Farmers Market Brings Fresh Produce and Products from Local Vendors | Poster

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By Carolynne Keenan, Guest Writer Every summer, you can shop for fresh fruits, veggies, flowers, honey, and plenty of other homemade goodies at the NCI at Frederick Farmers’ Market. Buying at the Farmers’ Market means you’re supporting a local farmer, crafter, or other type of vendor. The products are brought to you, so you don’t have to drive to get freshly picked produce and

A Comparative Study of Natural Antimicrobial Delivery Systems for Microbial Safety and Quality of Fresh-Cut Lettuce.

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Hill, Laura E; Oliveira, Daniela A; Hills, Katherine; Giacobassi, Cassie; Johnson, Jecori; Summerlin, Harvey; Taylor, T Matthew; Gomes, Carmen L

2017-05-01

Nanoencapsulation can provide a means to effectively deliver antimicrobial compounds and enhance the safety of fresh produce. However, to date there are no studies which directly compares how different nanoencapsulation systems affect fresh produce safety and quality. This study compared the effects on quality and safety of fresh-cut lettuce treated with free and nanoencapsulated natural antimicrobial, cinnamon bark extract (CBE). A challenge study compared antimicrobial efficacy of 3 different nanoencapsulated CBE systems. The most effective antimicrobial treatment against Listeria monocytogenes was chitosan-co-poly-N-isopropylacrylamide (chitosan-PNIPAAM) encapsulated CBE, with a reduction on bacterial load up to 2 log 10 CFU/g (P lettuce was stored at 5 °C and 10 °C for 15 d. Subsequently, chitosan-PNIPAAM-CBE nanoparticles (20, 40, and 80 mg/mL) were compared to a control and free CBE (400, 800, and 1600 μg/mL) for its effects on fresh-cut lettuce quality over 15 d at 5 °C. By the 10th day, the most effective antimicrobial concentration was 80 mg/mL for chitosan-PNIPAAM-CBE, up to 2 log 10 CFU/g reduction (P lettuce shelf-life. Overall, nanoencapsulation provided a method to effectively deliver essential oil and enhanced produce safety, while creating little to no detrimental quality changes on the fresh-cut lettuce. © 2017 Institute of Food Technologists®.

Discrimination methods for biological contaminants in fresh-cut lettuce based on VNIR and NIR hyperspectral imaging

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Mo, Changyeun; Kim, Giyoung; Kim, Moon S.; Lim, Jongguk; Lee, Seung Hyun; Lee, Hong-Seok; Cho, Byoung-Kwan

2017-09-01

The rapid detection of biological contaminants such as worms in fresh-cut vegetables is necessary to improve the efficiency of visual inspections carried out by workers. Multispectral imaging algorithms were developed using visible-near-infrared (VNIR) and near-infrared (NIR) hyperspectral imaging (HSI) techniques to detect worms in fresh-cut lettuce. The optimal wavebands that can detect worms in fresh-cut lettuce were investigated for each type of HSI using one-way ANOVA. Worm-detection imaging algorithms for VNIR and NIR imaging exhibited prediction accuracies of 97.00% (RI547/945) and 100.0% (RI1064/1176, SI1064-1176, RSI-I(1064-1173)/1064, and RSI-II(1064-1176)/(1064+1176)), respectively. The two HSI techniques revealed that spectral images with a pixel size of 1 × 1 mm or 2 × 2 mm had the best classification accuracy for worms. The results demonstrate that hyperspectral reflectance imaging techniques have the potential to detect worms in fresh-cut lettuce. Future research relating to this work will focus on a real-time sorting system for lettuce that can simultaneously detect various defects such as browning, worms, and slugs.

Lytic bacteriophages reduce Escherichia coli O157: H7 on fresh cut lettuce introduced through cross-contamination.

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Ferguson, Sean; Roberts, Cheryl; Handy, Eric; Sharma, Manan

2013-01-01

The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli O157:H7 (4.10 CFU/cm 2 ) following exposure to 50 μg/ml chlorine for 30 sec. After immersion studies, lettuce was spot-inoculated with E. coli O157:H7 (2.38 CFU/cm 2 ). Phage-treated, inoculated lettuce pieces were stored at 4°C for and analyzed for E. coli O157:H7 populations for up to 7 d. Immersion of lettuce in 9.8 log PFU/ml EcoShield™ for 2 min significantly (p PFU/ml) resulted in the deposition of high concentrations (7.8 log log PFU/cm 2 ) of bacteriophages on the surface of fresh cut lettuce, potentially contributing to the efficacy of the lytic phages on lettuce. Spraying phages on to inoculated fresh cut lettuce after being washed in hypochlorite solution was significantly more effective in reducing E. coli O157:H7 populations (2.22 log CFU/cm 2 ) on day 0 compared with control treatments (4.10 log CFU/cm 2 ). Both immersion and spray treatments provided protection from E. coli O157:H7 contamination on lettuce, but spray application of lytic bacteriophages to lettuce was more effective in immediately reducing E. coli O157:H7 populations fresh cut lettuce.

CONSUMER ATTITUDES TOWARD ORGANICALLY GROWN LETTUCE

OpenAIRE

Wolf, Marianne McGarry; Johnson, Bradey; Cochran, Kerry; Hamilton, Lynn L.

2002-01-01

This research shows that approximately 29 percent of lettuce purchases in California expect to purchase an organically grown lettuce product in the future. Organic lettuce purchasers are more likely to be female, have a higher household income and a higher level of education. Consumers are concerned with the freshness, quality, price, and environmental impact of the lettuce they purchase.

Effect of processing on the disappearance of pesticide residues in fresh-cut lettuce: Bioavailability and dietary risk.

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Camara, Miguel A; Barba, Alberto; Cermeño, Sandra; Martinez, Gracia; Oliva, Jose

2017-12-02

The aim of this research is to establish the processing factors of six pesticides durong the preparation of fresh-cut lettuce and to assess the risk of ingestion of pesticide residues associated with the consumption of the same. A field study was carried out on the dissipation of three insecticides (imidacloprid, tebufenozide, cypermethrin) and three fungicides (metalaxyl, tebuconazole, azoxystrobin) during treatment conditions simulating those used for commercial fresh-cut lettuce. A simultaneous residue analysis method is validated using QuEChERS extraction with acetonitrile and CG-MS and LC-MS/MS analysis. The residues detected after field application never exceed the established Maximum Residue Limits. The processing factors were generally less than 1 (between 0.34 for tebufenozide and 0.53 for imidacloprid), indicating that the process, as a whole, considerably reduces residue levels in processed lettuce compared to fresh lettuce. It is confirmed that cutting, followed by washing and drying, considerably reduces the residues. A matrix effect in the dialyzation of the pesticides is observed and the in vitro study of bioavailability establishes a low percentage of stomach absorption capacity (lettuce showed no concerns for consumer health.

Production system and harvesting stage influence on nitrate content and quality of butterhead lettuce

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Siti Fairuz Yosoff

2015-01-01

Full Text Available Leafy vegetables such as lettuce grown under different production systems may accumulate different concentrations of nitrate which may reach to the levels potentially toxic to humans. Moreover, nitrate accumulation varies in various plant parts and physiological age of the plant. Therefore, to determine the effect of production system and harvesting stage on nitrate accumulation and quality of butterhead lettuce, a study was conducted considering two lettuce production systems namely hydroponic and organic, and four different harvesting stages such as 35, 38, 41 and 44 days after transplanting (DAT. The experimental design was complete randomized design (CRD with four replications. Hydroponic and organic systems performed similar in terms of yield, quality and nitrate content of butterhead lettuce. Delaying harvesting can not only increase yield but also can minimize nitrate accumulation and health hazard risk as well. Delay in harvesting stage may result in quality deterioration of lettuce and increased production cost. Thus, a compromise is necessary to consider 41 DAT as the optimum stage to harvest butterhead lettuce with significantly higher reduction of nitrate content in both outer adult leaf blades and young leaves of hydroponic lettuce. Fresh weight, firmness and color of butterhead lettuce at this stage were still acceptable.

Effects of pre-and postharvest lighting on quality and shelf life of fresh-cut lettuce

NARCIS (Netherlands)

Woltering, E.J.; Witkowska, I.M.

2016-01-01

The effects of pre-and postharvest lighting on quality and shelf life of fresh-cut lettuce was investigated. Lettuce was grown under different light intensities (120 and 250 μmol m^-2 s^-1 PAR from fluorescent tubes) and quality at harvest and subsequent postharvest

Omics approaches on fresh-cut lettuce reveal global molecular responses to sodium hypochlorite and peracetic acid treatment.

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Daddiego, Loretta; Bianco, Linda; Capodicasa, Cristina; Carbone, Fabrizio; Dalmastri, Claudia; Daroda, Lorenza; Del Fiore, Antonella; De Rossi, Patrizia; Di Carli, Mariasole; Donini, Marcello; Lopez, Loredana; Mengoni, Alessio; Paganin, Patrizia; Perrotta, Gaetano; Bevivino, Annamaria

2018-01-01

Lettuce is a leafy vegetable that is extensively commercialized as a ready-to-eat product because of its widespread use in human nutrition as salad. It is well known that washing treatments can severely affect the quality and shelf-life of ready-to-eat vegetables. The study presented here evaluated the effect of two washing procedures on fresh-cut lettuce during storage. An omics approach was applied to reveal global changes at molecular level induced by peracetic acid washing in comparison with sodium hypochlorite treatment. Microbiological analyses were also performed to quantify total bacterial abundance and composition. The study revealed wide metabolic alterations induced by the two sanitizers. In particular, transcriptomic and proteomic analyses pointed out a number of transcripts and proteins differentially accumulated in response to peracetic acid washing, mainly occurring on the first day of storage. In parallel, different microbiota composition and significant reduction in total bacterial load following washing were also observed. The results provide useful information for the fresh-cut industry to select an appropriate washing procedure preserving fresh-like attributes as much as possible during storage of the end product. Molecular evidence indicated peracetic acid to be a valid alternative to sodium hypochlorite as sanitizer solution. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Potentials for export of fresh raspberries from Serbia to EU fresh markets

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Nikolić Ivan

2012-12-01

Full Text Available The aim of this paper is to present potentials of the most significant EU national markets for imports of fresh raspberries from Serbia. We carried out analysis of three markets with highest trade deficit of fresh raspberries expressed in quantities: Germany, Netherlands and Austria. The paper further analyses production and foreign trade trends in selected countries. According to results of this analysis, we identified monthly periods with highest potential for exports of fresh raspberries from Serbia to target markets. The paper also analyses wholesale prices of fresh raspberries and EU policy of direct support to raspberry producers.

Efficacy of chlorine dioxide on Escherichia coli inactivation during pilot-scale fresh-cut lettuce processing.

