among commercial brewing strains and spoilage strains of B. bruxellensis and B. anomalus. These properties vary widely among the different strains tested and between the HCAs analyzed. Brewing strains showed more efficient metabolism of ferulic acid over p-coumaric acid, a trait not shared among the spoilage strains.

  7. Analysis of Growth Inhibition and Metabolism of Hydroxycinnamic Acids by Brewing and Spoilage Strains of Brettanomyces Yeast.

    Science.gov (United States)

    Lentz, Michael; Harris, Chad

    2015-10-15

    Brettanomyces yeasts are well-known as spoilage organisms in both the wine and beer industries, but also contribute important desirable characters to certain beer styles. These properties are mediated in large part by Brettanomyces' metabolism of hydroxycinnamic acids (HCAs) present in beverage raw materials. Here we compare growth inhibition by, and metabolism of, HCAs among commercial brewing strains and spoilage strains of B. bruxellensis and B. anomalus. These properties vary widely among the different strains tested and between the HCAs analyzed. Brewing strains showed more efficient metabolism of ferulic acid over p-coumaric acid, a trait not shared among the spoilage strains.

  8. Secondary metabolites of endophytic Xylaria species with potential applications in medicine and agriculture.

    Science.gov (United States)

    Macías-Rubalcava, Martha Lydia; Sánchez-Fernández, Rosa Elvira

    2017-01-01

    Fungal endophytes are important sources of bioactive secondary metabolites. The genus Xylaria Hill (ex Schrank, 1789, Xylariaceae) comprises various endophytic species associated to both vascular and non vascular plants. The secondary metabolites produced by Xylaria species include a variety of volatile and non-volatile compounds. Examples of the former are sesquiterpenoids, esters, and alcohols, among others; and of the latter we find terpenoids, cytochalasins, mellein, alkaloids, polyketides, and aromatic compounds. Some of these metabolites have shown potential activity as herbicides, fungicides, and insecticides; others possess antibacterial, antimalarial, and antifungal activities, or α-glucosidase inhibitory activity. Thus metabolites from Xylaria are promising compounds for applications in agriculture for plague control as biopesticides, and biocontrol agents; and in medicine, for example as drugs for the treatment of infectious and non-infectious diseases. This review seeks to show the great value of the secondary metabolites of Xylaria, particularly in the agriculture and medicine fields.

  9. In Situ Real-Time Monitoring of Volatile Metabolites of Fermented Milk by Dynamic Headspace Sampling - Atmospheric Pressure Ionization Mass Spectrometry%动态顶空取样-大气压化学电离质谱原位实时监测发酵乳挥发性代谢产物

    Institute of Scientific and Technical Information of China (English)

    梁华正; 杨水平; 刘维佳; 李媛

    2012-01-01

    Volatile metabolites produced from fermented milk were monitored in situ real-time by atmospheric pressure dynamic headspace sampling coupled with chemical ionization mass spectrometry. The ion current signal of volatile metabolites was recorded during 3.0 h to 4.7 h after the start of fermentation. The signal of 2,3-butanedione (m/z 104,M+H2O·+ ) was weak in the first 4 h followed by a gradual increase, reaching a rapid upward trend after 4.2 b, the signal of ethyl acetate (m/z 106, M+H2O·+) began gradually increasing after 3 h, but the signal of benzaldehyde (m/z 124, M+H2O·+ ) remained relatively stable. The mass spectrum of 6 h fermented milk mainly included the signals of lactic acid (mlz 91, MH+ and m/z 108,M+H2O·+), 2,3-butanedione (m/z 104, M+H2O·+ ), benzaldehyde (m/z 107, MH+ and m/z 124,M+H2O·+ ), ethyl acetate (m/z 89, MH+ and m/z 106, M+H2O·+ ), hexanal (m/z 101, MH+and m/z 118, M+H2O·+ ), acrolein (m/z 74, M+H2O·+), etc. Atmospheric pressure dynamic headspace sampling coupled with chemical ionization mass spectrometry has many advantages such as rapid and non-destructive and can be used for quality control in the production of fermented milk.%采用大气压化学电离质谱法,利用动态顶空取样技术对发酵乳生产过程中产生的挥发性代谢产物进行原位实时监测。从发酵开始后3.0~4.7h连续用质谱仪记录发酵乳挥发物的离子流信号,结果表明:2,3-丁二酮(m/z104,M+H2O·+)在前4h信号较弱,4h后开始逐渐增大,4.2h后呈快速增大的趋势;乙酸乙酯(m/z106,M+H2O·+)信号从发酵3h后开始呈逐渐增大趋势;苯甲醛(m/z124,M+H2O·+)信号较平稳。发酵进行到6h的质谱图中质谱信号主要有乳酸(m/z291,MH+和m/z108,M+H2O·+),2,3-丁二酮(m/z 104,M+H2O·+),苯甲醛(m/z107,MH+和m/z124,M+H2O·+),乙酸乙酯(m/z 89,MH+和m/z106,M+H2O

  10. Understanding Financial Market Volatility

    NARCIS (Netherlands)

    A. Opschoor (Anne)

    2014-01-01

    markdownabstract__Abstract__ Volatility has been one of the most active and successful areas of research in time series econometrics and economic forecasting in recent decades. Loosely speaking, volatility is defined as the average magnitude of fluctuations observed in some phenomenon over time. Wi

  11. Improving Garch Volatility Forecasts

    NARCIS (Netherlands)

    Klaassen, F.J.G.M.

    1998-01-01

    Many researchers use GARCH models to generate volatility forecasts. We show, however, that such forecasts are too variable. To correct for this, we extend the GARCH model by distinguishing two regimes with different volatility levels. GARCH effects are allowed within each regime, so that our model

  12. Understanding Financial Market Volatility

    NARCIS (Netherlands)

    A. Opschoor (Anne)

    2014-01-01

    markdownabstract__Abstract__ Volatility has been one of the most active and successful areas of research in time series econometrics and economic forecasting in recent decades. Loosely speaking, volatility is defined as the average magnitude of fluctuations observed in some phenomenon over

  13. Quantitative analyses of the bacterial microbiota of rearing environment, tilapia and common carp cultured in earthen ponds and inhibitory activity of its lactic acid bacteria on fish spoilage and pathogenic bacteria.

    Science.gov (United States)

    Kaktcham, Pierre Marie; Temgoua, Jules-Bocamdé; Ngoufack Zambou, François; Diaz-Ruiz, Gloria; Wacher, Carmen; Pérez-Chabela, María de Lourdes

    2017-02-01

    The present study aimed to evaluate the bacterial load of water, Nile Tilapia and common Carp intestines from earthen ponds, isolate lactic acid bacteria (LAB) and assess their antimicrobial activity against fish spoilage and pathogenic bacteria. Following enumeration and isolation of microorganisms the antimicrobial activity of the LAB isolates was evaluated. Taxonomic identification of selected antagonistic LAB strains was assessed, followed by partial characterisation of their antimicrobial metabolites. Results showed that high counts (>4 log c.f.u ml(-1) or 8 log c.f.u g(-1)) of total aerobic bacteria were recorded in pond waters and fish intestines. The microbiota were also found to be dominated by Salmonella spp., Vibrio spp., Staphylococcus spp. and Escherichia coli. LAB isolates (5.60%) exhibited potent direct and extracellular antimicrobial activity against the host-derived and non host-derived spoilage and pathogenic bacteria. These antagonistic isolates were identified and Lactococcus lactis subsp. lactis was found as the predominant (42.85%) specie. The strains displayed the ability to produce lactic, acetic, butyric, propionic and valeric acids. Bacteriocin-like inhibitory substances with activity against Gram-positive and Gram-negative (Vibrio spp. and Pseudomonas aeruginosa) bacteria were produced by three L. lactis subsp. lactis strains. In this study, the LAB from the microbiota of fish and pond water showed potent antimicrobial activity against fish spoilage or pathogenic bacteria from the same host or ecological niche. The studied Cameroonian aquatic niche is an ideal source of antagonistic LAB that could be appropriate as new fish biopreservatives or disease control agents in aquaculture under tropical conditions in particular or worldwide in general.

  14. Isolation and identification of spoilage microorganisms using food-based media combined with rDNA sequencing: ranch dressing as a model food.

    Science.gov (United States)

    Waite, Joy G; Jones, Joseph M; Yousef, Ahmed E

    2009-05-01

    Investigating microbial spoilage of food is hampered by the lack of suitable growth media and protocols to characterize the causative agents. Microbial spoilage of salad dressing is sporadic and relatively unpredictable, thus processors struggle to develop strategies to minimize or prevent spoilage of this product. The objectives of this study were to (i) induce and characterize spoilage events in ranch-style dressing as a model food, and (ii) isolate and identify the causative microorganisms using traditional and food-based media, coupled with rDNA sequence analysis. Ranch dressing (pH 4.4) was prepared and stored at 25 degrees C for 14 d and microbial populations were recovered on MRS agar and ranch dressing agar (RDA), a newly formulated food-based medium. When isolates suspected as the spoilage agents were inoculated into ranch dressing and held at 25 degrees C for 9-10 d, three unique spoilage events were characterized. Using rDNA sequence comparisons, spoilage organisms were identified as Lactobacillus brevis, Pediococcus acidilactici, and Torulaspora delbrueckii. P. acidilactici produced flat-sour spoilage, whereas Lb. brevis resulted in product acidification and moderate gas production. The RDA medium allowed for optimum recovery of the excessive gas-producing spoilage yeast, T. delbrueckii. The isolation and identification strategy utilized in this work should assist in the characterization of spoilage organisms in other food systems.

  15. Genome Sequence and Transcriptome Analysis of Meat-Spoilage-Associated Lactic Acid Bacterium Lactococcus piscium MKFS47

    National Research Council Canada - National Science Library

    Andreevskaya, Margarita; Johansson, Per; Laine, Pia; Smolander, Olli-Pekka; Sonck, Matti; Rahkila, Riitta; Jääskeläinen, Elina; Paulin, Lars; Auvinen, Petri; Björkroth, Johanna

    2015-01-01

    Lactococcus piscium is a psychrotrophic lactic acid bacterium and is known to be one of the predominant species within spoilage microbial communities in cold-stored packaged foods, particularly in meat products...

  16. Latest about Spoilage by Yeasts: Focus on the Deterioration of Beverages and Other Plant-Derived Products.

    Science.gov (United States)

    Krisch, Judit; Chandrasekaran, Muthusamy; Kadaikunnan, Shine; Alharbi, Naiyf S; Vágvölgyi, Csaba

    2016-05-01

    Food and beverage deterioration by spoilage yeasts is a serious problem that causes substantial financial losses each year. Yeasts are able to grow under harsh environmental conditions in foods with low pH, low water activity, and high sugar and/or salt content. Some of them are extremely resistant to the traditional preservatives used in the food industry. The search for new methods and agents for prevention of spoilage by yeasts is ongoing, but most of these are still at laboratory scale. This minireview gives an overview of the latest research issues relating to spoilage by yeasts, with a focus on wine and other beverages, following the interest of the research groups. It seems that a better understanding of the mechanisms to combat food-related stresses, the characteristics leading to resistance, and rapid identification of strains of yeasts in foods are the tools that can help control spoilage yeasts.

  17. Penicillium expansum volatiles reduce pine weevil attraction to host plants.

    Science.gov (United States)

    Azeem, Muhammad; Rajarao, Gunaratna Kuttuva; Nordenhem, Henrik; Nordlander, Göran; Borg-Karlson, Anna Karin

    2013-01-01

    The pine weevil Hylobius abietis (L.) is a severe pest of conifer seedlings in reforested areas of Europe and Asia. To identify minimally toxic and ecologically sustainable compounds for protecting newly planted seedlings, we evaluated the volatile metabolites produced by microbes isolated from H. abietis feces and frass. Female weevils deposit feces and chew bark at oviposition sites, presumably thus protecting eggs from feeding conspecifics. We hypothesize that microbes present in feces/frass are responsible for producing compounds that deter weevils. Here, we describe the isolation of a fungus from feces and frass of H. abietis and the biological activity of its volatile metabolites. The fungus was identified by morphological and molecular methods as Penicillium expansum Link ex. Thom. It was cultured on sterilized H. abietis frass medium in glass flasks, and volatiles were collected by SPME and analyzed by GC-MS. The major volatiles of the fungus were styrene and 3-methylanisole. The nutrient conditions for maximum production of styrene and 3-methylanisole were examined. Large quantities of styrene were produced when the fungus was cultured on grated pine bark with yeast extract. In a multi-choice arena test, styrene significantly reduced male and female pine weevils' attraction to cut pieces of Scots pine twigs, whereas 3-methylanisole only reduced male weevil attraction to pine twigs. These studies suggest that metabolites produced by microbes may be useful as compounds for controlling insects, and could serve as sustainable alternatives to synthetic insecticides.

  18. Broth and agar hop-gradient plates used to evaluate the beer-spoilage potential of Lactobacillus and Pediococcus isolates.

    Science.gov (United States)

    Haakensen, M; Schubert, A; Ziola, B

    2009-03-15

    Identification of the beer-spoilage Lactobacillus and Pediococcus bacteria has largely taken two approaches; identification of spoilage-associated genes or identification of specific species of bacteria regardless of ability to grow in beer. The problem with these two approaches is that they are either overly inclusive (i.e., detect all bacteria of a given species regardless of spoilage potential) or overly selective (i.e., rely upon individual, putative spoilage-associated genes). Our goal was to design a method to assess the ability of Lactobacillus and Pediococcus to spoil beer that is independent of speciation or genetic background. In searching for a method by which to differentiate between beer-spoilage bacteria and bacteria that cannot grow in beer, we explored the ability of lactobacilli and pediococci isolates to grow in the presence of varying concentrations of hop-compounds and ethanol in broth medium versus on agar medium. The best method for differentiating between bacteria that can grow in beer and bacteria that do not pose a threat as beer-spoilage organisms was found to be a hop-gradient agar plate containing ethanol. This hop-gradient agar plate technique provides a rapid and simple solution to the dilemma of assessing the ability of Lactobacillus and Pediococcus isolates to grow in beer, and provides new insights into the different strategies used by these bacteria to survive under the stringent conditions of beer.

  19. Idiosyncratic Volatility Puzzle

    DEFF Research Database (Denmark)

    Aslanidis, Nektarios; Christiansen, Charlotte; Lambertides, Neophytos;

    from a large pool of macroeconomic and Önancial variables. Cleaning for macro-Önance e§ects reverses the puzzling negative relation between returns and idiosyncratic volatility documented previously. Portfolio analysis shows that the e§ects from macro-Önance factors are economically strong......In this paper, we scrutinize the cross-sectional relation between idiosyncratic volatility and stock returns. As a novelty, the idiosyncratic volatility is obtained by conditioning upon macro-Önance factors as well as upon traditional asset pricing factors. The macro-Önance factors are constructed...

  20. Molecular and physiological comparison of spoilage wine yeasts.

    Science.gov (United States)

    Sangorrín, M P; García, V; Lopes, C A; Sáez, J S; Martínez, C; Ganga, M A

    2013-04-01

    Dekkera bruxellensis and Pichia guilliermondii are contaminating yeasts in wine due to the production of phenolic aromas. Although the degradation pathway of cinnamic acids, precursors of these phenolic compounds has been described in D. bruxellensis, no such pathway has been described in P. guilliermondii. A molecular and physiological characterization of 14 D. bruxellensis and 15 P. guilliermondii phenol-producing strains was carried out. Both p-coumarate decarboxylase (CD) and vinyl reductase (VR) activities, responsible for the production of volatile phenols, were quantified and the production of 4-vinylphenol and 4-ethylphenol were measured. All D. bruxellensis and some P. guilliermondii strains showed the two enzymatic activities, whilst 11 of the 15 strains of this latter species showed only CD activity and did not produce 4-EP in the assay conditions. Furthermore, PCR products obtained with degenerated primers showed a low homology with the sequence of the gene for a phenyl acrylic acid decarboxylase activity described in Saccharomyces cerevisiae. D. bruxellensis and P. guilliermondii may share a similar metabolic pathway for the degradation of cinnamic acids. This is the first work that analyses the CD and VR activities in P. guilliermondii, and the results suggest that within this species, there are differences in the metabolization of cinnamic acids. © 2013 The Society for Applied Microbiology.

  1. Bacterial surface antigen-specific monoclonal antibodies used to detect beer spoilage pediococci.

    Science.gov (United States)

    Whiting, M S; Ingledew, W M; Lee, S Y; Ziola, B

    1999-08-01

    Fourteen monoclonal antibodies (Mabs) were isolated that react with surface antigens of Pediococcus beer spoilage organisms, including P. damnosus, P. pentosaceous, P. acidilactici, and unspeciated isolates. Immunoblotting, enzyme immunoassays (EIAs) of protease- and neuraminidase-treated surface antigen extracts, carbohydrate competition EIAs, and cardiolipin EIAs were used to characterize the bacterial antigens involved in Mab binding. Antigen stability in situ was tested by protease treatment or surface antigen extraction of washed bacteria. In most cases, the Mabs bind to Pediococcus surface antigens that appear to be covalently bound cell wall polymers resistant to alteration or removal from the bacterial surface. These bacterial surface antigen reactive Mabs show good potential for rapid, sensitive, and specific immunoassay detection of Pediococcus beer spoilage organisms.

  2. Antimicrobial characteristics of chitosans against food spoilage microorganisms in liquid media and mayonnaise.

    Science.gov (United States)

    Oh, H I; Kim, Y J; Chang, E J; Kim, J Y

    2001-11-01

    Four different kinds of chitosans were prepared by treating crude chitin with various NaOH concentrations. The antimicrobial activities of the chitosans were tested against four species of food spoilage microorganisms (Lactobacillus plantarum, Lactobacillus fructivorans, Serratia liquefaciens, and Zygosaccharomyces bailii). The initial effect of the chitosans was biocidal, and counts of viable cells were significantly reduced. After an extended lag phase, some strains recovered and resumed growth. The activities of chitosan against these microorganisms increased with the concentration. Chitosan-50 was most effective against L. fructivorans, but inhibition of L. plantarum was greatest with chitosan-55. There was no significant difference among the chitosans in their antimicrobial activity against S. liquefaciens and Z. bailii. The addition of chitosan to mayonnaise significantly decreased the viable cell counts of L. fructivorans and Z. bailii during storage at 25 degrees C. These results suggest that chitosan can be used as a food preservative to inhibit the growth of spoilage microorganisms in mayonnaise.

  3. The Fate of Acetic Acid during Glucose Co-Metabolism by the Spoilage Yeast Zygosaccharomyces bailii

    OpenAIRE

    Fernando Rodrigues; Maria João Sousa; Paula Ludovico; Helena Santos; Manuela Côrte-Real; Cecília Leão

    2012-01-01

    Zygosaccharomyces bailii is one of the most widely represented spoilage yeast species, being able to metabolise acetic acid in the presence of glucose. To clarify whether simultaneous utilisation of the two substrates affects growth efficiency, we examined growth in single- and mixed-substrate cultures with glucose and acetic acid. Our findings indicate that the biomass yield in the first phase of growth is the result of the weighted sum of the respective biomass yields on single-substrate me...

  4. Spoilage-related microbiota associated with chilled beef stored in air or vacuum pack.

    Science.gov (United States)

    Pennacchia, C; Ercolini, D; Villani, F

    2011-02-01

    In order to study the spoilage-related microbiota of beef at species level, a combination of culture-independent and culture-dependent methods was used to analyse nine different beef samples stored at 4°C in air or in vacuum pack. Plate counts on selective agars after 0, 7 and 20 days of storage showed that vacuum packaging reduced the viable counts of Brochothrix thermosphacta, Pseudomonas spp. and Enterobacteriaceae, whereas the growth of lactic acid bacteria (LAB) was unaffected. Storage in vacuum pack mainly affected viable counts and not necessarily the species diversity of microbial populations on meat. Such populations were studied by PCR-DGGE of DNA directly extracted from meat and from bulk cells from culture media, followed by sequencing of DGGE fragments. Pseudomonas spp., Carnobacterium divergens, B. thermosphacta, Rahnella spp. and Serratia grimesii, or close relatives were detected in the meat at time zero. The use of the culture-independent method highlighted the occurrence of species that were not detected by plating. Photobacterium spp. occurred in most meat samples stored in air or in vacuum pack, which indicates this organism probably has a role in spoilage. In contrast, culture-dependent analysis allowed detection of bacterial species that were not found in DNA extracted directly from meat. This was the case for several species of Serratia or Rhanella among the enterobacteria, and Leuconostoc spp. among the LAB. Besides advancing our knowledge of the species involved in the spoilage of vacuum-packaged meat, this study shows the benefits of combining culture-based and direct approaches to enhance understanding of populations of spoilage bacteria.

  5. Enhanced metabolite generation

    Science.gov (United States)

    Chidambaram, Devicharan [Middle Island, NY

    2012-03-27

    The present invention relates to the enhanced production of metabolites by a process whereby a carbon source is oxidized with a fermentative microbe in a compartment having a portal. An electron acceptor is added to the compartment to assist the microbe in the removal of excess electrons. The electron acceptor accepts electrons from the microbe after oxidation of the carbon source. Other transfers of electrons can take place to enhance the production of the metabolite, such as acids, biofuels or brewed beverages.

  6. Spoilage and shelf-life extension of fresh fish and shellfish.

    Science.gov (United States)

    Ashie, I N; Smith, J P; Simpson, B K

    1996-01-01

    Fresh fish and shellfish are highly perishable products due to their biological composition. Under normal refrigerated storage conditions, the shelf life of these products is limited by enzymatic and microbiological spoilage. However, with increasing consumer demands for fresh products with extended shelf life and increasing energy costs associated with freezing and frozen storage, the fish-processing industry is actively seeking alternative methods of shelf life preservation and marketability of fresh, refrigerated fish and at the same time economizing on energy costs. Additional methods that could fulfill these objectives include chemical decontamination, low-dose irradiation, ultra-high pressure, and modified atmosphere packaging (MAP). This review focuses on the biochemical and microbiological composition of fresh fish/shellfish, the spoilage patterns in these products, factors influencing spoilage, and the combination treatments that can be used in conjunction with refrigeration to extend the shelf life and keeping quality of fresh fish/shellfish. The safety concerns of minimally processed/MAP fish, specifically with respect to the growth of Clostridium botulinum type E, is also addressed.

  7. Spoilage of foods monitored by native fluorescence spectroscopy with selective excitation wavelength

    Science.gov (United States)

    Pu, Yang; Wang, Wubao; Alfano, Robert R.

    2015-03-01

    The modern food processing and storage environments require the real-time monitoring and rapid microbiological testing. Optical spectroscopy with selective excitation wavelengths can be the basis of a novel, rapid, reagent less, noncontact and non-destructive technique for monitoring the food spoilage. The native fluorescence spectra of muscle foods stored at 2-4°C (in refrigerator) and 20-24°C (in room temperature) were measured as a function of time with a selective excitation wavelength of 340nm. The contributions of the principal molecular components to the native fluorescence spectra of meat were measured spectra of each fluorophore: collagen, reduced nicotinamide adenine dinucleotide (NADH), and flavin. The responsible components were extracted using a method namely Multivariate Curve Resolution with Alternating Least-Squares (MCR-ALS). The native fluorescence combined with MCR-ALS can be used directly on the surface of meat to produce biochemically interpretable "fingerprints", which reflects the microbial spoilage of foods involved with the metabolic processes. The results show that with time elapse, the emission from NADH in meat stored at 24°C increases much faster than that at 4°C. This is because multiplying of microorganisms and catabolism are accompanied by the generation of NADH. This study presents changes of relative content of NADH may be used as criterion for detection of spoilage degree of meat using native fluorescence spectroscopy.

  8. Molecular characterization of spoilage bacteria as a means to observe the microbiological quality of carrot.

    Science.gov (United States)

    Kahala, Minna; Blasco, Lucia; Joutsjoki, Vesa

    2012-03-01

    This study characterized the bacteria causing decay of carrots during storage and marketing. Spoilage strains were identified by 16S-amplified rDNA restriction analysis and intergenic transcribed spacer-PCR-restriction fragment length polymorphism (ITS-PCR-RFLP). Genotypic fingerprinting by RFLP-pulsed-field gel electrophoresis was used to assess the genetic diversity of the isolates. A total of 252 Pseudomonas isolates from carrots were identified and classified into eight separate groups. Most strains belonged to group A (Pseudomonas fluorescens, Pseudomonas marginalis, and Pseudomonas veronii) and group B (Pseudomonas putida). The strains identified as Pectobacterium carotovorum subsp. carotovorum, Pectobacterium atrosepticum, Dickeya chrysanthemi, and Erwinia rhapontici were distinguished by ITS-PCR-RFLP. All isolates belonging to the genera Pectobacterium and Erwinia were responsible for carrot spoilage. This work has led to the development of new strategies for the identification and genotyping of vegetable-spoiling strains of Pseudomonas, Pectobacterium, and Erwinia. This is also the first report describing the occurrence of carrot-spoiling E. rhapontici. Early recognition of spoilage bacteria in vegetables is important for the implementation of effective handling strategies. Pectolytic bacteria may cause considerable financial losses because they account for a large proportion of bacterial rot of fruits and vegetables during storage, transit, and marketing.

  9. TdKT, a new killer toxin produced by Torulaspora delbrueckii effective against wine spoilage yeasts.

    Science.gov (United States)

    Villalba, María Leticia; Susana Sáez, Julieta; Del Monaco, Silvana; Lopes, Christian Ariel; Sangorrín, Marcela Paula

    2016-01-18

    Microbiological spoilage is a major concern throughout the wine industry, and control tools are limited. This paper addresses the identification and partial characterization of a new killer toxin from Torulaspora delbrueckii with potential biocontrol activity of Brettanomyces bruxellensis, Pichia guilliermondii, Pichia manshurica and Pichia membranifaciens wine spoilage. A panel of 18 different wine strains of T. delbrueckii killer yeasts was analysed, and the strain T. delbrueckii NPCC 1033 (TdKT producer) showed a significant inhibitory effect on the growth of all different spoilage yeasts evaluated. The TdKT toxin was then subjected to a partial biochemical characterization. Its estimated molecular weight was N30 kDa and it showed glucanase and chitinase enzymatic activities. The killer activity was stable between pH 4.2 and 4.8 and inactivated at temperature above 40 °C. Pustulan and chitin — but not other cell wall polysaccharides — prevented sensitive yeast cells from being killed by TdKT, suggesting that those may be the first toxin targets in the cell wall. TdKT provoked an increase in necrosis cell death after 3 h treatment and apoptotic cell death after 24 h showing time dependence in its mechanisms of action. Killer toxin extracts were active at oenological conditions, confirming their potential use as a biocontrol tool in winemaking.

  10. EFFECT OF ELECTROMAGNETIC FIELD ON THE SPOILAGE FUNGI OF SOME SELECTED EDIBLE FRUITS IN SOUTHWESTERN, NIGERIA

    Directory of Open Access Journals (Sweden)

    Bamidele J. Akinyele

    2012-10-01

    Full Text Available The influence of electromagnetic field wave on the survival of spoilage fungi associated with some edible fruits consumed in southwestern, Nigeria was studied using cashew (Anacardium occidentale L., pineapple (Ananas comosus, carrot (Daucus carota, cucumber (Cucumis sativus, apple (Malus domestica and African star apple (Chrysophyllum africanum. The spoilage fungi used include the genera of Aspergillus, Penicillium, Articulospora, Mucor, Staphylotrichum, Bisbyopeltis, Fusarium, Rhizopus and a yeast, Saccharomyces cerevisiae. There was a general decrease in fungal growth as shown in the number of spores produced with increase in exposure time of isolates to electromagnetic field except in Articulospora inflata, Penicillium italicum and Mucor mucedo where there was stimulatory effect as there was increase in the fungal spores compared to the control. A decrease was also observed in growth of the fungal isolates with increase in the intensity of the electromagnetic field at voltage of 7 V to 10 V and from 10 V to 13 V. The highest percentage reduction was recorded by Bisbyopeltis phoebesii at intensity of voltage 13V after 60 minutes of exposure. Exposure of the fruits to electromagnetic field wave did not alter the nutrient components of the fruits as observed in the proximate and mineral contents of the treated and untreated fruits. The result of the study revealed that electromagnetic field wave has great potential for use in the control of fruits spoilage and food preservation.

  11. Inactivation of wine spoilage yeasts Dekkera bruxellensis using low electric current treatment (LEC).

    Science.gov (United States)

    Lustrato, G; Vigentini, I; De Leonardis, A; Alfano, G; Tirelli, A; Foschino, R; Ranalli, G

    2010-08-01

    The objective of this study was to investigate the inactivation of a selected yeast Dekkera bruxellensis strain 4481 in red wine by application of low electric current treatment (LEC). LEC (200 mA) was applied for 60 days to a red wine, Montepulciano d'Abruzzo, in an alternative strategy to the SO(2) addition during wine storage. The LEC effect on both cell activity and microflora viability was assessed. LEC decreased significantly the survival viable cells and increased the death rate of D. bruxellensis strain 4481 yeast. A final comparison was made of the main physico-chemical parameters of the wine after the different treatments. The study suggests the importance of an appropriate LEC treatment which limits wine deterioration in terms of off-flavours synthesis. The results demonstrate that the growth of undesirable Dekkera can be inhibited by low voltage treatment; LEC was shown to be useful to prevent wine spoilage and has the potential of being a concrete alternative method for controlling wine spoilage. Wine spoilage can be avoided by preventing the growth of undesirable Dekkera yeasts, through the effective use of LEC in the winemaking process.

  12. Development of a portable spectrofluorimeter for measuring the microbial spoilage of minced beef.

    Science.gov (United States)

    Aït-Kaddour, Abderrahmane; Boubellouta, Tahar; Chevallier, Isabelle

    2011-08-01

    The evaluation of meat spoilage is based on sensory and microbiological analyses. The disadvantages of sensory analyses are its reliance on highly trained panelists, a procedure which makes it costly and unattractive for routine analyses. Moreover, the classical microbiological analyses are lengthy, costly and destructive. In this study a portable fluorescence spectrometer was tested to quantify minced beef spoilage. This study was investigated on samples stored aerobically and under vacuum at 5 and 15 °C. Total viable counts (TVC), Pseudomonas, lactic acid bacteria, and yeast/molds counts were investigated with classical culture methods. Fluorescence spectra were recorded on the same samples using different excitation LEDs (280, 320, and 380 nm). PLS-R with leave-one-out cross validation was used to perform calibration and validation models. The PLS-R models presented good R²(CV) (0.50-0.99) and ratio of standard deviation (RPD(CV): 1.40-8.95) values after cross-validation. It could be concluded that portable spectrofluorimeters are promising devices to evaluate spoilage in minced beef.

  13. On guidance and volatility

    NARCIS (Netherlands)

    Billings, M.B.; Jennings, R.; Lev, B.

    2013-01-01

    Survey evidence suggests that managers voluntarily disclose information, particularly earnings guidance, with an aim toward dampening share price volatility. Yet, consultants and influential institutions advise against providing guidance — citing fears of litigation and market penalties associated w

  14. Dynamic Volatility Arbitrage

    DEFF Research Database (Denmark)

    Dorn, Jochen

    profit on well-developed markets. Dynamic participation features on cross asset portfolios are at rst sight a remedy to that dilemma. Based on volatility thresholds and portfolio re-balancing, the fund engineers try to create a "volatility guaranteed" investment opportunity by surfing on the unusual high...... concepts, next to nothing is known about position reverting strategies and how, and -even more important- in which context they are applied in practice. In the recent market downturn only one sector generated signicant profits for the leading investment banks: Volatility trading activities, namely on Forex......, interest rates and commodities. If an investor positions himself on the (volatility) market within a long/short trading framework, he typically bets on a traditional mispricing arbitrage. However as this corresponds to a call spread with equal exercise prices, this strategy alone would not generate enough...

  15. It’s all about volatility of volatility

    DEFF Research Database (Denmark)

    Grassi, Stefano; Santucci de Magistris, Paolo

    2015-01-01

    for the realized volatility series. It emerges that during the recent financial crisis the relative weight of the daily component dominates over the monthly term. The estimates of the two factor stochastic volatility model suggest that the change in the dynamic structure of the realized volatility during...... the financial crisis is due to the increase in the volatility of the persistent volatility term. A set of Monte Carlo simulations highlights the robustness of the methodology adopted in tracking the dynamics of the parameters....

  16. Comparision of Methods Used for Determination of Total Volatile Basic Nitrogen (TVB-N) in Rainbow Trout (Oncorhynchus mykiss)

    OpenAIRE

    ÖZOĞUL, Fatih; Özoğul, Yeşim

    2000-01-01

    TVB-N (total volatile basic nitrogen) concentration in fish muscle was used as an index of freshness quality to compare the spoilage of rainbow trout wrapped in cling film and in aluminium foil. TVB-N levels in different muscle tissue and in the whole fish were measured every two days for a period of 16 days at 4-6°C. In addition, three different methods of determining of TVB-N were evaluated in terms of sensitivity, reliability, speed, and cost. Regardless of the method of analysis, there wa...

  17. Effect of high oxygen and high carbon dioxide atmosphere packaging on the microbial spoilage and shelf-life of fresh-cut honeydew melon.

    Science.gov (United States)

    Zhang, Bao-Yu; Samapundo, Simbarashe; Pothakos, Vasileios; Sürengil, Göknur; Devlieghere, Frank

    2013-09-16

    This study evaluated the potential of modified atmospheres (MAs) combining high oxygen (O₂) and high carbon dioxide (CO₂) levels to extend the shelf-life of fresh-cut honeydew melon. Firstly, the effect of MA on the growth and volatile organic metabolite production of Candida sake, Leuconostoc mesenteroides and Leuconostoc gelidum, which had all been previously isolated from spoiled commercial fresh-cut honeydew melon, was evaluated separately on honeydew melon agar at 7 °C. Additionally, the effect of selected MAs on the microbial, physico-chemical and sensory quality of commercial fresh-cut honeydew melon cubes was evaluated at 7 °C. The results showed that MAs with high O₂ and high CO₂ levels greatly retarded the growth, CO₂ and volatile metabolite production (i.e. ethanol, 2-methyl-1-butanol, ethyl acetate, phenylacetic acid, nonanal) of C. sake on honeydew melon agar; especially MAs consisting of 50% O₂+50% CO₂ and 70% O₂+30% CO₂. In contrast, the MAs evaluated only had a minor effect on the growth and volatile metabolite production of L. mesenteroides and L. gelidum. Overall, the effect of MAs on colour, juice leakage, juiciness, and firmness of fresh-cut honeydew melon was small during storage. Sensory preference was generally for fresh-cut honeydew melon cubes packaged in MA of 50% O₂+50% CO₂. These were still acceptable on day five of storage and had appreciably lower populations of yeasts and lactic acid bacteria, lower quantities of volatile organic compounds, but slightly stronger colour oxidation compared to honeydew melon that was packaged in air. Additionally, most of the samples packed in air had blown by day five due to the large quantity of CO₂ production during storage. Therefore, 50% O₂+50% CO₂ is a potential MA solution for extending the shelf-life of fresh-cut honeydew melon.

  18. Non-volatile memories

    CERN Document Server

    Lacaze, Pierre-Camille

    2014-01-01

    Written for scientists, researchers, and engineers, Non-volatile Memories describes the recent research and implementations in relation to the design of a new generation of non-volatile electronic memories. The objective is to replace existing memories (DRAM, SRAM, EEPROM, Flash, etc.) with a universal memory model likely to reach better performances than the current types of memory: extremely high commutation speeds, high implantation densities and retention time of information of about ten years.

  19. Identification of lactic acid bacteria from spoilage associations of cooked and brined shrimps stored under modified atmosphere between 0 degrees C and 25 degrees C

    DEFF Research Database (Denmark)

    Dalgaard, Paw; Vancanneyt, M.; Vilalta, N.E.

    2003-01-01

    Aims: To evaluate spoilage and identify lactic acid bacteria (LAB) from spoilage associations of cooked and brined shrimps stored under modified atmosphere packaging (MAP) at 0, 5, 8, 15 and 25degreesC. Methods and Results: Bacterial isolates (102) from spoilage associations of cooked and brined...... to chemical changes in spoiled products. Carnobacterium divergens , a non-motile Carnobacterium sp. nov. and Lactobacillus curvatus were the LAB species observed in spoilage associations of products stored at 0degreesC, 5degreesC and 8degreesC. Conclusions: Enterococcus spp. and Carnobacterium spp. were...

  20. Study on seafood volatile profile characteristics during storage and its potential use for freshness evaluation by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhang, Zhuomin; Li, Gongke; Luo, Lin; Chen, Guonan

    2010-02-05

    Seafood volatile profile characteristics at different storage phases are various and can be used for freshness evaluation during storage. It is imperative to obtain the full volatile information prior to the further study of seafood volatile profile characteristics during storage. Also, the efficient data-processing method is another important factor for the interpretation of seafood volatile profile characteristics during storage and related potential volatile markers. In this work, a new analytical strategy, including the efficient sampling technique, sensitive detection and suitable data-processing method, for seafood freshness evaluation was developed based on the volatile profile characteristics during storage. First, the study of volatiles of seafood samples including razor clam, redspot swimming crab and prawn at different storage phases were conducted by headspace solid phase microextraction (HSSPME) followed by gas chromatography-mass spectrometry (GC-MS) detection. Then, seafood volatile profile characteristics at different storage phases were statistically interpreted by a combination data-processing method including normalization, principle component analysis (PCA) and common model strategy. The different seafood volatile profile characteristics and potential volatile markers were attempted to be distilled. The results tentatively suggested that the different seafood volatile profile characteristics during storage could reflect the transitional changing seafood freshness and provide more precise warning information for seafood spoilage during storage than any single chemical markers. This work developed an analytical method for study of seafood volatile profile characteristics and tentatively proposed a new idea of using seafood volatile profile characteristics during storage for the freshness evaluation from the point of view of analytical chemistry.

  1. Characterization of aerobic spore-forming bacteria associated with industrial dairy processing environments and product spoilage.

    Science.gov (United States)

    Lücking, Genia; Stoeckel, Marina; Atamer, Zeynep; Hinrichs, Jörg; Ehling-Schulz, Monika

    2013-09-02

    Due to changes in the design of industrial food processing and increasing international trade, highly thermoresistant spore-forming bacteria are an emerging problem in food production. Minimally processed foods and products with extended shelf life, such as milk products, are at special risk for contamination and subsequent product damages, but information about origin and food quality related properties of highly heat-resistant spore-formers is still limited. Therefore, the aim of this study was to determine the biodiversity, heat resistance, and food quality and safety affecting characteristics of aerobic spore-formers in the dairy sector. Thus, a comprehensive panel of strains (n=467), which originated from dairy processing environments, raw materials and processed foods, was compiled. The set included isolates associated with recent food spoilage cases and product damages as well as isolates not linked to product spoilage. Identification of the isolates by means of Fourier-transform infrared spectroscopy and molecular methods revealed a large biodiversity of spore-formers, especially among the spoilage associated isolates. These could be assigned to 43 species, representing 11 genera, with Bacillus cereus s.l. and Bacillus licheniformis being predominant. A screening for isolates forming thermoresistant spores (TRS, surviving 100°C, 20 min) showed that about one third of the tested spore-formers was heat-resistant, with Bacillus subtilis and Geobacillus stearothermophilus being the prevalent species. Strains producing highly thermoresistant spores (HTRS, surviving 125°C, 30 min) were found among mesophilic as well as among thermophilic species. B. subtilis and Bacillus amyloliquefaciens were dominating the group of mesophilic HTRS, while Bacillus smithii and Geobacillus pallidus were dominating the group of thermophilic HTRS. Analysis of spoilage-related enzymes of the TRS isolates showed that mesophilic strains, belonging to the B. subtilis and B. cereus

  2. Oil and stock market volatility: A multivariate stochastic volatility perspective

    Energy Technology Data Exchange (ETDEWEB)

    Vo, Minh, E-mail: minh.vo@metrostate.edu

    2011-09-15

    This paper models the volatility of stock and oil futures markets using the multivariate stochastic volatility structure in an attempt to extract information intertwined in both markets for risk prediction. It offers four major findings. First, the stock and oil futures prices are inter-related. Their correlation follows a time-varying dynamic process and tends to increase when the markets are more volatile. Second, conditioned on the past information, the volatility in each market is very persistent, i.e., it varies in a predictable manner. Third, there is inter-market dependence in volatility. Innovations that hit either market can affect the volatility in the other market. In other words, conditioned on the persistence and the past volatility in their respective markets, the past volatility of the stock (oil futures) market also has predictive power over the future volatility of the oil futures (stock) market. Finally, the model produces more accurate Value-at-Risk estimates than other benchmarks commonly used in the financial industry. - Research Highlights: > This paper models the volatility of stock and oil futures markets using the multivariate stochastic volatility model. > The correlation between the two markets follows a time-varying dynamic process which tends to increase when the markets are more volatile. > The volatility in each market is very persistent. > Innovations that hit either market can affect the volatility in the other market. > The model produces more accurate Value-at-Risk estimates than other benchmarks commonly used in the financial industry.

  3. A breath fungal secondary metabolite signature to diagnose invasive aspergillosis.

    Science.gov (United States)

    Koo, Sophia; Thomas, Horatio R; Daniels, S David; Lynch, Robert C; Fortier, Sean M; Shea, Margaret M; Rearden, Preshious; Comolli, James C; Baden, Lindsey R; Marty, Francisco M

    2014-12-15

    Invasive aspergillosis (IA) remains a leading cause of mortality in immunocompromised patients, in part due to the difficulty of diagnosing this infection. Using thermal desorption-gas chromatography/mass spectrometry, we characterized the in vitro volatile metabolite profile of Aspergillus fumigatus, the most common cause of IA, and other pathogenic aspergilli. We prospectively collected breath samples from patients with suspected invasive fungal pneumonia from 2011 to 2013, and assessed whether we could discriminate patients with proven or probable IA from patients without aspergillosis, as determined by European Organization for Research and Treatment of Cancer/Mycoses Study Group consensus definitions, by direct detection of fungal volatile metabolites in these breath samples. The monoterpenes camphene, α- and β-pinene, and limonene, and the sesquiterpene compounds α- and β-trans-bergamotene were distinctive volatile metabolites of A. fumigatus in vitro, distinguishing it from other pathogenic aspergilli. Of 64 patients with suspected invasive fungal pneumonia based on host risk factors, clinical symptoms, and radiologic findings, 34 were diagnosed with IA, whereas 30 were ultimately diagnosed with other causes of pneumonia, including other invasive mycoses. Detection of α-trans-bergamotene, β-trans-bergamotene, a β-vatirenene-like sesquiterpene, or trans-geranylacetone identified IA patients with 94% sensitivity (95% confidence interval [CI], 81%-98%) and 93% specificity (95% CI, 79%-98%). In patients with suspected fungal pneumonia, an Aspergillus secondary metabolite signature in breath can identify individuals with IA. These results provide proof-of-concept that direct detection of exogenous fungal metabolites in breath can be used as a novel, noninvasive, pathogen-specific approach to identifying the precise microbial cause of pneumonia. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America

  4. Metabolomic profiling of beer reveals effect of temperature on non-volatile small molecules during short-term storage.

    Science.gov (United States)

    Heuberger, Adam L; Broeckling, Corey D; Lewis, Matthew R; Salazar, Lauren; Bouckaert, Peter; Prenni, Jessica E

    2012-12-01

    The effect of temperature on non-volatile compounds in beer has not been well characterised during storage. Here, a metabolomics approach was applied to characterise the effect of storage temperature on non-volatile metabolite variation after 16weeks of storage, using fresh beer as a control. The metabolite profile of room temperature stored (RT) and cold temperature stored (CT) beer differed significantly from fresh, with the most substantial variation observed between RT and fresh beer. Metabolites that changed during storage included prenylated flavonoids, purines, and peptides, and all showed reduced quantitative variation under the CT storage conditions. Corresponding sensory panel observations indicated significant beer oxidation after 12 and 16weeks of storage, with higher values reported for RT samples. These data support that temperature affected beer oxidation during short-term storage, and reveal 5-methylthioadenosine (5-MTA) as a candidate non-volatile metabolite marker for beer oxidation and staling.

  5. The volatile compound BinBase mass spectral database

    Directory of Open Access Journals (Sweden)

    Barupal Dinesh K

    2011-08-01

    Full Text Available Abstract Background Volatile compounds comprise diverse chemical groups with wide-ranging sources and functions. These compounds originate from major pathways of secondary metabolism in many organisms and play essential roles in chemical ecology in both plant and animal kingdoms. In past decades, sampling methods and instrumentation for the analysis of complex volatile mixtures have improved; however, design and implementation of database tools to process and store the complex datasets have lagged behind. Description The volatile compound BinBase (vocBinBase is an automated peak annotation and database system developed for the analysis of GC-TOF-MS data derived from complex volatile mixtures. The vocBinBase DB is an extension of the previously reported metabolite BinBase software developed to track and identify derivatized metabolites. The BinBase algorithm uses deconvoluted spectra and peak metadata (retention index, unique ion, spectral similarity, peak signal-to-noise ratio, and peak purity from the Leco ChromaTOF software, and annotates peaks using a multi-tiered filtering system with stringent thresholds. The vocBinBase algorithm assigns the identity of compounds existing in the database. Volatile compound assignments are supported by the Adams mass spectral-retention index library, which contains over 2,000 plant-derived volatile compounds. Novel molecules that are not found within vocBinBase are automatically added using strict mass spectral and experimental criteria. Users obtain fully annotated data sheets with quantitative information for all volatile compounds for studies that may consist of thousands of chromatograms. The vocBinBase database may also be queried across different studies, comprising currently 1,537 unique mass spectra generated from 1.7 million deconvoluted mass spectra of 3,435 samples (18 species. Mass spectra with retention indices and volatile profiles are available as free download under the CC-BY agreement (http

  6. Comparison of three Bacillus amyloliquefaciens strains growth behaviour and evaluation of the spoilage risk during bread shelf-life.

    Science.gov (United States)

    Valerio, F; Di Biase, M; Huchet, V; Desriac, N; Lonigro, S L; Lavermicocca, P; Sohier, D; Postollec, F

    2015-02-01

    This study aims at the characterisation of growth behaviour of three strains of Bacillus amyloliquefaciens, isolated from ropy bread (ATCC8473), wheat grain (ISPA-S109.3) and semolina (ISPA-N9.1) to estimate rope spoilage risk in pan bread during shelf-life using the Sym'Previus tool. Cardinal values and growth/no growth boundaries were determined in broth, while artificial spore inoculations were performed in dough for various pan bread recipes to compare experimental counts with in silico growth simulations. Finally, two storage scenarios were tested to determine the probability to reach a spoilage threshold during bread shelf-life. Similarly to the safety criteria fixed for Listeria monocytogenes contamination in foodstuff complying with EC regulation, a potential rope spoilage threshold was arbitrary fixed at 5 log CFU/g for B. amyloliquefaciens. This study further underlines a higher rope spoilage potential of the ISPA strains as compared to the ATCC strain, thus emphasizing the interest to characterise both wild strains and reference strain to account for biological variability. In conclusion, this study showed that available decision making tools which are largely recognized to predict behaviour of pathogenic strains, shall also be used with spoilage strains to help maintain food quality and extend shelf-life.

  7. Understanding Interest Rate Volatility

    DEFF Research Database (Denmark)

    Volker, Desi

    This thesis is the result of my Ph.D. studies at the Department of Finance of the Copenhagen Business School. It consists of three essays covering topics related to the term structure of interest rates, monetary policy and interest rate volatility. The rst essay, \\Monetary Policy Uncertainty...... and Interest Rates", examines the role of monetary policy uncertainty on the term structure of interest rates. The second essay, \\A Regime-Switching A ne Term Structure Model with Stochastic Volatility" (co-authored with Sebastian Fux), investigates the ability of the class of regime switching models...... with and without stochastic volatility to capture the main stylized features of U.S. interest rates. The third essay, \\Variance Risk Premia in the Interest Rate Swap Market", investigates the time-series and cross-sectional properties of the compensation demanded for holding interest rate variance risk. The essays...

  8. Volatiles in protoplanetary disks

    CERN Document Server

    Pontoppidan, Klaus M; Bergin, Edwin A; Brittain, Sean; Marty, Bernard; Mousis, Olvier; Oberg, Karin L

    2014-01-01

    Volatiles are compounds with low sublimation temperatures, and they make up most of the condensible mass in typical planet-forming environments. They consist of relatively small, often hydrogenated, molecules based on the abundant elements carbon, nitrogen and oxygen. Volatiles are central to the process of planet formation, forming the backbone of a rich chemistry that sets the initial conditions for the formation of planetary atmospheres, and act as a solid mass reservoir catalyzing the formation of planets and planetesimals. This growth has been driven by rapid advances in observations and models of protoplanetary disks, and by a deepening understanding of the cosmochemistry of the solar system. Indeed, it is only in the past few years that representative samples of molecules have been discovered in great abundance throughout protoplanetary disks - enough to begin building a complete budget for the most abundant elements after hydrogen and helium. The spatial distributions of key volatiles are being mapped...

  9. Stochastic volatility selected readings

    CERN Document Server

    Shephard, Neil

    2005-01-01

    Neil Shephard has brought together a set of classic and central papers that have contributed to our understanding of financial volatility. They cover stocks, bonds and currencies and range from 1973 up to 2001. Shephard, a leading researcher in the field, provides a substantial introduction in which he discusses all major issues involved. General Introduction N. Shephard. Part I: Model Building. 1. A Subordinated Stochastic Process Model with Finite Variance for Speculative Prices, (P. K. Clark). 2. Financial Returns Modelled by the Product of Two Stochastic Processes: A Study of Daily Sugar Prices, 1961-7, S. J. Taylor. 3. The Behavior of Random Variables with Nonstationary Variance and the Distribution of Security Prices, B. Rosenberg. 4. The Pricing of Options on Assets with Stochastic Volatilities, J. Hull and A. White. 5. The Dynamics of Exchange Rate Volatility: A Multivariate Latent Factor ARCH Model, F. X. Diebold and M. Nerlove. 6. Multivariate Stochastic Variance Models. 7. Stochastic Autoregressive...

  10. Pricing Volatility of Stock Returns with Volatile and Persistent Components

    DEFF Research Database (Denmark)

    Zhu, Jie

    2009-01-01

    This paper introduces a two-component volatility model based on first moments of both components to describe the dynamics of speculative return volatility. The two components capture the volatile and the persistent part of volatility, respectively. The model is applied to 10 Asia-Pacific stock...... markets. Their in-mean effects on returns are tested. The empirical results show that the persistent component is much more important for the volatility dynamic process than is the volatile component. However, the volatile component is found to be a significant pricing factor of asset returns for most...... markets. A positive or risk-premium effect exists between the return and the volatile component, yet the persistent component is not significantly priced for the return dynamic process....

  11. Mapping the structural requirements of inducers and substrates for decarboxylation of weak acid preservatives by the food spoilage mould Aspergillus niger.

    Science.gov (United States)

    Stratford, Malcolm; Plumridge, Andrew; Pleasants, Mike W; Novodvorska, Michaela; Baker-Glenn, Charles A G; Pattenden, Gerald; Archer, David B

    2012-07-16

    Moulds are able to cause spoilage in preserved foods through degradation of the preservatives using the Pad-decarboxylation system. This causes, for example, decarboxylation of the preservative sorbic acid to 1,3-pentadiene, a volatile compound with a kerosene-like odour. Neither the natural role of this system nor the range of potential substrates has yet been reported. The Pad-decarboxylation system, encoded by a gene cluster in germinating spores of the mould Aspergillus niger, involves activity by two decarboxylases, PadA1 and OhbA1, and a regulator, SdrA, acting pleiotropically on sorbic acid and cinnamic acid. The structural features of compounds important for the induction of Pad-decarboxylation at both transcriptional and functionality levels were investigated by rtPCR and GCMS. Sorbic and cinnamic acids served as transcriptional inducers but ferulic, coumaric and hexanoic acids did not. 2,3,4,5,6-Pentafluorocinnamic acid was a substrate for the enzyme but had no inducer function; it was used to distinguish induction and competence for decarboxylation in combination with the analogue chemicals. The structural requirements for the substrates of the Pad-decarboxylation system were probed using a variety of sorbic and cinnamic acid analogues. High decarboxylation activity, ~100% conversion of 1mM substrates, required a mono-carboxylic acid with an alkenyl double bond in the trans (E)-configuration at position C2, further unsaturation at C4, and an overall molecular length between 6.5Å and 9Å. Polar groups on the phenyl ring of cinnamic acid abolished activity (no conversion). Furthermore, several compounds were shown to block Pad-decarboxylation. These compounds, primarily aldehyde analogues of active substrates, may serve to reduce food spoilage by moulds such as A. niger. The possible ecological role of Pad-decarboxylation of spore self-inhibitors is unlikely and the most probable role for Pad-decarboxylation is to remove cinnamic acid-type inhibitors from

  12. Microbial spoilage and formation of biogenic amines in fresh and thawed modified atmosphere-packed salmon ( Salmo salar ) at 2 degrees C

    DEFF Research Database (Denmark)

    Emborg, Jette; Laursen, B.G.; Rathjen, T.;

    2002-01-01

    -2 weeks. Carnobacterium piscicola dominated the spoilage microflora of thawed MAP salmon and probably produced the ca 40 mg kg-1 tyramine detected in this product at the end of its shelf life.Conclusions: Photobacterium phosphoreum dominated the spoilage microflora of fresh MAP salmon but produced only...

  13. Secondary metabolites from Ganoderma.

    Science.gov (United States)

    Baby, Sabulal; Johnson, Anil John; Govindan, Balaji

    2015-06-01

    Ganoderma is a genus of medicinal mushrooms. This review deals with secondary metabolites isolated from Ganoderma and their biological significance. Phytochemical studies over the last 40years led to the isolation of 431 secondary metabolites from various Ganoderma species. The major secondary compounds isolated are (a) C30 lanostanes (ganoderic acids), (b) C30 lanostanes (aldehydes, alcohols, esters, glycosides, lactones, ketones), (c) C27 lanostanes (lucidenic acids), (d) C27 lanostanes (alcohols, lactones, esters), (e) C24, C25 lanostanes (f) C30 pentacyclic triterpenes, (g) meroterpenoids, (h) farnesyl hydroquinones (meroterpenoids), (i) C15 sesquiterpenoids, (j) steroids, (k) alkaloids, (l) prenyl hydroquinone (m) benzofurans, (n) benzopyran-4-one derivatives and (o) benzenoid derivatives. Ganoderma lucidum is the species extensively studied for its secondary metabolites and biological activities. Ganoderma applanatum, Ganoderma colossum, Ganoderma sinense, Ganoderma cochlear, Ganoderma tsugae, Ganoderma amboinense, Ganoderma orbiforme, Ganoderma resinaceum, Ganoderma hainanense, Ganoderma concinna, Ganoderma pfeifferi, Ganoderma neo-japonicum, Ganoderma tropicum, Ganoderma australe, Ganoderma carnosum, Ganoderma fornicatum, Ganoderma lipsiense (synonym G. applanatum), Ganoderma mastoporum, Ganoderma theaecolum, Ganoderma boninense, Ganoderma capense and Ganoderma annulare are the other Ganoderma species subjected to phytochemical studies. Further phytochemical studies on Ganoderma could lead to the discovery of hitherto unknown biologically active secondary metabolites.

  14. Role of Plasmids in Lactobacillus brevis BSO 464 Hop Tolerance and Beer Spoilage

    Science.gov (United States)

    Bergsveinson, Jordyn; Baecker, Nina; Pittet, Vanessa

    2014-01-01

    Specific isolates of lactic acid bacteria (LAB) can grow in the harsh beer environment, thus posing a threat to brew quality and the economic success of breweries worldwide. Plasmid-localized genes, such as horA, horC, and hitA, have been suggested to confer hop tolerance, a trait required for LAB survival in beer. The presence and expression of these genes among LAB, however, do not universally correlate with the ability to grow in beer. Genome sequencing of the virulent beer spoilage organism Lactobacillus brevis BSO 464 revealed the presence of eight plasmids, with plasmids 1, 2, and 3 containing horA, horC, and hitA, respectively. To investigate the roles that these and the other five plasmids play in L. brevis BSO 464 growth in beer, plasmid curing with novobiocin was used to derive 10 plasmid variants. Multiplex PCRs were utilized to determine the presence or absence of each plasmid, and how plasmid loss affected hop tolerance and growth in degassed (noncarbonated) beer was assessed. Loss of three of the eight plasmids was found to affect hop tolerance and growth in beer. Loss of plasmid 2 (horC and 28 other genes) had the most dramatic effect, with loss of plasmid 4 (120 genes) and plasmid 8 (47 genes) having significant, but smaller, impacts. These results support the contention that genes on mobile genetic elements are essential for bacterial growth in beer and that beer spoilage ability is not dependent solely on the three previously described hop tolerance genes or on the chromosome of a beer spoilage LAB isolate. PMID:25501474

  15. Characterization and evaluation of the spoilage potential of Lactococcus piscium isolates from modified atmosphere packaged meat.

    Science.gov (United States)

    Rahkila, Riitta; Nieminen, Timo; Johansson, Per; Säde, Elina; Björkroth, Johanna

    2012-05-01

    A total of 222 psychrotrophic lactococci isolated from use-by day, modified atmosphere packaged (MAP) meat were identified to the species level by numerical analyses of EcoRI and ClaI ribopatterns and phylogenetic sequence analyses of 16S, rpoA and pheS genes. In addition, their meat spoilage potential was studied. The majority of the isolates (n=215) were identified as Lactococcus piscium, while seven isolates belonged to Lactococcus raffinolactis. L. piscium was shown to be adapted to growing in a variety of MAP meat products including broiler, turkey, pork, and minced meat from beef and pork, where they belonged to the predominating microbiota at the end of the storage. Numerical analyses of EcoRI and ClaI ribopatterns, and phylogenetic sequence analyses of rpoA and pheS genes were shown to be reliable tools in species level identification of meat lactococci. The spoilage potential of L. piscium was evaluated by inoculating representative isolates to MAP pork stored at 6 °C for 22 days. Development of spoilage population was monitored using a culture-independent T-RFLP approach. The sensory shelf life of pork inoculated with L. piscium was shortened compared to the uninoculated control. Alongside with the inoculated L. piscium isolates, Leuconostoc spp. present as initial contaminants in the samples thrived. This shows that even though lactococci were inoculated at higher levels compared to the natural microbiota, they did not occupy the niche and prevent the growth of other lactic acid bacteria. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Role of plasmids in Lactobacillus brevis BSO 464 hop tolerance and beer spoilage.

    Science.gov (United States)

    Bergsveinson, Jordyn; Baecker, Nina; Pittet, Vanessa; Ziola, Barry

    2015-02-01

    Specific isolates of lactic acid bacteria (LAB) can grow in the harsh beer environment, thus posing a threat to brew quality and the economic success of breweries worldwide. Plasmid-localized genes, such as horA, horC, and hitA, have been suggested to confer hop tolerance, a trait required for LAB survival in beer. The presence and expression of these genes among LAB, however, do not universally correlate with the ability to grow in beer. Genome sequencing of the virulent beer spoilage organism Lactobacillus brevis BSO 464 revealed the presence of eight plasmids, with plasmids 1, 2, and 3 containing horA, horC, and hitA, respectively. To investigate the roles that these and the other five plasmids play in L. brevis BSO 464 growth in beer, plasmid curing with novobiocin was used to derive 10 plasmid variants. Multiplex PCRs were utilized to determine the presence or absence of each plasmid, and how plasmid loss affected hop tolerance and growth in degassed (noncarbonated) beer was assessed. Loss of three of the eight plasmids was found to affect hop tolerance and growth in beer. Loss of plasmid 2 (horC and 28 other genes) had the most dramatic effect, with loss of plasmid 4 (120 genes) and plasmid 8 (47 genes) having significant, but smaller, impacts. These results support the contention that genes on mobile genetic elements are essential for bacterial growth in beer and that beer spoilage ability is not dependent solely on the three previously described hop tolerance genes or on the chromosome of a beer spoilage LAB isolate.

  17. High pressure inactivation of Escherichia coli, Campylobacter jejuni, and spoilage microbiota on poultry meat.

    Science.gov (United States)

    Liu, Yang; Betti, Mirko; Gänzle, Michael G

    2012-03-01

    This study evaluated the high pressure inactivation of Campylobacter jejuni, Escherichia coli, and poultry meat spoilage organisms. All treatments were performed in aseptically prepared minced poultry meat. Treatment of 19 strains of C. jejuni at 300 MPa and 30°C revealed a large variation of pressure resistance. The recovery of pressure-induced sublethally injured C. jejuni depended on the availability of iron. The addition of iron content to enumeration media was required for resuscitation of sublethally injured cells. Survival of C. jejuni during storage of refrigerated poultry meat was analyzed in fresh and pressuretreated poultry meat, and in the presence or absence of spoilage microbiota. The presence of spoilage microbiota did not significantly influence the survival of C. jejuni. Pressure treatment at 400 MPa and 40°C reduced cell counts of Brochothrix thermosphacta, Carnobacterium divergens, C. jejuni, and Pseudomonas fluorescens to levels below the detection limit. Cell counts of E. coli AW1.7, however, were reduced by only 3.5 log (CFU/g) and remained stable during subsequent refrigerated storage. The resistance to treatment at 600 MPa and 40°C of E. coli AW1.7 was compared with Salmonella enterica, Shiga toxin-producing E. coli and nonpathogenic E. coli strains, and Staphylococcus spp. Cell counts of all organisms except E. coli AW 1.7 were reduced by more than 6 log CFU/g. Cell counts of E. coli AW1.7 were reduced by 4.5 log CFU/g only. Moreover, the ability of E. coli AW1.7 to resist pressure was comparable to the pressure-resistant mutant E. coli LMM1030. Our results indicate that preservation of fresh meat requires a combination of high pressure with high temperature (40 to 60°C) or other antimicrobial hurdles.

  18. Pricing Volatility of Stock Returns with Volatile and Persistent Components

    DEFF Research Database (Denmark)

    Zhu, Jie

    In this paper a two-component volatility model based on the component's first moment is introduced to describe the dynamic of speculative return volatility. The two components capture the volatile and persistent part of volatility respectively. Then the model is applied to 10 Asia-Pacific stock m......, a positive or risk-premium effect exists between return and the volatile component, yet the persistent component is not significantly priced for return dynamic process.......In this paper a two-component volatility model based on the component's first moment is introduced to describe the dynamic of speculative return volatility. The two components capture the volatile and persistent part of volatility respectively. Then the model is applied to 10 Asia-Pacific stock...... markets. Their in-mean effects on return are also tested. The empirical results show that the persistent component accounts much more for volatility dynamic process than the volatile component. However the volatile component is found to be a significant pricing factor of asset returns for most markets...

  19. The use of chitooligosaccharide in beer brewing for protection against beer-spoilage bacteria and its influence on beer performance.

    Science.gov (United States)

    Zhao, Xue; Yu, Zhimin; Wang, Ting; Guo, Xuan; Luan, Jing; Sun, Yumei; Li, Xianzhen

    2016-04-01

    To identify a biological preservative that can protect beer from microbial contamination, which often results in the production of turbidity and off-flavor. The antimicrobial activity of a chitooligosaccharide against beer-spoilage bacteria and its effect on the fermentation performance of brewer's yeast was studied. Chitooligosaccharide with an average 2 kDa molecular weight was the best at inhibiting all tested beer-spoilage bacteria. The application of chitooligosaccharide in the brewing process did not influence the fermentation of brewer's yeast. The change in beer performance induced by the contamination of Lactobacillus brevis could be effectively controlled by application of chitooligosaccharide in the beer brewing process. The experimental data suggested that chitooligosaccharide should be an excellent preservative to inhibit beer-spoilage bacteria in the brewing process and in the end product.

  20. Role of Plasmids in Lactobacillus brevis BSO 464 Hop Tolerance and Beer Spoilage

    OpenAIRE

    Bergsveinson, Jordyn; Baecker, Nina; Pittet, Vanessa; Ziola, Barry

    2014-01-01

    Specific isolates of lactic acid bacteria (LAB) can grow in the harsh beer environment, thus posing a threat to brew quality and the economic success of breweries worldwide. Plasmid-localized genes, such as horA, horC, and hitA, have been suggested to confer hop tolerance, a trait required for LAB survival in beer. The presence and expression of these genes among LAB, however, do not universally correlate with the ability to grow in beer. Genome sequencing of the virulent beer spoilage organi...

  1. Classification of photobacteria associated with spoilage of fish products by numerical taxanomy and pyrolysis mass spectrometry

    DEFF Research Database (Denmark)

    Dalgaard, Paw; Manfio, G.P.; Goodfellow, M.

    1997-01-01

    , from spoiled products and by using a specific detection method. The data were analysed using the similarity coefficient and the unweighted pair-group with arithmetic averages algorithm. In addition twenty-six of the fish isolates and five reference strains were analysed by Curie-point pyrolysis mass...... sub-groups. One sub-group of psychrotolerant P. phosphoreum strains, which was selected in modified atmosphere packed fish stored at low temperature, was also highlighted using each of the methods. The importance of classifying food spoilage bacteria has been shown and a simple key generated...

  2. Behaviour of co-inoculated pathogenic and spoilage bacteria on poultry following several decontamination treatments.

    Science.gov (United States)

    Alonso-Hernando, Alicia; Capita, Rosa; Alonso-Calleja, Carlos

    2012-10-01

    The potential of chemical decontaminants to cause harmful effects on human health is among the causes of the rejection of antimicrobial treatments for removing surface contamination from poultry carcasses in the European Union. This study was undertaken to determine whether decontaminants might give a competitive advantage to pathogenic bacteria on poultry and involve a potential risk to consumer. A total of 144 chicken legs were co-inoculated with similar concentrations of pathogenic bacteria (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica serotype Enteritidis or Escherichia coli) and spoilage bacteria (Brochothrix thermosphacta or Pseudomonas fluorescens). Samples were dipped for 15min in solutions (w/v) of trisodium phosphate (12%; TSP), acidified sodium chlorite (1200ppm; ASC), citric acid (2%; CA), peroxyacids (220ppm; PA) or chlorine dioxide (50ppm; CD), or were left untreated (control). Microbiological analyses were carried out on day 0 and every 24h until day 7 of storage (at 10±1°C). The modified Gompertz equation was used as the primary model to fit observed data. TSP, ASC and CA were effective in extending the lag phase (L, ranging from 1.47±1.34days to 4.06±1.16days) and in decreasing the concentration of bacteria during the stationary phase (D, ranging from 2.46±0.51 log(10) cfu/cm(2) to 8.64±0.53 log(10) cfu/cm(2)), relative to the control samples (L values ranging from 0.59±0.38days and 2.52±2.28days, and D values ranging from 6.32±0.89 log(10) cfu/cm(2) to 9.39±0.39 log(10) cfu/cm(2), respectively). Both on untreated and on most decontaminated samples the overgrowth of spoilage bacteria among the species tested was observed throughout storage, suggesting that spoilage would occur prior to any noteworthy increase in the levels of pathogenic microorganisms. However, L. monocytogenes counts similar to, or higher than, those for spoilage bacteria were observed on samples treated with TSP, ASC or CA, suggesting that these

  3. Dynamic Volatility Arbitrage

    DEFF Research Database (Denmark)

    Dorn, Jochen

    concepts, next to nothing is known about position reverting strategies and how, and -even more important- in which context they are applied in practice. In the recent market downturn only one sector generated signicant profits for the leading investment banks: Volatility trading activities, namely on Forex...

  4. Stock markets liberalization affects volatility?

    OpenAIRE

    Ioan Alin NISTOR; Maria-Lenuţa CIUPAC-ULICI; GHERMAN Mircea-Cristian

    2012-01-01

    Regarding the impact of liberalization, the results show that, in general, market opening is accompanied by a significant increase in market volatility. In particular, volatility tends to decrease due to large capital inflows and domestic growth.The study analyzes the impact of stock market liberalization on volatility in six emerging stock markets by using GARCH methodology. Theory on the effects of financial liberalization on volatility has been ambiguous, and empirical work has yielded con...

  5. Understanding and classifying metabolite space and metabolite-likeness.

    Directory of Open Access Journals (Sweden)

    Julio E Peironcely

    Full Text Available While the entirety of 'Chemical Space' is huge (and assumed to contain between 10(63 and 10(200 'small molecules', distinct subsets of this space can nonetheless be defined according to certain structural parameters. An example of such a subspace is the chemical space spanned by endogenous metabolites, defined as 'naturally occurring' products of an organisms' metabolism. In order to understand this part of chemical space in more detail, we analyzed the chemical space populated by human metabolites in two ways. Firstly, in order to understand metabolite space better, we performed Principal Component Analysis (PCA, hierarchical clustering and scaffold analysis of metabolites and non-metabolites in order to analyze which chemical features are characteristic for both classes of compounds. Here we found that heteroatom (both oxygen and nitrogen content, as well as the presence of particular ring systems was able to distinguish both groups of compounds. Secondly, we established which molecular descriptors and classifiers are capable of distinguishing metabolites from non-metabolites, by assigning a 'metabolite-likeness' score. It was found that the combination of MDL Public Keys and Random Forest exhibited best overall classification performance with an AUC value of 99.13%, a specificity of 99.84% and a selectivity of 88.79%. This performance is slightly better than previous classifiers; and interestingly we found that drugs occupy two distinct areas of metabolite-likeness, the one being more 'synthetic' and the other being more 'metabolite-like'. Also, on a truly prospective dataset of 457 compounds, 95.84% correct classification was achieved. Overall, we are confident that we contributed to the tasks of classifying metabolites, as well as to understanding metabolite chemical space better. This knowledge can now be used in the development of new drugs that need to resemble metabolites, and in our work particularly for assessing the metabolite

  6. Behaviour and Biological Control of Bacteriocin-Producing Leuconostocs Associated with Spoilage of Vacuum-Packaged Sucuk

    OpenAIRE

    OSMANAĞAOĞLU, Özlem

    2014-01-01

    Non-motile, Gram-positive and catalase-negative anaerobic Leuconostoc sp. were found to be involved in the spoilage of vacuum-packaged refrigerated sucuk samples. The spoilage was associated with an accumulation of large quantities of foul-smelling gas and purge in the bag and loss of colour and texture in the meat. Many of these isolates produce bacteriocins, to which the predominant Gram-positive bacteria normally found in these products are sensitive. As the leuconostocs grew at low temper...

  7. The exploitation of volatile oil

    Institute of Scientific and Technical Information of China (English)

    MENG Teng; ZHANG Da; TENG Xiangjin; LINing; HAO Zaibin

    2007-01-01

    Rose is a kind of favorite ornamental plant. This article briefly introduced the cultivation and the use of rose around the world both in ancient time and nowadays. Today, volatile oil becomes the mainstream of the rose industry. People pay attention to the effect of volatile oil; meanwhile, they speed up their research on extracting volatile oil and the ingredients.

  8. Plant volatiles and the environment

    NARCIS (Netherlands)

    Loreto, F.; Dicke, M.; Schnitzler, J.P.; Turlings, T.C.J.

    2014-01-01

    Volatile organic compounds emitted by plants represent the largest part of biogenic volatile organic compounds (BVOCs) released into our atmosphere. Plant volatiles are formed through many biochemical pathways, constitutively and after stress induction. In recent years, our understanding of the func

  9. Latent Integrated Stochastic Volatility, Realized Volatility, and Implied Volatility: A State Space Approach

    DEFF Research Database (Denmark)

    Bach, Christian; Christensen, Bent Jesper

    We include simultaneously both realized volatility measures based on high-frequency asset returns and implied volatilities backed out of individual traded at the money option prices in a state space approach to the analysis of true underlying volatility. We model integrated volatility as a latent...... fi…rst order Markov process and show that our model is closely related to the CEV and Barndorff-Nielsen & Shephard (2001) models for local volatility. We show that if measurement noise in the observable volatility proxies is not accounted for, then the estimated autoregressive parameter in the latent...... process is downward biased. Implied volatility performs better than any of the alternative realized measures when forecasting future integrated volatility. The results are largely similar across the stock market (S&P 500), bond market (30-year U.S. T-bond), and foreign currency exchange market ($/£ )....

  10. Characterization of spoilage bacteria in pork sausage by PCR-DGGE analysis

    Directory of Open Access Journals (Sweden)

    Francesca Silva Dias

    2013-09-01

    Full Text Available To investigate microbial diversity and identify spoilage bacteria in fresh pork sausages during storage, twelve industrial pork sausages of different trademarks were stored at 4 ºC for 0, 14, 28 and 42 days, 80% relative humidity and packaged in sterile plastic bags. Microbiological analysis was performed. The pH and water activity (a w were measured. The culture-independent method performed was the Polymerase Chain Reaction - Denaturing Gradient Gel Electrophoresis (PCR-DGGE. The culture-dependent method showed that the populations of mesophilic bacteria and Lactic Acid Bacteria (LAB increased linearly over storage time. At the end of the storage time, the average population of microorganisms was detected, in general, at the level of 5 log cfu g-1. A significant (P < 0.005 increase was observed in pH and a w values at the end of the storage time. The PCR-DGGE allowed a rapid identification of dominant communities present in sausages. PCR-DGGE discriminated 15 species and seven genera of bacteria that frequently constitute the microbiota in sausage products. The most frequent spoilage bacteria identified in the sausages were Lactobacillus sakei and Brochothrix thermosphacta. The identification of dominant communities present in fresh pork sausages can help in the choice of the most effective preservation method for extending the product shelf-life.

  11. Characterisation and detection of spoilage mould responsible for black spot in dry-cured fermented sausages.

    Science.gov (United States)

    Lozano-Ojalvo, Daniel; Rodríguez, Alicia; Cordero, Mirian; Bernáldez, Victoria; Reyes-Prieto, Mariana; Córdoba, Juan J

    2015-02-01

    Moulds responsible for black spot spoilage of dry-cured fermented sausages were characterised. For this purpose, samples were taken from those dry-cured fermented sausages which showed black spot alteration. Most of the mould strains were first tentatively identified as Penicillium spp. due to their morphological characteristics in different culture conditions, with one strain as Cladosporium sp. The Cladosporium strain was the only one which provoked blackening in culture media. This strain was further characterised by sequencing of ITS1-5.8S-ITS2 rRNA and β-tubulin genes. This mould strain was able to reproduce black spot formation in dry-cured fermented sausage 'salchichón' throughout the ripening process. In addition, a specific and sensitive real-time PCR method was also developed to detect Cladosporium oxysporum responsible for the black spot formation in sausages. This method could be of great interest for the meat industry to detect samples contaminated with this mould before spoilage of product avoiding economic losses for this sector.

  12. The Occurrence of Beer Spoilage Lactic Acid Bacteria in Craft Beer Production.

    Science.gov (United States)

    Garofalo, Cristiana; Osimani, Andrea; Milanović, Vesna; Taccari, Manuela; Aquilanti, Lucia; Clementi, Francesca

    2015-12-01

    Beer is one of the world's most ancient and widely consumed fermented alcoholic beverages produced with water, malted cereal grains (generally barley and wheat), hops, and yeast. Beer is considered an unfavorable substrate of growth for many microorganisms, however, there are a limited number of bacteria and yeasts, which are capable of growth and may spoil beer especially if it is not pasteurized or sterile-filtered as craft beer. The aim of this research study was to track beer spoilage lactic acid bacteria (LAB) inside a brewery and during the craft beer production process. To that end, indoor air and work surface samples, collected in the brewery under study, together with commercial active dry yeasts, exhausted yeasts, yeast pellet (obtained after mature beer centrifugation), and spoiled beers were analyzed through culture-dependent methods and PCR-DGGE in order to identify the contaminant LAB species and the source of contamination. Lactobacillus brevis was detected in a spoiled beer and in a commercial active dry yeast. Other LAB species and bacteria ascribed to Staphylococcus sp., Enterobaceriaceae, and Acetobacter sp. were found in the brewery. In conclusion, the PCR-DGGE technique coupled with the culture-dependent method was found to be a useful tool for identifying the beer spoilage bacteria and the source of contamination. The analyses carried out on raw materials, by-products, final products, and the brewery were useful for implementing a sanitization plan to be adopted in the production plant.

  13. Characterization of the spoilage lactic acid bacteria in "sliced vacuum-packed cooked ham".

    Science.gov (United States)

    Kalschne, Daneysa Lahis; Womer, Rute; Mattana, Ademir; Sarmento, Cleonice Mendes Pereira; Colla, Luciane Maria; Colla, Eliane

    2015-03-01

    The lactic acid bacteria are involved with food fermentation and in such cases with food spoilage. Considering the need to reduce the lactic acid bacteria growth in meat products, the aim of this work was to enumerated and investigated the lactic acid bacteria present on sliced vacuum-packed cooked ham stored at 4 °C and 8 °C for 45 days by phenotypic and molecular techniques. The quantification showed that the lactic acid bacteria were present from the first day with mean count of 1.98 log cfu/g for the four batches analyzed. The lactic acid bacteria grew rapidly on the samples, and plate counts around 7.59 log cfu/g and 8.25 log cfu/g were detected after 45 days of storage at 4 °C and 8 °C, respectively; storage temperatures studied showed significant influence on the microorganism in study growth. The predominant lactic acid bacteria associated with the spoilage samples at one day of storage includes Lactobacillus sp., the phenotypic overlap Leuconostoc / Weissella sp. and Enterococcus sp. At 45 days of storage at 4 and 8 °C the mainly specie was Lactobacillus curvatus , following by Lactobacillus sakei and Leuconostoc mesentereoides ; the Enterococcus sp. was not present in the samples.

  14. Identification of lactic acid bacteria involved in the spoilage of pasteurized "foie gras" products.

    Science.gov (United States)

    Matamoros, S; André, S; Hue, I; Prévost, H; Pilet, M F

    2010-07-01

    The spoiling microflora of a re-packaged French "foie gras" product was studied. A total of 54 isolates, originating from two different factories, were identified using phenotypical and molecular methods (partial 16S rDNA sequencing). Weissella viridescens was the main species detected in the products from factory 1 (64% of the isolates). These products had a low lactic acid concentration and were considered as non-spoiled. The microflora of factory 2 was dominated mainly by the genus Lactobacillus (95% of the isolates), and the high lactic acid concentration of these products was linked with a strong spoilage. Among the 30 Lactobacillus strains, three species were predominant: Lactobacillus sakei (nine isolates), Lactobacillus coryniformis (eight isolates) and Lactobacillus paraplantarum (five isolates). Challenge tests were performed to confirm the involvement of the Lactobacillus strains in the spoilage of the product. Sterile "foie gras" samples were inoculated with 14 LAB strains from the collection. The most acidifying strains belonged to the species L. sakei, Lactobacillus plantarum and L. paraplantarum. This confirmed the role of the strains from the Lactobacillus genus as the main spoilers of "foie gras" products and will be useful to design new quality protocols and extend the shelf-life of these products.