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Banach, J L; van Overbeek, L S; Nierop Groot, M N; van der Zouwen, P S; van der Fels-Klerx, H J

2018-03-23

Controlling water quality is critical in preventing cross-contamination during fresh produce washing. Process wash water (PWW) quality can be controlled by implementing chemical disinfection strategies. The aim of this study was to evaluate the pilot-scale efficacy of chlorine dioxide (ClO 2 ) during processing on the reduction of Escherichia coli in the PWW and on processed fresh-cut 'Lollo Rossa' lettuce. The objective was to have a residual target concentration of either 5 or 3 mg/L ClO 2 in the washing tank (3.5 m 3 ) before and during 800 kg of lettuce processing (90 min). After 90 min., a nonpathogenic, non-Extended Spectrum Beta-Lactamase (ESBL) E. coli inoculum from an overnight culture broth (37 °C) was added to the tank resulting in an approximate final level of 10 6  CFU/mL. PWW and lettuce samples for microbiological and chemical analyses were taken before and after the input and supply halted. ClO 2 concentrations quickly decreased after ClO 2 input halted, yet a residual concentration of ≥2.5 mg/L and ≥2.1 mg/L ClO 2 , respectively for 5 and 3 mg/L pilots, was present 12 min after the supply halted. No detectable levels of E. coli (limit of detection 5 log) were determined in the water within 1 min after E. coli was added to the ClO 2 containing wash water. Results demonstrated that ClO 2 use at the semi-commercial pilot scale was able to reduce the E. coli peak contamination in the PWW. After storage (5 days, 4 °C), background microbial communities (i.e., fluorescent Pseudomonads and total heterotrophic bacteria) grew out on lettuce. Overall, ClO 2 decreased the potential for cross-contamination between batches compared to when no sanitizer was used. Chlorate levels of the lettuce sampled before entering the wash water ranged from 7.3-11.6 μg/kg. The chlorate levels of the lettuce sampled after being washed in the ClO 2 containing wash water, as well as after rinsing and centrifugation, ranged from 22.8-60.4�

Produção comercial de cultivares de alface em Bananeiras Marketable production of lettuce cultivars in Bananeiras, Brazil

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Djail Santos

2011-12-01

Full Text Available Um aspecto importante na escolha de cultivares para uma determinada condição ambiental é a determinação da produção comercial, que indica o potencial de produção por área. O objetivo do trabalho foi avaliar a produção comercial de cultivares de alface nas condições de solo e clima de Bananeiras, Paraíba, durante a estação chuvosa. Foram avaliadas oito cultivares (Cindy, Elba, Grand Rapids, Kaesar, Mimosa, Sabrina, Summer Green e Verônica, no delineamento experimental de blocos casualizados, com quatro repetições. As parcelas tinham 27 plantas, espaçadas de 30 cm entre fileiras e entre linhas. Aos 51 dias após o transplante, as plantas foram colhidas e avaliadas quanto à massa fresca total e comercial, massa seca de folhas, número de folhas, diâmetro da planta, índice comercial e produção comercial. Os maiores valores de massa fresca total e comercial, de diâmetro da planta e produção comercial foram verificados para a cultivar Kaesar. Quanto à massa seca, 'Kaesar' e 'Elba' apresentaram os valores mais elevados. Os maiores números de folha foram obtidos com 'Mimosa', 'Elba', 'Sabrina' e 'Summer Green'. As cultivares Grand Rapids, Verônica e Kaesar mostraram-se mais suscetíveis à septoriose, principalmente nas folhas mais velhas. Considerando-se os resultados e a preferência dos consumidores, 'Kaesar' e 'Summer Green' foram as mais promissoras para introdução e testes em áreas de produção comercial de alface.An important issue when choosing cultivars for specific environmental conditions is to estimate the marketable production, which indicates the potential production per area. The objective of this study was to evaluate the marketable production of lettuce cultivars under the soil and climatic conditions of Bananeiras, Paraíba, Brazil, during the rainy season. The experiment was carried out as a complete randomized blocks design with eight cultivars (Cindy, Elba, Grand Rapids, Kaesar, Mimosa, Sabrina

Microbial Profile of Soil-Free versus In-Soil Grown Lettuce and Intervention Methodologies to Combat Pathogen Surrogates and Spoilage Microorganisms on Lettuce

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Sujata A. Sirsat

2013-11-01

Full Text Available Aquaponics is an effective method to practice sustainable agriculture and is gaining popularity in the US; however, the microbial safety of aquaponically grown produce needs to be ascertained. Aquaponics is a unique marriage of fish production and soil-free produce (e.g., leafy greens production. Fish are raised in fresh water tanks that are connected to water filled beds where fruits and vegetables are grown. The fish bi-products create nutrient-rich water that provides the key elements for the growth of plants and vegetables. The objective of this study was to perform a comparative analysis of the microbial safety and quality of aquaponic lettuce and soil grown lettuce (conventional, bagged, certified organic, and field lettuce. Following this, an intervention study was performed to combat foodborne pathogen surrogates (Salmonella and E. coli, spoilage, and fecal microorganisms using 2.5% acetic acid. The results of the comparative analysis study showed that aquaponically grown lettuce had significantly lower concentration of spoilage and fecal microorganisms compared to in-soil grown lettuce. The intervention study showed that diluted vinegar (2.5% acetic acid significantly reduced Salmonella, E. coli, coliforms, and spoilage microorganisms on fresh lettuce by 2 to 3 log CFU/g. Irrespective of growing methods (in-soil or soilless, it is crucial to incorporate good agricultural practices to reduce microbial contamination on fresh produce. The intervention employed in this study can be proposed to small farmers and consumers to improve quality and safety of leafy greens.

Microbial Profile of Soil-Free versus In-Soil Grown Lettuce and Intervention Methodologies to Combat Pathogen Surrogates and Spoilage Microorganisms on Lettuce.

Science.gov (United States)

Sirsat, Sujata A; Neal, Jack A

2013-11-11

Aquaponics is an effective method to practice sustainable agriculture and is gaining popularity in the US; however, the microbial safety of aquaponically grown produce needs to be ascertained. Aquaponics is a unique marriage of fish production and soil-free produce (e.g., leafy greens) production. Fish are raised in fresh water tanks that are connected to water filled beds where fruits and vegetables are grown. The fish bi-products create nutrient-rich water that provides the key elements for the growth of plants and vegetables. The objective of this study was to perform a comparative analysis of the microbial safety and quality of aquaponic lettuce and soil grown lettuce (conventional, bagged, certified organic, and field lettuce). Following this, an intervention study was performed to combat foodborne pathogen surrogates ( Salmonella and E. coli ), spoilage, and fecal microorganisms using 2.5% acetic acid. The results of the comparative analysis study showed that aquaponically grown lettuce had significantly lower concentration of spoilage and fecal microorganisms compared to in-soil grown lettuce. The intervention study showed that diluted vinegar (2.5% acetic acid) significantly reduced Salmonella , E. coli , coliforms, and spoilage microorganisms on fresh lettuce by 2 to 3 log CFU/g. Irrespective of growing methods (in-soil or soilless), it is crucial to incorporate good agricultural practices to reduce microbial contamination on fresh produce. The intervention employed in this study can be proposed to small farmers and consumers to improve quality and safety of leafy greens.

Sustainable lettuce: Adaptability to uncertain production conditions

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Lettuce is a popular and widely consumed leafy vegetable. California and Arizona annually produce more than 250,000 acres of iceberg, romaine, leaf, and specialty types of lettuce, supplying more than 95% of the U.S market as well as exports to Canada and other countries. These states have dominat...

Parasitic contamination of fresh vegetables sold at central markets in Khartoum state, Sudan.

Science.gov (United States)

Mohamed, Mona Ali; Siddig, Emmanuel Edwar; Elaagip, Arwa Hassan; Edris, Ali Mahmoud Mohammed; Nasr, Awad Ahmed

2016-03-11

Fresh vegetables are considered as vital nutrients of a healthy diet as they supply the body with essential supplements. The consumption of raw vegetables is the main way for transmission of intestinal parasitic organisms. This study was aimed at detecting the parasitic contamination in fresh vegetables sold in two central open-aired markets in Khartoum state, Sudan. In this prospective cross-sectional study, a total of 260 fresh vegetable samples and 50 water samples used to sprinkle vegetable(s) were collected from two central open-aired markets (namely; Elshaabi and Central markets) during November 2011 to May 2012. The samples were microscopically examined for detection of parasitic life forms using standardized parasitological techniques for protozoans and helminthes worms. Of the 260 fresh vegetable samples, 35 (13.5 %) were microscopically positive for intestinal parasites whereas 7/50 (14 %) of water samples used to sprinkle vegetable(s) were found positives. Remarkably, high level of contamination in fresh vegetable samples was recorded in lettuce (Lactuca sativa) 36.4 % (4/11) while cayenne pepper (Capsicum annuum) and cucumber (Cucumis sativus) were not contaminated. The identified protozoans and helminthes were Entamoeba histolytica/dispar, Entamoeba coli, Giardia lamblia, Ascaris lumbricoides, Strongyloides stercoralis, T. trichiura and hookworms. The most predominant parasite encountered was E. histolytica/dispar (42.9 %) whereas both T. trichiura and A. lumbricoides (2.9 %) were the least detected parasites. None of the fresh vegetables had single parasitic contamination. The highest percentages found in water samples used to sprinkle vegetable(s) was for Strongyloides larvae 60 % (3/5). It is worth-mentioned that the rate of contamination in Elshaabi market was higher compared with Central market. However, there was no significant correlation between the type of vegetables and existence of parasites in both markets and a high significant

New views for sustainable production in family agriculture: Assessment of American lettuce cultivated with different types of organic fertilizers

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Renan Borro Celestrino

2017-07-01

Full Text Available The general objective of this work was to evaluate the response of the American Lettuce to its development, using different types of organic fertilizers. Specifically, the objective was to outline the potential market for this type of food with agroecological production, with emphasis on small producers of family agriculture and to seek alternatives for legal marketing of organic products through family farming, based on Law 10.831/2003. Data collection on lettuce response to fertilization was completely randomized, with five treatments and four repetitions. It is a descriptive, exploratory research. Through a bibliographical survey, it was concluded that the insertion in the system of agroecological-organic production is opportune to establish competitiveness in family farming, in the primary productive sector of the production chain of olericulture, where the American Lettuce is among the main cultivated varieties. It was observed that the fertilization with manure of hardened chicken showed a higher development of lettuce in relation to other treatments. The consumer market confirms a demand for healthy food with the focus on vegetables. For legal marketing, organic food needs to get a special seal. Brazilian legislation establishes three guarantee instruments: third-party certification, participatory guarantee systems and social control for direct sale without certification. This last recommended for family farmers.