  15. Molecular characterization of Shewanella and Aeromonas isolates associated with spoilage of Common carp (Cyprinus carpio).

    Science.gov (United States)

    Beaz-Hidalgo, Roxana; Agüeria, Daniela; Latif-Eugenín, Fadua; Yeannes, Maria I; Figueras, Maria J

    2015-01-01

    Storage in ice is a common way of preserving commercial fish species but some microorganisms can still contaminate and participate in the spoilage of the product; therefore, identification of potential harmful microbes is important. Thirteen colonies were isolated from common carp (Cyprinus carpio) that had been stored in ice, whose phenotypic identification revealed that they belonged to the genera Aeromonas (n = 5) and Shewanella (n = 8). Molecular genotyping with ERIC-PCR showed clonality only among two of the five Aeromonas isolates and for two groups (n = 3; n = 2) of the eight Shewanella isolates. Sequencing the rpoD gene showed that four Aeromonas isolates belonged to the species Aeromonas salmonicida and one to A. sobria. Of the eight Shewanella, seven isolates cluster with Shewanella putrefaciens and one with Shewanella profunda in the 16S rRNA phylogenetic tree. However, analysis of the gyrB gene showed that these eight isolates could constitute a new species closely related to S. baltica. The Shewanella and A. salmonicida isolates produce off-odours and reduce trimethylamine oxide, indicating that they might contribute to the spoilage of the fish. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. Proteomic assessment of the role of N-acyl homoserine lactone in Shewanella putrefaciens spoilage.

    Science.gov (United States)

    Zhang, Caili; Zhu, Suqin; Jatt, Abdul-Nabi; Pan, Yurong; Zeng, Mingyong

    2017-08-21

    Shewanella spp. are the common spoilage organisms found in aquatic food products stored at low temperature and their spoilage mechanism has been reported to be mediated by quorum sensing (QS). However, the specifically expressed proteins responding to N-acyl homoserine-lactone (AHLs) were seldom reported. The present study aims to evaluate the effects of different AHL signal molecules on Shewanella putrefaciens Z4 isolated from refrigerated turbot (Scophthalmus maximus) at the proteome level. The results revealed that exogenous AHLs were utilized as QS signal molecules by S. putrefaciens Z4, and AHLs were not degraded by intracellular or extracellular enzymes secreted by S. putrefaciens Z4. Twenty-three differently expressed spots upon the addition of AHLs were selected and identified by liquid chromatography-mass spectrometry (LC-MS). The results indicated that proteins involving in growth and metabolism (i.e., citrate synthase, succinate semialdehyde dehydrogenase), environment adaptation and regulators (i.e., polysaccharide deacetylases, transaldolase) were down-regulated upon three kinds of AHLs (C4-HSL, C6-HSL, and O-C6-HSL), whereas the abundance of stress response protein and DNA ligase were elevated by the addition of exogenous AHLs. Moreover, the effects of exogenous C6-HSL and O-C6-HSLwere prominent. These results provide evidence that AHL-based QS signal molecules affected some important metabolic properties of S. putrefaciens. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  17. Optimized dispersion of ZnO nanoparticles and antimicrobial activity against foodborne pathogens and spoilage microorganisms

    Science.gov (United States)

    Espitia, Paula Judith Perez; Soares, Nilda de Fátima Ferreira; Teófilo, Reinaldo F.; Vitor, Débora M.; Coimbra, Jane Sélia dos Reis; de Andrade, Nélio José; de Sousa, Frederico B.; Sinisterra, Rubén D.; Medeiros, Eber Antonio Alves

    2013-01-01

    Single primary nanoparticles of zinc oxide (nanoZnO) tend to form particle collectives, resulting in loss of antimicrobial activity. This work studied the effects of probe sonication conditions: power, time, and the presence of a dispersing agent (Na4P2O7), on the size of nanoZnO particles. NanoZnO dispersion was optimized by response surface methodology (RSM) and characterized by the zeta potential (ZP) technique. NanoZnO antimicrobial activity was investigated at different concentrations (1, 5, and 10 % w/w) against four foodborne pathogens and four spoilage microorganisms. The presence of the dispersing agent had a significant effect on the size of dispersed nanoZnO. Minimum size after sonication was 238 nm. An optimal dispersion condition was achieved at 200 W for 45 min of sonication in the presence of the dispersing agent. ZP analysis indicated that the ZnO nanoparticle surface charge was altered by the addition of the dispersing agent and changes in pH. At tested concentrations and optimal dispersion, nanoZnO had no antimicrobial activity against Pseudomonas aeruginosa, Lactobacillus plantarum, and Listeria monocytogenes. However, it did have antimicrobial activity against Escherichia coli, Salmonella choleraesuis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger. Based on the exhibited antimicrobial activity of optimized nanoZnO against some foodborne pathogens and spoilage microorganisms, nanoZnO is a promising antimicrobial for food preservation with potential application for incorporation in polymers intended as food-contact surfaces.

  18. Characterization of the spoilage lactic acid bacteria in “sliced vacuum-packed cooked ham”

    Directory of Open Access Journals (Sweden)

    Daneysa Lahis Kalschne

    2015-03-01

    Full Text Available The lactic acid bacteria are involved with food fermentation and in such cases with food spoilage. Considering the need to reduce the lactic acid bacteria growth in meat products, the aim of this work was to enumerated and investigated the lactic acid bacteria present on sliced vacuum-packed cooked ham stored at 4 °C and 8 °C for 45 days by phenotypic and molecular techniques. The quantification showed that the lactic acid bacteria were present from the first day with mean count of 1.98 log cfu/g for the four batches analyzed. The lactic acid bacteria grew rapidly on the samples, and plate counts around 7.59 log cfu/g and 8.25 log cfu/g were detected after 45 days of storage at 4 °C and 8 °C, respectively; storage temperatures studied showed significant influence on the microorganism in study growth. The predominant lactic acid bacteria associated with the spoilage samples at one day of storage includes Lactobacillus sp., the phenotypic overlap Leuconostoc/Weissella sp. and Enterococcus sp. At 45 days of storage at 4 and 8 °C the mainly specie was Lactobacillus curvatus, following by Lactobacillus sakei and Leuconostoc mesentereoides; the Enterococcus sp. was not present in the samples.

  19. American lobsters (Homarus americanus not surviving during air transport: evaluation of microbial spoilage

    Directory of Open Access Journals (Sweden)

    Erica Tirloni

    2016-05-01

    Full Text Available Eighteen American lobsters (Homarus americanus, dead during air transport, were analysed in order to evaluate the microbial population of meat, gills and gut: no specific studies have ever been conducted so far on the microbiological quality of American lobsters’ meats in terms of spoilage microbiota. The meat samples showed very limited total viable counts, in almost all the cases below the level of 6 Log CFU/g, while higher loads were found, as expected, in gut and gills, the most probable source of contamination. These data could justify the possibility to commercialise these notsurviving subjects, without quality concerns for the consumers. Most of the isolates resulted to be clustered with type strains of Pseudoalteromonas spp. (43.1% and Photobacterium spp. (24.1%, and in particular to species related to the natural marine environment. The distribution of the genera showed a marked inhomogeneity among the samples. The majority of the isolates identified resulted to possess proteolytic (69.3% and lipolytic ability (75.5%, suggesting their potential spoilage ability. The maintanance of good hygienical practices, especially during the production of ready-to-eat lobsters-based products, and a proper storage could limit the possible replication of these microorganisms.

  20. Spoilage of vacuum-packed beef by the yeast Kazachstania psychrophila.

    Science.gov (United States)

    Kabisch, Jan; Erl-Höning, Constanze; Wenning, Mareike; Böhnlein, Christina; Gareis, Manfred; Pichner, Rohtraud

    2016-02-01

    A survey of the psychrotolerant yeast microbiota of vacuum-packed beef was conducted between 2010 and 2012. Chilled vacuum-packed beef (n = 50) sampled from 15 different producers was found to have a mean psychrotolerant yeast count of 3.76 log cfu per cm(2). During this assessment, a recently described yeast named Kazachstania psychrophila was shown to be associated with this product. In order to gain basic knowledge about the spoilage potential of K. psychrophila in vacuum-packed beef, challenge studies were performed and the survival of three different K. psychrophila strains was analyzed during storage of artificially contaminated beef. Beef samples were inoculated with the yeasts at a contamination level of 2 log cfu per cm(2). Survival and growth of K. psychrophila strains was monitored on malt extract agar at regular intervals over 84 days. Kazachstania levels rapidly increased about 5 log units within 16 days under chill conditions (4 °C). Gas bubbles were observed after 16 days, while discoloration and production of off-flavors became evident after 42 days in inoculated samples. This study demonstrates for the first time, that the psychrotolerant yeast K. psychrophila is a dominant spoilage microorganism of vacuum-packed beef products stored at low temperatures, causing sensory defects which result in reduced shelf life, and consequently in considerable economic losses. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Emerging preservation techniques for controlling spoilage and pathogenic microorganisms in fruit juices.

    Science.gov (United States)

    Aneja, Kamal Rai; Dhiman, Romika; Aggarwal, Neeraj Kumar; Aneja, Ashish

    2014-01-01

    Fruit juices are important commodities in the global market providing vast possibilities for new value added products to meet consumer demand for convenience, nutrition, and health. Fruit juices are spoiled primarily due to proliferation of acid tolerant and osmophilic microflora. There is also risk of food borne microbial infections which is associated with the consumption of fruit juices. In order to reduce the incidence of outbreaks, fruit juices are preserved by various techniques. Thermal pasteurization is used commercially by fruit juice industries for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, and ultrasound and irradiations have also been employed in fruit juices to overcome the negative effects of thermal pasteurization. Some of these techniques have already been commercialized. Some are still in research or pilot scale. Apart from these emerging techniques, preservatives from natural sources have also shown considerable promise for use in some food products. In this review article, spoilage, pathogenic microflora, and food borne outbreaks associated with fruit juices of last two decades are given in one section. In other sections various prevention methods to control the growth of spoilage and pathogenic microflora to increase the shelf life of fruit juices are discussed.

  2. Emerging Preservation Techniques for Controlling Spoilage and Pathogenic Microorganisms in Fruit Juices

    Directory of Open Access Journals (Sweden)

    Kamal Rai Aneja

    2014-01-01

    Full Text Available Fruit juices are important commodities in the global market providing vast possibilities for new value added products to meet consumer demand for convenience, nutrition, and health. Fruit juices are spoiled primarily due to proliferation of acid tolerant and osmophilic microflora. There is also risk of food borne microbial infections which is associated with the consumption of fruit juices. In order to reduce the incidence of outbreaks, fruit juices are preserved by various techniques. Thermal pasteurization is used commercially by fruit juice industries for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, and ultrasound and irradiations have also been employed in fruit juices to overcome the negative effects of thermal pasteurization. Some of these techniques have already been commercialized. Some are still in research or pilot scale. Apart from these emerging techniques, preservatives from natural sources have also shown considerable promise for use in some food products. In this review article, spoilage, pathogenic microflora, and food borne outbreaks associated with fruit juices of last two decades are given in one section. In other sections various prevention methods to control the growth of spoilage and pathogenic microflora to increase the shelf life of fruit juices are discussed.

  3. Study of kefir grains application in sourdough bread regarding rope spoilage caused by Bacillus spp.

    Science.gov (United States)

    Mantzourani, I; Plessas, S; Saxami, G; Alexopoulos, A; Galanis, A; Bezirtzoglou, E

    2014-01-15

    Sourdough breads prepared with kefir grains resulted in appearance of rope spoilage at the 15th day of bread storage, while the control samples (sourdough breads prepared with wild microflora) were spoiled approximately at the 7th day. Denaturing Gradient Gel Electrophoresis (DGGE) analysis confirmed the above macroscopic observation since Bacillus spp. were detected on sourdough breads prepared with kefir grains at the 15th day of bread storage. The content of organic acids that play synergistic role regarding the enhancement of bread self life was also determined. Lactic acid concentration of sourdough breads prepared with kefir grains were approximately 41-82% higher than the control samples, while acetic acid concentration was about 0.5-1-fold higher respectively. The concentration of some other organic acids studied was also found in higher levels (up to 0.06μg/g) than the control samples. These findings could probably explain the stability of breads prepared with kefir grains against rope spoilage.

  4. Antagonistic intestinal microflora produces antimicrobial substance inhibitory to Pseudomonas species and other spoilage organisms.

    Science.gov (United States)

    Hatew, Bayissa; Delessa, Tenagne; Zakin, Vered; Gollop, Natan

    2011-10-01

    Chicken intestine harbors a vast number of bacterial strains. In the present study, antimicrobial substance produced by lactic acid bacteria (LAB) isolated from the gastrointestinal tract of healthy chicken was detected, characterized, and purified. Based on 16S rRNA sequencing, the bacteria were identified as Lactobacillus plantarum vN. The antimicrobial substance produced by this bacterium was designated vN-1 and exhibited a broad-spectrum of activity against many important pathogenic and spoilage microorganisms, including Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus luteus, Salmonella Typhimurium, and Erwinia amylovova. vN-1 was determined to be thermostable, insensitive to pH values ranging from 2.0 to 8.0, resistant to various organic solvents and to enzymatic inactivation. The inhibition kinetics displayed a bactericidal mode of action. This study revealed an antimicrobial substance with low molecular mass of less than 1 kDa as determined by ultrafiltration and having features not previously reported for LAB isolated from chicken intestines. The detection of this antimicrobial substance addresses an important aspect of biotechnological control agents of spoilage caused by Pseudomonas spp. and promises the possibility for preservation of refrigerated poultry meat. Practical Application:  The newly characterized antimicrobial substance and designated as vN-1 may have the potential to be used in food preservation.

  5. An overview of plant volatile metabolomics, sample treatment and reporting considerations with emphasis on mechanical damage and biological control of weeds.

    Science.gov (United States)

    Beck, John J; Smith, Lincoln; Baig, Nausheena

    2014-01-01

    The technology for the collection and analysis of plant-emitted volatiles for understanding chemical cues of plant-plant, plant-insect or plant-microbe interactions has increased over the years. Consequently, the in situ collection, analysis and identification of volatiles are considered integral to elucidation of complex plant communications. Due to the complexity and range of emissions the conditions for consistent emission of volatiles are difficult to standardise. To discuss: evaluation of emitted volatile metabolites as a means of screening potential target- and non-target weeds/plants for insect biological control agents; plant volatile metabolomics to analyse resultant data; importance of considering volatiles from damaged plants; and use of a database for reporting experimental conditions and results. Recent literature relating to plant volatiles and plant volatile metabolomics are summarised to provide a basic understanding of how metabolomics can be applied to the study of plant volatiles. An overview of plant secondary metabolites, plant volatile metabolomics, analysis of plant volatile metabolomics data and the subsequent input into a database, the roles of plant volatiles, volatile emission as a function of treatment, and the application of plant volatile metabolomics to biological control of invasive weeds. It is recommended that in addition to a non-damaged treatment, plants be damaged prior to collecting volatiles to provide the greatest diversity of odours. For the model system provided, optimal volatile emission occurred when the leaf was punctured with a needle. Results stored in a database should include basic environmental conditions or treatments. Copyright © 2013 John Wiley & Sons, Ltd.

  6. Scaling Foreign Exchange Volatility

    OpenAIRE

    Jonathan Batten; Craig Ellis

    2001-01-01

    When asset returns are normally distributed the risk of an asset over a long return interval may be estimated by scaling the risk from shorter return intervals. While it is well known that asset returns are not normally distributed a key empirical question concerns the effect that scaling the volatility of dependent processes will have on the pricing of related financial assets. This study provides an insight into this issue by investigating the return properties of the most important currenc...

  7. Evaluation of Volatilization Potential for Legacy Chlordane in Military Housing Area Soils

    Science.gov (United States)

    2011-10-01

    likely due to the process of chlordane volatilization from treated soil and re- adsorption to less contaminated soil as it moved upward in the vadose...metabolites using high-resolution gas chromatography with a ß- cyclodextrin derivative as chiral selector and electron- capture negative ion mass

  8. Modulation of population density and size of silver nanoparticles embedded in bacterial cellulose via ammonia exposure: visual detection of volatile compounds in a piece of plasmonic nanopaper

    Science.gov (United States)

    Heli, B.; Morales-Narváez, E.; Golmohammadi, H.; Ajji, A.; Merkoçi, A.

    2016-04-01

    The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging.The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and

  9. Development and mining of a volatile organic compound database.

    Science.gov (United States)

    Abdullah, Azian Azamimi; Altaf-Ul-Amin, Md; Ono, Naoaki; Sato, Tetsuo; Sugiura, Tadao; Morita, Aki Hirai; Katsuragi, Tetsuo; Muto, Ai; Nishioka, Takaaki; Kanaya, Shigehiko

    2015-01-01

    Volatile organic compounds (VOCs) are small molecules that exhibit high vapor pressure under ambient conditions and have low boiling points. Although VOCs contribute only a small proportion of the total metabolites produced by living organisms, they play an important role in chemical ecology specifically in the biological interactions between organisms and ecosystems. VOCs are also important in the health care field as they are presently used as a biomarker to detect various human diseases. Information on VOCs is scattered in the literature until now; however, there is still no available database describing VOCs and their biological activities. To attain this purpose, we have developed KNApSAcK Metabolite Ecology Database, which contains the information on the relationships between VOCs and their emitting organisms. The KNApSAcK Metabolite Ecology is also linked with the KNApSAcK Core and KNApSAcK Metabolite Activity Database to provide further information on the metabolites and their biological activities. The VOC database can be accessed online.

  10. Comparison of some physical techniques for detection of spoilage in apple juice inoculated with Saccharomyces cerevisiae: Optical and photothermal methods

    NARCIS (Netherlands)

    Chirtoc, I.; Chirtoc, M.; Bicanic, D.D.; Cozijnsen, J.L.; Breeuwer, P.

    2003-01-01

    Several physical techniques were used to study the extent of spoilage in apple juice deliberately inoculated with yeast (concentration of Saccharomyces cerevisiae ranged from 25 cells mL(-1) to 2.5 x 10(6) cells mL(-1), respectively) and their performance compared in terms of detection limit achieve

  11. Lactic acid bacteria associated with vacuum-packed cooked meat product spoilage: population analysis by rDNA-based methods.

    Science.gov (United States)

    Chenoll, E; Macián, M C; Elizaquível, P; Aznar, R

    2007-02-01

    To determine the lactic acid bacteria (LAB) implicated in bloating spoilage of vacuum-packed and refrigerated meat products. A total of 18 samples corresponding to four types of meat products, with and without spoilage symptoms, were studied. In all, 387 colonies growing on de Man, Rogosa and Sharpe, yeast glucose lactose peptone and trypticase soy yeast extract plates were identified by internal spacer region (ISR), ISR-restriction fragment length polymorphism and rapid amplified ribosomal DNA restriction analysis profiles as Lactobacillus (37%), Leuconostoc (43%), Carnobacterium (11%), Enterococcus (4%) and Lactococcus (2%). Leuconostoc mesenteroides dominated the microbial population of spoiled products and was always present at the moment bloating occurred. Lactobacillus sakei, Lactobacillus plantarum and Lactobacillus curvatus were found in decreasing order of abundance. The analysis of two meat products, 'morcilla' and 'fiambre de magro adobado' obtained from production lines revealed a common succession pattern in LAB populations in both products and showed that Leuc. mesenteroides became the main species during storage, despite being below the detection level of culture methods after packing. Our results pointed to Leuc. mesenteroides as the main species responsible for bloating spoilage in vacuum-packed meat products. Prevention of bloating spoilage in vacuum-packed cooked meat products requires the sensitive detection of Leuc. mesenteroides (i.e. by PCR).

  12. Interaction between fish spoilage bacteria Pseudomonas sp and Shewanella putrefaciens in fish extracts and on fish tissue

    DEFF Research Database (Denmark)

    Gram, Lone; Melchiorsen, Jette

    1996-01-01

    The interaction between fish spoilage bacteria, Pseudomonas sp. and Shewanella putrefaciens, was investigated using fish extract and fish tissue as model systems. Isolates of Pseudomonas that produced iron chelators, siderophores, inhibited growth of S. putrefaciens in a fish-extract-agar diffusion...

  13. Factors affecting microbial spoilage and shelf-life of chilled vacuum-packed lamb transported to distant markets: a review.

    Science.gov (United States)

    Mills, John; Donnison, Andrea; Brightwell, Gale

    2014-09-01

    Vacuum-packaging and stringent control of storage temperatures enable the export of meat to distant markets, supplying a chilled product that can favourably compete with local fresh meats. To save fuel and reduce emissions, the speed of ships travelling to international markets has decreased resulting in requirement for the shelf-life of chilled lamb to be extended beyond the recognised time of 60-70 days. Growth of microorganisms and ability to cause spoilage of vacuum-packed lamb are dependent on many factors, including the type and initial concentration of spoilage bacteria, meat pH, water activity, availability of substrates, oxygen availability and, most importantly, storage time and temperature of the packaged product. This paper reviews the existing knowledge of the spoilage bacteria affecting vacuum-packed lamb, discusses the impact of these bacteria on product quality, shelf-life and spoilage, and concludes that under specified conditions the shelf-life of chilled lamb can be extended to beyond 70 days.

  14. Molecular identification of Brettanomyces bruxellensis strains isolated from red wines and volatile phenol production.

    Science.gov (United States)

    Oelofse, A; Lonvaud-Funel, A; du Toit, M

    2009-06-01

    The spoilage yeast Brettanomyces/Dekkera can persist throughout the winemaking process and has the potential to produce off-flavours that affect the sensory quality of wine. The main objective of this study was to select different strains of Brettanomyces bruxellensis isolated from red wines and to compare their volatile phenol production. From a collection of 63 strains, eight strains of B. bruxellensis were selected for volatile phenol production after the application of molecular techniques such as ISS-PCR, PCR-DGGE and REA-PFGE. All strains showed three large chromosomes of similar size with PFGE. However, unique restriction profiles of the chromosomes were visible after NotI digestion that clearly distinguished the strains. All strains were capable of producing large quantities of 4-ethylphenol and 4-ethylguaiacol from p-coumaric acid and ferulic acid, respectively in synthetic media. However, the diversity among strains for volatile phenol production differed between synthetic media and wine with regard to the maximum production levels of 4-ethylphenol and 4-ethylguaiacol. This study illustrated the diversity of B. bruxellensis strains that occur during winemaking.

  15. Spoilage Science

    Science.gov (United States)

    Science and Children, 2005

    2005-01-01

    Have you ever tucked away a piece of fruit for later and returned to find it past its prime? Or found some leftovers that had outlived their welcome in the refrigerator? Whether it's fresh or processed, all food eventually spoils. Methods such as freezing, canning, and the use of preservatives lengthen the lifespan of foods, and we--and the modern…

  16. Occurrence and growth of yeasts in processed meat products - Implications for potential spoilage.

    Science.gov (United States)

    Nielsen, Dennis S; Jacobsen, Tomas; Jespersen, Lene; Koch, Anette Granly; Arneborg, Nils

    2008-11-01

    Spoilage of meat products is in general attributed to bacteria but new processing and storage techniques inhibiting growth of bacteria may provide opportunities for yeasts to dominate the microflora and cause spoilage of the product. With the aim of obtaining a deeper understanding of the potential role of yeast in spoilage of five different processed meat products (bacon, ham, salami and two different liver patés), yeasts were isolated, enumerated and identified during processing, in the final product and in the final product at the end of shelf life. Yeasts were isolated along the bacon production line in numbers up to 4.2 log (CFU/g). Smoking of the bacon reduced the yeast counts to lower than 1.0 log (CFU/g) or non-detectable levels. In general, yeasts were only isolated in low numbers during the production of salami, cooked ham and liver paté. In the final products yeasts were detected in low numbers in a few samples (3 out of 30) samples, 1.0-1.3 log (CFU/g). By the end of storage, yeasts were only detected in 1 out of 25 investigated samples 1.8 log (CFU/g). A combination of phenotypic and genotypic methods was used to identify the yeast microflora present during production of the processed meat products. The yeast microflora was complex with 4-12 different species isolated from the different production sites. In general, Candida zeylanoides, Debaryomyces hansenii and the newly described Candida alimentaria were found to be the dominant yeast species. In addition, three putatively previously undescribed yeast species were isolated. Fourteen isolates, representing seven different species isolated during the production of the processed meat products and one species isolated from spoiled, modified atmosphere packed, sliced ham, were screened for their ability to grow in a meat model substrate under a low oxygen/high carbon-dioxide atmosphere (0.5% O(2), 20% CO(2), 79.5% N(2)) at two different temperatures (5 and 8°C). Eleven out of the tested 14 strains were

  17. Production of Metabolites

    DEFF Research Database (Denmark)

    2011-01-01

    A recombinant micro-organism such as Saccharomyces cerevisiae which produces and excretes into culture medium a stilbenoid metabolite product when grown under stilbenoid production conditions, which expresses in above native levels a ABC transporter which transports said stilbenoid out of said...... micro-organism cells to the culture medium. The genome of the Saccharomyces cerevisiae produces an auxotrophic phenotype which is compensated by a plasmid which also expresses one or more of said enzymes constituting said metabolic pathway producing said stilbenoid, an expression product of the plasmid...

  18. Development of Models To Relate Microbiological and Headspace Volatile Parameters in Stored Atlantic Salmon to Acceptance and Willingness To Prepare the Product by Senior Consumers.

    Science.gov (United States)

    Erickson, Marilyn C; Ma, Li M; Doyle, Michael P

    2015-12-01

    Microbial spoilage of salmon occurs during extended refrigerated storage and is often accompanied by unpleasant aromas. When spoilage is detected, it is assumed that consumers will reject the product for consumption. Because sensory panels of trained individuals or consumers are expensive and labor intensive, identification of microbiological or chemical indicators to characterize the extent to which fish has spoiled is needed when experimental process and storage treatments are being evaluated. A consumer panel of 53 senior citizens (60 to 85 years of age) evaluated in duplicate raw salmon subjected to 10 storage conditions, and the fish quality was targeted to range from fresh to very spoiled. This population group was chosen because they would be expected to have a greater prevalence of olfactory impairments and higher odor thresholds than the general population; in turn, a shorter safety margin or time period between product rejection due to spoilage and the generation of Clostridium botulinum toxins would be likely. Low hedonic scores for aroma and overall acceptance (2 or 3 of 9), corresponding to "dislike very much" to "dislike moderately," did not equate with unwillingness to prepare the sample for consumption by up to seven panelists (13%) when the product was presumed to have already been purchased. Despite these outliers, significant models (P = 0.0000) were developed for the willingness of consumers to prepare the sample for consumption and the sample's aerobic and anaerobic microbiological populations and two volatile peaks with Kovats indices of 640 and 753. However, these models revealed that the levels of microbiological and chemical markers must be very high before some consumers would reject the sample; hence, spoilage detection by smell would likely not be an adequate safeguard against consuming salmon in which C. botulinum toxin had been generated.

  19. Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs

    Directory of Open Access Journals (Sweden)

    Mariana Greco

    2015-09-01

    Full Text Available Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60% were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%. These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.

  20. Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs.

    Science.gov (United States)

    Greco, Mariana; Kemppainen, Minna; Pose, Graciela; Pardo, Alejandro

    2015-09-02

    Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.

  1. Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs

    Science.gov (United States)

    Greco, Mariana; Kemppainen, Minna; Pose, Graciela; Pardo, Alejandro

    2015-01-01

    Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds. PMID:26364643

  2. Option Pricing using Realized Volatility

    DEFF Research Database (Denmark)

    Stentoft, Lars Peter

    In the present paper we suggest to model Realized Volatility, an estimate of daily volatility based on high frequency data, as an Inverse Gaussian distributed variable with time varying mean, and we examine the joint properties of Realized Volatility and asset returns. We derive the appropriate...... benchmark model estimated on return data alone. Hence the paper provides evidence on the value of using high frequency data for option pricing purposes....

  3. Option Pricing using Realized Volatility

    DEFF Research Database (Denmark)

    Stentoft, Lars Peter

    In the present paper we suggest to model Realized Volatility, an estimate of daily volatility based on high frequency data, as an Inverse Gaussian distributed variable with time varying mean, and we examine the joint properties of Realized Volatility and asset returns. We derive the appropriate d...... benchmark model estimated on return data alone. Hence the paper provides evidence on the value of using high frequency data for option pricing purposes....

  4. Activity of essential oils from Mediterranean Lamiaceae species against food spoilage yeasts.

    Science.gov (United States)

    Araújo, C; Sousa, M J; Ferreira, M F; Leão, C

    2003-04-01

    The essential oils from aerial parts of Melissa officinalis, Lavandula angustifolia, Salvia officinalis, and Mentha piperita were analyzed by gas chromatography and gas chromatography-mass spectrometry. Their antimicrobial activities were evaluated against five food spoilage yeasts, Torulaspora delbrueckii, Zygosaccharomyces bailii, Pichia membranifaciens, Dekkera anomala, and Yarrowia lipolytica. Saccharomyces cerevisiae was also used as a reference. The oils were preliminarily screened by a disc diffusion technique, with the most active being the oil from M. officinalis. MICs were determined by the broth dilution method, and the main components of the oils were also tested by this method. The essential oil of M. officinalis at 500 microg/ml completely inhibited the growth of all yeast species. The main component of the oil of M. officinalis is citral (neral plus geranial) (58.3%), which showed a marked fungitoxic effect, contributing to its high activity.

  5. Meat spoilage: a critical review of a neglected alteration due to ropy slime producing bacteria

    Directory of Open Access Journals (Sweden)

    Maria F. Iulietto

    2015-07-01

    Full Text Available The shelf-life of a product is the period of time during which the food retains its qualitative characteristics. Bacteria associated with meat spoilage produce unattractive odours and flavours, discolouration, gas and slime. There are several neglected alterations that deserve more attention from food business operators and competent authorities. Ropy slime is a typical alteration of the surface of vacuum and modified atmosphere packed cooked meat products, that causes major economic losses due to the increasingly sophisticated consumer requirements. This is a review article that aims at raising awareness of an old problem of new concern, in the light of new advances and trends for understanding the aetiology of the phenomenon, the origins of contamination and the prevention measures.

  6. At-Line Methods for Controlling Microbial Growth and Spoilage in Meat Processing Abattoirs

    Science.gov (United States)

    Fung, Daniel Y. C.; Edwards, Jessica R.; Crozier-Dodson, Beth Ann

    Many decontamination strategies are available to the meat industry for the control of spoilage and disease causing microorganisms. Most of these strategies are spraywash methods, and a variety of other methods are becoming increasingly popular in the industry as new research and developments are made. Hide-on decontamination has been shown to be extremely effective for controlling pathogens and may become more commonly incorporated into the hazard analysis and critical control point (HACCP) plans. A comprehensive review of decontamination of Escherichia coli O157:H7 in meat processing was made by Edwards and Fung (2006). The current chapter is for at-line consideration of all types of microorganisms related to meat processing with E. coli O157:H7 as the main model. Another detailed analysis of the entire topic of meat safety was made by Fung et al.

  7. ANTIBACTERIAL ACTIVITY OF SIMAROUBA GLAUCA LEAF EXTRACTS AGAINST FOOD BORNE SPOILAGE AND PATHOGENIC MICROORGANISMS

    Directory of Open Access Journals (Sweden)

    B. L. Jangale et al.

    2012-02-01

    Full Text Available Crude ethanol and methanol extracts from dried and fresh leaves of Simarouba glauca were tested for their inhibitory activity against two food borne pathogenic microorganisms (Staphylococcus aeureus and Escherichia coli and two food spoilage microorganism (Bacillus subtilis and Pseudomonas aeurogenosa. Screening for antimicrobial activity using well diffusion assay showed the inhibition against entire tested microorganisms. On the other hand the maximum zone of inhibition was recorded of fresh leaves methanol extract (FLM about 11 mm against Escherichia coli and the lowest zone of inhibition was recorded of fresh leaves methanol extract (FLM about 2 mm against Bacillus subtilis. Minimum inhibitory concentrations (MIC’s of extracts were determined using agar dilution method on the same test microorganisms. Fresh leaves methanol (FLM extract gave MIC value ranging from 160 to 10,240 parts per million (ppm. Result showed that the Bacillus subtilis was the most sensitive microorganism.

  8. Interaction of monolaurin, eugenol and sodium citrate on growth of common meat spoilage and pathogenic organisms.

    Science.gov (United States)

    Blaszyk, M; Holley, R A

    1998-02-17

    Interactions of monolaurin, eugenol (phenolic compound) and sodium citrate (chelator) on the growth of six organisms including common meat spoilage (Lactobacillus curvatus, Lactobacillus sake, Leuconostoc mesenteroides, Brochothrix thermosphacta) and pathogenic (Escherichia coli O157:H7 and Listeria monocytogenes) organisms were investigated. The combinations of 100 to 250 ppm monolaurin with 500 and 1000 ppm eugenol, and 0.2 and 0.4% sodium citrate were more effective than each component separately. More than one combination prevented detectable growth of each organism. Lactic acid bacteria (LAB) and E. coli O157:H7 were most resistant and L. monocytogenes and B. thermosphacta most sensitive to control by the chosen combinations. The presence of sodium citrate was necessary to yield potent inhibition of Lb. curvatus and Lb. sake growth by the monolaurin and eugenol combinations.

  9. SPOILAGE BACTERIA AND QUALITY INDEX METHOD SCORE IN REARED GILTHEAD SEABREAM

    Directory of Open Access Journals (Sweden)

    A. Panebianco

    2008-12-01

    Full Text Available A model to predict the Quality Index Method (QIM score increase during the storage was set for Sparus aurata. In this regard, 126 specimens were analysed during the storage in ice, enumerating the spoilage bacteria in Iron Agar as well as evaluating the QIM. The growth curves and the observed QIM scores were used to calculate (fitting method the terms a and b which relate the bacterial growth to the predicted QIM values. The presumptive Pseudomonas better explains the QIM trends; furthermore the model was validated with regard to other QIM curves obtained during a temperature fluctuating storage, introducing into the predictive system the secondary model for Shewanella spp. (Dalgard, 1995 and Rasmussen et al. (2002. In this case, the model produced a good estimation of the observed QIM.

  10. Evaluation of Antibacterial Activity of Lactobacillus Spp. on Selected Food Spoilage Bacteria.

    Science.gov (United States)

    Sharma, Anurag; Gupta, Piyush; Bhattacharya, Susinjan

    2015-01-01

    This study was done to isolate Lactobacillus species from curd, amla/Indian gooseberry and orange and to assess their antagonistic ability against selected food spoilage bacteria, Escherichia coli, Pseudomonas spp. and Bacillus spp. isolated from natural food sources. In the approaches used, native Lactobacillus spp. were isolated from amla, orange and curd and identified by standard microbiological methods. Their antagonistic affect was tested by disc diffusion tests against three selected test isolates, Escherichia coli, Pseudomonas and Bacillus spp. isolated from tomato, pumpkin, cauliflower, lady's finger, carrot, and milk. There are recent patents also suggesting use of novel strains of Lactobacillus for microbial antagonism. In our present work, the lactobacilli isolated from different food sources showed varied ability to inhibit the growth of test isolates. The growth of test isolates was inhibited by Lactobacillus isolates with one of the Lactobacillus isolate from amla being the most potent inhibitor.

  11. Toxigenic genes, spoilage potential, and antimicrobial resistance of Bacillus cereus group strains from ice cream.

    Science.gov (United States)

    Arslan, Seza; Eyi, Ayla; Küçüksarı, Rümeysa

    2014-02-01

    Bacillus spp. can be recovered from almost every environment. It is also found readily in foods, where it may cause food spoilage and/or food poisoning due to its toxigenic and pathogenic nature, and extracellular enzymes. In this study, 29 Bacillus cereus group strains from ice cream were examined for the presence of following virulence genes hblC, nheA, cytK and ces genes, and tested for a range of the extracellular enzymes, and antimicrobial susceptibility. The strains were found to produce extracellular enzymes: proteolytic and lipolytic activity, gelatin hydrolysis and lecithinase production (100%), DNase production (93.1%) and amylase activity (93.1%). Of 29 strains examined, 24 (82.8%) showed hemolytic activity on blood agar. Beta-lactamase enzyme was only produced by 20.7% of B. cereus group. Among 29 B. cereus group from ice cream, nheA was the most common virulence gene detected in 44.8% of the strains, followed by hblC gene with 17.2%. Four (13.8%) of the 29 strains were positive for both hblC gene and nheA gene. Contrarily, cytK and ces genes were not detected in any of the strains. Antimicrobial susceptibility of ice cream isolates was tested to 14 different antimicrobial agents using the disc diffusion method. We detected resistance to penicillin and ampicillin with the same rate of 89.7%. Thirty-one percent of the strains were multiresistant to three or more antibiotics. This study emphasizes that the presence of natural isolates of Bacillus spp. harboring one or more enterotoxin genes, producing extracellular enzymes which may cause spoilage and acquiring antibiotic resistance might hold crucial importance in the food safety and quality.

  12. Optimized dispersion of ZnO nanoparticles and antimicrobial activity against foodborne pathogens and spoilage microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Perez Espitia, Paula Judith; Ferreira Soares, Nilda de Fatima, E-mail: nfsoares1@gmail.com [Department of Food Technology, Federal University of Vicosa (Brazil); Teofilo, Reinaldo F. [Federal University of Vicosa, Department of Chemistry (Brazil); Vitor, Debora M.; Reis Coimbra, Jane Selia dos; Andrade, Nelio Jose de [Department of Food Technology, Federal University of Vicosa (Brazil); Sousa, Frederico B. de; Sinisterra, Ruben D. [Federal University of Minas Gerais, Department of Chemistry (Brazil); Medeiros, Eber Antonio Alves [Department of Food Technology, Federal University of Vicosa (Brazil)

    2013-01-15

    Single primary nanoparticles of zinc oxide (nanoZnO) tend to form particle collectives, resulting in loss of antimicrobial activity. This work studied the effects of probe sonication conditions: power, time, and the presence of a dispersing agent (Na{sub 4}P{sub 2}O{sub 7}), on the size of nanoZnO particles. NanoZnO dispersion was optimized by response surface methodology (RSM) and characterized by the zeta potential (ZP) technique. NanoZnO antimicrobial activity was investigated at different concentrations (1, 5, and 10 % w/w) against four foodborne pathogens and four spoilage microorganisms. The presence of the dispersing agent had a significant effect on the size of dispersed nanoZnO. Minimum size after sonication was 238 nm. An optimal dispersion condition was achieved at 200 W for 45 min of sonication in the presence of the dispersing agent. ZP analysis indicated that the ZnO nanoparticle surface charge was altered by the addition of the dispersing agent and changes in pH. At tested concentrations and optimal dispersion, nanoZnO had no antimicrobial activity against Pseudomonas aeruginosa, Lactobacillus plantarum, and Listeria monocytogenes. However, it did have antimicrobial activity against Escherichia coli, Salmonella choleraesuis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger. Based on the exhibited antimicrobial activity of optimized nanoZnO against some foodborne pathogens and spoilage microorganisms, nanoZnO is a promising antimicrobial for food preservation with potential application for incorporation in polymers intended as food-contact surfaces.