Purification and Characterization of Polyphenol Oxidase, Peroxidase and Lipoxygenase from Freshly Cut Lettuce (L. sativa

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Vural Gökmen

2011-01-01

Full Text Available Enzymatic reactions taking place in minimally processed vegetables are considered as a major problem, because they adversely affect sensorial and nutritional quality. Polyphenol oxidase (PPO, peroxidase (POD and lipoxygenase (LOX from lettuce were purified on a column packed with positively charged diethylaminoethyl (DEAE cellulose by applying pH gradient elution from pH=4.0 to 9.0. The main purified fractions (PPO1 and PPO4, POD1 and POD2, LOX1 and LOX2 were characterized for enzyme concentration-reaction rate relationship, thermal stability, pH activity and kinetic parameters. Kinetic properties of each isoform were considerably different. Cysteine was found as the most effective inhibitor of both fractions of PPO. Kinetic parameters of lettuce POD were presented using guaiacol at various H2O2 concentrations. β-carotene directly influences lettuce LOX in the reaction medium available for the catalytic conversion of linoleic acid into hydroperoxides. Ascorbic and oxalic acids appear as effective PPO inhibitors, protecting phenolic compounds against oxidation in lettuce. Understanding the characteristics of deteriorative enzymes becomes important to maintain suitable conditions for fresh-like quality of lettuce. The results can be useful to keep the nutritional quality of minimally processed lettuce during shelf-life.

Influence of nutrient solutions in an open-field soilless system on the quality characteristics and shelf life of fresh-cut red and green lettuces (Lactuca sativa L.) in different seasons.

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Luna, María C; Martínez-Sánchez, Ascensión; Selma, María V; Tudela, Juan A; Baixauli, Carlos; Gil, María I

2013-01-01

Little information is available about the impact of nutrient solution ion concentration on quality characteristics and shelf life of fresh-cut lettuce grown in soilless systems in open field. Three lettuce genotypes, lollo rosso and red oak leaf as red-leafed genotypes and butterhead as green-leafed genotype, were studied. The influence of three nutrient solutions with low, medium and high ion concentrations, which varied in the macroanion (NO₃⁻) and macrocations (K⁺, Ca²⁺ and NH₄⁺), were compared in summer and winter. The nutrient solutions evaluated in this study for the production of lettuce in a soilless system did not strongly influence the quality characteristics of the raw material. When the ion concentration of the nutrient solution was increased, fresh weight decreased, although it depended on the genotype and season. Maturity index and dry matter content varied with the season but independently of the nutrient solution. In summer, maturity index was higher and dry matter lower than in winter. Initial texture and visual quality were not influenced by the nutrient solution. Medium ion concentration provided the highest content of vitamin C and phenolic compounds. Our observations pointed out that the genotype had a strong influence on the shelf life of the fresh-cut product with minor differences among nutrient solutions. In general, red-leafed lettuces showed the highest antioxidant content, helping the maintenance of sensory characteristics throughout storage. The combination of optimal nutrient solution ion concentration and suitable cultivar is considered essential to ensure lettuce post-cutting life. Copyright © 2012 Society of Chemical Industry.

Production and photosynthetic activity of Mimosa Verde and Mimosa Roxa lettuce in two farming systems

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Aline Mabel Rosa

2014-08-01

Full Text Available Lettuce (Lactuca sativa L. is the most commonly consumed leaf vegetable in the Brazilian diet, and it is a good source of vitamins and minerals. It is widely grown in the conventional farming system. However, the hydroponic farming system has been gaining importance in the market, wining confidence from consumers, who are becoming increasingly more demanding on food quality. The objective of this study was to evaluate the performance of two lettuce cultivars on hydroponic and conventional farming systems for the production of fresh mass (FM and dry mass (DM, photosynthesis, contents of chlorophyll and anthocyanin. The following two experiments were carried out: hydroponics farming (HF and conventional farming (CF, performed in protect and unprotect environments, respectively, in Florianópolis, SC. Mimosa Verde cultivar (MV showed greater fresh mass than Mimosa Roxa (MR, in both farming systems and the two cultivars presented better performance in the hydroponic system (287.7 g MV and 139.1 g MR than the conventional system (129.7 g MV and 111.8 g MR. Mimosa Verde cultivar presented lower average contents of total chlorophyll (7.7 mg g-¹ FM than Mimosa Roxa (11.8 mg g-¹FM, and both cultivars displayed higher means for this variable in the hydroponic farming system. Mimosa Roxa presented higher contents of anthocyanin in the conventional system (88.24 mg g-¹ FM than the ones in the hydroponic system (36.89 mg g-¹ FM. The best results for CO2 net assimilation rate regarded to photosyntheticaly active photon flux density were found in the hydroponic system, for both lettuce cultivars. Variation in the contents of chlorophyll were also found. Those variations were higher in the protected system than in the hydroponic system and contents of anthocyanin were higher in the conventional system.

Economic aspects of the application of different organic materials as N-sources in organic production of lettuce

OpenAIRE

Cabilovski, dipl ing Ranko; Manojlovic, Prof Maja; Bogdanovic, Prof Darinka; Bavec, Prof Martina

2008-01-01

In a field experiment on a farm registered for organic production, we studied the effect of the application of different organic materials (OM): farmyard manure (FYM), guano (G), soybean seed (S), forage pea seed (P) on lettuce yield. Besides yield, we also analyzed the economic profitability of the application of different OM. Fresh lettuce yield was significantly higher with OM treatments than with the treatments without fertilization. The highest yield was obtained with the FYM treatment (...

Precut prepackaged lettuce: a risk for listeriosis?

Science.gov (United States)

Hanning, Irene B; Johnson, Michael G; Ricke, Steven C

2008-12-01

The most recent outbreaks of listeriosis have been traced back to contaminated ready-to-eat (RTE) poultry and meat products. However, Listeria monocytogenes can be isolated from every food group, including fresh vegetables. This review is focused on one of the most popular RTE vegetable products, precut prepackaged lettuce. The available literature concerning Listeria contamination of vegetables is reviewed, and possible reasons why no recent outbreaks or sporadic cases of listeriosis due to contaminated precut prepackaged lettuce are explored.

Simulation of Escherichia coli O157:H7 behavior in fresh-cut lettuce under dynamic temperature conditions during distribution from processing to retail.

Science.gov (United States)

McKellar, Robin C; LeBlanc, Denyse I; Lu, Jianbo; Delaquis, Pascal

2012-03-01

The temperature of packaged lettuce was recorded throughout a retail supply chain in Canada during the various stages of storage and shipping from the processor to retail. Temperatures were monitored in 27 cases of lettuce destined for three stores in three replicate trials conducted during the winter. A dynamic model that predicts the effect of temperature on the growth or die-off of Escherichia coli O157:H7 in packaged fresh-cut lettuce was applied to simulate the behavior of E. coli O157:H7 in the system. Simulations were carried out using distributions to account for variation in the temperature parameter and the die-off coefficient of the dynamic growth/death model. The results indicate that there was a predicted overall mean decline in cell numbers of 0.983 log cfu g⁻¹ and that the extent of cell death was proportional to the total time spent in the cold chain. Slight growth was predicted in a few instances when the dynamic temperature was above the permissive temperature of 5°C. These results suggest that generally there would be little or no growth of E. coli O157:H7 in product maintained at the proper temperature in the chain. Moreover, the predicted decline in cell numbers at refrigeration temperatures suggests that storage at 5°C or below prior to consumption would reduce populations of the pathogen in fresh-cut lettuce.

Reduction of radiation injury of fresh agricultural products by saccharide

International Nuclear Information System (INIS)

Hayashi, Toru; Todoroki, Setsuko

1998-01-01

To establish irradiation technologies as one of alternative technology of methyl bromide fumigation, radiation sensitivities for each kind of fresh agricultural products and reduction of radiation injury were investigated. Fresh vegetables and flowers such as cabbage, sprouts, asparagus, lettuce, chrysanthemum, carnation, rose, etc. were used and irradiated with 750 Gy γ-ray. Flowers received radiation injury were soaked into various kinds of solutions for one night, then they were irradiated with 500 Gy γ-ray. They showed different radiation sensitivities. Cruciferae plant showed radioresistance and Compositae plant radiosensitivity. A keeping quality agent for cut flowers indicated protection effect on radiation injury. (S.Y.)

Reduction of radiation injury of fresh agricultural products by saccharide

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Toru; Todoroki, Setsuko [National Food Research Inst., Tsukuba, Ibaraki (Japan)

1998-02-01

To establish irradiation technologies as one of alternative technology of methyl bromide fumigation, radiation sensitivities for each kind of fresh agricultural products and reduction of radiation injury were investigated. Fresh vegetables and flowers such as cabbage, sprouts, asparagus, lettuce, chrysanthemum, carnation, rose, etc. were used and irradiated with 750 Gy {gamma}-ray. Flowers received radiation injury were soaked into various kinds of solutions for one night, then they were irradiated with 500 Gy {gamma}-ray. They showed different radiation sensitivities. Cruciferae plant showed radioresistance and Compositae plant radiosensitivity. A keeping quality agent for cut flowers indicated protection effect on radiation injury. (S.Y.)

Effect of gamma irradiation and refrigeration storage on microbial, sensorial and chemical quality of fresh-cut lettuce

International Nuclear Information System (INIS)

Hammad, A. A.; Taha, S. M.; Amal, S. M.; Gebreel, H. M.

2010-01-01

Fresh-cut lettuce samples were collected and examined for their microbial, sensory and chemical qualities. All the examined samples had high level of microbial load. All examined samples contained Escherichia coli (E. coli), Enterococcus faecalis (Ent. faecalis), Staphylococcus aureus (S. aureus) and Aeromonas hydrophila (A. hydrophila), indicating that most these samples were unsatisfactory. Listeria monocytogenes (L monocytogenes) and Salmonella spp were not detected. Irradiation caused a great reduction in all microbial loads. During refrigerated storage, the counts of all microorganisms increased, but the rate of increase was slower in irradiated samples. Irradiation dose of 3 kGy was the optimum dose for preservation of fresh-cut lettuce which extended the refrigeration shelf-life up to 20 days and it was sufficient in eliminating all pathogenic bacteria without adverse effect on sensorial quality and slight effect on chemical quality.

Bacterial population dynamics and sensorial quality loss in modified atmosphere packed fresh-cut iceberg lettuce

NARCIS (Netherlands)

Paillart, M.J.M.; Vossen, J.M.B.M.; Levin, E.; Lommen, E.; Otma, E.C.; Snels, J.C.M.A.; Woltering, E.J.

2017-01-01

The end of shelf life of fresh-cut iceberg lettuce packed in modified atmosphere (MA) is determined by its visual quality and by its microbial load. The total microbial load should not exceed 6–7 log CFU g−1 mesophilic counting and be free of human pathogens. Not much is known about specific

Microbiological evaluation of ready-to-eat iceberg lettuce during shelf-life and effectiveness of household washing methods

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Daniela Bencardino

2018-04-01

Full Text Available The aim of this study was to assess the microbiological quality of ready-to-eat (RTE iceberg lettuce. Our investigation was based on the consumption tendency of university students considered a target market for this product. A total of 78 RTE samples were collected from chain supermarkets and analysed for the enumeration of aerobic mesophilic count (AMC, Escherichia coli and the detection of Salmonella spp. and Listeria monocytogenes. All samples were negative for the presence of pathogens. The mean value of AMC at the beginning, in the middle and after the expiration date was: 6.88, 8.51 and 8.72 log CFU g-1, respectively. The same investigation was performed on 12 samples of fresh iceberg lettuce samples. No pathogens were found and the mean value of AMC was lower than the RTE category (5.73 log CFU g-1; P<0.05. The effectiveness of 5 washing methods was determined on 15 samples of both fresh and RTE iceberg lettuce. Samples were washed for 15’ and 30’ in tap water (500 mL, tap water with NaCl (4 g/500 mL, tap water with bicarbonate (8 g/500 mL, tap water with vinegar (10 mL/500 mL and tap water with chlorine-based disinfectant (10 mL/500 mL. A significant bacterial load reduction was recorded for vinegar and disinfectant after 30’ and 15’, respectively. Overall, these results showed that RTE iceberg lettuce is more contaminated than the fresh product. Also, the consumption in the first few days of packaging and after washing with disinfectants reduces the risk for health consumers.

Low-dose irradiation of cut iceberg lettuce in modified atmosphere packaging

International Nuclear Information System (INIS)

Hagenmaier, R.D.; Baker, R.A.

1997-01-01

Irradiation at a mean dosage of 0.19 kGy of commercially prepared fresh-cut lettuce resulted in a product that had, 8 days after irradiation, microbial population of 290 cfu/g and yeast population of 60 cfu/g, compared with values of 220 000 and 1 400 cfu/g, respectively, for the nonirradiated control. Irradiation also caused moderate changes in respiration rate and headspace gas concentrations. It appears feasible to combine chlorination with irradiation at 0.15-0.5 kGy to produce fresh-cut, chopped lettuce with reduced microbial population

The distribution of submersed aquatic vegetation and water lettuce in the fresh and oligohaline tidal Potomac River, 2007

Science.gov (United States)

Campbell, Sarah Hunter; Rybicki, Nancy B.; Schenk, Edward R.

2015-01-01

Surveys documenting the composition of species of submersed aquatic vegetation (SAV) have been conducted in the Potomac River for decades. These surveys can help managers assess the proportion of native and exotic plants in the river or can be used to determine relationships between native and exotic plants, environmental conditions, and wildlife. SAV coverage increased from 2005 to 2007 throughout the fresh and oligohaline study area. The 2007 survey documented here determined that eleven species of SAV were present. The abundance of the exotic species Hydrilla verticillata (hydrilla) was relatively low, and species diversity was relatively high compared to previous years. The survey also revealed a new population of the invasive, floating aquatic plant Pistia stratiotes (water lettuce). In 2007, water lettuce, the latest exotic aquatic plant to be found in the fresh to oligohaline portion of the Potomac River, was most abundant in Mattawoman Creek, Charles County, Maryland. However, it was not observed in the fresh to oligohaline portion of the Potomac River in the summer of 2008. An understanding of the distribution of SAV species and factors governing the abundance of native and invasive aquatic species is enhanced by long-term surveys.

Stimulating productivity of hydroponic lettuce in controlled environments with triacontanol

Science.gov (United States)

Knight, S. L.; Mitchell, C. A.

1987-01-01

Triacontanol (1-triacontanol) applied as a foliar spray at 10(-7) M to 4-day-old, hydroponically grown leaf lettuce (Lactuca sativa L.) seedlings in a controlled environment increased leaf fresh and dry weight 13% to 20% and root fresh and dry weight 13% to 24% 6 days after application, relative to plants sprayed with water. When applied at 8 as well as 4 days after seeding, triacontanol increased plant fresh and dry weight, leaf area, and mean relative growth rate 12% to 37%. There was no benefit of repeating application of triacontanol in terms of leaf dry weight gain.

Lettuce production in greenhouse under fertirrgation with nitrogen and potassium silicate

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Renan Soares de Souza

2017-04-01

Full Text Available The objective of this study was to evaluate the effect of nitrogen and potassium silicate on the productive and commercial aspects of curly lettuce, Vera cultivar. The experimental design was completely randomized (CRD, with ten treatments and three replications. The treatments, arranged in a factorial design according to the Plan Puebla III matrix (Turrent & Laird, 1975, consisted of the combination of five doses of nitrogen (9; 54; 90; 126 and 171 kg ha-1 and five doses of potassium silicate (1.15; 6.90; 11.50; 16.10 and 21.85 kg ha-1. A control treatment without application of nitrogen and potassium silicate was also inserted. The crop was grown in a greenhouse and the doses were applied as sidedressing using drip micro-irrigation system. Total fresh matter, commercial fresh matter, non-commercial fresh matter, number of leaves and commercial trade index were evaluated. The commercial fresh matter and the number of commercial leaves per plant were affected only by nitrogen fertigation and increased linearly with the increase in the nitrogen dose of N, with the best responses observed at the highest dose of this element (171 kg ha-1. Potassium silicate had effect only in non-commercial fresh matter, not influencing the other characteristics.

Fertilization effect on yield and nitrate content in organically produced lettuce

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Čabilovski Ranko

2010-01-01

Full Text Available The effect of applying different organic materials (OM on yield and nitrate content in lettuce was studied in a field experiment on a farm registered for organic production during two years (2007 and 2008. Treatments were: farmyard manure (ST, guano (G, milled soybean (Glicine hispida seed (S; milled forage pea (Pisum sativum seed (P and control treatment (q. Biannual average fresh matter (FM yield of lettuce on fertilized plots ranges from 45.44 t ha-1 (P to 46,38 t ha-1 (ST and was significantly higher than fresh matter yield of the control (39.34 t ha-1, while the differences between fertilized treatments were not significant. Nitrate content in the fresh mass of lettuce in all treatments in both years was below the maximum allowed content (2.500 mg kg-1 regulated by the EU (Commission Regulation (EC, No 466/2001. In both years, the lowest nitrate content in the fresh mass of lettuce was recorded with the control treatment (q and highest with S treatment. Nitrate contents with G, P and S treatments were significantly higher than that recorded with FYM and q, whereas the differences between FYM and q were not significant in either the first or the second year of research. Linear correlation (r = 0.83**in 2007; r = 0.91** in 2008 was found between the content of mineral N in the soil and nitrate content in the FM of lettuce at the moment of harvesting in both years. .

LC-MS Untargeted Metabolomics To Explain the Signal Metabolites Inducing Browning in Fresh-Cut Lettuce.

Science.gov (United States)

García, Carlos J; García-Villalba, Rocío; Gil, María I; Tomas-Barberan, Francisco A

2017-06-07

Enzymatic browning is one of the main causes of quality loss in lettuce as a prepared and ready-to-eat cut salad. An untargeted metabolomics approach using UPLC-ESI-QTOF-MS was performed to explain the wound response of lettuce after cutting and to identify the metabolites responsible of browning. Two cultivars of Romaine lettuce with different browning susceptibilities were studied at short time intervals after cutting. From the total 5975 entities obtained from the raw data after alignment, filtration reduced the number of features to 2959, and the statistical analysis found that only 1132 entities were significantly different. Principal component analysis (PCA) clearly showed that these samples grouped according to cultivar and time after cutting. From those, only 15 metabolites belonging to lysophospholipids, oxylipin/jasmonate metabolites, and phenolic compounds were able to explain the browning process. These selected metabolites showed different trends after cutting; some decreased rapidly, others increased but decreased thereafter, whereas others increased during the whole period of storage. In general, the fast-browning cultivar showed a faster wound response and a higher raw intensity of some key metabolites than the slow-browning one. Just after cutting, the fast-browning cultivar contained 11 of the 15 browning-associated metabolites, whereas the slow-browning cultivar only had 5 of them. These metabolites could be used as biomarkers in breeding programs for the selection of lettuce cultivars with lower browning potential for fresh-cut applications.

Irradiation of lettuce (Lactuca sativa. L.): microbiological and sensory aspects

International Nuclear Information System (INIS)

Tsuhako, Vanessa Provenzano

2005-01-01

The increasing demand for fresh foods have stimulated the marketing of minimally processed vegetables. However, these products maintain most of their natural microbiota even after being sanitized, including pathogenic microorganisms. Refrigerated storage allows the growth of psychotropic microorganisms and among them the pathogen Listeria monocytogenes. The ingestion of food contaminated with L. monocytogenes may represent a risk to pregnant women and their fetuses and to immunocompromised people. Non-thermal alternative processes for food preservation, such as irradiation, can reduce pathogenic and spoilage microorganism populations without impairing substantial changes in sensory, physical or chemical attributes. The aims of this research were to evaluate the effect of gamma radiation on L. monocytogenes artificially inoculated on minimally processed lettuce, to evaluate its effect on lettuce leaves through acceptance sensory test and to determine the irradiated vegetable shelf life through sensory and microbiological tests. A mixture of 4 types of lettuce (Iceberg, Boston, Loose-leaf and Red loose-leaf) were artificially inoculated with L. monocytogenes (7 log UFC/g lettuce) and then exposed to 0.3; 0.6; 0.9 and 1.2 kGy, under refrigeration. The DlO values for L. monocytogenes varied fram 0.18 to 0.21 kGy. Sensory and microbiological tests indicated that the shelf life of Iceberg lettuce stored at 7 deg C was 5 and 7 days for the irradiated and non-irradiated samples, respectively, and for the irradiated and non-irradiated Loose-leaf lettuce samples were 10 days. For the non-irradiated Boston sample, the shelf life was 3 days and for the Irradiated 7 days. Red loose-leaf showed 5 and 4 days of shelf lives for the irradiated and non-irradiated, respectively. Irradiated samples presented better microbiological quality than non-irradiated ones. The irradiation is feasible process to improve quality and safety of lettuce leaves. (author)

Microbiological quality and safety assessment of lettuce production in Brazil.

Science.gov (United States)

Ceuppens, Siele; Hessel, Claudia Titze; de Quadros Rodrigues, Rochele; Bartz, Sabrina; Tondo, Eduardo César; Uyttendaele, Mieke

2014-07-02

The microbiological quality and safety of lettuce during primary production in Brazil were determined by enumeration of hygiene indicators Escherichia coli, coliforms and enterococci and detection of enteric pathogens Salmonella and E. coli O157:H7 in organic fertilizers, soil, irrigation water, lettuce crops, harvest boxes and worker's hands taken from six different lettuce farms throughout the crop growth cycle. Generic E. coli was a suitable indicator for the presence of Salmonella and E. coli O157:H7, while coliforms and enterococci were not. Few pathogens were detected: 5 salmonellae and 2 E. coli O157:H7 from 260 samples, of which only one was lettuce and the others were manure, soil and water. Most (5/7) pathogens were isolated from the same farm and all were from organic production. Statistical analysis revealed the following environmental and agro-technical risk factors for increased microbial load and pathogen prevalence in lettuce production: high temperature, flooding of lettuce fields, application of contaminated organic fertilizer, irrigation with water of inferior quality and large distances between the field and toilets. Control of the composting process of organic fertilizers and the irrigation water quality appear most crucial to improve and/or maintain the microbiological quality and safety during the primary production of lettuce. Copyright © 2014 Elsevier B.V. All rights reserved.