  13. Pulsed-light inactivation of pathogenic and spoilage bacteria on cheese surface.

    Science.gov (United States)

    Proulx, J; Hsu, L C; Miller, B M; Sullivan, G; Paradis, K; Moraru, C I

    2015-09-01

    Cheese products are susceptible to postprocessing cross-contamination by bacterial surface contamination during slicing, handling, or packaging, which can lead to food safety issues and significant losses due to spoilage. This study examined the effectiveness of pulsed-light (PL) treatment on the inactivation of the spoilage microorganism Pseudomonas fluorescens, the nonenterohemorrhagic Escherichia coli ATCC 25922 (nonpathogenic surrogate of Escherichia coli O157:H7), and Listeria innocua (nonpathogenic surrogate of Listeria monocytogenes) on cheese surface. The effects of inoculum level and cheese surface topography and the presence of clear polyethylene packaging were evaluated in a full factorial experimental design. The challenge microorganisms were grown to early stationary phase and subsequently diluted to reach initial inoculum levels of either 5 or 7 log cfu/slice. White Cheddar and process cheeses were cut into 2.5×5 cm slices, which were spot-inoculated with 100 µL of bacterial suspension. Inoculated cheese samples were exposed to PL doses of 1.02 to 12.29 J/cm(2). Recovered survivors were enumerated by standard plate counting or the most probable number technique, as appropriate. The PL treatments were performed in triplicate and data were analyzed using a general linear model. Listeria innocua was the least sensitive to PL treatment, with a maximum inactivation level of 3.37±0.2 log, followed by P. fluorescens, with a maximum inactivation of 3.74±0.8 log. Escherichia coli was the most sensitive to PL, with a maximum reduction of 5.41±0.1 log. All PL inactivation curves were nonlinear, and inactivation reached a plateau after 3 pulses (3.07 J/cm(2)). The PL treatments through UV-transparent packaging and without packaging consistently resulted in similar inactivation levels. This study demonstrates that PL has strong potential for decontamination of the cheese surface. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc

  14. The fate of acetic acid during glucose co-metabolism by the spoilage yeast Zygosaccharomyces bailii.

    Directory of Open Access Journals (Sweden)

    Fernando Rodrigues

    Full Text Available Zygosaccharomyces bailii is one of the most widely represented spoilage yeast species, being able to metabolise acetic acid in the presence of glucose. To clarify whether simultaneous utilisation of the two substrates affects growth efficiency, we examined growth in single- and mixed-substrate cultures with glucose and acetic acid. Our findings indicate that the biomass yield in the first phase of growth is the result of the weighted sum of the respective biomass yields on single-substrate medium, supporting the conclusion that biomass yield on each substrate is not affected by the presence of the other at pH 3.0 and 5.0, at least for the substrate concentrations examined. In vivo(13C-NMR spectroscopy studies showed that the gluconeogenic pathway is not operational and that [2-(13C]acetate is metabolised via the Krebs cycle leading to the production of glutamate labelled on C(2, C(3 and C(4. The incorporation of [U-(14C]acetate in the cellular constituents resulted mainly in the labelling of the protein and lipid pools 51.5% and 31.5%, respectively. Overall, our data establish that glucose is metabolised primarily through the glycolytic pathway, and acetic acid is used as an additional source of acetyl-CoA both for lipid synthesis and the Krebs cycle. This study provides useful clues for the design of new strategies aimed at overcoming yeast spoilage in acidic, sugar-containing food environments. Moreover, the elucidation of the molecular basis underlying the resistance phenotype of Z. bailii to acetic acid will have a potential impact on the improvement of the performance of S. cerevisiae industrial strains often exposed to acetic acid stress conditions, such as in wine and bioethanol production.

  15. Effect of poultry decontaminants concentration on growth kinetics for pathogenic and spoilage bacteria.

    Science.gov (United States)

    del Río, Elena; González de Caso, Beatriz; Prieto, Miguel; Alonso-Calleja, Carlos; Capita, Rosa

    2008-10-01

    Various chemical compounds are currently under review for final approval as poultry decontaminants in the European Union (EU). Concentration is among the factors considered by the EU authorities in the evaluation of these treatments. The aim of this research was to compare the growth parameters for pathogenic and spoilage bacteria in presence of high and low concentrations of poultry decontaminants to assess whether such treatments could involve a potential sanitary risk for consumers. Growth curves for Salmonella enterica serotype Enteritidis, Listeria monocytogenes, Pseudomonas fluorescens and Brochothrix thermosphacta were obtained at different levels of trisodium phosphate (TSP; 1.74%; 0.58%), acidified sodium chlorite (ASC; 210 ppm; 70 ppm) and citric acid (CA; 0.27%; 0.09%). The modified Gompertz equation was used as primary model to fit observed data. ASC and TSP were the most effective compounds in increasing lag phase (L) and reducing maximum growth rate (mu) in Gram-negative bacteria. Gram-positive bacteria were more influenced by CA. At high TSP levels, mu for Salmonella decreased. Low TSP levels increased mu for Salmonella and Listeria relative to control samples. In presence of 0.27% CA, Brochothrix showed the highest L and the lowest mu among strains tested. These results suggest that low TSP and high CA concentrations could favour the outgrowth of pathogenic bacteria (e.g. Salmonella) relative to spoilage bacteria, rending these treatments potentially dangerous for consumers. The findings of this study may be useful to the EU authorities and meat processors in their efforts to select adequate treatments for control of bacteria on poultry.

  16. Volatile signals during pregnancy.

    Science.gov (United States)

    Vaglio, Stefano

    2010-01-01

    Scents play a key role in mediating reproductive interactions in many vertebrates including mammals. Nowadays, several studies indicate that humans seem to use remarkably olfactory communication and are even able to produce and perceive pheromones. Furthermore, over the past several years, it became increasingly clear that pheromone-like chemical signals probably play a role in offspring identification and mother recognition. Recently developed technical procedures (solid-phase microextraction and dynamic headspace extraction) now allow investigators to characterize volatile compounds with high reliability. We analyzed the volatile compounds in sweat patch samples collected from the para-axillary and nipple-areola regions of women during pregnancy and after childbirth. We hypothesized that, at the time of birth and during the first weeks of life, the distinctive olfactory pattern of the para-axillary area is probably useful to newborn babies for recognizing and distinguishing their own mother, whereas the characteristic pattern of the nipple-areola region is probably useful as a guide to nourishment.

  17. Molecular plant volatile communication.

    Science.gov (United States)

    Holopainen, Jarmo K; Blande, James D

    2012-01-01

    Plants produce a wide array of volatile organic compounds (VOCs) which have multiple functions as internal plant hormones (e.g., ethylene, methyl jasmonate and methyl salicylate), in communication with conspecific and heterospecific plants and in communication with organisms of second (herbivores and pollinators) and third (enemies of herbivores) trophic levels. Species specific VOCs normally repel polyphagous herbivores and those specialised on other plant species, but may attract specialist herbivores and their natural enemies, which use VOCs as host location cues. Attraction of predators and parasitoids by VOCs is considered an evolved indirect defence, whereby plants are able to indirectly reduce biotic stress caused by damaging herbivores. In this chapter we review these interactions where VOCs are known to play a crucial role. We then discuss the importance of volatile communication in self and nonself detection. VOCs are suggested to appear in soil ecosystems where distinction of own roots from neighbours roots is essential to optimise root growth, but limited evidence of above-ground plant self-recognition is available.

  18. Enhanced volatile phenols in wine fermented with Saccharomyces cerevisiae and spoiled with Pichia guilliermondii and Dekkera bruxellensis.

    Science.gov (United States)

    Sáez, J S; Lopes, C A; Kirs, V C; Sangorrín, M P

    2010-08-01

    To investigate whether the presence of Pichia guilliermondii impacts on the production of volatile phenols from mixed wine fermentations with Dekkera bruxellensis and Saccharomyces cerevisiae. Four inoculation strategies were performed in small-scale fermentations involving P. guilliermondii, D. bruxellensis and S. cerevisiae using Syrah grape juice supplemented with 100 mg l(-1) of p-coumaric acid. High pressure liquid chromatography was used for the quantification or volatile phenols. Significant high levels of 4-ethylphenol and 4-ethylguaicol (720 and 545 microg l(-1), respectively), as well as the highest levels of 4-vinylphenol (>4500 microg l(-1)), were observed when P. guilliermondii species was inoculated from the beginning of the fermentation. The metabolic interaction occurring between the high vinylphenol producer species P. guilliermondii and D. bruxellensis exhibiting a high vinylphenol reductase activity resulted in an increased production of volatile phenols in wine. Pichia guilliermondii must be considered a very important spoilage yeast in the wine industry capable of producing large amounts of volatile phenols.

  19. Lactococcus lactis and Lactobacillus sakei as bio-protective culture to eliminate Leuconostoc mesenteroides spoilage and improve the shelf life and sensorial characteristics of commercial cooked bacon.

    Science.gov (United States)

    Comi, Giuseppe; Andyanto, Debbie; Manzano, Marisa; Iacumin, Lucilla

    2016-09-01

    Cooked bacon is a typical Italian meat product. After production, cooked bacon is stored at 4 ± 2 °C. During storage, the microorganisms that survived pasteurisation can grow and produce spoilage. For the first time, we studied the cause of the deterioration in spoiled cooked bacon compared to unspoiled samples. Moreover, the use of bio-protective cultures to improve the quality of the product and eliminate the risk of spoilage was tested. The results show that Leuconostoc mesenteroides is responsible for spoilage and produces a greening colour of the meat, slime and various compounds that result from the fermentation of sugars and the degradation of nitrogen compounds. Finally, Lactococcus lactis spp. lactis and Lactobacillus sakei were able to reduce the risk of Leuconostoc mesenteroides spoilage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Identification of lactic acid bacteria from spoilage associations of cooked and brined shrimps stored under modified atmosphere between 0 degrees C and 25 degrees C

    DEFF Research Database (Denmark)

    Dalgaard, Paw; Vancanneyt, M.; Vilalta, N.E.

    2003-01-01

    Aims: To evaluate spoilage and identify lactic acid bacteria (LAB) from spoilage associations of cooked and brined shrimps stored under modified atmosphere packaging (MAP) at 0, 5, 8, 15 and 25degreesC. Methods and Results: Bacterial isolates (102) from spoilage associations of cooked and brined...... MAP shrimps were characterized by phenotypic tests and identified as lactic acid bacteria (78 isolates), other Gram-positive bacteria (13 isolates) and Gram-negative bacteria (11 isolates). A selection of 48 LAB isolates were further characterized and identified by phenotypic tests and SDS...... to chemical changes in spoiled products. Carnobacterium divergens , a non-motile Carnobacterium sp. nov. and Lactobacillus curvatus were the LAB species observed in spoilage associations of products stored at 0degreesC, 5degreesC and 8degreesC. Conclusions: Enterococcus spp. and Carnobacterium spp. were...

  1. Isolation of a hop-sensitive variant of Lactobacillus lindneri and identification of genetic markers for beer spoilage ability of lactic acid bacteria.

    Science.gov (United States)

    Suzuki, Koji; Iijima, Kazumaru; Ozaki, Kazutaka; Yamashita, Hiroshi

    2005-09-01

    We have isolated a hop-sensitive variant of the beer spoilage bacterium Lactobacillus lindneri DSM 20692. The variant lost a plasmid carrying two contiguous open reading frames (ORF s) designated horB(L) and horC(L) that encode a putative regulator and multidrug transporter presumably belonging to the resistance-nodulation-cell division superfamily. The loss of hop resistance ability occurred with the loss of resistance to other drugs, including ethidium bromide, novobiocin, and cetyltrimethylammonium bromide. PCR and Southern blot analysis using 51 beer spoilage strains of various species of lactic acid bacteria (LAB) revealed that 49 strains possessed homologs of horB and horC. No false-positive results have been observed for nonspoilage LAB or frequently encountered brewery isolates. These features are superior to those of horA and ORF 5, previously reported genetic markers for determining the beer spoilage ability of LAB. It was further shown that the combined use of horB/horC and horA is able to detect all 51 beer spoilage strains examined in this study. Furthermore sequence comparison of horB and horC homologs identified in four different beer spoilage species indicates these homologs are 96.6 to 99.5% identical, which is not typical of distinct species. The wide and exclusive distribution of horB and horC homologs among beer spoilage LAB and their sequence identities suggest that the hop resistance ability of beer spoilage LAB has been acquired through horizontal gene transfer. These insights provide a foundation for applying trans-species genetic markers to differentiating beer spoilage LAB including previously unencountered species.

  2. Consistent ranking of volatility models

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    2006-01-01

    We show that the empirical ranking of volatility models can be inconsistent for the true ranking if the evaluation is based on a proxy for the population measure of volatility. For example, the substitution of a squared return for the conditional variance in the evaluation of ARCH-type models can...

  3. Political institutions and economic volatility

    NARCIS (Netherlands)

    Klomp, Jeroen; de Haan, Jakob

    2009-01-01

    We examine the effect of political 'institutions' on economic growth volatility, using data from more than 100 countries over the period 1960 to 2005, taking into account various control variables as suggested in previous studies. Our indicator of volatility is the relative standard deviation of the

  4. Emerging non-volatile memories

    CERN Document Server

    Hong, Seungbum; Wouters, Dirk

    2014-01-01

    This book is an introduction to the fundamentals of emerging non-volatile memories and provides an overview of future trends in the field. Readers will find coverage of seven important memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), Multiferroic RAM (MFRAM), Phase-Change Memories (PCM), Oxide-based Resistive RAM (RRAM), Probe Storage, and Polymer Memories. Chapters are structured to reflect diffusions and clashes between different topics. Emerging Non-Volatile Memories is an ideal book for graduate students, faculty, and professionals working in the area of non-volatile memory. This book also: Covers key memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), and Multiferroic RAM (MFRAM), among others. Provides an overview of non-volatile memory fundamentals. Broadens readers' understanding of future trends in non-volatile memories.

  5. Psychrotrophic lactic acid bacteria associated with production batch recalls and sporadic cases of early spoilage in Belgium between 2010 and 2014.

    Science.gov (United States)

    Pothakos, Vasileios; Taminiau, Bernard; Huys, Geert; Nezer, Carine; Daube, Georges; Devlieghere, Frank

    2014-11-17

    Between 2010 and 2014 several spoilage cases in Belgium occurring in retail foodstuffs prior to the end of shelf-life have been reported to our laboratory. Overall, seven cases involved strictly psychrotrophic lactic acid bacteria (LAB) contamination in packaged and chilled-stored food products. The products derived either from recalls of entire production batches or as specimens of sporadic spoilage manifestations. Some of these samples were returned to the manufacturing companies by consumers who observed the alterations after purchasing the products. The products covered a wide range of foodstuffs (i.e. meat, dairy, vegetable, egg products and composite food) and denoted different spoilage defects. However, the microbiota determined by means of 16S rRNA gene high-throughput sequencing analysis underpin few LAB genera (i.e. Leuconostoc, Lactobacillus, Weissella and Lactococcus), which are frequently encountered nowadays as specific spoilage organisms (SSO) albeit overlooked by mesophilic enumeration methods due to their strictly psychrotrophic character. The present study confirms the spreading of psychrotrophic LAB in Belgian food processing environments leading to unexpected spoilage, corroborating their spoilage dynamics and prevalence in all kinds of packaged and refrigerated foodstuffs in Northern Europe. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Governmentally amplified output volatility

    Science.gov (United States)

    Funashima, Yoshito

    2016-11-01

    Predominant government behavior is decomposed by frequency into several periodic components: updating cycles of infrastructure, Kuznets cycles, fiscal policy over business cycles, and election cycles. Little is known, however, about the theoretical impact of such cyclical behavior in public finance on output fluctuations. Based on a standard neoclassical growth model, this study intends to examine the frequency at which public investment cycles are relevant to output fluctuations. We find an inverted U-shaped relationship between output volatility and length of cycle in public investment. This implies that periodic behavior in public investment at a certain frequency range can cause aggravated output resonance. Moreover, we present an empirical analysis to test the theoretical implication, using the U.S. data in the period from 1968 to 2015. The empirical results suggest that such resonance phenomena change from low to high frequency.

  7. Volatility Exposure for Strategic Asset Allocation

    OpenAIRE

    Briere, Marie; Burgues, Alexandre; Signori, Ombretta

    2010-01-01

    The authors examine the advantages of incorporating strategic exposure to equity volatility into the investment opportunity set of a long-term equity investor. They consider two standard volatility investments: implied volatility and volatility risk premium strategies. An analytical framework, which offers pragmatic solutions for long-term investors who seek exposure to volatility, is used to calibrate and assess the risk-return profiles of portfolios. The benefit of volatility exposure for a...

  8. Reduced Heart Rate Volatility

    Science.gov (United States)

    Grogan, Eric L.; Morris, John A.; Norris, Patrick R.; France, Daniel J.; Ozdas, Asli; Stiles, Renée A.; Harris, Paul A.; Dawant, Benoit M.; Speroff, Theodore

    2004-01-01

    Objective: To determine if using dense data capture to measure heart rate volatility (standard deviation) measured in 5-minute intervals predicts death. Background: Fundamental approaches to assessing vital signs in the critically ill have changed little since the early 1900s. Our prior work in this area has demonstrated the utility of densely sampled data and, in particular, heart rate volatility over the entire patient stay, for predicting death and prolonged ventilation. Methods: Approximately 120 million heart rate data points were prospectively collected and archived from 1316 trauma ICU patients over 30 months. Data were sampled every 1 to 4 seconds, stored in a relational database, linked to outcome data, and de-identified. HR standard deviation was continuously computed over 5-minute intervals (CVRD, cardiac volatility–related dysfunction). Logistic regression models incorporating age and injury severity score were developed on a test set of patients (N = 923), and prospectively analyzed in a distinct validation set (N = 393) for the first 24 hours of ICU data. Results: Distribution of CVRD varied by survival in the test set. Prospective evaluation of the model in the validation set gave an area in the receiver operating curve of 0.81 with a sensitivity and specificity of 70.1 and 80.0, respectively. CVRD predict death as early as 24 hours in the validation set. Conclusions: CVRD identifies a subgroup of patients with a high probability of dying. Death is predicted within first 24 hours of stay. We hypothesize CVRD is a surrogate for autonomic nervous system dysfunction. PMID:15319726

  9. Use of indirect conductimetry to predict the growth of spoilage yeasts, with special consideration of Zygosaccharomyces bailii.

    Science.gov (United States)

    Deak, T; Beuchat, L R

    1994-11-01

    In recent years, modeling for the purpose of predicting microbiological spoilage of foods has gained much interest. Predictive modeling requires a concentrated mathematical and experimental approach; to collect data of adequate quality is a technically demanding task when several experimental parameters are involved. Rapid, non-traditional, automated techniques are particularly useful in modeling. Of these, electrometric techniques appear to be most promising. Indirect conductimetry was used to study the effect of temperature, aw, pH and potassium sorbate concentration on the growth of Zygosaccharomyces bailii. The automated Malthus 2000 instrument proved to be convenient for gathering a large amount of data that were then used to develop polynomial models describing the response of the yeast to combinations of experimental factors in terms of conductimetric detection time and maximum rate of change in conductance. Results demonstrated that indirect conductimetry is suitable for monitoring the effect of environmental factors on the growth and activity of Z. bailii and perhaps other food spoilage yeasts.

  10. Influence of different proteolytic strains of Streptococcus thermophilus in co-culture with Lactobacillus delbrueckii subsp. bulgaricus on the metabolite profile of set-yoghurt.

    Science.gov (United States)

    Settachaimongkon, Sarn; Nout, M J Robert; Antunes Fernandes, Elsa C; Hettinga, Kasper A; Vervoort, Jacques M; van Hooijdonk, Toon C M; Zwietering, Marcel H; Smid, Eddy J; van Valenberg, Hein J F

    2014-05-02

    Proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus is one of the key factors that determine the fermentation process and final quality of yoghurt. In this study, the interaction between different proteolytic strains of S. thermophilus and L. delbrueckii subsp. bulgaricus was investigated in terms of microbial growth, acidification and changes in the biochemical composition of milk during set-yoghurt fermentation. A complementary metabolomics approach was applied for global characterization of volatile and non-volatile polar metabolite profiles of yoghurt associated with proteolytic activity of the individual strains in the starter cultures. The results demonstrated that only non-proteolytic S. thermophilus (Prt-) strain performed proto-cooperation with L. delbrueckii subsp. bulgaricus. The proto-cooperation resulted in significant higher populations of the two species, faster milk acidification, significant abundance of aroma volatiles and non-volatile metabolites desirable for a good organoleptic quality of yoghurt. Headspace SPME-GC/MS and (1)H NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Furthermore, multivariate statistical analysis allows discriminating set-yoghurts fermented by different types of starter cultures according to their metabolite profiles. Our finding underlines that selection of suitable strain combinations in yoghurt starters is important for achieving the best technological performance regarding the quality of product. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Bacterial Ecology of Fermented Cucumber Rising pH Spoilage as Determined by Nonculture-Based Methods.

    Science.gov (United States)

    Medina, Eduardo; Pérez-Díaz, Ilenys M; Breidt, Fred; Hayes, Janet; Franco, Wendy; Butz, Natasha; Azcarate-Peril, María Andrea

    2016-01-01

    Fermented cucumber spoilage (FCS) characterized by rising pH and the appearance of manure- and cheese-like aromas is a challenge of significant economical impact for the pickling industry. Previous culture-based studies identified the yeasts Pichia manshurica and Issatchenkia occidentalis, 4 Gram-positive bacteria, Lactobacillus buchneri, Lactobacillus parrafaraginis, Clostridium sp., and Propionibacterium and 1 Gram-negative genus, Pectinatus, as relevant in various stages of FCS given their ability to metabolize lactic acid. It was the objective of this study to augment the current knowledge of FCS using culture-independent methods to microbiologically characterize commercial spoilage samples. Ion Torrent data and 16S rRNA cloning library analyses of samples collected from commercial fermentation tanks confirmed the presence of L. rapi and L. buchneri and revealed the presence of additional species involved in the development of FCS such as Lactobacillus namurensis, Lactobacillus acetotolerans, Lactobacillus panis, Acetobacter peroxydans, Acetobacter aceti, and Acetobacter pasteurianus at pH below 3.4. The culture-independent analyses also revealed the presence of species of Veillonella and Dialister in spoilage samples with pH above 4.0 and confirmed the presence of Pectinatus spp. during lactic acid degradation at the higher pH. Acetobacter spp. were successfully isolated from commercial samples collected from tanks subjected to air purging by plating on Mannitol Yeast Peptone agar. In contrast, Lactobacillus spp. were primarily identified in samples of FCS collected from tanks not subjected to air purging for more than 4 mo. Thus, it is speculated that oxygen availability may be a determining factor in the initiation of spoilage and the leading microbiota.

  12. Bacterial Ecology of Fermented Cucumber Rising pH Spoilage as Determined by Non-Culture Based Methods

    Science.gov (United States)

    Medina, Eduardo; Pérez-Díaz, Ilenys M.; Breidt, Fred; Hayes, Janet; Franco, Wendy; Butz, Natasha; Azcarate-Peril, María Andrea

    2016-01-01

    Fermented cucumber spoilage (FCS) characterized by rising pH and the appearance of manure and cheese like aromas is a challenge of significant economical impact for the pickling industry. Previous culture based studies identified the yeasts Pichia manshurica and Issatchenkia occidentalis, four gram positive bacteria, Lactobacillus buchneri, Lactobacillus parrafaraginis, Clostridium sp. and Propionibacterium and one gram-negative genus, Pectinatus as relevant in various stages of FCS given their ability to metabolize lactic acid. It was the objective of this study to augment the current knowledge of FCS using culture independent methods to microbiologically characterize commercial spoilage samples. Ion Torrent data and 16S rRNA cloning library analyses of samples collected from commercial fermentation tanks confirmed the presence of L. rapi and L. buchneri and revealed the presence of additional species involved in the development of FCS such as Lactobacillus namurensis, Lactobacillus acetotolerans, Lactobacillus panis, Acetobacter peroxydans, Acetobacter aceti, and Acetobacter pasteurianus at pH below 3.4. The culture independent analyses also revealed the presence of species of Veillonella and Dialister in spoilage samples with pH above 4.0 and confirmed the presence of Pectinatus spp. during lactic acid degradation at the higher pH. Acetobacter spp. were successfully isolated from commercial samples collected from tanks subjected to air purging by plating on Mannitol Yeast Peptone agar. In contrast, Lactobacillus spp. were primarily identified in samples of FCS collected from tanks not subjected to air purging for more than 4 months. Thus, it is speculated that oxygen availability may be a determining factor in the initiation of spoilage and the leading microbiota. Practical Application Understanding of the underlying microbiology and biochemistry driving FCS is essential to enhancing the sodium chloride (NaCl)-free cucumber fermentation technology and in

  13. The Biodiversity of the Microbiota Producing Heat-Resistant Enzymes Responsible for Spoilage in Processed Bovine Milk and Dairy Products

    Science.gov (United States)

    Machado, Solimar G.; Baglinière, François; Marchand, Sophie; Van Coillie, Els; Vanetti, Maria C. D.; De Block, Jan; Heyndrickx, Marc

    2017-01-01

    Raw bovine milk is highly nutritious as well as pH-neutral, providing the ideal conditions for microbial growth. The microbiota of raw milk is diverse and originates from several sources of contamination including the external udder surface, milking equipment, air, water, feed, grass, feces, and soil. Many bacterial and fungal species can be found in raw milk. The autochthonous microbiota of raw milk immediately after milking generally comprises lactic acid bacteria such as Lactococcus, Lactobacillus, Streptococcus, and Leuconostoc species, which are technologically important for the dairy industry, although they do occasionally cause spoilage of dairy products. Differences in milking practices and storage conditions on each continent, country and region result in variable microbial population structures in raw milk. Raw milk is usually stored at cold temperatures, e.g., about 4°C before processing to reduce the growth of most bacteria. However, psychrotrophic bacteria can proliferate and contribute to spoilage of ultra-high temperature (UHT) treated and sterilized milk and other dairy products with a long shelf life due to their ability to produce extracellular heat resistant enzymes such as peptidases and lipases. Worldwide, species of Pseudomonas, with the ability to produce these spoilage enzymes, are the most common contaminants isolated from cold raw milk although other genera such as Serratia are also reported as important milk spoilers, while for others more research is needed on the heat resistance of the spoilage enzymes produced. The residual activity of extracellular enzymes after high heat treatment may lead to technological problems (off flavors, physico-chemical instability) during the shelf life of milk and dairy products. This review covers the contamination patterns of cold raw milk in several parts of the world, the growth potential of psychrotrophic bacteria, their ability to produce extracellular heat-resistant enzymes and the consequences for

  14. Origin and ecological selection of core and food-specific bacterial communities associated with meat and seafood spoilage

    Science.gov (United States)

    Chaillou, Stéphane; Chaulot-Talmon, Aurélie; Caekebeke, Hélène; Cardinal, Mireille; Christieans, Souad; Denis, Catherine; Hélène Desmonts, Marie; Dousset, Xavier; Feurer, Carole; Hamon, Erwann; Joffraud, Jean-Jacques; La Carbona, Stéphanie; Leroi, Françoise; Leroy, Sabine; Lorre, Sylvie; Macé, Sabrina; Pilet, Marie-France; Prévost, Hervé; Rivollier, Marina; Roux, Dephine; Talon, Régine; Zagorec, Monique; Champomier-Vergès, Marie-Christine

    2015-01-01

    The microbial spoilage of meat and seafood products with short shelf lives is responsible for a significant amount of food waste. Food spoilage is a very heterogeneous process, involving the growth of various, poorly characterized bacterial communities. In this study, we conducted 16S ribosomal RNA gene pyrosequencing on 160 samples of fresh and spoiled foods to comparatively explore the bacterial communities associated with four meat products and four seafood products that are among the most consumed food items in Europe. We show that fresh products are contaminated in part by a microbiota similar to that found on the skin and in the gut of animals. However, this animal-derived microbiota was less prevalent and less abundant than a core microbiota, psychrotrophic in nature, mainly originated from the environment (water reservoirs). We clearly show that this core community found on meat and seafood products is the main reservoir of spoilage bacteria. We also show that storage conditions exert strong selective pressure on the initial microbiota: alpha diversity in fresh samples was 189±58 operational taxonomic units (OTUs) but dropped to 27±12 OTUs in spoiled samples. The OTU assemblage associated with spoilage was shaped by low storage temperatures, packaging and the nutritional value of the food matrix itself. These factors presumably act in tandem without any hierarchical pattern. Most notably, we were also able to identify putative new clades of dominant, previously undescribed bacteria occurring on spoiled seafood, a finding that emphasizes the importance of using culture-independent methods when studying food microbiota. PMID:25333463

  15. The Biodiversity of the Microbiota Producing Heat-Resistant Enzymes Responsible for Spoilage in Processed Bovine Milk and Dairy Products.

    Science.gov (United States)

    Machado, Solimar G; Baglinière, François; Marchand, Sophie; Van Coillie, Els; Vanetti, Maria C D; De Block, Jan; Heyndrickx, Marc

    2017-01-01

    Raw bovine milk is highly nutritious as well as pH-neutral, providing the ideal conditions for microbial growth. The microbiota of raw milk is diverse and originates from several sources of contamination including the external udder surface, milking equipment, air, water, feed, grass, feces, and soil. Many bacterial and fungal species can be found in raw milk. The autochthonous microbiota of raw milk immediately after milking generally comprises lactic acid bacteria such as Lactococcus, Lactobacillus, Streptococcus, and Leuconostoc species, which are technologically important for the dairy industry, although they do occasionally cause spoilage of dairy products. Differences in milking practices and storage conditions on each continent, country and region result in variable microbial population structures in raw milk. Raw milk is usually stored at cold temperatures, e.g., about 4°C before processing to reduce the growth of most bacteria. However, psychrotrophic bacteria can proliferate and contribute to spoilage of ultra-high temperature (UHT) treated and sterilized milk and other dairy products with a long shelf life due to their ability to produce extracellular heat resistant enzymes such as peptidases and lipases. Worldwide, species of Pseudomonas, with the ability to produce these spoilage enzymes, are the most common contaminants isolated from cold raw milk although other genera such as Serratia are also reported as important milk spoilers, while for others more research is needed on the heat resistance of the spoilage enzymes produced. The residual activity of extracellular enzymes after high heat treatment may lead to technological problems (off flavors, physico-chemical instability) during the shelf life of milk and dairy products. This review covers the contamination patterns of cold raw milk in several parts of the world, the growth potential of psychrotrophic bacteria, their ability to produce extracellular heat-resistant enzymes and the consequences for

  16. Modelling and predicting the simultaneous growth of Listeria monocytogenes and spoilage micro-organisms in cold-smoked salmon

    DEFF Research Database (Denmark)

    Gimenez, B.; Dalgaard, Paw

    2004-01-01

    Aims: To evaluate and model the simultaneous growth of Listeria monocytogenes and spoilage micro-organisms in cold-smoked salmon.Methods and Results: Growth kinetics of L. monocytogenes, lactic acid bacteria (LAB), Enterobacteriaceae, enterococci and Photobacterium phosphoreum were determined...... in two series of challenge tests with sliced and vacuum-packed cold-smoked salmon (SVP-CSS). The product contained a high level of smoke components and at 2degreesC levels of L. monocytogenes increased...

  17. An investigation of the effect of rapid slurry chilling on blown pack spoilage of vacuum-packaged beef primals.

    Science.gov (United States)

    Reid, R; Fanning, S; Whyte, P; Kerry, J; Bolton, D

    2017-02-01

    The aim of this study was to investigate if rapid slurry chilling would retard or prevent blown pack spoilage (BPS) of vacuum-packaged beef primals. Beef primals were inoculated with Clostridium estertheticum subspp. estertheticum (DSMZ 8809), C. estertheticum subspp. laramenise (DSMZ 14864) and C. gasigenes (DSMZ 12272), and vacuum-packaged with and without heat shrinkage (90°C for 3 s). These packs were then subjected to immediate chilling in an ice slurry or using conventional blast chilling systems and stored at 2°C for up to 100 days. The onset and progress of BPS was monitored using the following scale; 0-no gas bubbles in drip; 1-gas bubbles in drip; 2-loss of vacuum; 3-'blown'; 4-presence of sufficient gas inside the packs to produce pack distension and 5-tightly stretched, 'overblown' packs/packs leaking. Rapid slurry chilling (as compared to conventional chilling) did not significantly affect (P > 0.05) the time to the onset or progress of BPS. It was therefore concluded that rapid chilling of vacuum-packaged beef primals, using an ice slurry system, may not be used as a control intervention to prevent or retard blown pack spoilage. This study adds to our growing understanding of blown pack spoilage of vacuum-packaged beef primals and suggests that rapid chilling of vacuum-packaged beef primals is not a control option for the beef industry. The results suggest that neither eliminating the heat shrinkage step nor rapid chilling of vacuum-packaged beef retard the time to blown pack spoilage. © 2016 The Society for Applied Microbiology.

  18. Origin and ecological selection of core and food-specific bacterial communities associated with meat and seafood spoilage.

    Science.gov (United States)

    Chaillou, Stéphane; Chaulot-Talmon, Aurélie; Caekebeke, Hélène; Cardinal, Mireille; Christieans, Souad; Denis, Catherine; Desmonts, Marie Hélène; Dousset, Xavier; Feurer, Carole; Hamon, Erwann; Joffraud, Jean-Jacques; La Carbona, Stéphanie; Leroi, Françoise; Leroy, Sabine; Lorre, Sylvie; Macé, Sabrina; Pilet, Marie-France; Prévost, Hervé; Rivollier, Marina; Roux, Dephine; Talon, Régine; Zagorec, Monique; Champomier-Vergès, Marie-Christine

    2015-05-01

    The microbial spoilage of meat and seafood products with short shelf lives is responsible for a significant amount of food waste. Food spoilage is a very heterogeneous process, involving the growth of various, poorly characterized bacterial communities. In this study, we conducted 16S ribosomal RNA gene pyrosequencing on 160 samples of fresh and spoiled foods to comparatively explore the bacterial communities associated with four meat products and four seafood products that are among the most consumed food items in Europe. We show that fresh products are contaminated in part by a microbiota similar to that found on the skin and in the gut of animals. However, this animal-derived microbiota was less prevalent and less abundant than a core microbiota, psychrotrophic in nature, mainly originated from the environment (water reservoirs). We clearly show that this core community found on meat and seafood products is the main reservoir of spoilage bacteria. We also show that storage conditions exert strong selective pressure on the initial microbiota: alpha diversity in fresh samples was 189±58 operational taxonomic units (OTUs) but dropped to 27±12 OTUs in spoiled samples. The OTU assemblage associated with spoilage was shaped by low storage temperatures, packaging and the nutritional value of the food matrix itself. These factors presumably act in tandem without any hierarchical pattern. Most notably, we were also able to identify putative new clades of dominant, previously undescribed bacteria occurring on spoiled seafood, a finding that emphasizes the importance of using culture-independent methods when studying food microbiota.

  19. Susceptibility of Pediococcus isolates to antimicrobial compounds in relation to hop-resistance and beer-spoilage

    Directory of Open Access Journals (Sweden)

    Ziola Barry

    2009-09-01

    Full Text Available Abstract Background Though important in the context of food microbiology and as potential pathogens in immuno-compromised humans, bacterial isolates belonging to the genus Pediococcus are best known for their association with contamination of ethanol fermentation processes (beer, wine, or fuel ethanol. Use of antimicrobial compounds (e.g., hop-compounds, Penicillin by some industries to combat Pediococcus contaminants is long-standing, yet knowledge about the resistance of pediococci to antimicrobial agents is minimal. Here we examined Pediococcus isolates to determine whether antibiotic resistance is associated with resistance to hops, presence of genes known to correlate with beer spoilage, or with ability to grow in beer. Results Lactic acid bacteria susceptibility test broth medium (LSM used in combination with commercially available GPN3F antimicrobial susceptibility plates was an effective method for assessing antimicrobial susceptibility of Pediococcus isolates. We report the finding of Vancomycin-susceptible Pediococcus isolates from four species. Interestingly, we found that hop-resistant, beer-spoilage, and beer-spoilage gene-harbouring isolates had a tendency to be more susceptible, rather than more resistant, to antimicrobial compounds. Conclusion Our findings indicate that the mechanisms involved in conferring hop-resistance or ability to spoil beer by Pediococcus isolates are not associated with resistance to antibiotics commonly used for treatment of human infections. Also, Vancomycin-resistance was found to be isolate-specific and not intrinsic to the genus as previously believed.

  20. Susceptibility of Pediococcus isolates to antimicrobial compounds in relation to hop-resistance and beer-spoilage

    Science.gov (United States)

    2009-01-01

    Background Though important in the context of food microbiology and as potential pathogens in immuno-compromised humans, bacterial isolates belonging to the genus Pediococcus are best known for their association with contamination of ethanol fermentation processes (beer, wine, or fuel ethanol). Use of antimicrobial compounds (e.g., hop-compounds, Penicillin) by some industries to combat Pediococcus contaminants is long-standing, yet knowledge about the resistance of pediococci to antimicrobial agents is minimal. Here we examined Pediococcus isolates to determine whether antibiotic resistance is associated with resistance to hops, presence of genes known to correlate with beer spoilage, or with ability to grow in beer. Results Lactic acid bacteria susceptibility test broth medium (LSM) used in combination with commercially available GPN3F antimicrobial susceptibility plates was an effective method for assessing antimicrobial susceptibility of Pediococcus isolates. We report the finding of Vancomycin-susceptible Pediococcus isolates from four species. Interestingly, we found that hop-resistant, beer-spoilage, and beer-spoilage gene-harbouring isolates had a tendency to be more susceptible, rather than more resistant, to antimicrobial compounds. Conclusion Our findings indicate that the mechanisms involved in conferring hop-resistance or ability to spoil beer by Pediococcus isolates are not associated with resistance to antibiotics commonly used for treatment of human infections. Also, Vancomycin-resistance was found to be isolate-specific and not intrinsic to the genus as previously believed. PMID:19735560

  1. Identification and growth dynamics of meat spoilage microorganisms in modified atmosphere packaged poultry meat by MALDI-TOF MS.

    Science.gov (United States)

    Höll, Linda; Behr, Jürgen; Vogel, Rudi F

    2016-12-01

    Modified atmosphere packaging (MAP) is widely used in food industry to extend the microbiological shelf-life of meat. Typically, poultry meat has been packaged in a CO2/N2 atmosphere (with residual low O2). Recently, some producers use high O2 MAP for poultry meat to empirically reach comparable shelf lifes. In this work, we compared spoilage microbiota of skinless chicken breast in high (80% O2, 20% CO2) and low O2 MAP (65% N2 and 35% CO2). Two batches of meat were incubated in each atmosphere for 14 days at 4 °C and 10 °C. Atmospheric composition of each pack and colony forming units (25 °C, 48 h, BHI agar) of poultry samples were determined at seven timepoints. Identification of spoilage organisms was carried out by MALDI-TOF MS. Brochothrix thermosphacta, Carnobacterium sp. and Pseudomonas sp. were the main organisms found after eight days at 4 °C and 10 °C in high O2 MAP. In low O2 MAP, the main spoilage microbiota was represented by species Hafnia alvei at 10 °C, and genera Carnobacterium sp., Serratia sp., and Yersinia sp. at 4 °C. High O2 MAP is suggested as preferential gas because were less detrimental and pathogens like Yersinia were not observed.

  2. Factors Affecting Microbial Load and Profile of Potential Pathogens and Food Spoilage Bacteria from Household Kitchen Tables.