Potential internalisation of caliciviruses in lettuce.

Science.gov (United States)

Urbanucci, A; Myrmel, M; Berg, I; von Bonsdorff, C-H; Maunula, L

2009-10-31

Fresh produce such as lettuce (Lactuca sativa) has often been linked to epidemic viral gastroenteritis. In these cases, it is unknown whether the viral contamination has occurred during the growing or the processing of the implicated product. In this study lettuce was grown in the presence of enteric viruses, and the uptake of viruses via the roots into the edible parts (leaves and stem) of the lettuce plants was investigated, for plants with both intact and damaged roots. The roots of lettuce, growing either in hydroponic culture or in soil, were exposed to canine calicivirus (CaCV) and a human genogroup 2 norovirus (HuNoV) by these being added into the water or soil in which the lettuce was growing. Leaves from lettuce plants and seedlings were examined for viruses by real-time RT-PCR. When the lettuce plants were exposed to very high concentrations of CaCV, the virus was detected in lettuce leaves, indicating contamination via the roots, but the frequency of positive results was low. Internalisation occurred in both seedlings and grown plants, in both hydroponic and soil cultures, and occurred whether the roots were intact or damaged. However, internalisation of HuNoV was not detected in any of the experimental set ups, although the concentrations to which the plants were exposed were relatively high. Based on these results, viral contamination of lettuce plants via roots cannot be excluded, but is apparently not an important transmission route for viruses.

Scientific rationale for cos lettuce growing technology Lactuca sativa var. longifolia L. in the Forest-Steppe of Ukraine

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Н. В. Лещук

2014-04-01

Full Text Available Scientifically validated items of growing technology disclosed for cos lettuce marketable products in the conditions of Forest-Steppe of Ukraine. Impact of environmental factors onto growth and development of Lactuca sativa var. longifolia L. plants. Sowing terms established for the seed of cos lettuce at field-seeded growing. Development parameters are quoted for plant productivity indices and marketable product indices for cos lettuce of national and foreign breeding. According to VCU characteristics a  typical model has been designed for the cos lettuce indices of suitability for dissemination in Ukraine.

Lettuce contact allergy.

Science.gov (United States)

Paulsen, Evy; Andersen, Klaus E

2016-02-01

Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22%. The majority of cases are non-occupational, and may partly be caused by cross-reactivity. The sesquiterpene lactone mix seems to be a poor screening agent for lettuce contact allergy, as the prevalence of positive reactions is significantly higher in non-occupationally sensitized patients. Because of the easy degradability of lettuce allergens, it is recommended to patch test with freshly cut lettuce stem and supplement this with Compositae mix. As contact urticaria and protein contact dermatitis may present as dermatitis, it is important to perform prick-to-prick tests, and possibly scratch patch tests as well. Any person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Combination of peracetic acid and ultrasound reduces Salmonella Typhimurium on fresh lettuce (Lactuca sativa L. var. crispa).

Science.gov (United States)

Silveira, Luiza Oliveira; do Rosário, Denes Kaic Alves; Giori, Ana Carolina Garcia; Oliveira, Syllas Borburema Silva; da Silva Mutz, Yhan; Marques, Clara Suprani; Coelho, Jussara Moreira; Bernardes, Patrícia Campos

2018-04-01

Salmonella outbreaks related to fruits and vegetables have been reported being lettuce one of the most contaminated. Peracetic acid (PA) at 50 mg/L, sodium dichloroisocyanurate (SD) at 100 mg/L, and the combination of SD at 100 mg/L and babaçu coconut ( Attalea speciosa ) oil detergent at 100 mg/L were applied to fresh lettuce. Natural contaminant microbiota, physicochemical characteristics, and sensory attributes were evaluated. PA and SD reduced mesophilic aerobic counts by 2.1 and 1.5 log cfu/g, respectively. The most efficient treatment in reducing natural microbiota (i.e., PA) was applied alone and in combination with ultrasound (US). It reduced Salmonella enterica Typhimurium counts to undetectable levels (< 1 log cfu/g). US further reduced S. Typhimurium counts by 0.6 log cfu/g in relation to PA, treatment which lessened the pH but increased the titratable acidity of lettuce, but did not cause total color difference. Therefore, the combination of PA and US holds a potential industrial application for sanitization purposes.

Effect of Salt Stress on Morphological Traits of Lettuce Genotypes (Lactuca Sativa L.

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maryam zare

2017-02-01

Full Text Available Introduction: The recognition of salt tolerant plants is important as a result ofincreasing saline lands in Iran and world. Cultivation of plants in hydroponic environment is a reliable and economical method in order to select the salt tolerant plant. Salt stress can effect on plant growth and development by ion toxicity, ionic disturb the balance and osmotic potential. Lettuce is one of the most important vegetable crops. This plant is one of the most important leafy vegetables which is used for salad and fresh marketing, also some types of this vegetable is used in baked type. The aim of this study was to investigate the genetic diversity of lettuce genotypes undersalt stress in the hydroponic system. Materials and Methods: To assess response of lettuce seedlings to salt stress, a factorial experiment was conducted in a completely randomized design with three replications at Biotechnology Research Institute for hydroponic cultivation of Zabol. In this experiment, the effects of three salinity levels (0, 2 and 4 dS/m on morphological characteristics of 15 lettuce genotypes were evaluated. The seeds were sterilized for ten seconds in ethanol 96% and then 15% sodium hypochlorite solution for 50 seconds, then rinsed several times with distilled water, then disinfected seeds were cultured in plastic pots containing coco peat and perlite. After …days plants were transferred to hydroponic system containing Hoagland solution. Collected data were analyzed and means comparisons were made using LSD by SAS software. Results and Discussion: The results showed that salinity has a significant effect on seedling growth of lettuce genotypes (p≤0.01. significant difference between salinity levels and genotype were observed for all traits. Interaction of genotype and salinity for all the traits except root length, plant length and leaf were significant at 1%. Based on the results, the greatest root length was belong to Esfahan Varzaneh leafy lettuce and

Effect of Salt Stress on Morphological Traits of Lettuce Genotypes (Lactuca Sativa L.

Directory of Open Access Journals (Sweden)

maryam zare

2017-09-01

Full Text Available Introduction: The recognition of salt tolerant plants is important as a result ofincreasing saline lands in Iran and world. Cultivation of plants in hydroponic environment is a reliable and economical method in order to select the salt tolerant plant. Salt stress can effect on plant growth and development by ion toxicity, ionic disturb the balance and osmotic potential. Lettuce is one of the most important vegetable crops. This plant is one of the most important leafy vegetables which is used for salad and fresh marketing, also some types of this vegetable is used in baked type. The aim of this study was to investigate the genetic diversity of lettuce genotypes undersalt stress in the hydroponic system. Materials and Methods: To assess response of lettuce seedlings to salt stress, a factorial experiment was conducted in a completely randomized design with three replications at Biotechnology Research Institute for hydroponic cultivation of Zabol. In this experiment, the effects of three salinity levels (0, 2 and 4 dS/m on morphological characteristics of 15 lettuce genotypes were evaluated. The seeds were sterilized for ten seconds in ethanol 96% and then 15% sodium hypochlorite solution for 50 seconds, then rinsed several times with distilled water, then disinfected seeds were cultured in plastic pots containing coco peat and perlite. After …days plants were transferred to hydroponic system containing Hoagland solution. Collected data were analyzed and means comparisons were made using LSD by SAS software. Results and Discussion: The results showed that salinity has a significant effect on seedling growth of lettuce genotypes (p≤0.01. significant difference between salinity levels and genotype were observed for all traits. Interaction of genotype and salinity for all the traits except root length, plant length and leaf were significant at 1%. Based on the results, the greatest root length was belong to Esfahan Varzaneh leafy lettuce and

Stimulation of lettuce seed germination by ethylene.

Science.gov (United States)

Abeles, F B; Lonski, J

1969-02-01

Ethylene increased the germination of freshly imbibed lettuce (Lactuca sativa L. var. Grand Rapids) seeds. Seeds receiving either red or far-red light or darkness all showed a positive response to the gas. However, ethylene was apparently without effect on dormant seeds, those which failed to germinate after an initial red or far-red treatment. Carbon dioxide, which often acts as a competitive inhibitor of ethylene, failed to clearly reverse ethylene-enhanced seed germination. While light doubled ethylene production from the lettuce seeds, its effect was not mediated by the phytochrome system since both red and far-red light had a similar effect.

Lettuce and spinach breeding

Science.gov (United States)

Lettuce and spinach production is beset by numerous biotic an abiotic challenges, thus the leafy-vegetable industry of California requires continued development of improved, adapted cultivars to meet new disease and insect problems, changes in the market, and changes in growing procedures. The lettu...

Effete of Gamma Radiation and N.P.K on Lettuce yield

International Nuclear Information System (INIS)

Abo Elkhier, O.H.M.M.

2013-01-01

Two field experiment were carried out during 2005/2006 winter growing seasons at the experiment at farm of Nuclear Research Center, Atomic Energy Authority, Inshas, Egypt – The experiments were conducted to study the effect of irradiated sowing seeds with 0, 2, 4, 6 and 8 Gray (Gy) of gamma radiation and / or the effect of different levels of NPK fertilizer 0, (NPK)1, (NPK)2, (NPK)3, (NPK)4 and (NPK)5 on the morphological and chemical parameters of the lettuce yield. The fresh weight of the plant in the line, length of the plant in the line, the number of leaves in the line, the number of plants in the line and the fresh weight in Fadden per ton were studied. There were significant effects of NPK contents on the lettuce leaves at (NPK) 4 in the dose level 6 Gy and on Calcium and Vitamins. We found that the most effective doses on leaf lettuce is 6 Gy dose of gamma radiation which gives strong and early seedlings in maturity upwards in the production of seedlings dose of 4 Gy. While the dose 8 Gray did not occur any increase at dose level 6 Gy. The Level (NPK) 4 increase the production of fresh per acre more upwards for all levels with 6 Gray and fourth level was the best in the natural qualities and characteristics of chemical terms of delay growth harvest lettuce, as well as influence on the plant content of calcium, nitrogen, protein and all the natural qualities among the first season and the second season.

Insight into the prevalence and distribution of microbial contamination to evaluate water management in the fresh produce processing industry.

Science.gov (United States)

Holvoet, Kevin; Jacxsens, Liesbeth; Sampers, Imca; Uyttendaele, Mieke

2012-04-01

This study provided insight into the degree of microbial contamination in the processing chain of prepacked (bagged) lettuce in two Belgian fresh-cut produce processing companies. The pathogens Salmonella and Listeria monocytogenes were not detected. Total psychrotrophic aerobic bacterial counts (TPACs) in water samples, fresh produce, and environmental samples suggested that the TPAC is not a good indicator of overall quality and best manufacturing practices during production and processing. Because of the high TPACs in the harvested lettuce crops, the process water becomes quickly contaminated, and subsequent TPACs do not change much throughout the production process of a batch. The hygiene indicator Escherichia coli was used to assess the water management practices in these two companies in relation to food safety. Practices such as insufficient cleaning and disinfection of washing baths, irregular refilling of the produce wash baths with water of good microbial quality, and the use of high product/water ratios resulted in a rapid increase in E. coli in the processing water, with potential transfer to the end product (fresh-cut lettuce). The washing step in the production of fresh-cut lettuce was identified as a potential pathway for dispersion of microorganisms and introduction of E. coli to the end product via cross-contamination. An intervention step to reduce microbial contamination is needed, particularly when no sanitizers are used as is the case in some European Union countries. Thus, from a food safety point of view proper water management (and its validation) is a critical point in the fresh-cut produce processing industry.

Production and characterization of cyanocobalamin-enriched lettuce (Lactuca sativa L.) grown using hydroponics.

Science.gov (United States)

Bito, Tomohiro; Ohishi, Noriharu; Hatanaka, Yuka; Takenaka, Shigeo; Nishihara, Eiji; Yabuta, Yukinori; Watanabe, Fumio

2013-04-24

When lettuces (Lactuca sativa L.) grown for 30 days in hydroponic culture were treated with various concentrations of cyanocobalamin for 24 h, its content in their leaves increased significantly from nondetectable to 164.6 ± 74.7 ng/g fresh weight. This finding indicated that consumption of only two or three of these fresh leaves is sufficient to meet the Recommended Dietary Allowance for adults of 2.4 μg/day. Analyses using a cobalamin-dependent Escherichia coli 215 bioautogram and LC/ESI-MS/MS demonstrated that the cyanocobalamin absorbed from the nutrient solutions by the leaves did not alter any other compounds such as coenzymes and inactive corrinoids. Gel filtration indicated that most (86%) of the cyanocobalamin in the leaves was recovered in the free cyanocobalamin fractions. These results indicated that cyanocobalamin-enriched lettuce leaves would be an excellent source of free cyanocobalamin, particularly for strict vegetarians or elderly people with food-bound cobalamin malabsorption.

7 CFR 457.148 - Fresh market pepper crop insurance provisions.

Science.gov (United States)

2010-01-01

... 7 Agriculture 6 2010-01-01 2010-01-01 false Fresh market pepper crop insurance provisions. 457.148... pepper crop insurance provisions. The fresh market pepper crop insurance provisions for the 1999 and... Fresh Market Pepper Crop Provisions If a conflict exists among the policy provisions, the order of...

Influence of production time on quality and height of yield of crisp lettuce

International Nuclear Information System (INIS)

Odziemkowski, S.; Gajc-Wolska, J.; Skapski, H.

1998-01-01

The cultivar of crisp lettuce Saladin, was grown in the field in 10 production terms starting from spring to autumn in 1993-95. The highest average weight of head of crisp lettuce was obtained in earlier terms of production. The head weight at the time of harvest depended on the amount of solar radiation during the time of lettuce head formation

Organic acids produced by lactic acid bacteria (Leuconostoc sp.) contribute to sensorial quality loss in modified-atmosphere-packed fresh-cut iceberg lettuce

NARCIS (Netherlands)

Paillart, M.J.M.; Vossen, J.M.B.M. van der; Lommen, E.; Levin, E.; Otma, E.C.; Snels, J.C.M.A.; Woltering, E.J.

2016-01-01

The shelf-life of fresh-cut lettuce packed in a modified atmosphere (MA) is determined by its "overall visual quality" (OVQ), being a measure of its general appearance based on colour and shape criteria. In addition to the OVQ, the development of off-flavour and acid off-smell reduces consumer

Organic acids produced by lactic acid bacteria (Leuconostoc sp.) contribute to sensorial quality loss in modified-atmosphere-packed fresh-cut iceberg lettuce

NARCIS (Netherlands)

Paillart, M.J.M.; Vossen, van der J.M.B.M.; Lommen, E.; Levin, E.; Otma, E.C.; Snels, J.C.M.A.; Woltering, E.J.

2016-01-01

The shelf-life of fresh-cut lettuce packed in a modified atmosphere (MA) is determined by its "overall visual quality" (OVQ), being a measure of its general appearance based on colour and shape criteria. In addition to the OVQ, the development of off-flavour and acid off-smell reduces consumer

Fate of Salmonella enterica in a mixed ingredient salad containing lettuce, cheddar cheese, and cooked chicken meat.

Science.gov (United States)

Bovo, Federica; De Cesare, Alessandra; Manfreda, Gerardo; Bach, Susan; Delaquis, Pascal

2015-03-01

Food service and retail sectors offer consumers a variety of mixed ingredient salads that contain fresh-cut vegetables and other ingredients such as fruits, nuts, cereals, dairy products, cooked seafood, cooked meat, cured meats, or dairy products obtained from external suppliers. Little is known about the behavior of enteric bacterial pathogens in mixed ingredient salads. A model system was developed to examine the fate of Salmonella enterica (inoculum consisting of S. enterica serovars Agona, Typhimurium, Enteritidis, Brandenberg, and Kentucky) on the surface of romaine lettuce tissues incubated alone and in direct contact with Cheddar cheese or cooked chicken. S. enterica survived but did not grow on lettuce tissues incubated alone or in contact with Cheddar cheese for 6 days at either 6 or 14°C. In contrast, populations increased from 2.01 ± 0.22 to 9.26 ± 0.22 CFU/cm(2) when lettuce washed in water was incubated in contact with cooked chicken at 14°C. Populations on lettuce leaves were reduced to 1.28 ± 0.14 CFU/cm(2) by washing with a chlorine solution (70 ppm of free chlorine) but increased to 8.45 ± 0.22 CFU/cm(2) after 6 days at 14°C. Experimentation with a commercial product in which one third of the fresh-cut romaine lettuce was replaced with inoculated lettuce revealed that S. enterica populations increased by 4 log CFU/g during storage for 3 days at 14°C. These findings indicate that rapid growth of bacterial enteric pathogens may occur in mixed ingredient salads; therefore, strict temperature control during the manufacture, distribution, handling, and storage of these products is critical.

Evaluation of sanitary quality of lettuce (Lactuca sativa, L. irrigated with reused water in comparison with commercialized lettuce

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Claudinei Fonseca Souza

2011-08-01

Full Text Available Inadequate use of water resources reduces their availability and therefore, research focused on their reutilization is required. This work evaluated the sanitary quality of lettuce irrigated with reused water in comparison with samples of lettuce commercialized in Taubaté (SP market. An experiment was developed in a greenhouse with three beds of lettuce irrigated with reused water and three beds of lettuce irrigated with urban water supply. After lettuce biological cycle had been completed, lettuce samples were collected from the beds (irrigated and non-irrigated with reused water and from samples of lettuce commercialized in the city market that were analyzed in the laboratory. The analyses were done using the multiple tubes methodology. The results showed that the samples from lettuce irrigated with urban water supply were not contaminated by either total or thermotolerant coliforms while samples of irrigated lettuce with reused water were contaminated by total coliforms. Samples from commercialized lettuce were contaminated by both kinds of coliforms. Results indicated that the application of reused water for agricultural purposes should occur only after carefully treatment to allow a safe use and to contribute to the water use sustainability.

Factors important for the shelf-life of minimally processed lettuce

OpenAIRE

Deza Durand, Karla Michelle

2013-01-01

The minimally processed vegetable industry has been increasing rapidly due to change in lifestyle. Both women and men work outside home and have less time to cook and need more convenience and time saving products, which also present fresh and healthy characteristics. Iceberg lettuce (Lactuca sativa L.) is one of the most popular fresh-cut vegetables. Although an increase in the number of mixed salads in retail food chains is evident, their short shelf-life due to rapid browning and off-odour...

76 FR 81468 - Notice of Decision to Authorize the Importation of Shredded Lettuce From Egypt Into the...

Science.gov (United States)

2011-12-28

...] Notice of Decision to Authorize the Importation of Shredded Lettuce From Egypt Into the Continental... fresh shredded lettuce from Egypt. Based on the findings of a pest risk analysis, which we made... introducing or disseminating plant pests or noxious weeds via the importation of fresh shredded lettuce from...

Public health risk of trace metals in fresh chicken meat products on the food markets of a major production region in southern China.

Science.gov (United States)

Hu, Yuanan; Zhang, Wenfeng; Chen, Gang; Cheng, Hefa; Tao, Shu

2018-03-01

Because most chickens are reared in intensive farms, where a range of feed additives are used routinely, concerns have been raised on the potential public health risk of chicken product consumption. This study was conducted to characterize the contents of trace metals in fresh chicken tissues (354 samples) on the food markets in Guangdong province of southern China, a major region of chicken production with heavy per capita chicken consumption, and to assess the public health risk from chronic dietary exposure to the trace metals through chicken consumption. With the exception of Cr, Ni, and Pb, the contents of trace metals were generally higher in the chicken giblets (livers, gizzards, hearts, and kidneys) compared to muscles (breasts and drumsticks). Chicken tissues from the urban markets generally contained higher levels of As, Cu, Mn, and Zn than those from the rural markets, while the contents of Pb were typically higher in the chicken muscles from the rural markets. Results of statistical analyses indicate that Cu, Zn, and As in the chicken tissues derived mainly from the feeds, which is consistent with the widespread use of Cu, Zn, and phenylarsenic compounds as feed supplements/additives in intensive poultry farming. No non-carcinogenic risk is found with the consumption of fresh chicken meat products on the food markets, while approximately 70% of the adult population in Guangzhou and 30% of those in Lianzhou have bladder and lung cancer risk above the serious or priority level (10 -4 ), which arises from the inorganic arsenic contained in the chicken tissues. These findings indicate that the occurrence of inorganic arsenic at elevated levels in chicken tissues on the food markets in Guangdong province poses a significant public health risk, thus the use of phenylarsenic feed additives in China's poultry farming should be significantly reduced and eventually phased out. Copyright © 2017 Elsevier Ltd. All rights reserved.

Marketing of agricultural products: case findings

NARCIS (Netherlands)

Hingley, M.; Lindgreen, A.