    Science.gov (United States)

    Biranjia-Hurdoyal, Susheela; Latouche, Melissa Cathleen

    2016-01-01

    The aim was to study the bacterial load and isolate potential pathogens and food spoilage bacteria from kitchen tables, including preparation tables and dining tables. Methods. A total of 53 households gave their consent for participation. The samples were collected by swabbing over an area of 5 cm by 5 cm of the tables and processed for bacterial count which was read as colony forming units (CFU), followed by isolation and identification of potential pathogens and food spoilage bacteria. Result. Knowledge about hygiene was not always put into practice. Coliforms, Enterococcus spp., Pseudomonas spp., Proteus spp., and S. aureus were detected from both dining and preparation tables. The mean CFU and presence of potential pathogens were significantly affected by the hygienic practices of the main food handler of the house, materials of kitchen tables, use of plastic covers, time of sample collection, use of multipurpose sponges/towels for cleaning, and the use of preparation tables as chopping boards (p Kitchen tables could be very important source of potential pathogens and food spoilage bacteria causing foodborne diseases. Lack of hygiene was confirmed by presence of coliforms, S. aureus, and Enterococcus spp. The use of plastic covers, multipurpose sponges, and towels should be discouraged.

  3. Lactococcus piscium: a psychrotrophic lactic acid bacterium with bioprotective or spoilage activity in food-a review.

    Science.gov (United States)

    Saraoui, T; Leroi, F; Björkroth, J; Pilet, M F

    2016-10-01

    The genus Lactococcus comprises 12 species, some known for decades and others more recently described. Lactococcus piscium, isolated in 1990 from rainbow trout, is a psychrotrophic lactic acid bacterium, probably disregarded because most of the strains are unable to grow at 30°C. During the last 10 years, this species has been isolated from a large variety of food: meat, seafood and vegetables, mostly packed under vacuum (VP) or modified atmosphere (MAP) and stored at chilled temperature. Recently, culture-independent techniques used for characterization of microbial ecosystems have highlighted the importance of Lc. piscium in food. Its role in food spoilage varies according to the strain and the food matrix. However, most studies have indicated that Lc. piscium spoils meat, whereas it does not degrade the sensory properties of seafood. Lactococcus piscium strains have a large antimicrobial spectrum, including Gram-positive and negative bacteria. In various seafoods, some strains have a protective effect against spoilage and can extend the sensory shelf-life of the products. They can also inhibit the growth of Listeria monocytogenes, by a cell-to-cell contact-dependent. This article reviews the physiological and genomic characteristics of Lc. piscium and discusses its spoilage or protective activities in food.

  4. Flavour compounds in tomato fruits: identification of loci and potential pathways affecting volatile composition.

    Science.gov (United States)

    Mathieu, Sandrine; Cin, Valeriano Dal; Fei, Zhangjun; Li, Hua; Bliss, Peter; Taylor, Mark G; Klee, Harry J; Tieman, Denise M

    2009-01-01

    The unique flavour of a tomato fruit is the sum of a complex interaction among sugars, acids, and a large set of volatile compounds. While it is generally acknowledged that the flavour of commercially produced tomatoes is inferior, the biochemical and genetic complexity of the trait has made breeding for improved flavour extremely difficult. The volatiles, in particular, present a major challenge for flavour improvement, being generated from a diverse set of lipid, amino acid, and carotenoid precursors. Very few genes controlling their biosynthesis have been identified. New quantitative trait loci (QTLs) that affect the volatile emissions of red-ripe fruits are described here. A population of introgression lines derived from a cross between the cultivated tomato Solanum lycopersicum and its wild relative, S. habrochaites, was characterized over multiple seasons and locations. A total of 30 QTLs affecting the emission of one or more volatiles were mapped. The data from this mapping project, combined with previously collected data on an IL population derived from a cross between S. lycopersicum and S. pennellii populations, were used to construct a correlational database. A metabolite tree derived from these data provides new insights into the pathways for the synthesis of several of these volatiles. One QTL is a novel locus affecting fruit carotenoid content on chromosome 2. Volatile emissions from this and other lines indicate that the linear and cyclic apocarotenoid volatiles are probably derived from separate carotenoid pools.

  5. Rethinking cycad metabolite research.

    Science.gov (United States)

    Snyder, Laura R; Marler, Thomas E

    2011-01-01

    Cycads are among the most ancient of extant Spermatophytes, and are known for their numerous pharmacologically active compounds. One compound in particular, β-methylamino-L-alanine (BMAA), has been implicated as the cause of amyotrophic lateral sclerosis/Parkinson dementia complex (ALS/PDC) on Guam. Previous studies allege that BMAA is produced exclusively by cyanobacteria, and is transferred to cycads through the symbiotic relationship between these cyanobacteria and the roots of cycads. We recently published data showing that Cycas micronesica seedlings grown without endophytic cyanobacteria do in fact increase in BMAA, invalidating the foundation of the BMAA hypothesis. We use this example to suggest that the frenzy centered on BMAA and other single putative toxins has hindered progress. The long list of cycad-specific compounds may have important roles in signaling or communication, but these possibilities have been neglected during decades of attempts to force single metabolites into a supposed anti-herbivory function. We propose that an unbiased, comprehensive approach may be a more appropriate means of proceeding with cycad biochemistry research.

  6. Synthesis Of Labeled Metabolites

    Science.gov (United States)

    Martinez, Rodolfo A.; Silks, III, Louis A.; Unkefer, Clifford J.; Atcher, Robert

    2004-03-23

    The present invention is directed to labeled compounds, for example, isotopically enriched mustard gas metabolites including: [1,1',2,2'-.sup.13 C.sub.4 ]ethane, 1,1'-sulfonylbis[2-(methylthio); [1,1',2,2'-.sup.13 C.sub.4 ]ethane, 1-[[2-(methylsulfinyl)ethyl]sulfonyl]-2-(methylthio); [1,1',2,2'-.sup.13 C.sub.4 ]ethane, 1,1'-sulfonylbis[2-(methylsulfinyl)]; and, 2,2'-sulfinylbis([1,2-.sup.13 C.sub.2 ]ethanol of the general formula ##STR1## where Q.sup.1 is selected from the group consisting of sulfide (--S--), sulfone (--S(O)--), sulfoxide (--S(O.sub.2)--) and oxide (--O--), at least one C* is .sup.13 C, X is selected from the group consisting of hydrogen and deuterium, and Z is selected from the group consisting of hydroxide (--OH), and --Q.sup.2 --R where Q.sup.2 is selected from the group consisting of sulfide (--S--), sulfone(--S(O)--), sulfoxide (--S(O.sub.2)--) and oxide (--O--), and R is selected from the group consisting of hydrogen, a C.sub.1 to C.sub.4 lower alkyl, and amino acid moieties, with the proviso that when Z is a hydroxide and Q.sup.1 is a sulfide, then at least one X is deuterium.

  7. Whole-plant C allocation priorities: do secondary metabolites and VOCs matter?

    Science.gov (United States)

    Hartmann, Henrik; Huang, Jianbei; Forkelova, Lenka; Behrendt, Thomas; Reichelt, Michael; Hammerbacher, Almuth

    2017-04-01

    Whole-plant carbon (C) allocation is a critical issue for understanding plant functioning and has been studied for many decades. Plants fix CO2 from the atmosphere and partition the resulting photosynthetic products (carbohydrates) among several functional pools including growth of structural and reproductive biomass, metabolic processes like respiration but also for the synthesis of secondary metabolites promoting defense and communication. Allocation to secondary metabolites is conceptually viewed as a trade-off between growth and defense. Plants either invest carbohydrates to produce biomass which may be lost - at least partially -to herbivory or they increase allocation to secondary metabolites to deter herbivores from consuming existing biomass. While conceptually intuitive, trade-off hypotheses all suffer from one important shortcoming: the whole-plant carbon balance, critical for determining trade-off relationships, is usually unknown. In the research group on Plant Allocation, we manipulate and measure the whole-plant carbon balance in different species and use tracers to investigate carbon fluxes through the plant and into functional allocation pools. Inducing carbon limitation by reducing atmospheric [CO2] allows us to infer allocation priorities. In this presentation I will show several examples of studies on whole-plant carbon allocation patterns in different plant species. These investigations include assessments of different functional pools like growth, storage, secondary metabolites and volatile emissions as well as the underlying phytohormonal patterns and show that allocation to secondary metabolites and volatiles has a high priority in the whole-plant carbon balance.

  8. Evolutionary patterns of volatile terpene emissions across 202 tropical tree species.

    Science.gov (United States)

    Courtois, Elodie A; Dexter, Kyle G; Paine, Charles Eliot Timothy; Stien, Didier; Engel, Julien; Baraloto, Christopher; Chave, Jérôme

    2016-05-01

    Plant responses to natural enemies include formation of secondary metabolites acting as direct or indirect defenses. Volatile terpenes represent one of the most diverse groups of secondary metabolites. We aimed to explore evolutionary patterns of volatile terpene emission. We measured the composition of damage-induced volatile terpenes from 202 Amazonian tree species, spanning the angiosperm phylogeny. Volatile terpenes were extracted with solid-phase micro extraction and desorbed in a gas chromatography-mass spectrometry for compound identification. The chemical diversity of the terpene blend showed a strong phylogenetic signal as closely related species emitted a similar number of compounds. Closely related species also tended to have compositionally similar blends, although this relationship was weak. Meanwhile, the ability to emit a given compound showed no significant phylogenetic signal for 200 of 286 compounds, indicating a high rate of diversification in terpene synthesis and/or great variability in their expression. Three lineages (Magnoliales, Laurales, and Sapindales) showed exceptionally high rates of terpene diversification. Of the 70 compounds found in >10% of their species, 69 displayed significant correlated evolution with at least one other compound. These results provide insights into the complex evolutionary history of volatile terpenes in angiosperms, while highlighting the need for further research into this important class of compounds.

  9. Lipidomics as an important key for the identification of beer-spoilage bacteria.

    Science.gov (United States)

    Řezanka, T; Matoulková, D; Benada, O; Sigler, K

    2015-06-01

    Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) was used for characterizing intact plasmalogen phospholipid molecules in beer-spoilage bacteria. Identification of intact plasmalogens was carried out using collision-induced dissociation and the presence of suitable marker molecular species, both qualitative and quantitative, was determined in samples containing the anaerobic bacteria Megasphaera and Pectinatus. Using selected ion monitoring (SIM), this method had a limit of detection at 1 pg for the standard, i.e. 1-(1Z-octadecenyl)-2-oleoyl-sn-glycero-3-phosphoethanolamine and be linear in the range of four orders of magnitude from 2 pg to 20 ng. This technique was applied to intact plasmalogen extracts from the samples of contaminated and uncontaminated beer without derivatization and resulted in the identification of contamination of beer by Megasphaera and Pectinatus bacteria. The limit of detection was about 830 cells of anaerobic bacteria, i.e. bacteria containing natural cyclopropane plasmalogenes (c-p-19:0/15:0), which is the majority plasmalogen located in both Megasphaera and Pectinatus. The SIM ESI-MS method has been shown to be useful for the analysis of low concentration of plasmalogens in all biological samples, which were contaminated with anaerobic bacteria, e.g. juice, not only in beer. Significance and impact of the study: Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) using collision-induced dissociation was used to characterize intact plasmalogen phospholipid molecules in beer-spoilage anaerobic bacteria Megasphaera and Pectinatus. Using selected ion monitoring (SIM), this method has a detection limit of 1 pg for the standard 1-(1Z-octadecenyl)-2-oleoyl-sn-glycero-3-phosphoethanolamine and is linear within four orders of magnitude (2 pg to 20 ng). The limit of detection was about 830 cells of bacteria containing natural cyclopropane plasmalogen (c-p-19:0/15:0). SIM ESI-MS method is useful for analyzing low

  10. Role of bacteria isolates in the spoilage of fermented African oil bean seed ugba.

    Science.gov (United States)

    Nwamaka, Nwagu Tochukwu; Chike, Amadi; Obiajulu, Alaekwe

    2010-05-15

    Study was carried out to determine the spoilage association of traditionally fermented ugba, product of African oil bean seed. Samples were collected from three markets within Enugu metropolis in Eastern Nigeria. Microbial population of ugba was isolated, characterized and identified. Effect of time on product quality, total viable cell count and individual growth pattern of isolates was evaluated. Microorganisms isolated were Proteus sp., Klebsiella sp., Staphylococcus epidermidis, E. coli, Bacillus licheniformis and Bacillus subtilis. Initial viable cell count increased from 4.6 x 10(8) -6.2 x 10(8), 6.0 x 10(9) -6.9 x 10(9) and 3.9 x 10(8) -5 x 10(8) cfu g(-1) by the 4th day for samples from Mayor, Kenyatta and Garki markets, respectively. Organoleptic changes in texture and colour were seen to be a factor of time of storage. A decline in growth of Proteus sp., E. coli, Klebsiella sp. and S. epidermidis by the 4th day of storage was observed for all samples. Viable cells of B. licheniformis increased from 6.1 x 10(7) -17.7 x 10(7) cfu g(-1), 13.9 x 10(8) -20.0 x 10(8) and 8.7 x 10(7) -15.5 x 10(7) by the 4th day of storage for samples from Mayor, Kenyatta and Garki markets respectively. Growth of B. subtilis increased from 9.2 x 10(7) -19.9 x 10(7), 14.9 x 10(8) -21.2 x 10(8) and 11.5 x 10(7) -17.2 x 10(7) cfu g(-1) for samples from Mayor, Kenyatta and Garki markets respectively. Our results indicate that ugba spoilage is primarily a result of the continued activity of African oil bean seed fermentative organisms B. subtilis and B. licheniformis.

  11. Identification of a Solanum pennellii Chromosome 4 Fruit Flavor and Nutritional Quality-Associated Metabolite QTL

    Directory of Open Access Journals (Sweden)

    ZHONGYUAN LIU

    2016-11-01

    Full Text Available A major resource for tomato quality improvement and gene discovery is the collection of introgression lines (ILs of cultivated Solanum lycopersicum that contain different, defined chromosomal segments derived from the wild tomato relative, S. pennellii. Among these lines, IL4-4, in which the bottom of S. lycopersicum (cv. M82 chromosome 4 is replaced by the corresponding S. pennellii segment, is altered in many primary and secondary metabolites, including many related to fruit flavor and nutritional quality. Here, we provide a comprehensive profile of IL4-4 ripe fruit metabolites, the transcriptome and fine mapping of sub-ILs. Remarkably, out of 327 quantified metabolites, 185 were significantly changed in IL4-4 fruit, compared to the control. These altered metabolites include volatile organic compounds, primary and secondary metabolites. Partial least squares enhanced discriminant analysis of the metabolite levels among sub-ILs indicated that a genome region encompassing 20 putative open reading frames is responsible for most of the metabolic changes in IL4-4 fruit. This work provides comprehensive insights into IL4-4 fruit biochemistry, identifying a small region of the genome that has major effects on a large and diverse set of metabolites.

  12. Modules of co-regulated metabolites in turmeric (Curcuma longa) rhizome suggest the existence of biosynthetic modules in plant specialized metabolism.

    Science.gov (United States)

    Xie, Zhengzhi; Ma, Xiaoqiang; Gang, David R

    2009-01-01

    Turmeric is an excellent example of a plant that produces large numbers of metabolites from diverse metabolic pathways or networks. It is hypothesized that these metabolic pathways or networks contain biosynthetic modules, which lead to the formation of metabolite modules-groups of metabolites whose production is co-regulated and biosynthetically linked. To test whether such co-regulated metabolite modules do exist in this plant, metabolic profiling analysis was performed on turmeric rhizome samples that were collected from 16 different growth and development treatments, which had significant impacts on the levels of 249 volatile and non-volatile metabolites that were detected. Importantly, one of the many co-regulated metabolite modules that were indeed readily detected in this analysis contained the three major curcuminoids, whereas many other structurally related diarylheptanoids belonged to separate metabolite modules, as did groups of terpenoids. The existence of these co-regulated metabolite modules supported the hypothesis that the 3-methoxyl groups on the aromatic rings of the curcuminoids are formed before the formation of the heptanoid backbone during the biosynthesis of curcumin and also suggested the involvement of multiple polyketide synthases with different substrate selectivities in the formation of the array of diarylheptanoids detected in turmeric. Similar conclusions about terpenoid biosynthesis could also be made. Thus, discovery and analysis of metabolite modules can be a powerful predictive tool in efforts to understand metabolism in plants.

  13. Functional analysis of a tomato salicylic acid methyl transferase and its role in synthesis of the flavor volatile methyl salicylate

    Science.gov (United States)

    Methyl salicylate (MeSA) is a volatile plant secondary metabolite that is an important contributor to taste and scent of many fruits and flowers. It is synthesized from salicylic acid (SA), a phytohormone that contributes to plant pathogen defense. MeSA is synthesized by members of a family of O-met...

  14. Stochastic volatility and stochastic leverage

    DEFF Research Database (Denmark)

    Veraart, Almut; Veraart, Luitgard A. M.

    This paper proposes the new concept of stochastic leverage in stochastic volatility models. Stochastic leverage refers to a stochastic process which replaces the classical constant correlation parameter between the asset return and the stochastic volatility process. We provide a systematic...... treatment of stochastic leverage and propose to model the stochastic leverage effect explicitly, e.g. by means of a linear transformation of a Jacobi process. Such models are both analytically tractable and allow for a direct economic interpretation. In particular, we propose two new stochastic volatility...... models which allow for a stochastic leverage effect: the generalised Heston model and the generalised Barndorff-Nielsen & Shephard model. We investigate the impact of a stochastic leverage effect in the risk neutral world by focusing on implied volatilities generated by option prices derived from our new...

  15. Metabolite Space of Rheumatoid Arthritis

    OpenAIRE

    van Wietmarschen, Herman; van der Greef, Jan

    2012-01-01

    Metabolites play numerous roles in the healthy and diseased body, ranging from regulating physiological processes to providing building blocks for the body. Therefore, understanding the role of metabolites is important in elucidating the etiology and pathology of diseases and finding targets for new treatment options. Rheumatoid arthritis is a complex chronic disease for which new disease management strategies are needed. The aim of this review is to bring together and integrate information a...

  16. Volatiles of Curcuma mangga Val. & Zijp (Zingiberaceae) from Malaysia.

    Science.gov (United States)

    Wahab, Ikarastika Rahayu Abdul; Blagojević, Polina D; Radulović, Niko S; Boylan, Fabio

    2011-11-01

    Analysis by GC and GC/MS of the essential oil obtained from Malaysian Curcuma mangga Val. & Zijp (Zingiberaceae) rhizomes allowed the identification of 97 constituents, comprising 89.5% of the total oil composition. The major compounds were identified as myrcene (1; 46.5%) and β-pinene (2; 14.6%). The chemical composition of this and additional 13 oils obtained from selected Curcuma L. taxa were compared using multivariate statistical analyses (agglomerative hierarchical cluster analysis and principal component analysis). The results of the statistical analyses of this particular data set pointed out that 1 could be potentially used as a valuable infrageneric chemotaxonomical marker for C. mangga. Moreover, it seems that C. mangga, C. xanthorrhiza Roxb., and C. longa L. are, with respect to the volatile secondary metabolites, closely related. In addition, comparison of the essential oil profiles revealed a potential influence of the environmental (geographical) factors, alongside with the genetic ones, on the production of volatile secondary metabolites in Curcuma taxa. Copyright © 2011 Verlag Helvetica Chimica Acta AG, Zürich.

  17. Identification and control of moulds responsible for black spot spoilage in dry-cured ham.

    Science.gov (United States)

    Alía, Alberto; Andrade, María J; Rodríguez, Alicia; Reyes-Prieto, Mariana; Bernáldez, Victoria; Córdoba, Juan J

    2016-12-01

    The aims of this work were to identify moulds responsible for black spot spoilage in the drying and cellar stages of dry-cured ham processing and evaluate the effectiveness of preventive actions for controlling this alteration. Four mould strains isolated from spoiled hams were identified by morphological characteristics and the ITS and β-tubulin sequencing. Two of them were Cladosporium oxysporum, one was C. cladosporioides and the remaining one was C. herbarum. These spoiling strains reproduced the black spots on dry-cured ham-based media and ham slices. Additionally, the effect of water activity (aw) conditions reached throughout dry-cured ham ripening and the activity of the protective culture Penicillium chrysogenum CECT 20922 against the spoiling moulds were evaluated. In the dry-cured ham model system the growth of the Cladosporium strains was minimised when the aw approaches 0.84 or in P. chrysogenum CECT 20922 inoculated dry-cured ham slices. Therefore such combination could be used to avoid the black spot formation in dry-cured ham.

  18. Incorporation of nisin in natural casing for the control of spoilage microorganisms in vacuum packaged sausage

    Directory of Open Access Journals (Sweden)

    Joyce Regina de Barros

    2010-12-01

    Full Text Available This study aimed to evaluate the effectiveness of natural casing treatment with nisin and phosphoric acid on control of spoilage microorganisms in vacuum packaged sausages. Ovine casings were dipped in the following baths: 1 0.1% food grade phosphoric acid; 2 5.0 mg/L nisin; 3 0.1% phosphoric acid and 5.0 mg/L nisin; and 4 sterile water (control. The sausages were produced in a pilot plant, stuffed into the pretreated natural casings, vacuum packaged and stored at 4 and 10 °C for 56 days. The experiments were performed according to a full factorial design 2³, totalizing 8 treatments that were repeated in 3 blocks. Aerobic plate counts and lactic acid bacteria analysis were conducted at 1, 14, 28, 42 and 56 days of storage. Treatment of casings with phosphoric acid 0.1% alone did not inhibit the growth of lactic acid bacteria and reduced the aerobic plate count by 1 log. The activity of nisin against lactic acid bacteria was enhanced by the addition of phosphoric acid, demonstrating a synergistic effect. Furthermore nisin activity was more evident at lower storage temperature (4 ºC. Therefore treatment of the natural casings with nisin and phosphoric acid, combined with low storage temperature, are obstacles that present a potential for controlling the growth of lactic acid bacteria in vacuum packaged sausage.

  19. Coexistence of Lactic Acid Bacteria and Potential Spoilage Microbiota in a Dairy Processing Environment.

    Science.gov (United States)

    Stellato, Giuseppina; De Filippis, Francesca; La Storia, Antonietta; Ercolini, Danilo

    2015-11-01

    Microbial contamination in food processing plants can play a fundamental role in food quality and safety. In this study, the microbiota in a dairy plant was studied by both 16S rRNA- and 26S rRNA-based culture-independent high-throughput amplicon sequencing. Environmental samples from surfaces and tools were studied along with the different types of cheese produced in the same plant. The microbiota of environmental swabs was very complex, including more than 200 operational taxonomic units with extremely variable relative abundances (0.01 to 99%) depending on the species and sample. A core microbiota shared by 70% of the samples indicated a coexistence of lactic acid bacteria with a remarkable level of Streptococcus thermophilus and possible spoilage-associated bacteria, including Pseudomonas, Acinetobacter, and Psychrobacter, with a relative abundance above 50%. The most abundant yeasts were Kluyveromyces marxianus, Yamadazyma triangularis, Trichosporon faecale, and Debaryomyces hansenii. Beta-diversity analyses showed a clear separation of environmental and cheese samples based on both yeast and bacterial community structure. In addition, predicted metagenomes also indicated differential distribution of metabolic pathways between the two categories of samples. Cooccurrence and coexclusion pattern analyses indicated that the occurrence of potential spoilers was excluded by lactic acid bacteria. In addition, their persistence in the environment can be helpful to counter the development of potential spoilers that may contaminate the cheeses, with possible negative effects on their microbiological quality.

  20. The emulsifying effect of biosurfactants produced by food spoilage organisms in Nigeria

    Directory of Open Access Journals (Sweden)

    Christianah O. Ogunmola

    2016-04-01

    Full Text Available Food spoilage organisms were isolated using standard procedures on Nutrient Agar, Cetrimide Agar and Pseudomonas Agar Base (supplemented with CFC. The samples were categorized as animal products (raw fish, egg, raw chicken, corned beef, pasteurized milk and plant products (vegetable salad, water leaf (Talinium triangulare, boiled rice, tomatoes and pumpkin leaf (Teifairia occidentalis.They were characterised as Pseudomonas putida, Pseudomonas aeruginosa, Pseudomonas stutzeri, Burkholderia pseudomallei, Serratia rubidaea, Corynebacterium pilosum, Bacillus subtilis, Bacillus mycoides, Bacillus laterosporus, Bacillus laterosporus, Serratia marcescens, Bacillus cereus, Bacillus macerans, Alcaligenes faecalis and Alcaligenes eutrophus. Preliminary screening for biosurfactant production was done using red blood haemolysis test and confirmed by slide test, drop collapse and oil spreading assay. The biosurfactant produced was purified using acetone and the composition determined initially using Molisch’s test, thin layer chromatography and gas chromatography mass spectrometry. The components were found to be ethanol, amino acids, butoxyacetic acid, hexadecanoic acid, oleic acid, lauryl peroxide, octadecanoic acid and phthalic acid. The producing organisms grew readily on several hydrocarbons such as crude oil, diesel oil and aviation fuel when used as sole carbon sources.  The purified biosurfactants produced were able to cause emulsification of kerosene (19.71-27.14% as well as vegetable oil (16.91-28.12% based on the emulsification index. This result suggests that the isolates can be an asset and further work can exploit their optimal potential in industries.

  1. Assessment of system reliability for a stochastic-flow distribution network with the spoilage property

    Science.gov (United States)

    Lin, Yi-Kuei; Huang, Cheng-Fu; Yeh, Cheng-Ta

    2016-04-01

    In supply chain management, satisfying customer demand is the most concerned for the manager. However, the goods may rot or be spoilt during delivery owing to natural disasters, inclement weather, traffic accidents, collisions, and so on, such that the intact goods may not meet market demand. This paper concentrates on a stochastic-flow distribution network (SFDN), in which a node denotes a supplier, a transfer station, or a market, while a route denotes a carrier providing the delivery service for a pair of nodes. The available capacity of the carrier is stochastic because the capacity may be partially reserved by other customers. The addressed problem is to evaluate the system reliability, the probability that the SFDN can satisfy the market demand with the spoilage rate under the budget constraint from multiple suppliers to the customer. An algorithm is developed in terms of minimal paths to evaluate the system reliability along with a numerical example to illustrate the solution procedure. A practical case of fruit distribution is presented accordingly to emphasise the management implication of the system reliability.

  2. Identification of food and beverage spoilage yeasts from DNA sequence analyses.

    Science.gov (United States)

    Kurtzman, Cletus P

    2015-11-20

    Detection, identification and classification of yeasts have undergone major changes in the last decade and a half following application of gene sequence analyses and genome comparisons. Development of a database (barcode) of easily determined DNA sequences from domains 1 and 2 (D1/D2) of the nuclear large subunit rRNA gene and from ITS now permits many laboratories to identify species quickly and accurately, thus replacing the laborious and often inaccurate phenotypic tests previously used. Phylogenetic analysis of gene sequences has resulted in a major revision of yeast systematics resulting in redefinition of nearly all genera. This new understanding of species relationships has prompted a change of rules for naming and classifying yeasts and other fungi, and these new rules are presented in the recently implemented International Code of Nomenclature for algae, fungi, and plants (Melbourne Code). The use of molecular methods for species identification and the impact of Code changes on classification will be discussed, especially in the context of food and beverage spoilage yeasts.

  3. Growth inhibitory effect of grape phenolics against wine spoilage yeasts and acetic acid bacteria.

    Science.gov (United States)

    Pastorkova, E; Zakova, T; Landa, P; Novakova, J; Vadlejch, J; Kokoska, L

    2013-02-15

    This paper investigates the in vitro antimicrobial potential of 15 grape phenolic compounds of various chemical classes (phenolic acids, stilbenes and flavonoids) using the broth microdilution method against yeasts and acetic acid bacteria frequently occurring in deteriorated wine. Pterostilbene (MICs=32-128 μg/mL), resveratrol (MICs=256-512 μg/mL) and luteolin (MICs=256-512 μg/mL) are among six active compounds that possessed the strongest inhibitory effects against all microorganisms tested. In the case of phenolic acids, myricetin, p-coumaric and ferulic acids exhibited selective antimicrobial activity (MICs=256-512 μg/mL), depending upon yeasts and bacteria tested. In comparison with potassium metabisulphite, all microorganisms tested were more susceptible to the phenolics. The results revealed the antibacterial and antiyeast effects against wine spoilage microorganisms of several highly potent phenolics naturally occurring in grapes. These findings also provide arguments for further investigation of stilbenes as prospective compounds reducing the need for the use of sulphites in winemaking.

  4. Investigations on the Antifungal Effect of Nerol against Aspergillus flavus Causing Food Spoilage

    Directory of Open Access Journals (Sweden)

    Jun Tian

    2013-01-01

    Full Text Available The antifungal efficacy of nerol (NEL has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μL/mL and 0.1 μL/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B1 (AFB1 by A. flavus, totally restraining AFB1 production at 0.6 μL/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μL/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage.

  5. Antimicrobial Activity of Various Plant Extracts on Pseudomonas Species Associated with Spoilage of Chilled Fish

    Directory of Open Access Journals (Sweden)

    Osan Bahurmiz

    2016-11-01

    Full Text Available The antimicrobial activity of various plant extracts on Pseudomonas bacteria isolated from spoiled chilled tilapia (Oreochromis sp. was evaluated in this study. In the first stage of this study, red tilapia was subjected to chilled storage (4°C for 3 weeks, and spoilage bacteria were isolated and identified from the spoiled fish. Pseudomonas was the dominant bacteria isolated from the spoiled fish and further identification revealed that P. putida, P. fluorescens and Pseudomonas spp. were the main species of this group. In the second stage, methanolic extracts of 15 selected plant species were screened for their antimicrobial activity, by agar disc diffusion method, against the Pseudomonas isolates. Results indicated that most of the extracts had different degrees of activity against the bacterial isolates. The strongest activity was exhibited by bottlebrush flower (Callistemon viminalis extract. This was followed by extracts from guava bark (Psidium guajava and henna leaf (Lawsonia inermis. Moderate antimicrobial activities were observed in extracts of clove (Syzygium aromaticum, leaf and peel of tamarind (Tamarindus indica, cinnamon bark (Cinnamomum zeylanicum, wild betel leaf (Piper sarmentosum and fresh thyme (Thymus spp.. Weak or no antimicrobial activity was observed from the remaining extracts. The potential antimicrobial activity shown by some plant extracts in this study could significantly contribute to the fish preservation.

  6. PCR detection of thermophilic spore-forming bacteria involved in canned food spoilage.

    Science.gov (United States)

    Prevost, S; Andre, S; Remize, F

    2010-12-01

    Thermophilic bacteria that form highly heat-resistant spores constitute an important group of spoilage bacteria of low-acid canned food. A PCR assay was developed in order to rapidly trace these bacteria. Three PCR primer pairs were designed from rRNA gene sequences. These primers were evaluated for the specificity and the sensitivity of detection. Two primer pairs allowed detection at the species level of Geobacillus stearothermophilus and Moorella thermoacetica/thermoautrophica. The other pair allowed group-specific detection of anaerobic thermophilic bacteria of the genera Thermoanaerobacterium, Thermoanaerobacter, Caldanerobium and Caldanaerobacter. After a single enrichment step, these PCR assays allowed the detection of 28 thermophiles from 34 cans of spoiled low-acid food. In addition, 13 ingredients were screened for the presence of these bacteria. This PCR assay serves as a detection method for strains able to spoil low-acid canned food treated at 55°C. It will lead to better reactivity in the canning industry. Raw materials and ingredients might be qualified not only for quantitative spore contamination, but also for qualitative contamination by highly heat-resistant spores.

  7. Survival of spoilage bacteria subjected to sequential eugenol and temperature treatments.

    Science.gov (United States)

    Manrique, Yudith; Suriyarak, Sarisa; Gibis, Monika; Schmidt, Herbert; Weiss, Jochen

    2016-02-02

    Effects of a sequential application of eugenol and temperature on the survival of two model spoilage organisms, Staphylococcus carnosus LTH1502 and Escherichia coli K12 C600, were studied. To assess effects of a "temperature first-antimicrobial later" treatment, cultures were treated with eugenol at 20, 37 and 42 °C at the beginning of the incubation period, and after 3h and 8h. To assess effects of an "antimicrobial first-temperature later" treatment, eugenol was added at the beginning of the incubation period at 37 °C and temperature was changed to 20 or 42 °C after 3 or 8h. Cell numbers were determined in regular intervals during the incubation period using plate counts. Partitioning of eugenol was measured by HPLC, and cell morphology was assessed by electron microscopy. Combined treatments were more effective against the Gram negative E. coli than against S. carnosus. Order of application influenced the effectiveness of treatments, especially at 42 °C. There, the temperature first-eugenol later treatment was less effective than other treatments, likely due to temperature-induced adaptation processes occurring in cellular membranes making them more resistant against a later eugenol treatment. Results are of significance in situations where combinations of sublethal stresses are used to build a hurdle concept for food preservation.

  8. Antimicrobial activity of essential oils from Mediterranean aromatic plants against several foodborne and spoilage bacteria.

    Science.gov (United States)

    Silva, Nuno; Alves, Sofia; Gonçalves, Alexandre; Amaral, Joana S; Poeta, Patrícia

    2013-12-01

    The antimicrobial activity of essential oils extracted from a variety of aromatic plants, often used in the Portuguese gastronomy was studied in vitro by the agar diffusion method. The essential oils of thyme, oregano, rosemary, verbena, basil, peppermint, pennyroyal and mint were tested against Gram-positive (Listeria monocytogenes, Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Staphylococcus epidermidis) and Gram-negative strains (Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa). For most essential oils examined, S. aureus, was the most susceptible bacteria, while P. aeruginosa showed, in general, least susceptibility. Among the eight essential oils evaluated, thyme, oregano and pennyroyal oils showed the greatest antimicrobial activity, followed by rosemary, peppermint and verbena, while basil and mint showed the weakest antimicrobial activity. Most of the essential oils considered in this study exhibited a significant inhibitory effect. Thyme oil showed a promising inhibitory activity even at low concentration, thus revealing its potential as a natural preservative in food products against several causal agents of foodborne diseases and food spoilage. In general, the results demonstrate that, besides flavoring the food, the use of aromatic herbs in gastronomy can also contribute to a bacteriostatic effect against pathogens.

  9. Antimicrobial effect of emulsion-encapsulated isoeugenol against biofilms of food pathogens and spoilage bacteria.

    Science.gov (United States)

    Krogsgård Nielsen, Christina; Kjems, Jørgen; Mygind, Tina; Snabe, Torben; Schwarz, Karin; Serfert, Yvonne; Meyer, Rikke Louise

    2017-02-02

    Food-related biofilms can cause food-borne illnesses and spoilage, both of which are problems on a global level. Essential oils are compounds derived from plant material that have a potential to be used in natural food preservation in the future since they are natural antimicrobials. Bacterial biofilms are particularly resilient towards biocides, and preservatives that effectively eradicate biofilms are therefore needed. In this study, we test the antibacterial properties of emulsion-encapsulated and unencapsulated isoeugenol against biofilms of Lis. monocytogenes, S. aureus, P. fluorescens and Leu. mesenteroides in tryptic soy broth and carrot juice. We show that emulsion encapsulation enhances the antimicrobial properties of isoeugenol against biofilms in media but not in carrot juice. Some of the isoeugenol emulsions were coated with chitosan, and treatment of biofilms with these emulsions disrupted the biofilm structure. Furthermore, we show that addition of the surfactant Tween 80, which is commonly used to disperse oils in food, hampers the antibacterial properties of isoeugenol. This finding highlights that common food additives, such as surfactants, may have an adverse effect on the antibacterial activity of preservatives. Isoeugenol is a promising candidate as a future food preservative because it works almost equally well against planktonic bacteria and biofilms. Emulsion encapsulation has potential benefits for the efficacy of isoeugenol, but the effect of encapsulation depends on the properties of food matrix in which isoeugenol is to be applied.

  10. Antimicrobial activity of essential oil components against potential food spoilage microorganisms.

    Science.gov (United States)

    Klein, G; Rüben, C; Upmann, M

    2013-08-01

    The antimicrobial activity of six essential oil components against the potential food spoilage bacteria Aeromonas (A.) hydrophila, Escherichia (E.) coli, Brochothrix (B.) thermosphacta, and Pseudomonas (P.) fragi at single use and in combination with each other was investigated. At single use, the most effective oil components were thymol (bacteriostatic effect starting from 40 ppm, bactericidal effect with 100 ppm) and carvacrol (50 ppm/100 ppm), followed by linalool (180 ppm/720 ppm), α-pinene (400 ppm/no bactericidal effect), 1,8-cineol (1,400 ppm/2,800 ppm), and α-terpineol (600 ppm/no bactericidal effect). Antimicrobial effects occurred only at high, sensorial not acceptable concentrations. The most susceptible bacterium was A. hydrophila, followed by B. thermosphacta and E. coli. Most of the essential oil component combinations tested showed a higher antimicrobial effect than tested at single use. Antagonistic antimicrobial effects were observed particularly against B. thermosphacta, rarely against A. hydrophila. The results show that the concentration of at least one of the components necessary for an antibacterial effect is higher than sensorial acceptable. So the use of herbs with a high content of thymol, carvacrol, linalool, 1,8-cineol, α-pinene or α-terpineol alone or in combination must be weighted against sensorial quality.

  11. Composition and antimicrobial properties of Sardinian Juniperus essential oils against foodborne pathogens and spoilage microorganisms.

    Science.gov (United States)

    Cosentino, Sofia; Barra, Andrea; Pisano, Barbara; Cabizza, Maddalena; Pirisi, Filippo Maria; Palmas, Francesca

    2003-07-01

    In this work, the chemical compositions and antimicrobial properties of Juniperus essential oils and of their main components were determined. Five berry essential oils obtained from different species of Juniperus growing wild in Sardinia were analyzed. The components of the essential oils were identified by gas chromatography-mass spectrometry (GC-MS) analysis. The antimicrobial activities of the oils and their components against food spoilage and pathogenic microorganisms were determined by a broth microdilution method. The GC-MS analysis showed a certain variability in the concentrations of the main constituents of the oils. Alpha-pinene was largely predominant in the oils of the species J. phoenicea subsp. turbinata and J. oxycedrus. Alpha-pinene and myrcene constituted the bulk (67.56%) of the essential oil of J. communis. Significant quantitative differences were observed for myrcene, delta-3-carene, and D-germacrene. The results of the antimicrobial assay show that the oils of J. communis and J. oxycedrus failed to inhibit any of the microorganisms at the highest concentrations tested (MLC > or = 900 microg/ml), while the oils extracted from J. turbinata specimens were active against fungi, particularly against a strain of Aspergillus flavus (an aflatoxin B1 producer). Of the single compounds tested, delta-3-carene was found to possess the broadest spectrum of activity and appeared to contribute significantly to the antifungal activity observed for J. turbinata oils. This activity may be helpful in the prevention of aflatoxin contamination for many foods.