2002-01-01

This article focuses on the relationship marketing approach to marketing of agricultural products. The article provides specific insights into, and comparisons between, suppliers of two particular agricultural products sectors: in Britain, the fresh produce (fruits and vegetables) sector and, in New

Combinação de águas doce e salobra para produção de alface hidropônica Combination of fresh and brackish waters for hydroponic lettuce production

Directory of Open Access Journals (Sweden)

Tales M. Soares

2010-07-01

Full Text Available Plantas de alface crespa cv. Verônica foram cultivadas em condição hidropônica objetivando-se avaliar dois tipos de emprego combinado de águas doce e salobras, quais sejam: usar as águas salobras para preparar a solução nutritiva (SN e a água doce para repor a evapotranspiração da cultura (ETc (Experimento I e usar a água doce para preparar a SN e as salobras para a reposição da ETc (Experimento II. Uma estrutura de pesquisa com 40 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT foi construída. Os níveis de salinidade da água testados foram: 0,585; 1,17; 1,755; 2,925 e 4,095 g L-1 de NaCl. A salinidade diminuiu a produtividade da alface (massa de matéria fresca da parte aérea em 10,9 e 3,91% para cada acréscimo unitário na salinidade da água (g L-1 de NaCl, considerando-se os Experimentos I e II, respectivamente. De acordo com os resultados obtidos com os dois tipos de combinação de águas doce e salobras, o uso de águas salobras para repor a ETc pode aumentar a produtividade da alface em comparação com o uso dessas águas para preparar a SN.Plants of crisphead lettuce cv. Verônica were grown under hydroponic conditions aiming to evaluate two types of combination of brackish and fresh waters: using the brackish waters to prepare nutrient solution (NS and fresh water to replace the evapotranspiration loss (ETc (Experiment I and using the fresh water to prepare NS and the brackish waters to replace the ETc loss (Experiment II. A research structure was built up with 40 experimental units which simulated the nutrient film technique (NFT. The levels of water salinity were 0.585; 1.17; 1.755; 2.925 and 4.095 g L-1 NaCl. The lettuce yield (fresh shoot matter decreased 10.9 and 3.91% for each unit increase in water salinity (g L-1 NaCl in Experiments I and II, respectively. According to results obtained with the two types of combination of fresh and brackish waters, the use of brackish waters to replace

Antineurodegenerative effect of phenolic extracts and caffeic acid derivatives in romaine lettuce on neuron-like PC-12 cells.

Science.gov (United States)

Im, Sung-Eun; Yoon, Hyungeun; Nam, Tae-Gyu; Heo, Ho Jin; Lee, Chang Yong; Kim, Dae-Ok

2010-08-01

In recent decades, romaine lettuce has been one of the fastest growing vegetables with respect to its consumption and production. An understanding is needed of the effect of major phenolic phytochemicals from romaine lettuce on biological protection for neuron-like PC-12 cells. Phenolics in fresh romaine lettuce were extracted, and then its total phenolics and total antioxidant capacity were measured spectrophotometrically. Neuroprotective effects of phenolic extract of romaine lettuce and its pure caffeic acid derivatives (caffeic, chicoric, chlorogenic, and isochlorogenic acids) in PC-12 cells were evaluated using two different in vitro methods: lactate dehydrogenase release and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assays. Total phenolics and total antioxidant capacity of 100 g of fresh romaine lettuce averaged 22.7 mg of gallic acid equivalents and 31.0 mg of vitamin C equivalents, respectively. The phenolic extract of romaine lettuce protected PC-12 cells against oxidative stress caused by H(2)O(2) in a dose-dependent manner. Isochlorogenic acid, one of the phenolics in romaine lettuce, showed stronger neuroprotection than the other three caffeic acid derivatives also found in the lettuce. Although romaine lettuce had lower levels of phenolics and antioxidant capacity compared to other common vegetables, its contribution to total antioxidant capacity and antineurodegenerative effect in human diets would be higher because of higher amounts of its daily per capita consumption compared to other common vegetables.

A dose-response relationship for marketable yield reduction of two lettuce (Lactuca sativa L.) cultivars exposed to tropospheric ozone in Southern Europe.

Science.gov (United States)

Marzuoli, Riccardo; Finco, Angelo; Chiesa, Maria; Gerosa, Giacomo

2017-12-01

The present study investigated the response to ozone (O 3 ) of two cultivars (cv.'Romana' and cv. 'Canasta') of irrigated lettuce grown in an open-top chamber (OTC) experiment in Mediterranean conditions. Two different levels of O 3 were applied, ambient O 3 in non-filtered OTCs (NF-OTCs) and -40% of ambient O 3 in charcoal-filtered OTCs (CF-OTCs), during four consecutive growing cycles. At the end of each growing cycle, the marketable yield (fresh biomass) was assessed while during the growing periods, measurements of the stomatal conductance at leaf level were performed and used to define a stomatal conductance model for calculation of the phytotoxic ozone dose (POD) absorbed by the plants.Results showed that O 3 caused statistically significant yield reductions in the first and in the last growing cycle. In general, the marketable yield of the NF-OTC plants was always lower than the CF-OTC plants for both cultivars, with mean reductions of -18.5 and -14.5% for 'Romana' and 'Canasta', respectively. On the contrary, there was no statistically significant difference in marketable yield due to the cultivar factor or to the interaction between O 3 and cultivar in any of the growing cycle performed.Dose-response relationships for the marketable relative yield based on the POD values were calculated according to different flux threshold values (Y). The best regression fit was obtained using an instantaneous flux threshold of 6 nmol O 3 m -2  s -1 (POD 6 ); the same value was obtained also for other crops. According to the generic lettuce dose-response relationship, an O 3 critical level of 1 mmol O 3 m -2 of POD 6 for a 15% of marketable yield loss was found.

Exploring the Limits of Crop Productivity: High Light Studies with Lettuce

OpenAIRE

USU Crop Physiology Lab

2015-01-01

There are many different leaf lettuce cultivars and they range in color from light green and yellow to deep green as a result of higher concentrations of chlorophyll in the leaves. We tested four cultivars in high light to explore the limits of lettuce productivity.

Effects of marketing group on the quality of fresh and cured hams sourced from a commercial processing facility.

Science.gov (United States)

Arkfeld, E K; Wilson, K B; Overholt, M F; Harsh, B N; Lowell, J E; Hogan, E K; Klehm, B J; Bohrer, B M; Kroscher, K A; Peterson, B C; Stites, C R; Mohrhauser, D A; King, D A; Wheeler, T L; Dilger, A C; Shackelford, S D; Boler, D D

2016-12-01

The objective was: 1) to characterize the effect of marketing group on fresh and cured ham quality, and 2) to determine which fresh ham traits correlated to cured ham quality traits. Pigs raised in 8 barns representing 2 seasons (hot and cold) and 2 production focuses (lean and quality) were used. Three groups were marketed from each barn. A total of 7,684 carcasses were used for data collection at the abattoir. Every tenth carcass was noted as a select carcass for in-depth ham quality analyses. Leg primal weight and instrumental color were measured on 100% of the population. On the select 10% of the population, hams were fabricated into sub-primal pieces, and 3-piece hams were manufactured to evaluate cured ham quality and processing yield. Data were analyzed as a split-plot design in the MIXED procedure of SAS with production focus as the whole-plot factor, and marketing group as the split-plot factor. Pearson correlation coefficients between fresh and cured ham traits were computed. There were no differences ( ≥ 0.15) in instrumental color or ultimate pH ( ≥ 0.14) among fresh ham muscles from any marketing group. The only exception was the semimembranosus of marketing group 2 was lighter than marketing group 1 ( = 0.03) and the dark portion of the semitendinosus muscle from group 1 was lighter than from group 3 ( = 0.01). There were no differences ( ≥ 0.33) in ultimate pH of fresh ham muscles between production focuses, but several muscles from quality focus pigs were lighter in color than ham muscles from lean focus pigs. The lack of differences in fresh ham quality lead to few differences in cured ham quality. Cured hams from the quality focus pigs had greater lipid content ( marketing group 1 and 2 were 1.52 units lighter than hams from marketing group 3 ( 0.01). Overall, marketing group did not impact ham quality. Fresh ham quality was not strongly related to cured ham quality. Some correlations were present between fresh and cured ham traits, but

Agricultural recycling of biodigested vinasse for lettuce production

Directory of Open Access Journals (Sweden)

Camila Roberta Javorski Ueno

2014-10-01

Full Text Available The agricultural use of waste products represents an interesting alternative for nutrient cycling. Biodigested vinasse, the final waste product of vinasse biodigestion and biogas production, can be reused for agricultural purposes. The present work sought to quantify the shoot dry mass production of lettuce plants, as well as foliar nitrogen, phosphorus and potassium content following the application of biodigested vinasse on soil. Biodigested vinasse was produced from anaerobic vinasse digestion, using anaerobic sludge as a source of microorganisms. The treatments, with four replications in entirely randomized design, consisted of anaerobic sludge from a gelatin factory, vinasse in natura, biodigested vinasse and a control treatment. The experiment was conducted over 45 days using 5 L vases and applying a dose equivalent to 150 m3 ha-1 . Lettuce treated with biodigested vinasse showed higher shoot dry mass production and higher accumulation of nitrogen, phosphorus and potassium in its leaves than that treated with vinasse in natura.

Roles of a novel Crp/Fnr family transcription factor Lmo0753 in soil survival, biofilm production and surface attachment to fresh produce of Listeria monocytogenes.

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Joelle K Salazar

Full Text Available Listeria monocytogenes is a foodborne bacterial pathogen and the causative agent of an infectious disease, listeriosis. L. monocytogenes is ubiquitous in nature and has the ability to persist in food processing environments for extended periods of time by forming biofilms and resisting industrial sanitization. Human listeriosis outbreaks are commonly linked to contaminated dairy products, ready-to-eat meats, and in recent years, fresh produce such as lettuce and cantaloupes. We identified a putative Crp/Fnr family transcription factor Lmo0753 that is highly specific to human-associated genetic lineages of L. monocytogenes. Lmo0753 possesses two conserved functional domains similar to the major virulence regulator PrfA in L. monocytogenes. To determine if Lmo0753 is involved in environmental persistence-related mechanisms, we compared lmo0753 deletion mutants with respective wild type and complementation mutants of two fully sequenced L. monocytogenes genetic lineage II strains 10403S and EGDe for the relative ability of growth under different nutrient availability and temperatures, soil survival, biofilm productivity and attachment to select fresh produce surfaces including romaine lettuce leaves and cantaloupe rinds. Our results collectively suggested that Lmo0753 plays an important role in L. monocytogenes biofilm production and attachment to fresh produce, which may contribute to the environmental persistence and recent emergence of this pathogen in human listeriosis outbreaks linked to fresh produce.

7 CFR 457.129 - Fresh market sweet corn crop insurance provisions.

Science.gov (United States)

2010-01-01

... 7 Agriculture 6 2010-01-01 2010-01-01 false Fresh market sweet corn crop insurance provisions. 457... sweet corn crop insurance provisions. The fresh market sweet corn crop insurance provisions for the 2008... Reinsured Policies Fresh Market Sweet Corn Crop Provisions 1. Definitions Allowable cost.—The dollar amount...

Transfer of Escherichia coli O157:H7 from equipment surfaces to fresh-cut leafy greens during processing in a model pilot-plant production line with sanitizer-free water.