  12. Complex Nature of the Genome in a Wine Spoilage Yeast, Dekkera bruxellensis▿ †

    Science.gov (United States)

    Hellborg, Linda; Piškur, Jure

    2009-01-01

    When the genome organizations of 30 native isolates belonging to a wine spoilage yeast, Dekkera (Brettanomyces) bruxellensis, a distant relative of Saccharomyces cerevisiae, were examined, the numbers of chromosomes varied drastically, from 4 to at least 9. When single gene probes were used in Southern analysis, the corresponding genes usually mapped to at least two chromosomal bands, excluding a simple haploid organization of the genome. When different loci were sequenced, in most cases, several different haplotypes were obtained for each single isolate, and they belonged to two subtypes. Phylogenetic reconstruction using haplotypes revealed that the sequences from different isolates belonging to one subtype were more similar to each other than to the sequences belonging to the other subtype within the isolate. Reanalysis of the genome sequence also confirmed that partially sequenced strain Y879 is not a simple haploid and that its genome contains approximately 1% polymorphic sites. The present situation could be explained by (i) a hybridization event where two similar but different genomes have recently fused together or (ii) an event where the diploid progenitor of all analyzed strains lost a regular sexual cycle, and the genome started to accumulate mutations. PMID:19717738

  13. Complex nature of the genome in a wine spoilage yeast, Dekkera bruxellensis.

    Science.gov (United States)

    Hellborg, Linda; Piskur, Jure

    2009-11-01

    When the genome organizations of 30 native isolates belonging to a wine spoilage yeast, Dekkera (Brettanomyces) bruxellensis, a distant relative of Saccharomyces cerevisiae, were examined, the numbers of chromosomes varied drastically, from 4 to at least 9. When single gene probes were used in Southern analysis, the corresponding genes usually mapped to at least two chromosomal bands, excluding a simple haploid organization of the genome. When different loci were sequenced, in most cases, several different haplotypes were obtained for each single isolate, and they belonged to two subtypes. Phylogenetic reconstruction using haplotypes revealed that the sequences from different isolates belonging to one subtype were more similar to each other than to the sequences belonging to the other subtype within the isolate. Reanalysis of the genome sequence also confirmed that partially sequenced strain Y879 is not a simple haploid and that its genome contains approximately 1% polymorphic sites. The present situation could be explained by (i) a hybridization event where two similar but different genomes have recently fused together or (ii) an event where the diploid progenitor of all analyzed strains lost a regular sexual cycle, and the genome started to accumulate mutations.

  14. Inhibition of the wine spoilage yeast Dekkera bruxellensis by bovine lactoferrin-derived peptides.

    Science.gov (United States)

    Enrique, María; Marcos, Jose F; Yuste, María; Martínez, Mireia; Vallés, Salvador; Manzanares, Paloma

    2008-10-31

    The antimicrobial action of lactoferrin (LF)-derived peptides against Dekkera bruxellensis strains isolated from spoiled wines has been examined. The study included a fifteen-residue peptide (LfcinB(17-31)) derived from bovine lactoferricin B and a bovine LF pepsin hydrolysate (LFH). In vitro assays showed the inhibitory properties of LfcinB(17-31) on D. bruxellensis growth with IC(50) and MIC values in the micromolar range. Strains tested showed different sensitivity to the peptide. LfcinB(17-31) showed fungicidal properties towards all strains tested in laboratory growth medium. However, the extent of fungicidal activity was strain-dependent in must and wine, confirming the different antimicrobial action of peptides depending on both the food matrix and the target micro-organism. The binding of LfcinB(17-31) to D. bruxellensis cells was visualized by fluorescence microscopy and correlated with the fungicidal activity in the different matrixes. LfcinB(17-31) and LFH showed growth inhibitory properties in wine suggesting their potential use for spoilage control.

  15. Brettanomyces yeasts--From spoilage organisms to valuable contributors to industrial fermentations.

    Science.gov (United States)

    Steensels, Jan; Daenen, Luk; Malcorps, Philippe; Derdelinckx, Guy; Verachtert, Hubert; Verstrepen, Kevin J

    2015-08-03

    Ever since the introduction of controlled fermentation processes, alcoholic fermentations and Saccharomyces cerevisiae starter cultures proved to be a match made in heaven. The ability of S. cerevisiae to produce and withstand high ethanol concentrations, its pleasant flavour profile and the absence of health-threatening toxin production are only a few of the features that make it the ideal alcoholic fermentation organism. However, in certain conditions or for certain specific fermentation processes, the physiological boundaries of this species limit its applicability. Therefore, there is currently a strong interest in non-Saccharomyces (or non-conventional) yeasts with peculiar features able to replace or accompany S. cerevisiae in specific industrial fermentations. Brettanomyces (teleomorph: Dekkera), with Brettanomyces bruxellensis as the most commonly encountered representative, is such a yeast. Whilst currently mainly considered a spoilage organism responsible for off-flavour production in wine, cider or dairy products, an increasing number of authors report that in some cases, these yeasts can add beneficial (or at least interesting) aromas that increase the flavour complexity of fermented beverages, such as specialty beers. Moreover, its intriguing physiology, with its exceptional stress tolerance and peculiar carbon- and nitrogen metabolism, holds great potential for the production of bioethanol in continuous fermentors. This review summarizes the most notable metabolic features of Brettanomyces, briefly highlights recent insights in its genetic and genomic characteristics and discusses its applications in industrial fermentation processes, such as the production of beer, wine and bioethanol. Copyright © 2015. Published by Elsevier B.V.

  16. The emulsifying effect of biosurfactants produced by food spoilage organisms in Nigeria

    Directory of Open Access Journals (Sweden)

    Christianah O. Ogunmola

    2016-04-01

    Full Text Available Food spoilage organisms were isolated using standard procedures on Nutrient Agar, Cetrimide Agar and Pseudomonas Agar Base (supplemented with CFC. The samples were categorized as animal products (raw fish, egg, raw chicken, corned beef, pasteurized milk and plant products (vegetable salad, water leaf (Talinium triangulare, boiled rice, tomatoes and pumpkin leaf (Teifairia occidentalis.They were characterised as Pseudomonas putida, Pseudomonas aeruginosa, Pseudomonas stutzeri, Burkholderia pseudomallei, Serratia rubidaea, Corynebacterium pilosum, Bacillus subtilis, Bacillus mycoides, Bacillus laterosporus, Bacillus laterosporus, Serratia marcescens, Bacillus cereus, Bacillus macerans, Alcaligenes faecalis and Alcaligenes eutrophus. Preliminary screening for biosurfactant production was done using red blood haemolysis test and confirmed by slide test, drop collapse and oil spreading assay. The biosurfactant produced was purified using acetone and the composition determined initially using Molisch’s test, thin layer chromatography and gas chromatography mass spectrometry. The components were found to be ethanol, amino acids, butoxyacetic acid, hexadecanoic acid, oleic acid, lauryl peroxide, octadecanoic acid and phthalic acid. The producing organisms grew readily on several hydrocarbons such as crude oil, diesel oil and aviation fuel when used as sole carbon sources.  The purified biosurfactants produced were able to cause emulsification of kerosene (19.71-27.14% as well as vegetable oil (16.91-28.12% based on the emulsification index. This result suggests that the isolates can be an asset and further work can exploit their optimal potential in industries.

  17. On forecasting Exchange Rate Volatility.

    OpenAIRE

    Hafner, Christian

    2003-01-01

    In an efficient market, foreign exchange rates have to guarantee absence of triangular arbitrage. This note shows that the no-arbitrage condition can be exploited for forecasting the volatility of a single rate by using the information contained in the other rates. Linearly transforming the volatility forecasts of a bivariate model is shown to be more efficient than using a univariate model for the cross-rate.

  18. Secondary metabolites from marine microorganisms

    Directory of Open Access Journals (Sweden)

    KELECOM ALPHONSE

    2002-01-01

    Full Text Available After 40 years of intensive research, chemistry of marine natural products has become a mature field. Since 1995, there are signals of decreased interest in the search of new metabolites from traditional sources such as macroalgae and octocorals, and the number of annual reports on marine sponges stabilized. On the contrary, metabolites from microorganisms is a rapidly growing field, due, at least in part, to the suspicion that a number of metabolites obtained from algae and invertebrates may be produced by associated microorganisms. Studies are concerned with bacteria and fungi, isolated from seawater, sediments, algae, fish and mainly from marine invertebrates such as sponges, mollusks, tunicates, coelenterates and crustaceans. Although it is still to early to define tendencies, it may be stated that the metabolites from microorganisms are in most cases quite different from those produced by the invertebrate hosts. Nitrogenated metabolites predominate over acetate derivatives, and terpenes are uncommon. Among the latter, sesquiterpenes, diterpenes and carotenes have been isolated; among nitrogenated metabolites, amides, cyclic peptides and indole alkaloids predominate.

  19. Species-specific production of microbial volatile organic compounds (MVOC) by airborne fungi from a compost facility.

    Science.gov (United States)

    Fischer, G; Schwalbe, R; Möller, M; Ostrowski, R; Dott, W

    1999-08-01

    Thirteen airborne fungal species frequently isolated in composting plants were screened for microbial volatile organic compounds (MVOC), i.e., Aspergillus candidus, A. fumigatus, A. versicolor, Emericella nidulans, Paecilomyces variotii, Penicillium brevicompactum, Penicillium clavigerum, Penicillium crustosum, Penicillium cyclopium, Penicillium expansum, Penicillium glabrum, Penicillium verruculosum, and Tritirachium oryzae. Air samples from pure cultures were sorbed on Tenax GR and analyzed by thermal desorption in combination with GC/MS. Various hydrocarbons of different chemical groups and a large number of terpenes were identified. Some compounds such as 3-methyl-1-butanol and 1-octen-3-ol were produced by a number of species, whereas some volatiles were specific for single species. An inventory of microbial metabolites will allow identification of potential health hazards due to an exposure to fungal propagules and metabolites in the workplace. Moreover, species-specific volatiles may serve as marker compounds for the selective detection of fungal species in indoor domestic and working environments.

  20. Recent Advances in Volatiles of Teas

    Directory of Open Access Journals (Sweden)

    Xin-Qiang Zheng

    2016-03-01

    Full Text Available Volatile compounds are important components of tea aroma, a key attribute of sensory quality. The present review examines the formation of aromatic volatiles of various kinds of teas and factors influencing the formation of tea volatiles, including tea cultivar, growing environment and agronomic practices, processing method and storage of tea. The determination of tea volatiles and the relationship of active-aroma volatiles with the sensory qualities of tea are also discussed in the present paper.

  1. ESTIMATION OF VOLATILE CONSTITUENTS IN THE FISH FLESH FROM WILD AND FARMED CIRRHINA MRIGALA AND CYPRINUS CARPIO

    Institute of Scientific and Technical Information of China (English)

    Shahid Mahboob; Bilal Hussain; Zahid Iqbal; Abdul Shakoor Chaudhry

    2009-01-01

    Analysis of fish meat using gas chromatography is described. Flavor is the sensation arising from the interplay of the signals of sensing smell, taste and irritating stimuli from food stuff. For human, flavor and nutrition are inseparable. In fish, trace amount of volatile organic compounds (VOCs) are the major compounds to affect consumer's preference, which are produced during storage and spoilage. In the present study, volatile compounds were extracted by Likens-Nickerson con-current distillation apparatus from wild and farmed Cirrhina mrigala and Cyprinus carpio. The quantitative and qualitative estimation of volatiles was made by gas chromatography. Wild and farmed fish of different fish sizes were compared for these compounds (appearing in the form of peaks), which were identified from their retention time by comparing with the stand-ards. Fifteen major VOCs were found in these species which included hexadecane, 3-octanol, hexanal, decane, 3-hexene-1-ol, 2-undecanone, 2-heptanone, butanal, 2-nonanone, 1-heptanal, furaldehyde, 3-methyl-1-butanal, trans-3-hexene-1-ol, octanal and decanal. These compounds varied qualitatively and quantitatively in both wild and farmed fish of different fish sizes.

  2. Antifungal activity of essential oils evaluated by two different application techniques against rye bread spoilage fungi

    DEFF Research Database (Denmark)

    Suhr, Karin Isabel; Nielsen, Per Væggemose

    2003-01-01

    on the application method. Larger phenolic compounds such as thymol and eugenol (thyme, cinnamon and clove) had best effect applied directly to medium, whereas smaller compounds such as allyl isothiocyanate and citral (mustard and lemongrass) were most efficient when added as volatiles.Significance and Impact...

  3. Exploring the Saccharomyces cerevisiae Volatile Metabolome: Indigenous versus Commercial Strains.

    Directory of Open Access Journals (Sweden)

    Zélia Alves

    Full Text Available Winemaking is a highly industrialized process and a number of commercial Saccharomyces cerevisiae strains are used around the world, neglecting the diversity of native yeast strains that are responsible for the production of wines peculiar flavours. The aim of this study was to in-depth establish the S. cerevisiae volatile metabolome and to assess inter-strains variability. To fulfill this objective, two indigenous strains (BT2652 and BT2453 isolated from spontaneous fermentation of grapes collected in Bairrada Appellation, Portugal and two commercial strains (CSc1 and CSc2 S. cerevisiae were analysed using a methodology based on advanced multidimensional gas chromatography (HS-SPME/GC×GC-ToFMS tandem with multivariate analysis. A total of 257 volatile metabolites were identified, distributed over the chemical families of acetals, acids, alcohols, aldehydes, ketones, terpenic compounds, esters, ethers, furan-type compounds, hydrocarbons, pyrans, pyrazines and S-compounds. Some of these families are related with metabolic pathways of amino acid, carbohydrate and fatty acid metabolism as well as mono and sesquiterpenic biosynthesis. Principal Component Analysis (PCA was used with a dataset comprising all variables (257 volatile components, and a distinction was observed between commercial and indigenous strains, which suggests inter-strains variability. In a second step, a subset containing esters and terpenic compounds (C10 and C15, metabolites of particular relevance to wine aroma, was also analysed using PCA. The terpenic and ester profiles express the strains variability and their potential contribution to the wine aromas, specially the BT2453, which produced the higher terpenic content. This research contributes to understand the metabolic diversity of indigenous wine microflora versus commercial strains and achieved knowledge that may be further exploited to produce wines with peculiar aroma properties.

  4. Binary combination of epsilon-poly-L-lysine and isoeugenol affect progression of spoilage microbiota in fresh turkey meat, and delay onset of spoilage in Pseudomonas putida challenged meat.

    Science.gov (United States)

    Hyldgaard, Morten; Meyer, Rikke L; Peng, Min; Hibberd, Ashley A; Fischer, Jana; Sigmundsson, Arnar; Mygind, Tina

    2015-12-23

    Proliferation of microbial population on fresh poultry meat over time elicits spoilage when reaching unacceptable levels, during which process slime production, microorganism colony formation, negative organoleptic impact and meat structure change are observed. Spoilage organisms in raw meat, especially Gram-negative bacteria can be difficult to combat due to their cell wall composition. In this study, the natural antimicrobial agents ε-poly-L-lysine (ε-PL) and isoeugenol were tested individually and in combinations for their activities against a selection of Gram-negative strains in vitro. All combinations resulted in additive interactions between ε-PL and isoeugenol towards the bacteria tested. The killing efficiency of different ratios of the two antimicrobial agents was further evaluated in vitro against Pseudomonas putida. Subsequently, the most efficient ratio was applied to a raw turkey meat model system which was incubated for 96 h at spoilage temperature. Half of the samples were challenged with P. putida, and the bacterial load and microbial community composition was followed over time. CFU counts revealed that the antimicrobial blend was able to lower the amount of viable Pseudomonas spp. by one log compared to untreated samples of challenged turkey meat, while the single compounds had no effect on the population. However, the compounds had no effect on Pseudomonas spp. CFU in unchallenged meat. Next-generation sequencing offered culture-independent insight into population diversity and changes in microbial composition of the meat during spoilage and in response to antimicrobial treatment. Spoilage of unchallenged turkey meat resulted in decreasing species diversity over time, regardless of whether the samples received antimicrobial treatment. The microbiota composition of untreated unchallenged meat progressed from a Pseudomonas spp. to a Pseudomonas spp., Photobacterium spp., and Brochothrix thermosphacta dominated food matrix on the expense of low

  5. Bioactive and volatile organic compounds in Southern Brazilian blackberry (Rubus Fruticosus) fruit cv. Tupy

    OpenAIRE

    Andressa Carolina Jacques; Fábio Clasen Chaves; Rui Carlos Zambiazi; Márcia Campos Brasil; Elina Bastos Caramão

    2014-01-01

    Blackberry (Rubus fruticosus, cultivar Tupy), an expanding fruit crop in southern Brazil, is greatly appreciated for its flavor and bioactive potential with limited characterization of its metabolite content. The purpose of this study was to characterize the bioactive and volatile organic compound (VOC) content of mature blackberry fruit of cultivar Tupy. Gallic acid, (-)-epicatechin, ferulic acid, and quercetin were the main phenolic compounds found in mature fruit. Among the VOCs identified...

  6. Impact of protease activity of yeasts on wine fermentation and formation of volatile and non-volatile metabolites

    OpenAIRE

    Chomsri, Ni-orn

    2008-01-01

    Fifty yeast strains previously isolated from grapes and wines were investigated for extracellular protease activity. Saccharomyces yeasts showed no detectable protease activity, while most of the non-Saccharomyces yeasts exhibited proteolytic activity. Nine of the fifty yeast strains were cultivated in grape juice and were analysed for the production of extracellular proteases. The proteolytic activity of Metschnikowia pulcherrima (M 004) was as high as that of Rhodotolura sp. (R3). Very low ...

  7. A meta-analysis approach for assessing the diversity and specificity of belowground root and microbial volatiles

    Directory of Open Access Journals (Sweden)

    Denis eSchenkel

    2015-09-01

    Full Text Available Volatile organic compounds are secondary metabolites emitted by all organisms, especially by plants and microbes. Their role as aboveground signals has been established for decades. Recent evidence suggests that they might have a non-negligible role belowground and might be involved in root-root and root-microbial/pest interactions. Our aim here was to make a comprehensive review of belowground volatile diversity using a meta-analysis approach. At first we synthesized current literature knowledge on plant root volatiles and classified them in terms of chemical diversity. In a second step, relying on the mVOC database of microbial volatiles, we classified volatiles based on their emitters (bacteria versus fungi and their specific ecological niche (i.e. rhizosphere, soil. Our results highlight similarities and differences among root and microbial volatiles and also suggest that some might be niche specific. We further explored the possibility that volatiles might be involved in intra- and inter-specific root-root communication and discuss the ecological implications of such scenario. Overall this work synthesizes current knowledge on the belowground volatilome and the potential signaling role of its constituents. It also highlights that the total diversity of belowground volatiles might be numerous orders of magnitude larger that the few hundreds of compounds described to date.

  8. Spiral mining for lunar volatiles

    Science.gov (United States)

    Schmitt, H. H.; Kulcinski, G. L.; Sviatoslavsky, I. N.; Carrier, W. D., III

    Lunar spiral mining, extending outward from a periodically mobile central power and processing station represents an alternative for comparison with more traditional mining schemes. In this concept, a mining machine would separate regolith fines and extract the contained volatiles. Volatiles then would be pumped along the miner's support arm to the central station for refining and for export or storage. The basic architecture of the central processing station would be cylindrical. A central core area could house the power subsystem of hydrogen-oxygen engines or fuel cells. Habitat sections and other crew occupied areas could be arranged around the power generation core. The outer cylinder could include all volatile refining subsystems. Solar thermal power collectors and reflectors would be positioned on top of the central station. Long term exploitation of a volatile resource region would begin with establishment of a support base at the center of a long boundary of the region. The mining tract for each spiral mining system would extend orthogonal to this boundary. New spiral mining systems would be activated along parallel tracts as demand for lunar He-3 and other solar wind volatiles increased.

  9. RICE PRICE VOLATILITY IN EAST JAVA

    Directory of Open Access Journals (Sweden)

    Wati R.Y.E.

    2017-09-01

    Full Text Available The purpose of the research is analyzing the volatility and volatility spillover of monthly price of paddy at the level of farmers and consumers in 2010-2016. ARCH/GARCH used to analyze volatility and GARCH BEKK-model is used to analyze the volatility spillover. The results of the analysis show that price volatility at the farmer level is very high (extremely high volatility, price volatility at the consumer level is low (low volatility, and volatility spillover does not occur between the farmers and the consumers market. The need to guarantee an effective floor price as well as information disclosure related to the market commodity prices so that the pattern of prices transmission among interrelated markets can be symmetrical.

  10. The price of fixed income market volatility

    CERN Document Server

    Mele, Antonio

    2015-01-01

    Fixed income volatility and equity volatility evolve heterogeneously over time, co-moving disproportionately during periods of global imbalances and each reacting to events of different nature. While the methodology for options-based "model-free" pricing of equity volatility has been known for some time, little is known about analogous methodologies for pricing various fixed income volatilities. This book fills this gap and provides a unified evaluation framework of fixed income volatility while dealing with disparate markets such as interest-rate swaps, government bonds, time-deposits and credit. It develops model-free, forward looking indexes of fixed-income volatility that match different quoting conventions across various markets, and uncovers subtle yet important pitfalls arising from naïve superimpositions of the standard equity volatility methodology when pricing various fixed income volatilities. The ultimate goal of the authors´ efforts is to make interest rate volatility standardization a valuable...

  11. A powerful methodological approach combining headspace solid phase microextraction, mass spectrometry and multivariate analysis for profiling the volatile metabolomic pattern of beer starting raw materials.

    Science.gov (United States)

    Gonçalves, João L; Figueira, José A; Rodrigues, Fátima P; Ornelas, Laura P; Branco, Ricardo N; Silva, Catarina L; Câmara, José S

    2014-10-01

    The volatile metabolomic patterns from different raw materials commonly used in beer production, namely barley, corn and hop-derived products - such as hop pellets, hop essential oil from Saaz variety and tetra-hydro isomerized hop extract (tetra hop), were established using a suitable analytical procedure based on dynamic headspace solid-phase microextraction (HS-SPME) followed by thermal desorption gas chromatography-quadrupole mass spectrometry detection (GC-qMS). Some SPME extraction parameters were optimized. The best results, in terms of maximum signal recorded and number of isolated metabolites, were obtained with a 50/30 μm DVB/CAR/PDMS coating fiber at 40 °C for 30 min. A set of 152 volatile metabolites comprising ketones (27), sesquiterpenes (26), monoterpenes (19), aliphatic esters (19), higher alcohols (15), aldehydes (11), furan compounds (11), aliphatic fatty acids (9), aliphatic hydrocarbons (8), sulphur compounds (5) and nitrogen compounds (2) were positively identified. Each raw material showed a specific volatile metabolomic profile. Monoterpenes in hop essential oil and corn, sesquiterpenes in hop pellets, ketones in tetra hop and aldehydes and sulphur compounds in barley were the predominant chemical families in the targeted beer raw materials. β-Myrcene was the most dominant volatile metabolite in hop essential oil, hop pellets and corn samples while, in barley, the predominant volatile metabolites were dimethyl sulphide and 3-methylbutanal and, in tetra hop, 6-methyl-2-pentanone and 4-methyl-2-pentanone. Principal component analysis (PCA) showed natural sample grouping among beer raw materials.

  12. Microbial Spoilage, Actions of Preservatives and Phytochemical Screening of Mango (Mangifera indica Seed Powder

    Directory of Open Access Journals (Sweden)

    Musa Olusegun AREKEMASE

    2015-03-01

    Full Text Available The work was carried out to determine the organisms responsible for the microbial spoilage of kernels of Mangifera indica. A specialized kit was employed to confirm the Gram negative organisms present in the spoilt kernels of M. indica. The effects of chemical preservatives such as sodium benzoate, sodium acetate, citric acid and sodium chloride at different concentrations on the microbial counts and pH of mango seed powder stored at room temperature over a period of 12 weeks were studied. The mango seed kernel powder (MSK was screened for phytochemicals. The bacteria isolated include: Bacillus subtilis, Staphylococcus aureus, Enterobacter clocae, Enterobacter asburiae and Stenotrophomonas maltophilia. The Gram negative organisms confirmed were Enterobacter clocae, Enterobacter asburiae and Stenotrophomonas maltophilia. The isolated fungus was Aspergillus niger. In the analysis of different chemical preservatives on mango seed powder, the most effective preservative was 3.0% sodium benzoate followed by 5% sodium acetate and 5% common salt. Citric acid was the least effective of all the preservatives used at equal concentrations. Sodium benzoate at 3% had the least bacterial count of 0.8 x 103 CFU/ml which was maintained from the 8th week to the last week of storage. Citric acid at 0.1% and 1.0% concentrations had bacterial counts of 3.50 x 103 CFU/ml and 2.0 x 103 CFU/ml respectively at the end of the 12 weeks of storage. The pH of the chemically preserved powdered kernels of M. indica from the 1st to the 12th week ranged from 2.70-6.01. The phytochemicals present in the mango seed powder included tannins, saponnins, polyphenol, alkaloids, flavonoids, cardiac glycosides and steroids.

  13. Efficacy of commercial natural antimicrobials alone and in combinations against pathogenic and spoilage microorganisms.

    Science.gov (United States)

    Techathuvanan, Chayapa; Reyes, Fatima; David, Jairus R D; Davidson, P Michael

    2014-02-01

    Microbial control strategies are needed in the food industry to prevent foodborne illnesses and outbreaks and prolong product shelf life. The aim of this study was to investigate and compare the efficacy of the commercial natural antimicrobials white mustard essential oil (WMEO), citrus flavonoid and acid blend (CFAB), olive extract (OE), Nisaplin (a compound containing nisin), and lauric arginate (LAE) alone and in combinations against foodborne pathogens and spoilage microorganisms. MICs of individual and combined antimicrobials against Escherichia coli, Salmonella Enteritidis, Enterobacter aerogenes, Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus were determined at pH 6.0 and 25 °C. WMEO was most effective against B. cereus and S. aureus, with MICs of 250 and 500 mg/liter, respectively. CFAB inhibited all tested microorganisms, requiring only 12 to 35 mg/liter for gram-positive bacteria. For OE, 2,000 mg/liter was needed to achieve microbial inhibition. Nisaplin at 400 to 1,200 mg/liter inhibited only gram-positive bacteria. LAE was effective at low concentrations and required only 20 to 50 mg/liter to inhibit all tested microorganisms. When WMEO was combined with other antimicrobials, the effects were usually additive except for WMEO plus Nisaplin and WMEO+OE, which had synergistic activity against L. monocytogenes and Salmonella Enteritidis, respectively. An antagonistic effect was observed for WMEO+CFAB against E. aerogenes. For WMEO+LAE+CFAB, additive antimicrobial effects were noted against all strains tested except S. aureus, where a synergistic effect occurred. These findings suggest that these commercial natural antimicrobials have potential to enhance food safety by inhibiting foodborne pathogens and extending product shelf life.

  14. Growth kinetics of Listeria monocytogenes and spoilage microorganisms in fresh-cut cantaloupe.

    Science.gov (United States)

    Fang, Ting; Liu, Yanhong; Huang, Lihan

    2013-05-01

    The main objective of this study was to investigate the growth kinetics of Listeria monocytogenes and background microorganisms in fresh-cut cantaloupe. Fresh-cut cantaloupe samples, inoculated with three main serotypes (1/2a, 1/2b, and 4b) of L. monocytogenes, were incubated at different temperatures, ranging from 4 to 43 °C, to develop kinetic growth models. During storage studies, the population of both background microorganisms and L. monocytogenes began to increase almost immediately, with little or no lag phase for most growth curves. All growth curves, except for two growth curves of L. monocytogenes 1/2a at 4 °C, developed to full curves (containing exponential and stationary phases), and can be described by a 3-parameter logistic model. There was no significant difference (P = 0.28) in the growth behaviors and the specific growth rates of three different serotypes of L. monocytogenes inoculated to fresh-cut cantaloupe. The effect of temperature on the growth of L. monocytogenes and spoilage microorganisms was evaluated using three secondary models. For L. monocytogenes, the minimum and maximum growth temperatures were estimated by both the Ratkowsky square-root and Cardinal parameter models, and the optimum temperature and the optimum specific growth rate by the Cardinal parameter model. An Arrhenius-type model provided more accurate estimation of the specific growth rate of L. monocytogenes at temperatures <4 °C. The kinetic models developed in this study can be used by regulatory agencies and food processors for conducting risk assessment of L. monocytogenes in fresh-cut cantaloupe, and for estimating the shelf-life of fresh-cut products.

  15. The influence of bacterial inoculants on the microbial ecology of aerobic spoilage of barley silage.

    Science.gov (United States)

    Inglis, G D; Yanke, L J; Kawchuk, L M; McAllister, T A

    1999-01-01

    The aerobic decomposition of barley silage treated with two inoculants (LacA and LacB) containing mixtures of Lactobacillus plantarum and Enterococcus faecium was investigated over a 28-day period. Initially, yeast and bacterial populations were larger in silage inoculated with LacA than in silage treated with LacB or water alone (control). Differences in the succession of yeasts in silage treated with LacA were observed relative to the other two treatments. From silage treatment with LacA, Issatchenkia orientalis was the most prevalent yeast taxon over all of the sample times, and the filamentous fungus Microascus brevicaulis was also frequently isolated at later sample dates (> or = 14 days). In contrast, Saccharomyces exiguus was the most prominent yeast recovered from silage treated with LacB and water alone on days 2 and 4, although it was supplanted by I. orientalis at later sample times. Successional trends of bacteria were similar for all three treatments. Lactobacillus spp. were initially the most prevalent bacteria isolated, followed by Bacillus spp. (primarily Bacillus pumilus). However, the onset of Bacillus spp. prominence was faster in LacA silage, and Klebsiella planticola was frequently recovered at later sample times (> or = 14 days). More filamentous fungi were recovered from LacA silage on media containing carboxylmethylcellulose, pectin, or xylan. The most commonly isolated taxa were Absidia sp., Aspergillus flavus, Aspergillus fumigatus, Byssochlamys nivea, Monascus ruber, Penicillium brevicompactum, Pseudoallescheria boydii, and M. brevicaulis. The results of this study indicated that the two bacterial inoculants incorporated into barley at the time of ensilage affected the microbial ecology of silage decomposition following exposure to air. However, neither of the microbial inoculants effectively delayed aerobic spoilage of barley silage, and the rate of decomposition of silage treated with one of the inoculants (LacA) was actually enhanced.

  16. Synergized antimicrobial activity of eugenol incorporated polyhydroxybutyrate films against food spoilage microorganisms in conjunction with pediocin.

    Science.gov (United States)

    Narayanan, Aarthi; Neera; Mallesha; Ramana, Karna Venkata

    2013-07-01

    Biopolymers and biopreservatives produced by microorganisms play an essential role in food technology. Polyhydroxyalkanoates and bacteriocins produced by bacteria are promising components to safeguard the environment and for food preservation applications. Polyhydroxybutyrate (PHB)-based antimicrobial films were prepared incorporating eugenol, from 10 to 200 μg/g of PHB. The films were evaluated for antimicrobial activity against foodborne pathogens, spoilage bacteria, and fungi such as Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Bacillus cereus, Aspergillus flavus, Aspergillus niger, Penicillium sp., and Rhizopus sp. The synergistic antimicrobial activity of the films in the presence of crude pediocin was also investigated. The broth system containing pediocin (soluble form) as well as antimicrobial PHB film demonstrated an extended lag phase and a significant growth reduction at the end of 24 h against the bacteria. Crude pediocin alone could not elicit antifungal activity, while inhibition of growth and sporulation were observed in the presence of antimicrobial PHB film containing eugenol (80 μg/g) until 7 days in the case of molds, i.e., A. niger, A. flavus, Penicillium sp., and Rhizopus sp. in potato dextrose broth. In the present study, we identified that use of pediocin containing broth in conjunction with eugenol incorporated PHB film could function in synergized form, providing effective hurdle toward food contaminating microorganisms. Furthermore, tensile strength, percent crystallinity, melting point, percent elongation to break, glass transition temperature, and seal strength of the PHB film with and without eugenol incorporation were investigated. The migration of eugenol on exposure to different liquid food simulants was also analyzed using Fourier transform infrared spectroscopy. The study is expected to provide applications for pediocin in conjunction with eugenol containing PHB film to enhance the shelf life of foods in the

  17. Identification of beer-spoilage bacteria using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Wieme, Anneleen D; Spitaels, Freek; Aerts, Maarten; De Bruyne, Katrien; Van Landschoot, Anita; Vandamme, Peter

    2014-08-18

    Applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of beer-spoilage bacteria was examined. To achieve this, an extensive identification database was constructed comprising more than 4200 mass spectra, including biological and technical replicates derived from 273 acetic acid bacteria (AAB) and lactic acid bacteria (LAB), covering a total of 52 species, grown on at least three growth media. Sequence analysis of protein coding genes was used to verify aberrant MALDI-TOF MS identification results and confirmed the earlier misidentification of 34 AAB and LAB strains. In total, 348 isolates were collected from culture media inoculated with 14 spoiled beer and brewery samples. Peak-based numerical analysis of MALDI-TOF MS spectra allowed a straightforward species identification of 327 (94.0%) isolates. The remaining isolates clustered separately and were assigned through sequence analysis of protein coding genes either to species not known as beer-spoilage bacteria, and thus not present in the database, or to novel AAB species. An alternative, classifier-based approach for the identification of spoilage bacteria was evaluated by combining the identification results obtained through peak-based cluster analysis and sequence analysis of protein coding genes as a standard. In total, 263 out of 348 isolates (75.6%) were correctly identified at species level and 24 isolates (6.9%) were misidentified. In addition, the identification results of 50 isolates (14.4%) were considered unreliable, and 11 isolates (3.2%) could not be identified. The present study demonstrated that MALDI-TOF MS is well-suited for the rapid, high-throughput and accurate identification of bacteria isolated from spoiled beer and brewery samples, which makes the technique appropriate for routine microbial quality control in the brewing industry. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Genome Sequence and Transcriptome Analysis of Meat-Spoilage-Associated Lactic Acid Bacterium Lactococcus piscium MKFS47.

    Science.gov (United States)

    Andreevskaya, Margarita; Johansson, Per; Laine, Pia; Smolander, Olli-Pekka; Sonck, Matti; Rahkila, Riitta; Jääskeläinen, Elina; Paulin, Lars; Auvinen, Petri; Björkroth, Johanna

    2015-06-01

    Lactococcus piscium is a psychrotrophic lactic acid bacterium and is known to be one of the predominant species within spoilage microbial communities in cold-stored packaged foods, particularly in meat products. Its presence in such products has been associated with the formation of buttery and sour off-odors. Nevertheless, the spoilage potential of L. piscium varies dramatically depending on the strain and growth conditions. Additional knowledge about the genome is required to explain such variation, understand its phylogeny, and study gene functions. Here, we present the complete and annotated genomic sequence of L. piscium MKFS47, combined with a time course analysis of the glucose catabolism-based transcriptome. In addition, a comparative analysis of gene contents was done for L. piscium MKFS47 and 29 other lactococci, revealing three distinct clades within the genus. The genome of L. piscium MKFS47 consists of one chromosome, carrying 2,289 genes, and two plasmids. A wide range of carbohydrates was predicted to be fermented, and growth on glycerol was observed. Both carbohydrate and glycerol catabolic pathways were significantly upregulated in the course of time as a result of glucose exhaustion. At the same time, differential expression of the pyruvate utilization pathways, implicated in the formation of spoilage substances, switched the metabolism toward a heterofermentative mode. In agreement with data from previous inoculation studies, L. piscium MKFS47 was identified as an efficient producer of buttery-odor compounds under aerobic conditions. Finally, genes and pathways that may contribute to increased survival in meat environments were considered. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  19. 671-nm microsystem diode laser based on portable Raman sensor device for in-situ identification of meat spoilage

    Science.gov (United States)

    Sowoidnich, Kay; Schmidt, Heinar; Schwägele, Fredi; Kronfeldt, Heinz-Detlef

    2011-05-01

    Based on a miniaturized optical bench with attached 671 nm microsystem diode laser we present a portable Raman system for the rapid in-situ characterization of meat spoilage. It consists of a handheld sensor head (dimensions: 210 x 240 x 60 mm3) for Raman signal excitation and collection including the Raman optical bench, a laser driver, and a battery pack. The backscattered Raman radiation from the sample is analyzed by means of a custom-designed miniature spectrometer (dimensions: 200 x 190 x 70 mm3) with a resolution of 8 cm-1 which is fiber-optically coupled to the sensor head. A netbook is used to control the detector and for data recording. Selected cuts from pork (musculus longissimus dorsi and ham) stored refrigerated at 5 °C were investigated in timedependent measurement series up to three weeks to assess the suitability of the system for the rapid detection of meat spoilage. Using a laser power of 100 mW at the sample meat spectra can be obtained with typical integration times of 5 - 10 seconds. The complex spectra were analyzed by the multivariate statistical tool PCA (principal components analysis) to determine the spectral changes occurring during the storage period. Additionally, the Raman data were correlated with reference analyses performed in parallel. In that way, a distinction between fresh and spoiled meat can be found in the time slot of 7 - 8 days after slaughter. The applicability of the system for the rapid spoilage detection of meat and other food products will be discussed.

  20. Multilocus sequence typing of Leuconostoc gelidum subsp. gasicomitatum, a Psychrotrophic lactic acid bacterium causing spoilage of packaged perishable foods.

    Science.gov (United States)

    Rahkila, Riitta; Johansson, Per; Säde, Elina; Paulin, Lars; Auvinen, Petri; Björkroth, Johanna

    2015-04-01

    Leuconostoc gelidum subsp. gasicomitatum is a psychrotrophic lactic acid bacterium (LAB) that causes spoilage of a variety of modified-atmosphere-packaged (MAP) cold-stored food products. During the past 10 years, this spoilage organism has been increasingly reported in MAP meat and vegetable products in northern Europe. In the present study, the population structure within 252 L. gelidum subsp. gasicomitatum strains was determined based on a novel multilocus sequence-typing (MLST) scheme employing seven housekeeping genes. These strains had been isolated from meat and vegetable sources over a time span of 15 years, and all 68 previously detected pulsed-field gel electrophoresis (PFGE) genotypes were represented. A total of 46 sequence types (STs) were identified, with a majority of the strains (>60%) belonging to three major STs, which were grouped into three clonal complexes (CCs) and 17 singletons by Global Optimal eBURST (goeBURST). The results by Bayesian analysis of population structure (BAPS) mostly correlated with the grouping by goeBURST. Admixture analysis by BAPS indicated a very low level of exchange of genetic material between the subpopulations. Niche specificity was observed within the subpopulations: CC1 and BAPS cluster 1 consisted mostly of strains from a variety of MAP meats, whereas vegetable strains grouped together with strains from MAP poultry within CC2 and BAPS cluster 2. The MLST scheme presented in this study provides a shareable and continuously growing sequence database enabling global comparison of strains associated with spoilage cases. This will further advance our understanding of the microbial ecology of this industrially important LAB. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  1. 啤酒腐败细菌的PCR检测%Detection of Beer Spoilage Bacteria by Polymerase Chain Reaction Technology

    Institute of Scientific and Technical Information of China (English)

    王雪涵; 姚金城; 任河山; 钟俊辉; 蔡宝立

    2011-01-01

    Beer spoilage bacteria are able to survive in beer and to transform the appear-ance , flavour and quality of beer. Therefore rapid detection of these bacteria has important sig-nificance for brewers. Two primer pairs was designed for amplification of hop-resistance horA and horC genes in 28 beer spoilage strains. Experimental results showed that these strains con-tain at least one gene among horA and horC. This indicated that it is feasible to use horA and horC primers for detection of spoilage bacteria in beer samples. Forty-seven beer samples from brewer were detected for horA and horC and the identical ratio was 90% compared with plate cultivation method.%啤酒腐败细菌是一类能在啤酒中存活并使啤酒的外观、风味和品质发生改变的微生物,对其进行快速检测是啤酒生产急待解决的问题.设计了针对抗酒花(hop)基因horA和horC的引物,对28株已知啤酒腐败细菌进行PCR检测,证明这些菌株至少含有horA和horC中的一种基因,这表明用hor和horC双引物对啤酒样品进行腐败细菌的快速检测是可行的.对取自啤酒厂的47个成品和半成品啤酒样品进行了horA和horC检测,其结果与常规的平板培养法相比符合率为90%.

  2. Evidence for a role of biosurfactants produced by Pseudomonas fluorescens in the spoilage of fresh aerobically stored chicken meat.

    Science.gov (United States)

    Mellor, Glen E; Bentley, Jessica A; Dykes, Gary A

    2011-08-01

    Fresh chicken meat is a fat-rich environment and we therefore hypothesised that production of biosurfactants to increase bioavailability of fats may represent one way in which spoilage bacteria might enhance the availability of nutrients. Numbers of Pseudomonas were determined on a total of 20 fresh and 20 spoiled chicken thighs with skin. A total of 400 randomly isolated Pseudomonas colonies from fresh (200) and spoiled (200) chicken were screened for the presence of biosurfactant production. Biosurfactant producing strains represented 5% and 72% of the Pseudomonas spp. isolates from fresh (mean count 2.3 log(10) cfu g(-1)) and spoiled (mean count 7.4 log(10) cfu g(-1)) chicken skin, respectively. Partially-purified biosurfactants derived from a subgroup of four Pseudomonasfluorescens strains obtained through the screening process were subsequently used to investigate the role that the addition of these compounds plays in the spoilage of aerobically stored chicken. Emulsification potential of the four selected biosurfactants was measured against a range of hydrocarbons and oils. All four biosurfactants displayed a greater ability to emulsify rendered chicken fat than hydrocarbons (paraffin liquid, toluene and hexane) and oils (canola, olive, sunflower and vegetable). Storage trials (4 °C) of chicken meat treated with the four selected biosurfactants revealed a significantly greater (P < 0.05) total aerobic count in biosurfactant treated samples, as compared to untreated samples on each day (0, 1, 2, 3) of storage. For biosurfactant treated samples the greatest increase in total aerobic count (1.3-1.7 log(10) cfu g(-1)) occurred following one day of incubation. These results indicate that biosurfactants produced by Pseudomonas spp. may play an important role in the spoilage of aerobically stored chicken meat by making nutrients more freely available and providing strains producing them with a competitive advantage.

  3. Observability of market daily volatility

    Science.gov (United States)

    Petroni, Filippo; Serva, Maurizio

    2016-02-01

    We study the price dynamics of 65 stocks from the Dow Jones Composite Average from 1973 to 2014. We show that it is possible to define a Daily Market Volatility σ(t) which is directly observable from data. This quantity is usually indirectly defined by r(t) = σ(t) ω(t) where the r(t) are the daily returns of the market index and the ω(t) are i.i.d. random variables with vanishing average and unitary variance. The relation r(t) = σ(t) ω(t) alone is unable to give an operative definition of the index volatility, which remains unobservable. On the contrary, we show that using the whole information available in the market, the index volatility can be operatively defined and detected.

  4. Consistent ranking of volatility models

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    2006-01-01

    result in an inferior model being chosen as "best" with a probability that converges to one as the sample size increases. We document the practical relevance of this problem in an empirical application and by simulation experiments. Our results provide an additional argument for using the realized...... variance in out-of-sample evaluations rather than the squared return. We derive the theoretical results in a general framework that is not specific to the comparison of volatility models. Similar problems can arise in comparisons of forecasting models whenever the predicted variable is a latent variable.......We show that the empirical ranking of volatility models can be inconsistent for the true ranking if the evaluation is based on a proxy for the population measure of volatility. For example, the substitution of a squared return for the conditional variance in the evaluation of ARCH-type models can...

  5. Effect of non-Saccharomyces yeasts on the volatile chemical profile of Shiraz wine

    DEFF Research Database (Denmark)

    Whitener, M. E.B.; Stanstrup, J.; Carlin, S.

    2017-01-01

    with Saccharomyces cerevisiae (SC), had on the volatile chemical profile of Shiraz wine. Methods and Results: Shiraz grape must was inoculated with monocultures of the non-Saccharomyces yeasts, which were allowed to ferment until 2% v/v ethanol concentration was reached at which point, SC was added to complete...... the alcoholic fermentation. The control was SC in monoculture. The final wines were subjected to solid phase microextraction-GC × GC-time of flight-MS to evaluate the untargeted volatile metabolite profile of each treatment. Each fermentation produced a unique chemical profile. The LT–SC sequential fermentation...... for increased chemical complexity of the Shiraz volatile profile. Significance of the Study: The results demonstrate that there is no clear, singular trend for how different, non-Saccharomyces species of yeast – once thought to be wholly unfavourable in wine fermentations – will impact wine chemistry, flavour...

  6. Anticancer properties of Monascus metabolites.

    Science.gov (United States)

    Yang, Tao; Liu, Junwen; Luo, Feijun; Lin, Qinlu; Rosol, Thomas J; Deng, Xiyun

    2014-08-01

    This review provides up-to-date information on the anticancer properties of Monascus-fermented products. Topics covered include clinical evidence for the anticancer potential of Monascus metabolites, bioactive Monascus components with anticancer potential, mechanisms of the anticancer effects of Monascus metabolites, and existing problems as well as future perspectives. With the advancement of related fields, the development of novel anticancer Monascus food products and/or pharmaceuticals will be possible with the ultimate goal of decreasing the incidence and mortality of malignancies in humans.

  7. Oil Volatility Risk and Expected Stock Returns

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Pan, Xuhui (Nick)

    After the financialization of commodity futures markets in 2004-05 oil volatility has become a strong predictor of returns and volatility of the overall stock market. Furthermore, stocks' exposure to oil volatility risk now drives the cross-section of expected returns. The difference in average...... return between the quintile of stocks with low exposure and high exposure to oil volatility is significant at 0.66% per month, and oil volatility risk carries a significant risk premium of -0.60% per month. In the post-financialization period, oil volatility risk is strongly related with various measures...

  8. Understanding and classifying metabolite space and Metabolite-Likeness

    NARCIS (Netherlands)

    Peironcely, J.E.; Reijmers, T.; Coulier, L.; Bender, A.; Hankemeier, T.

    2011-01-01

    While the entirety of 'Chemical Space' is huge (and assumed to contain between 1063 and 10200 'small molecules'), distinct subsets of this space can nonetheless be defined according to certain structural parameters. An example of such a subspace is the chemical space spanned by endogenous metabolite

  9. Microbiological changes, shelf life and identification of initial and spoilage microbiota of sea bream fillets stored under various conditions using 16S rRNA gene analysis.

    Science.gov (United States)

    Parlapani, Foteini F; Kormas, Konstantinos Ar; Boziaris, Ioannis S

    2015-09-01

    Sea bream fillets are one of the most important value-added products of the seafood market. Fresh seafood spoils mainly owing to bacterial action. In this study an exploration of initial and spoilage microbiota of sea bream fillets stored under air and commercial modified atmosphere packaging (MAP) at 0 and 5 °C was conducted by 16S rRNA gene sequence analysis of isolates grown on plates. Sensory evaluation and enumeration of total viable counts and spoilage microorganisms were also conducted to determine shelf life and bacterial growth respectively. Different temperatures and atmospheres affected growth and synthesis of spoilage microbiota as well as shelf life. Shelf life under air at 0 and 5 °C was 14 and 5 days respectively, while under MAP it was 20 and 8 days respectively. Initial microbiota were dominated by Pseudomonas fluorescens, Psychrobacter and Macrococcus caseolyticus. Different temperatures and atmospheres affected the synthesis of spoilage microbiota. At the end of shelf life, different phylotypes of Pseudomonas closely related to Pseudomonas fragi were found to dominate in most cases, while Pseudomonas veronii dominated in fillets under MAP at 0 °C. Furthermore, in fillets under MAP at 5 °C, new dominant species such as Carnobacterium maltaromaticum, Carnobacterium divergens and Vagococcus fluvialis were revealed. Different temperature and atmospheric conditions affected bacterial growth, shelf life and the synthesis of spoilage microbiota. Molecular identification revealed species and strains of microorganisms that have not been reported before for sea bream fillets stored under various conditions, thus providing valuable information regarding microbiological spoilage. © 2014 Society of Chemical Industry.

  10. Rhenium volatilization in waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kai; Pierce, David A. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Hrma, Pavel, E-mail: pavel.hrma@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Schweiger, Michael J. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Kruger, Albert A. [U.S. Department of Energy, Office of River Protection, Richland, WA 99352 (United States)

    2015-09-15

    Highlights: • Re did not volatilize from a HLW feed until 1000 °C. • Re began to volatilize from LAW feeds at ∼600 °C. • The vigorous foaming and generation of gases from salts enhanced Re evaporation in LAW feeds. • The HLW glass with less foaming and salts is a promising medium for Tc immobilization. - Abstract: We investigated volatilization of rhenium (Re), sulfur, cesium, and iodine during the course of conversion of high-level waste melter feed to glass and compared the results for Re volatilization with those in low-activity waste borosilicate glasses. Whereas Re did not volatilize from high-level waste feed heated at 5 K min{sup −1} until 1000 °C, it began to volatilize from low-activity waste borosilicate glass feeds at ∼600 °C, a temperature ∼200 °C below the onset temperature of evaporation from pure KReO{sub 4}. Below 800 °C, perrhenate evaporation in low-activity waste melter feeds was enhanced by vigorous foaming and generation of gases from molten salts as they reacted with the glass-forming constituents. At high temperatures, when the glass-forming phase was consolidated, perrhenates were transported to the top surface of glass melt in bubbles, typically together with sulfates and halides. Based on the results of this study (to be considered preliminary at this stage), the high-level waste glass with less foaming and salts appears a promising medium for technetium immobilization.

  11. Application of Electronic Noses for Disease Diagnosis and Food Spoilage Detection

    Directory of Open Access Journals (Sweden)

    Paolo Di Francesco

    2006-11-01

    Full Text Available Over the last twenty years, newly developed chemical sensor systems (socalled“electronic noses" have odour analyses made possible. This paper describes theapplications of these systems for microbial detection in different fields such as medicineand the food industry, where fast detection methods are essential for appropriatemanagement of health care. Several groups have employed different electronic noses forclassification and quantification of bacteria and fungi to obtain accurate medicaldiagnosis and food quality control. So far, detection and identification of bacterial andfungal volatiles have been achieved by use of e-noses offering different correctclassification percentages. The present review includes examples of bacterial and fungalspecies producing volatile compounds and correlated to infectious diseases or fooddeterioration. The results suggest the possibility of using this new technology both inmedical diagnostics and in food control management.

  12. DOES ENERGY CONSUMPTION VOLATILITY AFFECT REAL GDP VOLATILITY? AN EMPIRICAL ANALYSIS FOR THE UK

    Directory of Open Access Journals (Sweden)

    Abdul Rashid

    2013-10-01

    Full Text Available This paper empirically examines the relation between energy consumption volatility and unpredictable variations in real gross domestic product (GDP in the UK. Estimating the Markov switching ARCH model we find a significant regime switching in the behavior of both energy consumption and GDP volatility. The results from the Markov regime-switching model show that the variability of energy consumption has a significant role to play in determining the behavior of GDP volatilities. Moreover, the results suggest that the impacts of unpredictable variations in energy consumption on GDP volatility are asymmetric, depending on the intensity of volatility. In particular, we find that while there is no significant contemporaneous relationship between energy consumption volatility and GDP volatility in the first (low-volatility regime, GDP volatility is significantly positively related to the volatility of energy utilization in the second (high-volatility regime.

  13. Effect of weak acid preservatives on growth of bakery product spoilage fungi at different water activities and pH values

    DEFF Research Database (Denmark)

    Suhr, Karin Isabel; Nielsen, Per Væggemose

    2004-01-01

    of bakery products was conducted using calcium propionate, potassium sorbate and sodium benzoate. The obtained data was modelled using survival analysis to determine 'spoilage-free time' for the fungi. At the low a(w) level (0.80) only Eurotium species grew within the test period of 30 days. Higher water...... activity levels as well as higher pH values decreased spoilage-free times of the fungi. The preservative calcium propionate was less effective than potassium sorbate and sodium benzoate....

  14. Effect of antimicrobial spice and herb extract combinations on Listeria monocytogenes, Staphylococcus aureus, and spoilage microflora growth on cooked ready-to-eat vacuum-packaged shrimp.

    Science.gov (United States)

    Weerakkody, Nimsha S; Caffin, Nola; Dykes, Gary A; Turner, Mark S

    2011-07-01

    Two spice and herb extract combinations from galangal (Alpinia galanga), rosemary (Rosmarinus officinalis), and lemon iron bark (Eucalyptus staigerana) were evaluated for their ability to inhibit the growth of inoculated Listeria monocytogenes and Staphylococcus aureus and naturally present spoilage microflora on cooked ready-to-eat shrimp stored for 16 days at 4 or 8 °C. A combination of galangal, rosemary, and lemon iron bark significantly reduced (P galangal and rosemary extract significantly reduced (P galangal, rosemary, and lemon iron bark extracts can be used to control the growth of spoilage microflora on ready-to-eat shrimp.

  15. Factors affecting the volatilization of volatile organic compounds from wastewater

    Directory of Open Access Journals (Sweden)

    Junya Intamanee

    2006-09-01

    Full Text Available This study aimed to understand the influence of the wind speed (U10cm, water depth (h and suspended solids (SS on mass transfer coefficient (KOLa of volatile organic compounds (VOCs volatilized from wastewater. The novelty of this work is not the method used to determine KOLa but rather the use of actual wastewater instead of pure water as previously reported. The influence of U10cm, h, and SS on KOLa was performed using a volatilization tank with the volume of 100-350 L. Methyl Ethyl Ketone (MEK was selected as a representative of VOCs investigated here in. The results revealed that the relationship between KOLa and the wind speeds falls into two regimes with a break at the wind speed of 2.4 m/s. At U10cm 2.4 m/s, KOLa increased more rapidly. The relationship between KOLa and U10cm was also linear but has a distinctly higher slope. For the KOLa dependency on water depth, the KOLa decreased significantly with increasing water depth up to a certain water depth after that the increase in water depth had small effect on KOLa. The suspended solids in wastewater also played an important role on KOLa. Increased SS resulted in a significant reduction of KOLa over the investigated range of SS. Finally, the comparison between KOLa obtained from wastewater and that of pure water revealed that KOLa from wastewater were much lower than that of pure water which was pronounced at high wind speed and at small water depth. This was due the presence of organic mass in wastewater which provided a barrier to mass transfer and reduced the degree of turbulence in the water body resulting in low volatilization rate and thus KOLa. From these results, the mass transfer model for predicting VOCs emission from wastewater should be developed based on the volatilization of VOCs from wastewater rather than that from pure water.

  16. Primary expectations of secondary metabolites

    Science.gov (United States)

    My program examines the plant secondary metabolites (i.e. phenolics) important for human health, and which impart the organoleptic properties that are quality indicators for fresh and processed foods. Consumer expectations such as appearance, taste, or texture influence their purchasing decisions; a...

  17. The secondary metabolite bioinformatics portal

    DEFF Research Database (Denmark)

    Weber, Tilmann; Kim, Hyun Uk

    2016-01-01

    . In this context, this review gives a summary of tools and databases that currently are available to mine, identify and characterize natural product biosynthesis pathways and their producers based on ‘omics data. A web portal called Secondary Metabolite Bioinformatics Portal (SMBP at http...

  18. Modeling the Volatility in Global Fertilizer Prices

    NARCIS (Netherlands)

    P-Y. Chen (Ping-Yu); C-L. Chang (Chia-Lin); C-C. Chen (Chi-Chung); M.J. McAleer (Michael)

    2010-01-01

    textabstractThe main purpose of this paper is to estimate the volatility in global fertilizer prices. The endogenous structural breakpoint unit root test and alternative volatility models, including the generalized autoregressive conditional heteroskedasticity (GARCH) model, Exponential GARCH (EGARC

  19. Fluctuation behaviors of financial return volatility duration

    Science.gov (United States)

    Niu, Hongli; Wang, Jun; Lu, Yunfan

    2016-04-01

    It is of significantly crucial to understand the return volatility of financial markets because it helps to quantify the investment risk, optimize the portfolio, and provide a key input of option pricing models. The characteristics of isolated high volatility events above certain threshold in price fluctuations and the distributions of return intervals between these events arouse great interest in financial research. In the present work, we introduce a new concept of daily return volatility duration, which is defined as the shortest passage time when the future volatility intensity is above or below the current volatility intensity (without predefining a threshold). The statistical properties of the daily return volatility durations for seven representative stock indices from the world financial markets are investigated. Some useful and interesting empirical results of these volatility duration series about the probability distributions, memory effects and multifractal properties are obtained. These results also show that the proposed stock volatility series analysis is a meaningful and beneficial trial.

  20. A Fractionally Integrated Wishart Stochastic Volatility Model

    NARCIS (Netherlands)

    M. Asai (Manabu); M.J. McAleer (Michael)

    2013-01-01

    textabstractThere has recently been growing interest in modeling and estimating alternative continuous time multivariate stochastic volatility models. We propose a continuous time fractionally integrated Wishart stochastic volatility (FIWSV) process. We derive the conditional Laplace transform of

  1. Stochastic Volatility and DSGE Models

    DEFF Research Database (Denmark)

    Andreasen, Martin Møller

    This paper argues that a specification of stochastic volatility commonly used to analyze the Great Moderation in DSGE models may not be appropriate, because the level of a process with this specification does not have conditional or unconditional moments. This is unfortunate because agents may...

  2. Genetically Encoded Sensors for Metabolites

    Science.gov (United States)

    Deuschle, Karen; Fehr, Marcus; Hilpert, Melanie; Lager, Ida; Lalonde, Sylvie; Looger, Loren L.; Okumoto, Sakiko; Persson, Jörgen; Schmidt, Anja; Frommer, Wolf B.

    2009-01-01

    Background Metabolomics, i.e., the multiparallel analysis of metabolite changes occurring in a cell or an organism, has become feasible with the development of highly efficient mass spectroscopic technologies. Functional genomics as a standard tool helped to identify the function of many of the genes that encode important transporters and metabolic enzymes over the past few years. Advanced expression systems and analysis technologies made it possible to study the biochemical properties of the corresponding proteins in great detail. We begin to understand the biological functions of the gene products by systematic analysis of mutants using systematic PTGS/RNAi, knockout and TILLING approaches. However, one crucial set of data especially relevant in the case of multicellular organisms is lacking: the knowledge of the spatial and temporal profiles of metabolite levels at cellular and subcellular levels. Methods We therefore developed genetically encoded nanosensors for several metabolites to provide a basic set of tools for the determination of cytosolic and subcellular metabolite levels in real time by using fluorescence microscopy. Results Prototypes of these sensors were successfully used in vitro and also in vivo, i.e., to measure sugar levels in fungal and animal cells. Conclusions One of the future goals will be to expand the set of sensors to a wider spectrum of substrates by using the natural spectrum of periplasmic binding proteins from bacteria and by computational design of proteins with altered binding pockets in conjunction with mutagenesis. This toolbox can then be applied for four-dimensional imaging of cells and tissues to elucidate the spatial and temporal distribution of metabolites as a discovery tool in functional genomics, as a tool for high-throughput, high-content screening for drugs, to test metabolic models, and to analyze the interplay of cells in a tissue or organ. PMID:15688353

  3. Evaluation of five essential oils from aromatic plants of Cameroon for controlling food spoilage and mycotoxin producing fungi.

    Science.gov (United States)

    Nguefack, J; Leth, V; Amvam Zollo, P H; Mathur, S B

    2004-08-01

    Five essential oils (EO) extracted from Cymbopogon citratus, Monodora myristica, Ocimum gratissimum, Thymus vulgaris and Zingiber officinale were investigated for their inhibitory effect against three food spoilage and mycotoxin producing fungi, Fusarium moniliforme, Aspergillus flavus and Aspergillus fumigatus. Five strains of each fungus were tested. The agar dilution technique was used to determine the inhibitory effect of each EO on the radial growth of the fungus, and a dose response was recorded. The EO from O. gratissimum, T. vulgaris and C. citratus were the most effective and prevented conidial germination and the growth of all three fungi on corn meal agar at 800, 1000 and 1200 ppm, respectively. Moderate activity was observed for the EO from Z. officinale between 800 and 2500 ppm, while the EO from M. myristica was less inhibitory. These effects against food spoilage and mycotoxin producing fungi indicated the possible ability of each essential oil as a food preservative. A comparative test on the preservative ability of the EO from O. gratissimum and potassium sorbate against A. flavus at pH 3.0 and 4.5 showed that the EO remained stable at both pH, whereas the efficacy of potassium sorbate was reduced at higher pH. We concluded that the EO from O. gratissimum is a potential food preservative with a pH dependent superiority against potassium sorbate, and these are novel scientific information.

  4. Plasma membrane H+ and K+ transporters are involved in the weak-acid preservative response of disparate food spoilage yeasts.

    Science.gov (United States)

    Macpherson, Neil; Shabala, Lana; Rooney, Henrietta; Jarman, Marcus G; Davies, Julia M

    2005-06-01

    The food spoilage yeasts Zygosaccharomyces bailii and Saccharomyces cerevisiae have been proposed to resist weak-acid preservative stress by different means; Z. bailii by limiting influx of preservative combined with its catabolism, S. cerevisiae by active extrusion of the preservative weak-acid anion and H(+). Measurement of H(+) extrusion by exponential-phase Z. bailii cells suggest that, in common with S. cerevisiae, this yeast uses a plasma membrane H(+)-ATPase to expel H(+) when challenged by weak-acid preservative (benzoic acid). Simultaneous measurement of Z. bailii net H(+) and K(+) fluxes showed that net K(+) influx accompanies net H(+) efflux during acute benzoic acid stress. Such ionic coupling is known for S. cerevisiae in short-term preservative stress. Both yeasts significantly accumulated K(+) on long-term exposure to benzoic acid. Analysis of S. cerevisiae K(+) transporter mutants revealed that loss of the high affinity K(+) uptake system Trk1 confers sensitivity to growth in preservative. The results suggest that cation accumulation is an important factor in adaptation to weak-acid preservatives by spoilage yeasts and that Z. bailii and S. cerevisiae share hitherto unsuspected adaptive responses at the level of plasma membrane ion transport.

  5. Modified atmosphere packaging for prevention of mold spoilage of bakery products with different pH and water activity levels.

    Science.gov (United States)

    Guynot, M E; Marín, S; Sanchis, V; Ramos, A J

    2003-10-01

    A sponge cake analog was used to study the influence of pH, water activity (aw), and carbon dioxide (CO2) levels on the growth of seven fungal species commonly causing bakery product spoilage (Eurotium amstelodami, Eurotium herbariorum, Eurotium repens, Eurotium rubrum, Aspergillus niger, Aspergillus flavus, and Penicillium corylophilum). A full factorial design was used. Water activity, CO2, and their interaction were the main factors significantly affecting fungal growth. Water activity at levels of 0.80 to 0.90 had a significant influence on fungal growth and determined the concentration of CO2 needed to prevent cake analog spoilage. At an aw level of 0.85, lag phases increased twofold when the level of CO2 in the headspace increased from 0 to 70%. In general, no fungal growth was observed for up to 28 days of incubation at 25 degrees C when samples were packaged with 100% CO2, regardless of the aw level. Partial least squares projection to latent structures regression was used to build a polynomial model to predict sponge cake shelf life on the basis of the lag phases of all seven species tested. The model developed explained quite well (R2 = 79%) the growth of almost all species, which responded similarly to changes in tested factors. The results of this study emphasize the importance of combining several hurdles, such as modified atmosphere packaging, aw, and pH, that have synergistic or additive effects on the inhibition of mold growth.

  6. Evaluation of natural antimicrobials on typical meat spoilage bacteria in vitro and in vacuum-packed pork meat.

    Science.gov (United States)

    Schirmer, Bjørn Christian; Langsrud, Solveig

    2010-03-01

    The aim of this study was to investigate the inhibitory effect of natural antimicrobials on the growth of typical spoilage bacteria from marinated pork. Minimum inhibitory concentrations (MIC) of thymol, cinnamaldehyde, allyl isothiocyanate, citric acid, ascorbic acid, a rosemary extract, and a grapefruit seed extract against Lactobacillus algidus, Leuconostoc mesenteroides, Leuconostoc carnosum, Carnobacterium maltaromaticum, Carnobacterium divergens, Brochothrix thermosphacta, and Serratia proteamaculans were determined in a microplate assay. Combinations of antimicrobials were tested and several combinations showed synergistic effects in inhibiting bacterial growth. Single and combined antimicrobials were added to vacuum-packed pork meat to evaluate preserving effects. Antimicrobial concentrations of up to 10 times the MIC values showed no effect on total bacterial growth in vacuum packed pork meaning that although most antimicrobials inhibited the growth of spoilage bacteria in vitro, results from the microplate assay could not be transferred to the meat system. Most natural antimicrobials possess strong odor and flavor that limit their use as a food preservative. In conclusion, this study showed that the use of natural antimicrobials in meat products is limited and that bacterial quality and shelf life was not enhanced under the chosen conditions.

  7. Characterization of the Biodiversity of the Spoilage Microbiota in Chicken Meat Using Next Generation Sequencing and Culture Dependent Approach.

    Science.gov (United States)

    Lee, Hee Soo; Kwon, Mirae; Heo, Sunhak; Kim, Min Gon; Kim, Geun-Bae

    2017-01-01

    This study investigated the psychrotrophic bacteria isolated from chicken meat to characterize their microbial composition during refrigerated storage. The bacterial community was identified by the Illumina MiSeq method based on bacterial DNA extracted from spoiled chicken meat. Molecular identification of the isolated psychrotrophic bacteria was carried out using 16S rDNA sequencing and their putrefactive potential was investigated by the growth at low temperature as well as their proteolytic activities in chicken meat. From the Illumina sequencing, a total of 187,671 reads were obtained from 12 chicken samples. Regardless of the type of chicken meat (i.e., whole meat and chicken breast) and storage temperatures (4°C and 10°C), Pseudomonas weihenstephanensis and Pseudomonas congelans were the most prominent bacterial species. Serratia spp. and Acinetobacter spp. were prominent in chicken breast and whole chicken meat, respectively. The 118 isolated strains of psychrotrophic bacteria comprised Pseudomonas spp. (58.48%), Serratia spp. (10.17%), and Morganella spp. (6.78%). All isolates grew well at 10°C and they induced different proteolytic activities depending on the species and strains. Parallel analysis of the next generation sequencing and culture dependent approach provides in-depth information on the biodiversity of the spoilage microbiota in chicken meat. Further study is needed to develop better preservation methods against these spoilage bacteria.

  8. Formation of Guaiacol by Spoilage Bacteria from Vanillic Acid, a Product of Rice Koji Cultivation, in Japanese Sake Brewing.

    Science.gov (United States)

    Ito, Toshihiko; Konno, Mahito; Shimura, Yoichiro; Watanabe, Seiei; Takahashi, Hitoshi; Hashizume, Katsumi

    2016-06-08

    The formation of guaiacol, a potent phenolic off-odor compound in the Japanese sake brewing process, was investigated. Eight rice koji samples were analyzed, and one contained guaiacol and 4-vinylguaiacol (4-VG) at extraordinarily high levels: 374 and 2433 μg/kg dry mass koji, respectively. All samples contained ferulic and vanillic acids at concentrations of mg/kg dry mass koji. Guaiacol forming microorganisms were isolated from four rice koji samples. They were identified as Bacillus subtilis, B. amyloliquefaciens/subtilis, and Staphylococcus gallinarum using 16S rRNA gene sequence. These spoilage bacteria convert vanillic acid to guaiacol and ferulic acid to 4-VG. However, they convert very little ferulic acid or 4-VG to guaiacol. Nine strains of koji fungi tested produced vanillic acid at the mg/kg dry mass koji level after cultivation. These results indicated that spoilage bacteria form guaiacol from vanillic acid, which is a product of koji cultivation in the sake brewing process.

  9. Business Cycles, Financial Crises, and Stock Volatility

    OpenAIRE

    G. William Schwert

    1989-01-01

    This paper shows that stock volatility increases during recessions and financial crises from 1834-1987. The evidence reinforces the notion that stock prices are an important business cycle indicator. Using two different statistical models for stock volatility, I show that volatility increases after major financial crises. Moreover. stock volatility decreases and stock prices rise before the Fed increases margin requirements. Thus, there is little reason to believe that public policies can con...

  10. Decomposing European bond and equity volatility

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    The paper investigates volatility spillover from US and aggregate European asset markets into European national asset markets. A main contribution is that bond and equity volatilities are analyzed simultaneously. A new model belonging to the "volatilityspillover" family is suggested: The conditio...... (stock) volatilities are mainly influenced by bond (stock) effects. Global, regional, and local volatility effects are all important. The introduction of the euro is associated with a structural break....

  11. The january effect across volatility regimes

    OpenAIRE

    Agnani, Betty; Aray, Henry

    2007-01-01

    Using a Markov regime switching model, this article presents evidence on the well-known January effect on stock returns. The specification allows a distinction to be drawn between two regimes, one with high volatility and other with low volatility. We obtain a time-varying January effect that is, in general, positive and significant in both volatility regimes. However, this effect is larger in the high volatility regime. In sharp contrast with most previous literature we find two major result...

  12. Exponential Smoothing, Long Memory and Volatility Prediction

    DEFF Research Database (Denmark)

    Proietti, Tommaso

    Extracting and forecasting the volatility of financial markets is an important empirical problem. The paper provides a time series characterization of the volatility components arising when the volatility process is fractionally integrated, and proposes a new predictor that can be seen as extensi...... methods for forecasting realized volatility, and that the estimated model confidence sets include the newly proposed fractional lag predictor in all occurrences....

  13. Possible Sources of Polar Volatiles

    Science.gov (United States)

    Schultz, P. H.

    2011-12-01

    Extensive analyses of returned Apollo samples demonstrated that the Moon is extremely volatile poor. While this conclusion remains true, various measurements since the late 90's implicated the presence of water: e.g., enhanced reflection of circularly polarized radar signals and suppression of epithermal neutrons near the poles. More recently, traces of H2O have been discovered inside volcanic glass, along with more significant amounts residing in hydrous minerals (apatite) returned from both highland and mare landing sites. Three recent lunar missions (DIXI, M3, Cassini) identified hydrous phases on/near the lunar surface, whereas the LCROSS probe detected significant quantities of volatiles (OH, H2O and other volatiles) excavated by the Centaur impact. These new mission results and sample studies, however, now allow testing different hypotheses for the generation, trapping, and replenishment of these volatiles. Solar-proton implantation must contribute to the hydrous phases in the lunar regolith in order to account for the observed time-varying abundances and occurrence near the lunar equator. This also cannot be the entire story. The relatively low speed LCROSS-Centaur impact (2.5km/s) could not vaporize such hydrous minerals, yet emissions lines of OH (from the thermal disassociation of H2O), along with other compounds (CO2, NH2) were detected within the first second, before ejecta could reach sunlight. Telescopic observations by Potter and Morgan (1985) discovered a tenuous lunar atmosphere of Na, but the LCROSS UV/Vis spectrometer did not detect the Na-D line until after the ejecta reached sunlight (along with a line pair attributed to Ag). With time, other volatile species emerged (OH, CO). The LAMP instrument on the Lunar Reconnaissance Orbiter had a different viewpoint from the side (rather than from above) and detected many other atomic species release by the LCROSS-Centaur impact. Consequently, it appears that there is a stratigraphy for trapped species

  14. Metabolite profiles of common Stemphylium species

    DEFF Research Database (Denmark)

    Andersen, Birgitte; Solfrizzo, Michelle; Visconti, Angelo

    1995-01-01

    Thirty-three isolates of Stemphylium spp. have been analysed for their metabolite profiles. Five metabolites, stemphylin, stemphyloxin II, stemphyperylenol, stemphol and a stemphol related compound, have been detected by high-performance liquid chromatography and thin-layer chromatography...

  15. Reducing the bloater spoilage incidence in fermented green olives during storage

    Directory of Open Access Journals (Sweden)

    Brito, D.

    2002-09-01

    Full Text Available Fermented green olives of the variety “Picholine” were brined in 5% NaCl solutions, which were adjusted to pH 4.00 and 5.00 with lactic acid. Potassium sorbate was added to the brine at 0.05 % and the assays were inoculated with Lactobacillus plantarum strain I159, and Pichia anomala strains S18 from our collection. The pH values and microbial counts including Gram negative bacteria, yeasts and moulds, and lactic acid bacteria were followed during 6 months of storage. Results showed that even if the olives were inoculated with a high gas producing yeast (P. anomala S18, the attack of the fruits by the “bloater” spoilage was drastically reduced in the assays adjusted to pH4, added with potassium sorbate and inoculated with L. plantarum, without affecting the organoleptic characteristics of the product.Aceitunas verdes fermentadas de la variedad Picholine fueron colocadas en soluciones de salmuera al 5% en NaCl, ajustando el pH a 4,00 y 5,00 con ácido láctico. Se agregó sorbato potásico a la salmuera a una concentración del 0,05% y las muestras se inocularon con cepas de Lactobacllius plantarum I159 y Pichia anomala S18 de nuestra procedencia. Los valores del pH y el recuento microbiano incluyendo a las bacterias Gram-negativas, levaduras y mohos y bacterias del ácido láctico se siguieron durante los seis meses de almacenamiento. Los resultados mostraron que incluso inoculando las aceitunas con la levadura (P. anomala S18, productora de alta cantidad de gas, el ataque de los frutos por el alambrado se redujo drásticamente en las muestras ajustadas a pH4, a las que se añadió sorbato potásico e inoculó con Lactobacllius plantarum, sin verse afectadas las características organolépticas del producto.

  16. Heat inactivation of wine spoilage yeast Dekkera bruxellensis by hot water treatment.

    Science.gov (United States)

    Fabrizio, V; Vigentini, I; Parisi, N; Picozzi, C; Compagno, C; Foschino, R

    2015-08-01

    Cell suspensions of four Dekkera bruxellensis strains (CBS 2499, CBS 2797, CBS 4459 and CBS 4601) were subjected to heat treatment in deionized water at four different temperatures (55·0, 57·5, 60·0 and 62·5°C) to investigate their thermal resistance. The decimal reduction times at a specific temperature were calculated from the resulting inactivation curves: the D-values at 55·0°C ranged from 63 to 79·4 s, at 57·5°C from 39·6 to 46·1 s, at 60·0°C from 19·5 to 20·7 s, at 62·5°C from 10·2 to 13·7 s. The z-values were between 9·2 and 10·2°C, confirming that heat resistance is a strain-dependent character. A protocol for the sanitization of 225 l casks by immersion in hot water was set up and applied to contaminated 3-year-old barrels. The heat penetration through the staves was evaluated for each investigated temperature by positioning a thermal probe at 8 mm deep. A treatment at 60°C for an exposure time of 19 min allowed to eliminate the yeast populations up to a log count reduction of 8. Brettanomyces/Dekkera bruxellensis is the main yeast involved in red wine spoilage that occurs during ageing in barrel, generating considerable economic losses. Current sanitization protocols, performed using different chemicals, are ineffective due to the porous nature of the wood. The thermal inactivation of D. bruxellensis cells by hot water treatment proves to be efficacious and easy to perform, provided that the holding time at the killing temperature takes into account the filling time of the vessel and the time for the heat penetration into the wood structure. © 2015 The Society for Applied Microbiology.

  17. Oil Volatility Risk and Expected Stock Returns

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Pan, Xuhui (Nick)

    After the financialization of commodity futures markets in 2004-05 oil volatility has become a strong predictor of returns and volatility of the overall stock market. Furthermore, stocks' exposure to oil volatility risk now drives the cross-section of expected returns. The difference in average r...

  18. Volatiles in inter-specific bacterial interactions

    NARCIS (Netherlands)

    Tyc, O.; Zweers, H.; De Boer, W.; Garbeva, P.V.

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures o

  19. Volatiles in inter-specific bacterial interactions

    NARCIS (Netherlands)

    Tyc, O.; Zweers, H.; De Boer, W.; Garbeva, P.V.

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures

  20. Ammonia volatilization from intensively managed dairy pastures.

    NARCIS (Netherlands)

    Bussink, D.W.

    1996-01-01

    The objectives of this thesis are (i) to quantify NH 3 volatilization from grassland, (ii) to gain understanding of the NH3 volatilization processes on grassland and (iii) to study measures how to reduce NH 3 volatilization from gra

  1. Oil Volatility Risk and Expected Stock Returns

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Pan, Xuhui (Nick)

    After the financialization of commodity futures markets in 2004-05 oil volatility has become a strong predictor of returns and volatility of the overall stock market. Furthermore, stocks' exposure to oil volatility risk now drives the cross-section of expected returns. The difference in average r...

  2. Cost Linkages Transmit Volatility Across Markets

    DEFF Research Database (Denmark)

    Nguyen, Daniel Xuyen; Schaur, Georg

    to link the domestic and export supply costs. This theoretical contribution has two new implications for the exporting firm. First, the demand volatility in the foreign market now directly affects the firm's domestic sales volatility. Second, firms hedge domestic demand volatility with exports. The model...

  3. Pharmacokinetics of Tyrosol Metabolites in Rats

    OpenAIRE

    Da-Hye Lee; Yang-Ji Kim; Min Jung Kim; Jiyun Ahn; Tae-Youl Ha; Sang Hee Lee; Young Jin Jang; Chang Hwa Jung

    2016-01-01

    Tyrosol is considered a potential antioxidant; however, little is known regarding the pharmacokinetics of its metabolites. To study the pharmacokinetics of tyrosol-derived metabolites after oral administration of a single dose of tyrosol, we attempted to identify tyrosol metabolites in rat plasma by using ultra-performance liquid chromatography and quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Two tyrosol metabolites (M1 and M2) were detected in the plasma. M1 was identified as...

  4. 冷藏鲤鱼和罗非鱼优势腐败菌腐败能力分析%Analysis of Spoilage Ability of Dominant Spoilage Bacteria from Stored Chilled Cyprinus carpio and Oreochromis niloticus

    Institute of Scientific and Technical Information of China (English)

    许振伟; 李学英; 杨宪时; 郭全友; 姜朝军

    2012-01-01

    通过分析接种腐败菌的鲤鱼和罗非鱼无菌鱼块贮藏中感官、腐败代谢产物和腐败菌的变化,以腐败菌的生长动力学参数和腐败代谢产物的产量因子(YTVBN/CFU)为指标,探讨冷藏鲤鱼和罗非鱼优势腐败菌假单胞菌和腐败希瓦氏菌的腐败能力。结果表明:接种腐败希瓦氏菌和恶臭假单胞菌的鲤鱼无菌鱼块的货架期分别为132h和162h,此时的TVBN值为27.12mg/100g和22.51mg/100g,腐败希瓦氏菌和恶臭假单胞菌菌数为8.961g(CFu/g)和9.071g(CFU/g),产量因子YTVBN/CFU为9.28×10^-9mgTVBN/CFU和1.81×10^-8mgTVBN/CFU。接种荧光假单胞菌和腐败希瓦氏菌的罗非鱼无菌鱼块的货架期分别为132h和144h,此时的TVBN值为23.46mg/100g和24.30mg/100g,荧光假单胞菌和腐败希瓦氏菌菌数为8.831g(CFU/g)和9.121g(CFU/g),产量因子YIWBNICWJ为1.67×10^-8mgTvBN/CFU和9.10×10^-9mgTVBN/CFU。结合两种养殖鱼冷藏过程中的菌相变化和腐败菌在腐败过程中的作用,初步得出冷藏罗非鱼和鲤鱼的特定腐败菌是假单胞菌,两种腐败菌都具有较强的腐败能力。%Sensory quality, the growth kinetic parameters of spoilage bacteria and the yield factor of metabolic products, YTVBN/CFU, were assayed on sterile Cyprinus carpio and Oreochromis niloticus tissue blocks inoculated with spoilage bacteria during chilled storage. The spoilage ability of two dominant spoilage bacteria, Pseudomonas spp. and Shewanella putrefaciens, were analyzed on Cyprinus carpio and Oreochromis niloticus stored aerobically under chilled conditions. The post-inoculation shelf-lives of sterile Cyprinus carpio tissue blocks inoculated with Shewanella putrefaciens and Pseudomonas putida were 132 h and 162 h, respectively, the TVBNs 27.12 mg/100 g and 22.51 mg/100 g, the bacterial counts 8.96 lg(CFU/g) and 9.07 lg(CFU/ g) and the YTWBN/CFU values 9.28

  5. Direct Analysis of Volatile Organic Compounds in Foods by Headspace Extraction Atmospheric Pressure Chemical Ionisation Mass Spectrometry.

    Science.gov (United States)

    Perez-Hurtado, P; Palmer, E; Owen, T; Aldcroft, C; Allen, M H; Jones, J; Creaser, C S; Lindley, M R; Turner, M A; Reynolds, J C

    2017-08-30

    The rapid screening of volatile organic compounds (VOCs) by direct analysis has potential applications in the areas of food and flavour science. Currently the technique of choice for VOC analysis is gas chromatography-mass spectrometry (GC/MS). However, the long chromatographic run times and elaborate sample preparation associated with this technique have led a movement towards direct analysis techniques, such as selected ion flow tube mass spectrometry (SIFT-MS), proton transfer reaction mass spectrometry (PTR-MS) and electronic noses. The work presented here describes the design and construction of a Venturi jet-pump based modification for a compact mass spectrometer which enables the direct introduction of volatiles for qualitative and quantitative analysis. Volatile organic compounds were extracted from the headspace of heated vials into the atmospheric pressure chemical ionization source of a quadrupole mass spectrometer using a Venturi pump. Samples were analysed directly with no prior sample preparation. Principal component analysis was used to differentiate between different classes of samples RESULTS: The interface is shown to be able to routinely detect problem analytes such as fatty acids and biogenic amines without the requirement of a derivatisation step, and is shown to be able to discriminate between four different varieties of cheese with good intra and inter-day reproducibility using an unsupervised principal component analysis model. Quantitative analysis is demonstrated using indole standards with limits of detection and quantification of 0.395 μg/mL and 1.316 μg/mL, respectively. The described methodology can routinely detect highly reactive analytes such as volatile fatty acids and diamines without the need for a derivatisation step or lengthy chromatographic separations. The capability of the system was demonstrated by discriminating between different varieties of cheese and monitoring the spoilage of meats. This article is protected by

  6. Mantle Volatiles - Distribution and Consequences

    Science.gov (United States)

    Luth, R. W.

    2003-12-01

    Volatiles in the mantle have, for many years, been the subject of intensive study from a number of perspectives. They are of interest because of their potential effects on melting relationships, on transport of major and trace elements, and on the rheological and other physical properties of the mantle. By convention, "volatiles" in this context are constituents that are liquid or gaseous at normal Earth surface conditions. This review will look at the behavior of C-O-H-S-halogen volatiles, beginning with H2O and C-O volatiles.There have been tremendous strides made recently towards understanding how volatiles in general and water in particular is transported and stored in the mantle. This progress is based on research on a number of fronts: studies of mantle-derived samples have provided insight into the nature and occurrence of hydrous phases such as amphibole, mica, and chlorite, and have provided constraints on the capacity of nominally anhydrous minerals (NAMs) such as olivine, pyroxenes, and garnet to contain "water" by a variety of substitution mechanisms. Experimental studies on mantle-derived magmas have provided constraints on volatile contents in their source regions. Other studies have constrained the pressure, temperature, and composition conditions over which hydrous phases are stable in the mantle.Fundamental questions remain about the geochemical cycling of volatiles in the mantle, and between the mantle and the surface. Much attention has focused on the capability of hydrous phases such as amphibole, mica, serpentine, chlorite, and a family of "dense hydrous magnesian silicates" (DHMSs) to act as carriers of water in subducting slabs back into the mantle. It has been clear since the work of Ito et al. (1983) that there is a discrepancy between the amount of volatiles subducted into the mantle and those returned to the surface by arc magmatism. A recent overview of volatile cycling in subduction systems by Bebout (1996) suggests that 5-15% of the H2

  7. Level Shifts in Volatility and the Implied-Realized Volatility Relation

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; de Magistris, Paolo Santucci

    to the multivariate case of the univariate level shift technique by Lu and Perron (2008). An application to the S&P500 index and a simulation experiment show that the recently documented empirical properties of strong persistence in volatility and forecastability of future realized volatility from current implied...... volatility, which have been interpreted as long memory (or fractional integration) in volatility and fractional cointegration between implied and realized volatility, are accounted for by occasional common level shifts....

  8. Volatile science? Metabolic engineering of terpenoids in plants.

    Science.gov (United States)

    Aharoni, Asaph; Jongsma, Maarten A; Bouwmeester, Harro J

    2005-12-01

    Terpenoids are important for plant survival and also possess biological properties that are beneficial to humans. Here, we describe the state of the art in terpenoid metabolic engineering, showing that significant progress has been made over the past few years. Subcellular targeting of enzymes has demonstrated that terpenoid precursors in subcellular compartments are not as strictly separated as previously thought and that multistep pathway engineering is feasible, even across cell compartments. These engineered plants show that insect behavior is influenced by terpenoids. In the future, we expect rapid progress in the engineering of terpenoid production in plants. In addition to commercial applications, such transgenic plants should increase our understanding of the biological relevance of these volatile secondary metabolites.

  9. 10 CFR 26.163 - Cutoff levels for drugs and drug metabolites.

    Science.gov (United States)

    2010-01-01

    ... metabolites Cutoff level Marijuana metabolites 50 Cocaine metabolites 300 Opiate metabolites 2000... Levels for Drugs and Drug Metabolites Drug or metabolites Cutoff level(ng/mL) Marijuana metabolite 1...

  10. Biogenic amine formation and microbial spoilage in chilled garfish ( Belone belone belone ) - effect of modified atmosphere packaging and previous frozen storage

    DEFF Research Database (Denmark)

    Dalgaard, Paw; Madsen, H.L.; Samieian, N.;

    2006-01-01

    Abstract Aims: To evaluate biogenic amine formation and microbial spoilage in fresh and thawed chilled garfish. Methods and Results: Storage trials were carried out with fresh and thawed garfish fillets at 0 or 5oC in air or in modified atmosphere packaging (MAP: 40% CO2 and 60% N2). During storage...

  11. Microbial spoilage and formation of biogenic amines in fresh and thawed modified atmosphere-packed salmon ( Salmo salar ) at 2 degrees C

    DEFF Research Database (Denmark)

    Emborg, Jette; Laursen, B.G.; Rathjen, T.

    2002-01-01

    Aims: To evaluate the microbial spoilage, formation of biogenic amines and shelf life of chilled fresh and frozen/thawed salmon packed in a modified atmosphere and stored at 2 degrees C.Methods and Results: The dominating microflora, formation of biogenic amines and shelf life were studied in two...

  12. Spoilage of value-added, high-oxygen modified-atmosphere packaged raw beef steaks by Leuconostoc gasicomitatum and Leuconostoc gelidum.

    Science.gov (United States)

    Vihavainen, Elina J; Björkroth, K Johanna

    2007-11-01

    Moisture-enhancing and marinating of meats are commonly used by the meat industry to add value to raw, retail products. Recently in Finland, certain value-added beef steak products have proven to be unusually susceptible to microbial spoilage leading to untoward quality deteriorations during producer-defined shelf-life. This study was conducted to evaluate the role of lactic acid bacteria (LAB) in the premature spoilage of value-added beef packaged under high-oxygen modified atmospheres. Spoilage was characterised by green discolouration and a buttery off-odour. The predominant LAB in eight packages of spoiled, marinated or moisture-enhanced beef steaks were identified by reference to a 16 and 23S rRNA gene restriction fragment length polymorphism pattern (ribotype) database. Leuconostoc gasicomitatum, Leuconostoc gelidum, Lactobacillus algidus, Lactobacillus sakei and Carnobacterium divergens were found to predominate in the LAB populations at numbers above 10(8) CFU/g. Inoculation of moisture-enhanced steaks with LAB strains and strain mixtures originating from the spoiled products demonstrated the spoilage potential of L. gasicomitatum and L. gelidum isolates. These two species produced green surface discolouration and buttery off-odours similar to these found in the spoiled, commercial products.

  13. ANTIBACTERIAL ACTIVITY OF GUAVA (PSIDIUM GUAJAVA L.) AND NEEM (AZADIRACHTA INDICA A. JUSS.)EXTRACTS AGAINST FOOD BORNE PATHOGENS AND SPOILAGE BACTERIA

    Science.gov (United States)

    The objective of this study was to investigate the antibacterial properties of guava (Psidium guajava) and neem (Azadirachta indica) extracts against a number of common food borne pathogens and spoilage bacteria. Screening for antibacterial activity was determined by disc diffusion assay against 21...

  14. Microbial, physical-chemical and sensory spoilage during the refrigerated storage of cooked pork loin processed by the sous vide method.

    Science.gov (United States)

    Díaz, Pedro; Nieto, Gema; Garrido, María Dolores; Bañón, Sancho

    2008-10-01

    The aim was to study spoilage during the refrigerated storage of cooked pork loin processed by the sous vide method. Samples were packaged under vacuum into polyamide-polypropylene pouches, cooked at an oven temperature/time of 70°C/12h, chilled at 3°C and stored at 2°C for 0, 5 or 10 weeks. Microbial (psychrotrophs, lactic acid bacteria, Enterobacteriaceae, moulds and yeasts), physical-chemical (pH, water activity, TBARS, acidity, L(∗)a(∗)b(∗) colour, texture profile analysis and shear force) and sensory (appearance, odour, flavour, texture and acceptance) parameters were determined. The results showed that sensory spoilage preceded microbiological spoilage of sous vide pork loin. Counts bellow 1logcfu/g of psychrotrophs, anaerobic psychrotrophs, Enterobacteriaceae and lactic acid bacteria were detected in any control week, while moderate counts (2-3logcfu/g) of moulds and yeasts were found. Minor changes in water activity, lipid oxidation, CIELab colour, hardness, cohesiveness or gumminess were associated with spoilage of pork loin, only decreases of lactic acid, springiness and shear force were observed. The pork loin was unacceptable after 10 weeks. This loss of acceptance was mainly due to the deterioration of meaty flavour and odour, although the loss of appearance, juiciness and firmness also contributed. Moderate warmed-over and rancidity were detected. The sensory analysis was the most effective method for determining the shelf life of the sous vide pork-based dishes.

  15. Activity of R(+) limonene on the maximum growth rate of fish spoilage organisms and related effects on shelf-life prolongation of fresh gilthead sea bream fillets.

    Science.gov (United States)

    Giarratana, Filippo; Muscolino, Daniele; Beninati, Chiara; Ziino, Graziella; Giuffrida, Alessandro; Panebianco, Antonio

    2016-11-21

    R(+)limonene (LMN) is the major aromatic compound in essential oils obtained from oranges, grapefruits, and lemons. The improvement of preservation techniques to reduce the growth and activity of spoilage microorganisms in foods is crucial to increase their shelf life and to reduce the losses due to spoilage. The aim of this work is to evaluate the effect of LMN on the shelf life of fish fillets. Its effectiveness was preliminarily investigated in vitro against 60 strains of Specific Spoilage Organisms (SSOs) and then on gilt-head sea bream fillets stored at 2±0.5°C for 15days under vacuum. LMN showed a good inhibitory effect against tested SSOs strains. On gilt-head sea bream fillets, LMN inhibited the growth SSOs effectively, and its use resulted in a shelf-life extension of ca. 6-9days of treated fillets, compared to the control samples. The LMN addition in Sparus aurata fillets giving a distinctive smell and like-lemon taste to fish fillets that resulted pleasant to panellists. Its use contributed to a considerable reduction of fish spoilage given that the fillets treated with LMN were still sensory acceptable after 15days of storage. LMN may be used as an effective antimicrobial system to reduce the microbial growth and to improve the shelf life of fresh gilt-head sea bream fillets.

  16. Global overview of the risk linked to the Bacillus cereus group in the egg product industry: identification of food safety and food spoilage markers.

    Science.gov (United States)

    Techer, C; Baron, F; Delbrassinne, L; Belaïd, R; Brunet, N; Gillard, A; Gonnet, F; Cochet, M-F; Grosset, N; Gautier, M; Andjelkovic, M; Lechevalier, V; Jan, S

    2014-05-01

    To evaluate the food safety and spoilage risks associated with psychrotrophic Bacillus cereus group bacteria for the egg product industry and to search for relevant risk markers. A collection of 68 psychrotrophic B. cereus group isolates, coming from pasteurized liquid whole egg products, was analysed through a principal component analysis (PCA) regarding their spoilage and food safety risk potentials. The principal component analysis showed a clear differentiation between two groups within the collection, one half of the isolates representing a safety risk and the other half a spoilage risk. Relevant risk markers were highlighted by PCA, that is (i) for the food safety risk, the presence of the specific 16S rDNA-1m genetic signature and the ability to grow at 43°C on solid medium and (ii) for the spoilage risk, the presence of the cspA genetic signature. This work represents a first step in the development of new diagnostic technologies for the assessment of the microbiological quality of foods likely to be contaminated with psychrotrophic B. cereus group bacteria. © 2014 The Society for Applied Microbiology.

  17. 冷却肉微生物腐败与冷链系统%Chilled meat microbial spoilage and chill chain system

    Institute of Scientific and Technical Information of China (English)

    金鑫; 周光宏; 徐幸莲

    2012-01-01

    冷却肉极易发生微生物腐败,温度是最关键的影响因素。冷链系统持续的低温能抑制微生物的生长繁殖,预防冷却肉腐败。本文简述了微生物代谢活动对冷却肉腐败的影响,重点将冷链系统分为加工冷链、运输冷链、销售冷链和家庭保藏四部分,分别从概念及存在的问题等方面加以阐述,并展望了其未来有待提高完善的地方。%Chilled meat highly prone to microbial spoilage,temperature seems to be the most important factor that influences the spoilage.Sustained low-temperature of chill chain can inhibit microbial growth and prevent chilled meat spoilage.The effect of microbial metabolism on chilled meat spoilage was briefly introduced.Attention was drawn to the chill chain system which divided into four parts of processing, transportation, retail and domestic storage,and separately discussed the concept and issues of each part. The advance of chilled meat were prosoected as well.

  18. The economic value of realized volatility

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Feunou, Bruno; Jacobs, Kris

    2014-01-01

    Many studies have documented that daily realized volatility estimates based on intraday returns provide volatility forecasts that are superior to forecasts constructed from daily returns only. We investigate whether these forecasting improvements translate into economic value added. To do so, we...... develop a new class of affine discrete-time option valuation models that use daily returns as well as realized volatility. We derive convenient closed-form option valuation formulas, and we assess the option valuation properties using Standard & Poor’s (S&P) 500 return and option data. We find...... that realized volatility reduces the pricing errors of the benchmark model significantly across moneyness, maturity, and volatility levels....

  19. Fungal metabolites with anticancer activity.

    Science.gov (United States)

    Evidente, Antonio; Kornienko, Alexander; Cimmino, Alessio; Andolfi, Anna; Lefranc, Florence; Mathieu, Véronique; Kiss, Robert

    2014-05-01

    Covering: 1964 to 2013. Natural products from bacteria and plants have played a leading role in cancer drug discovery resulting in a large number of clinically useful agents. In contrast, the investigations of fungal metabolites and their derivatives have not led to a clinical cancer drug in spite of significant research efforts revealing a large number of fungi-derived natural products with promising anticancer activity. Many of these natural products have displayed notable in vitro growth-inhibitory properties in human cancer cell lines and select compounds have been demonstrated to provide therapeutic benefits in mouse models of human cancer. Many of these compounds are expected to enter human clinical trials in the near future. The present review discusses the reported sources, structures and biochemical studies aimed at the elucidation of the anticancer potential of these promising fungal metabolites.

  20. Secondary metabolites from Eremostachys laciniata

    DEFF Research Database (Denmark)

    Calis, Ihsan; Güvenc, Aysegül; Armagan, Metin;

    2008-01-01

    From the aerial parts of Eremostachys laciniata (Lamiaceae), a new acidic iridoid glucoside, 5-desoxysesamosidic acid (1) was isolated in addition to thirteen known iridoid glucosides, 5-desoxysesamoside (2), sesamoside (3), 6β-hydroxy-7-epi-loganin (4), chlorotuberoside (5), 5-deoxypulchelloside...... elucidated from spectroscopic (UV, IR, 1D- and 2D-NMR) and ESI-MS evidence, as well as from their specific optical rotation. The presence of these metabolites of three different classes strongly supports the close relationship of the genera Eremostachys and Phlomis.......), and forsythoside B (18), and five flavone derivatives, luteolin (19), luteolin 7-O-β-D-glucopyranoside (20), luteolin 7-O-(6''-O-β-D-apiofuranosyl)-β-D-glucopyranoside (21), apigenin 7-O-β-D-glucopyranoside (22), and apigenin 7-O-(6''-O-p-coumaroyl)-β-D-glucopyranoside (23). The structures of the metabolites were...

  1. Presence of acylated homoserine lactones (AHLs) and AHL-producing bacteria in meat and potential role of AHL in spoilage of meat.

    Science.gov (United States)

    Bruhn, Jesper Bartholin; Christensen, Allan Beck; Flodgaard, Lars Ravn; Nielsen, Kristian Fog; Larsen, Thomas Ostenfeld; Givskov, Michael; Gram, Lone

    2004-07-01

    Quorum-sensing (QS) signals (N-acyl homoserine lactones [AHLs]) were extracted and detected from five commercially produced vacuum-packed meat samples. Ninety-six AHL-producing bacteria were isolated, and 92 were identified as Enterobacteriaceae. Hafnia alvei was the most commonly identified AHL-producing bacterium. Thin-layer chromatographic profiles of supernatants from six H. alvei isolates and of extracts from spoiling meat revealed that the major AHL species had an R(f) value and shape similar to N-3-oxo-hexanoyl homoserine lactone (OHHL). Liquid chromatography-mass spectrometry (MS) (high-resolution MS) analysis confirmed the presence of OHHL in pure cultures of H. alvei. Vacuum-packed meat spoiled at the same rate when inoculated with the H. alvei wild type compared to a corresponding AHL-lacking mutant. Addition of specific QS inhibitors to the AHL-producing H. alvei inoculated in meat or to naturally contaminated meat did not influence the spoilage of vacuum-packed meat. An extracellular protein of approximately 20 kDa produced by the H. alvei wild-type was not produced by the AHL-negative mutant but was restored in the mutant when complemented by OHHL, thus indicating that AHLs do have a regulatory role in H. alvei. Coinoculation of H. alvei wild-type with an AHL-deficient Serratia proteamaculans B5a, in which protease secretion is QS regulated, caused spoilage of liquid milk. By contrast, coinoculation of AHL-negative strains of H. alvei and S. proteamaculans B5a did not cause spoilage. In conclusion, AHL and AHL-producing bacteria are present in vacuum-packed meat during storage and spoilage, but AHL does not appear to influence the spoilage of this particular type of conserved meat. Our data indicate that AHL-producing H. alvei may induce food quality-relevant phenotypes in other bacterial species in the same environment. H. alvei may thus influence spoilage of food products in which Enterobacteriaceae participate in the spoilage process.

  2. Arbitrage and Volatility in Chinese Stock's Markets

    Science.gov (United States)

    Lu, Shu Quan; Ito, Takao; Zhang, Jianbo

    From the point of view of no-arbitrage pricing, what matters is how much volatility the stock has, for volatility measures the amount of profit that can be made from shorting stocks and purchasing options. With the short-sales constraints or in the absence of options, however, high volatility is likely to mean arbitrage from stock market. As emerging stock markets for China, investors are increasingly concerned about volatilities of Chinese two stock markets. We estimate volatility's models for Chinese stock markets' indexes using Markov chain Monte Carlo (MCMC) method and GARCH. We find that estimated values of volatility parameters are very high for all data frequencies. It suggests that stock returns are extremely volatile even at long term intervals in Chinese markets. Furthermore, this result could be considered that there seems to be arbitrage opportunities in Chinese stock markets.

  3. Forecasting volatility of crude oil markets

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sang Hoon [Department of Business Administration, Gyeongsang National University, Jinju, 660-701 (Korea); Kang, Sang-Mok; Yoon, Seong-Min [Department of Economics, Pusan National University, Busan, 609-735 (Korea)

    2009-01-15

    This article investigates the efficacy of a volatility model for three crude oil markets - Brent, Dubai, and West Texas Intermediate (WTI) - with regard to its ability to forecast and identify volatility stylized facts, in particular volatility persistence or long memory. In this context, we assess persistence in the volatility of the three crude oil prices using conditional volatility models. The CGARCH and FIGARCH models are better equipped to capture persistence than are the GARCH and IGARCH models. The CGARCH and FIGARCH models also provide superior performance in out-of-sample volatility forecasts. We conclude that the CGARCH and FIGARCH models are useful for modeling and forecasting persistence in the volatility of crude oil prices. (author)

  4. Chirospecific analysis of plant volatiles

    Energy Technology Data Exchange (ETDEWEB)

    Tkachev, A V [N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-10-31

    Characteristic features of the analysis of plant volatiles by enantioselective gas (gas-liquid) chromatography and gas chromatography/mass spectrometry are discussed. The most recent advances in the design of enantioselective stationary phases are surveyed. Examples of the preparation of the most efficient phases based on modified cyclodextrins are given. Current knowledge on the successful analytical resolution of different types of plant volatiles (aliphatic and aromatic compounds and mono-, sesqui- and diterpene derivatives) into optical antipodes is systematically described. Chiral stationary phases used for these purposes, temperature conditions and enantiomer separation factors are summarised. Examples of the enantiomeric resolution of fragrance compounds and components of plant extracts, wines and essential oils are given.

  5. Chirospecific analysis of plant volatiles

    Science.gov (United States)

    Tkachev, A. V.

    2007-10-01

    Characteristic features of the analysis of plant volatiles by enantioselective gas (gas-liquid) chromatography and gas chromatography/mass spectrometry are discussed. The most recent advances in the design of enantioselective stationary phases are surveyed. Examples of the preparation of the most efficient phases based on modified cyclodextrins are given. Current knowledge on the successful analytical resolution of different types of plant volatiles (aliphatic and aromatic compounds and mono-, sesqui- and diterpene derivatives) into optical antipodes is systematically described. Chiral stationary phases used for these purposes, temperature conditions and enantiomer separation factors are summarised. Examples of the enantiomeric resolution of fragrance compounds and components of plant extracts, wines and essential oils are given.

  6. Compost stability assessment using a secondary metabolite: geosmin.

    Science.gov (United States)

    Li, H F; Imai, T; Ukita, M; Sekine, M; Higuchi, T

    2004-11-01

    Composting is a process involved not only in transformation of organic matter (OM), but also for transition of the microbial community. Microorganisms can directly provide important information on the stages and characteristics of composting. This paper was aimed at characterizing compost stability by a microbial secondary metabolite, geosmin, which is a volatile compound presenting an earthy smell. Since secondary metabolite production is dependent on the nutrient state of microorganisms, its production in association with physical and chemical parameters was monitored in the laboratory-scale and plant-scale composting processes. The results showed that the peaked geosmin liberation was consistent with stable state of composting indicated by the ambient temperature achieved, a slightly alkaline product and steady states of dissolved organic carbon (DOC), N and P contents and OM degradation in the laboratory-scale experiment. It was also in accordance with the stability identified by the facilities and CO2 respiration rate in the plant-scale composting. In addition, the production of geosmin was correlated with the C/N ratio for the solid sample. These results demonstrated that geosmin levels could be used as an index for the compost stability assessment in different composting processes with various organic solid wastes.

  7. Secondary Metabolites from Leaves of Manilkara subsericea (Mart.) Dubard

    Science.gov (United States)

    de Almeida, Fernanda Borges; Fernandes, Caio Pinho; Romao, Wanderson; Vanini, Gabriela; Costa, Helber Barcelos; França, Hildegardo Seibert; Santos, Marcelo Guerra; Carvalho, José Carlos Tavares; Falcão, Deborah Quintanilha; Rocha, Leandro

    2015-01-01

    Background: Manilkara subsericea (Sapotaceae) is a species widely spread in the sandbanks of Restinga de Jurubatiba National Park (Rio de Janeiro, Brazil). It is commonly known as “maçaranduba”, “maçarandubinha” and “guracica”, being used in this locality as food, and timber. However, M. subsericea remains almost unexplored regarding its chemical constituents, including secondary metabolites from the leaves. Objective: Identify the chemical constituents from the leaves of M. subsericea. Materials and Methods: Leaves were macerated with ethanol (96% v/v), and dried crude ethanolic extract was sequentially washed with the organic solvents in order to obtain an ethyl acetate fraction. Substances from this fraction were identified by different techniques, such as negative-ion electrospray ionization Fourier and 1H and 13C nuclear magnetic resonance (NMR). Fresh leaves from M. subsericea were also submitted to hydrodistillation in order to obtain volatile substances, which were identified by gas chromatograph coupled to mass spectrometer. Results: NMR1H and 13C spectra allowed for the identification of the compounds myricetin, quercetin, and kaempferol from the ethyl acetate fraction. The negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry mass spectrum also revealed the presence in this fraction of a polyhydroxytriterpene acid (pomolic acid), and some flavonoids, such as quercitrin, and myricitrin. In all 34 volatile compounds were identified by gas chromatography-mass spectrometry, including monoterpenes, sesquiterpenes, and long chain hydrocarbons. Conclusion: This study describes the first reports concerning the phytochemical information about leaves from M. subsericea. SUMMARY Manilkara subsericea fruits proved to be a rich source of triterpenes. However, no phytochemical studies were carried out with leaves. Thus, we described identification of volatile substances from its essential oils, in addition to

  8. Volatiles in Inter-Specific Bacterial Interactions.

    Science.gov (United States)

    Tyc, Olaf; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well-described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium, and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal, and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide) were tested for their effect on three target bacteria. Here, we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  9. Volatiles in inter-specific bacterial interactions

    Directory of Open Access Journals (Sweden)

    Olaf eTyc

    2015-12-01

    Full Text Available The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide were tested for their effect on three target bacteria. Here we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  10. Money, banks and endogenous volatility

    OpenAIRE

    Pere Gomis-Porqueras

    2000-01-01

    In this paper I consider a monetary growth model in which banks provide liquidity, and the government fixes a constant rate of money creation. There are two underlying assets in the economy, money and capital. Money is dominated in rate of return. In contrast to other papers with a larger set of government liabilities, I find a unique equilibrium when agents' risk aversion is moderate. However, indeterminacies and endogenous volatility can be observed when agents are relatively risk averse.

  11. Volatility at Karachi Stock Exchange

    OpenAIRE

    Aslam Farid; Javed Ashraf

    1995-01-01

    Frequent “crashes” of the stock market reported during the year 1994 suggest that the Karachi bourse is rapidly converting into a volatile market. This cannot be viewed as a positive sign for this developing market of South Asia. Though heavy fluctuations in stock prices are not an unusual phenomena and it has been observed at almost all big and small exchanges of the world. Focusing on the reasons for such fluctuations is instructive and likely to have important policy implications. Proponen...

  12. Inhibition of biofilm development and spoilage potential of Shewanella baltica by quorum sensing signal in cell-free supernatant from Pseudomonas fluorescens.

    Science.gov (United States)

    Zhao, Aifei; Zhu, Junli; Ye, Xiaofeng; Ge, Yangyang; Li, Jianrong

    2016-08-02

    The objective of this study was to in vitro evaluate the effect of a cell-free supernatant (CFS) containing quorum sensing (QS) signal of Pseudomonas fluorescens on the growth, biofilm development and spoilage potential of Shewanella baltica, and preliminarily assess the interactive influences of various chemically synthesized autoinducers on spoilage phenotypes of S. baltica. PF01 strain isolated from spoiled Pseudosciaen crocea was identified P. fluorescens. The addition of 25% and 50% CFS to S. baltica culture had no effect on the growth rate during the lag and exponential phase, however, caused cell decline during the stationary phase. The presence of CFS from P. fluorescens significantly inhibited biofilm development, and greatly decreased the production of trimethylamine (TMA) and biogenic amino in S. baltica. Various signal molecules of QS in the CFS of P. fluorescens culture were detected, including seven N-acyl-l-homoserine lactones (AHLs), autoinducer-2 (AI-2) and two diketopiperazines (DKPs). Exogenous supplement of synthesized seven AHLs containing in the CFS decreased biofilm formation and TMA production in S. baltica, while exposure to exogenous cyclo-(l-Pro-l-Leu) was showed to promote spoilage potential, which revealed that S. baltica also sense the two QS molecules. Furthermore, the stimulating effect of cyclo-(l-Pro-l-Leu) was affected when AHL was simultaneously added, suggesting that the inhibitory activity of spoilage phenotypes in S. baltica might be attributed to a competitive effect of these QS compounds in the CFS of P. fluorescens. The present studies provide a good basis for future research on the role of QS in the regulation of spoilage microbial flora.

  13. Modelling spoilage of fresh turbot and evaluation of a time-temperature integrator (TTI) label under fluctuating temperature.

    Science.gov (United States)

    Nuin, Maider; Alfaro, Begoña; Cruz, Ziortza; Argarate, Nerea; George, Susie; Le Marc, Yvan; Olley, June; Pin, Carmen

    2008-10-31

    Kinetic models were developed to predict the microbial spoilage and the sensory quality of fresh fish and to evaluate the efficiency of a commercial time-temperature integrator (TTI) label, Fresh Check(R), to monitor shelf life. Farmed turbot (Psetta maxima) samples were packaged in PVC film and stored at 0, 5, 10 and 15 degrees C. Microbial growth and sensory attributes were monitored at regular time intervals. The response of the Fresh Check device was measured at the same temperatures during the storage period. The sensory perception was quantified according to a global sensory indicator obtained by principal component analysis as well as to the Quality Index Method, QIM, as described by Rahman and Olley [Rahman, H.A., Olley, J., 1984. Assessment of sensory techniques for quality assessment of Australian fish. CSIRO Tasmanian Regional Laboratory. Occasional paper n. 8. Available from the Australian Maritime College library. Newnham. Tasmania]. Both methods were found equally valid to monitor the loss of sensory quality. The maximum specific growth rate of spoilage bacteria, the rate of change of the sensory indicators and the rate of change of the colour measurements of the TTI label were modelled as a function of temperature. The temperature had a similar effect on the bacteria, sensory and Fresh Check kinetics. At the time of sensory rejection, the bacterial load was ca. 10(5)-10(6) cfu/g. The end of shelf life indicated by the Fresh Check label was close to the sensory rejection time. The performance of the models was validated under fluctuating temperature conditions by comparing the predicted and measured values for all microbial, sensory and TTI responses. The models have been implemented in a Visual Basic add-in for Excel called "Fish Shelf Life Prediction (FSLP)". This program predicts sensory acceptability and growth of spoilage bacteria in fish and the response of the TTI at constant and fluctuating temperature conditions. The program is freely

  14. Applicability of a microbial Time Temperature Indicator (TTI) for monitoring spoilage of modified atmosphere packed minced meat.

    Science.gov (United States)

    Vaikousi, Hariklia; Biliaderis, Costas G; Koutsoumanis, Konstantinos P

    2009-08-15

    The applicability of a microbial Time Temperature Indicator (TTI) prototype, based on the growth and metabolic activity of a Lactobacillus sakei strain developed in a previous study, in monitoring quality of modified atmosphere packed (MAP) minced beef was evaluated at conditions simulating the chill chain. At all storage temperatures examined (0, 5, 10, 15 degrees C), the results showed that lactic acid bacteria (LAB) were the dominant bacteria and can be used as a good spoilage index of MAP minced beef. The end of product's shelf life as revealed by the sensory evaluation coincided with a LAB population level of 7 log(10) CFU/g. For all temperatures tested, the growth of L. sakei in the TTI resembled closely the growth of LAB in the meat product, with similar temperature dependence of the micro(max) and thus similar activation energy values calculated as 111.90 and 106.90 kJ/mol, for the two systems, respectively. In addition, the end point of TTI colour change coincided with the time of sensory rejection point of the beef product during its storage under isothermal chilled temperature conditions. The estimated activation energy, E(alpha), values obtained for parameters related to the response of DeltaE (total colour change of the TTI) describing the kinetics of colour change of the TTI during isothermal storage (i.e. the maximum specific rate of DeltaEpsilon evolution curve, micro(DeltaEpsilon), and also the reciprocal of t(i), time at which half of the maximum DeltaEpsilon is reached), were 112.77 and 127.28 kJ/mol, respectively. Finally, the application of the microbial TTI in monitoring the quality deterioration of MAP minced beef due to spoilage was further evaluated under dynamic conditions of storage, using two separate low temperature periodic changing scenarios, resembling the actual conditions occurring in the distribution chill chain. The results showed that the end point of TTI, after storage at those fluctuating temperature conditions, was noted very

  15. Human skin volatiles: a review.

    Science.gov (United States)

    Dormont, Laurent; Bessière, Jean-Marie; Cohuet, Anna

    2013-05-01

    Odors emitted by human skin are of great interest to biologists in many fields; applications range from forensic studies to diagnostic tools, the design of perfumes and deodorants, and the ecology of blood-sucking insect vectors of human disease. Numerous studies have investigated the chemical composition of skin odors, and various sampling methods have been used for this purpose. The literature shows that the chemical profile of skin volatiles varies greatly among studies, and the use of different sampling procedures is probably responsible for some of these variations. To our knowledge, this is the first review focused on human skin volatile compounds. We detail the different sampling techniques, each with its own set of advantages and disadvantages, which have been used for the collection of skin odors from different parts of the human body. We present the main skin volatile compounds found in these studies, with particular emphasis on the most frequently studied body regions, axillae, hands, and feet. We propose future directions for promising experimental studies on odors from human skin, particularly in relation to the chemical ecology of blood-sucking insects.

  16. Volatile and non-volatile/semi-volatile compounds and in vitro bioactive properties of Chilean Ulmo (Eucryphia cordifolia Cav.) honey.

    Science.gov (United States)

    Acevedo, Francisca; Torres, Paulina; Oomah, B Dave; de Alencar, Severino Matias; Massarioli, Adna Prado; Martín-Venegas, Raquel; Albarral-Ávila, Vicenta; Burgos-Díaz, César; Ferrer, Ruth; Rubilar, Mónica

    2017-04-01

    Ulmo honey originating from Eucryphia cordifolia tree, known locally in the Araucania region as the Ulmo tree is a natural product with valuable nutritional and medicinal qualities. It has been used in the Mapuche culture to treat infections. This study aimed to identify the volatile and non-volatile/semi-volatile compounds of Ulmo honey and elucidate its in vitro biological properties by evaluating its antioxidant, antibacterial, antiproliferative and hemolytic properties and cytotoxicity in Caco-2 cells. Headspace volatiles of Ulmo honey were isolated by solid-phase microextraction (SPME); non-volatiles/semi-volatiles were obtained by removing all saccharides with acidified water and the compounds were identified by GC/MS analysis. Ulmo honey volatiles consisted of 50 compounds predominated by 20 flavor components. Two of the volatile compounds, lyrame and anethol have never been reported before as honey compounds. The non-volatile/semi-volatile components of Ulmo honey comprised 27 compounds including 13 benzene derivatives accounting 75% of the total peak area. Ulmo honey exhibited weak antioxidant activity but strong antibacterial activity particularly against gram-negative bacteria and methicillin-resistant Staphylococcus aureus (MRSA), the main strain involved in wounds and skin infections. At concentrations >0.5%, Ulmo honey reduced Caco-2 cell viability, released lactate dehydrogenase (LDH) and increased reactive oxygen species (ROS) production in a dose dependent manner in the presence of foetal bovine serum (FBS). The wide array of volatile and non-volatile/semi-volatile constituents of Ulmo honey rich in benzene derivatives may partly account for its strong antibacterial and antiproliferative properties important for its therapeutic use. Our results indicate that Ulmo honey can potentially inhibit cancer growth at least partly by modulating oxidative stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Metabolite

    Science.gov (United States)

    Kumar V, Abbas AK, Aster JC. Cellular responses to stress and toxic insults: Adaptation, injury, and death. In: Kumar V, Abbas AK, Aster JC, eds. Robbins and Cotran Pathologic Basis of Disease . 9th ed. Philadelphia, PA: ...

  18. An isotope dilution gas chromatography/mass spectrometry method for trace analysis of xylene and its metabolites in tissues following threshold limit value exposures

    Energy Technology Data Exchange (ETDEWEB)

    Pyon, K.H.; Kracko, D.A.; Strunk, M.R. [and others

    1995-12-01

    The existence of a nose-brain barrier that functions to protect the central nervous system (CNS) from inhaled toxicants has been postulated. Just as a blood-brain barrier protects the CNS from systemic toxicants, the nose-brain barrier may have similar characteristic functions. One component of interest is nasal xenobiotic metabolism and its effect on the transport of pollutants into the CNS at environmentally plausible levels of exposure. Previous results have shown that inhaled xylene are dimethyl phenol (DMP) and methyl benzyl alcohol (MBA), and the nonvolatile metabolites are toluic acid (TA) and methyl hippuric acid (MHA). The nonvolatile metabolites of xylene, along with a small quantity of volatiles, representing either parent xylene or volatile metabolites, are transported via the olfactory epithelium to the glomeruli within the olfactory bulbs of the brain. Further work will be done to establish the linearity for each analyte at the actual highest detection limit of the GC/MS.

  19. Isolation of lactic acid bacteria with inhibitory activity against pathogens and spoilage organisms associated with fresh meat.

    Science.gov (United States)

    Jones, Rhys J; Hussein, Hassan M; Zagorec, Monique; Brightwell, Gale; Tagg, John R

    2008-04-01

    The use of lactic acid bacteria (LAB) as protective cultures in vacuum-packed chill-stored meat has potential application for assuring and improving food quality, safety and market access. In a study to identify candidate strains suitable for evaluation in a meat model, agar-based methods were employed to screen 181 chilled meat and meat process-related LAB for strains inhibitory to pathogens and spoilage organisms of importance to the meat industry. Six meat-derived strains, including Lactobacillus sakei and Lactococcus lactis, were found to be inhibitory to one or more of the target strains Listeria monocytogenes, Brochothrix thermosphacta, Campylobacter jejuni and Clostridium estertheticum. The inhibitory agents appeared to be either cell-associated or molecules released extracellularly with bacteriocin-like properties. Variations detected in the antimicrobial activity of LAB associated with changes to test parameters such as substrate composition underlined the importance of further in situ evaluation of the inhibitory strains in stored meat trials.

  20. Interaction between fish spoilage bacteria Pseudomonas sp and Shewanella putrefaciens in fish extracts and on fish tissue

    DEFF Research Database (Denmark)

    Gram, Lone; Melchiorsen, Jette

    1996-01-01

    The interaction between fish spoilage bacteria, Pseudomonas sp. and Shewanella putrefaciens, was investigated using fish extract and fish tissue as model systems. Isolates of Pseudomonas that produced iron chelators, siderophores, inhibited growth of S. putrefaciens in a fish-extract-agar diffusion...... assay but no, or only weak, antagonistic activity was seen when the medium was supplemented with iran. Sterile- filtered supernatant fluid from a siderophore-producing Pseudomonas grown in fish extract was inhibitory to S. putrefaciens if the number of Pseudomonas was above 10(8) cfu ml(-1). In contrast......, supernatant fluids from siderophore- negative Pseudomonas isolates did not inhibit growth of S. putrefaciens. The inhibitory effect was, except for one strain of Pseudomonas, not seen in supernatant fluids from iron- enriched cultures of Pseudomonas sp. Finally, siderophore- producing Pseudomonas sp. lowered...