Science.gov (United States)

Buchholz, Annemarie L; Davidson, Gordon R; Marks, Bradley P; Todd, Ewen C D; Ryser, Elliot T

2012-11-01

Escherichia coli O157:H7 contamination of fresh-cut leafy greens has become a public health concern as a result of several large outbreaks. The goal of this study was to generate baseline data for E. coli O157:H7 transfer from product-inoculated equipment surfaces to uninoculated lettuce during pilot-scale processing without a sanitizer. Uninoculated cored heads of iceberg and romaine lettuce (22.7 kg) were processed using a commercial shredder, step conveyor, 3.3-m flume tank with sanitizer-free tap water, shaker table, and centrifugal dryer, followed by 22.7 kg of product that had been dip inoculated to contain ∼10(6), 10(4), or 10(2) CFU/g of a four-strain avirulent, green fluorescent protein-labeled, ampicillin-resistant E. coli O157:H7 cocktail. After draining the flume tank and refilling the holding tank with tap water, 90.8 kg of uninoculated product was similarly processed and collected in ∼5-kg aliquots. After processing, 42 equipment surface samples and 46 iceberg or 36 romaine lettuce samples (25 g each) from the collection baskets were quantitatively examined for E. coli O157:H7 by direct plating or membrane filtration using tryptic soy agar containing 0.6% yeast extract and 100 ppm of ampicillin. Initially, the greatest E. coli O157:H7 transfer was seen from inoculated lettuce to the shredder and conveyor belt, with all equipment surface populations decreasing 90 to 99% after processing 90.8 kg of uncontaminated product. After processing lettuce containing 10(6) or 10(4) E. coli O157:H7 CFU/g followed by uninoculated lettuce, E. coli O157:H7 was quantifiable throughout the entire 90.8 kg of product. At an inoculation level of 10(2) CFU/g, E. coli O157:H7 was consistently detected in the first 21.2 kg of previously uninoculated lettuce at 2 to 3 log CFU/100 g and transferred to 78 kg of product. These baseline E. coli O157:H7 transfer results will help determine the degree of sanitizer efficacy required to better ensure the safety of fresh-cut leafy

Qualidade de alface crespa minimamente processada armazenada sob refrigeração em dois sistemas de embalagem Quality of fresh-cut crisphead lettuce stored under refrigeration and two packaging systems

Directory of Open Access Journals (Sweden)

Leonora M Mattos

2007-12-01

Full Text Available O processamento mínimo acelera a perda de qualidade, reduz a vida de prateleira e modifica os atributos sensoriais de frutas e hortaliças. A alface minimamente processada sofre ainda o efeito do escurecimento enzimático resultante da descompartimentação de enzimas e seus substratos. Neste trabalho, avaliou-se a qualidade química, física e bioquímica de alface crespa minimamente processada e armazenada sob refrigeração em dois sistemas de embalagem. A alface cv. Verônica foi colhida em campos de produção comercial em Brasília, DF e processada nas formas de folha inteira e em tiras de 5 mm. O material processado foi acondicionado em filmes de polipropileno e polietileno de baixa densidade e armazenado a 5ºC durante 14 dias. A cada dois dias, as alfaces foram avaliadas quanto à acidez titulável, cor (L*a*b* e atividade das enzimas polifenoloxidase e peroxidase. A atividade tanto da polifenoloxidase como da peroxidase foi maior para o material processado como tiras de 5 mm, quando comparado à alface processada como folha inteira. A alface processada como tiras de 5 mm apresentou maior escurecimento enzimático, menor brilho e menores teores de ácidos orgânicos para as duas embalagens estudadas.Minimal processing usually causes quality loss, reduces shelf-life, and promotes sensory attributes alterations. The occurrence of browning in the midrib of fresh-cut lettuce is commonly observed and is associated with cell tissue disrupture, putting in contact enzymes and their respective substrates. Chemical, physical, and biochemical quality of fresh-cut crisphead lettuce stored under refrigeration and two different packaging systems were evaluated in the present work. Lettuce cv. Verônica was harvested in commercial fields in Brasilia, Brazil, and was minimally processed as whole leaves and 5 mm strips. Fresh-cut lettuce was then packed into polypropylene and low density polyethylene plastic films and was stored at 5ºC during 14 days

Fresh market to supermarket: nutrition transition insights from Chiang Mai, Thailand.

Science.gov (United States)

Isaacs, Bronwyn Alison; Dixon, Jane; Banwell, Cathy

2010-06-01

A preliminary investigation into different eating patterns among Thai consumers who shop at fresh markets as opposed to supermarkets in Chiang Mai. A short questionnaire adopted from a previous study was administered to the forty-four participants, who comprised supermarket users, fresh market users and people who consistently shopped at both supermarkets and fresh markets. Participants were recruited within four fresh markets and two food courts attached to supermarkets in Chiang Mai. Chiang Mai residents who agreed to participate in the study. Equal numbers were regular fresh market and supermarket users. Initial results suggest an association between shopping at supermarkets and attributing bread with culinary value. Supermarkets may be potentially significant players in the 'nutrition transition', providing Thais more convenient shopping at some cost to their healthy food choices.

76 FR 50992 - Notice of Availability of a Pest Risk Analysis for the Importation of Shredded Lettuce From Egypt

Science.gov (United States)

2011-08-17

...] Notice of Availability of a Pest Risk Analysis for the Importation of Shredded Lettuce From Egypt AGENCY... into the continental United States of fresh shredded lettuce from Egypt. Based on this analysis, we... fresh shredded lettuce from Egypt. We are making the pest risk analysis available to the public for...

Seed Production of Cutting Lettuce Varieties: Economical Facets

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Н. В. Лещук

2011-05-01

Full Text Available The article highlights current problems of cutting lettuce seed production for all its variants. Research background is provided to the composition of material expenditures for growing of every variant in particular. Economical efficiency of seed production in line with varietal certification requirements has been reproved.

Comparative Infection Progress Analysis of Lettuce big-vein virus and Mirafiori lettuce virus in Lettuce Crops by Developed Molecular Diagnosis Techniques.

Science.gov (United States)

Navarro, Jose A; Botella, Francisco; Maruhenda, Antonio; Sastre, Pedro; Sánchez-Pina, M Amelia; Pallas, Vicente

2004-05-01

ABSTRACT Nonisotopic molecular dot blot hybridization technique and multiplex reverse transcription-polymerase chain reaction assay for the specific detection of Lettuce big-vein virus (LBVV) and Mirafiori lettuce virus (MiLV) in lettuce tissue were developed. Both procedures were suitable for the specific detection of both viruses in a range of naturally infected lettuce plants from various Spanish production areas and seven different cultivars. The study of the distribution of both viruses in the plant revealed that the highest concentration of LBVV and MiLV occurred in roots and old leaves, respectively. LBVV infection progress in a lettuce production area was faster than that observed for MiLV. In spite of different rates of virus infection progress, most lettuce plants became infected with both viruses about 100 days posttransplant. The appearance of both viruses in lettuce crops was preceded by a peak in the concentration of resting spores and zoosporangia of the fungus vector Olpidium brassicae in lettuce roots.

Growth of wheat and lettuce and enzyme activities of soils under garlic stalk decomposition for different durations.

Science.gov (United States)

Han, Xu; Cheng, Zhihui; Meng, Huanwen

2017-07-01

Garlic (Allium sativum L.) stalk is a byproduct of garlic production that is normally thought of as waste but is now considered a useful biological resource. It is necessary to utilize this resource efficiently and reasonably to reduce environmental pollution and achieve sustainable agricultural development. The effect of garlic stalk decomposed for different durations was investigated in this study using wheat (Triticum aestivum L.) and lettuce (Lactuca sativa var. crispa L.) as test plants. Garlic stalk in early stages of decomposition inhibited the shoot and root lengths of wheat and lettuce, but it promoted the shoot and root lengths in later stages; longer durations of garlic stalk decomposition significantly increased the shoot and root fresh weights of wheat and lettuce, whereas shorter decomposing durations significantly decreased the shoot and root fresh weights; and garlic stalk at different decomposition durations increased the activities of urease, sucrase and alkaline phosphatase in soil where wheat or lettuce was planted. Garlic stalk decomposed for 30 or 40 days could promote the growth of wheat and lettuce plants as well as soil enzyme activities. These results may provide a scientific basis for the study and application of garlic stalk. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

FRESH FISH TRADE NETWORKS IN THE STREET MARKETS OF PALMAS, TOCANTINS STATE, BRAZIL

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Kelly Bessa

2016-12-01

Full Text Available This paper focuses on fresh fish trade networks found in the street markets of Palmas, capital of Tocantins state, Brazil, so as to identify the economic agents involved and the various geographical spaces which interact as a result of these networks. Fresh fish trade in Palmas takes place in distributor warehouses, grocery stores, supermarkets and hypermarkets, fish shops, and fishing communities, but it is street markets that constitute the most popular sale venues. Market sellers establish upstream supply networks with sectors in the fish food system (suppliers in primary and secondary production, distribution, and retail, whose interactions generate connections in Palmas (fishermen, distributors, retailers on a local scale, as well as connections with locations in Tocantins and Pará states (fishermen, fisheries, cold storage companies on a regional scale. Sellers also establish downstream trade networks with the end consumer at markets and with establishments in the food and small retail sectors, whose interactions produce mostly local connections, in Palmas and in the Luzimangues district (close to Palmas. Such connections are marked by consumption processes in these urban areas. Key-words: network, fresh fish trade, street markets.

Breeding highbush blueberry cultivars adapted to machine harvest for the fresh market

Science.gov (United States)

In recent years, world blueberry production has been split evenly between processing and fresh fruit markets. Machine harvest of highbush blueberry [northern highbush (NHB, Vaccinium corymbosum L.), southern highbush (SHB, Vaccinium corymbosum interspecific hybrids), and rabbiteye (RE, Vaccinium vi...

Effect of various conditions on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in fresh-cut lettuce using ultraviolet radiation.

Science.gov (United States)

Kim, Yoon-Hee; Jeong, Seul-Gi; Back, Kyeong-Hwan; Park, Ki-Hwan; Chung, Myung-Sub; Kang, Dong-Hyun

2013-09-16

The effect of various conditions on inactivation of foodborne pathogens and quality of fresh-cut lettuce during ultraviolet (254 nm, UVC) radiation was investigated. Lettuce was inoculated with a cocktail of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and treated at different temperatures (4 and 25 °C), distances between sample and lamp (10 and 50 cm), type of exposure (illuminated from one or two sides), UV intensities (1.36 to 6.80 mW/cm²), and exposure times (0.5 to 10 min), sequentially. UV treatment at 25 °C for 1 min achieved 1.45-, 1.35-, and 2.12-log reductions in surface-inoculated E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, whereas the reduction of these pathogens at 4 °C was 0.31, 0.57, and 1.16 log, respectively. UV radiation was most effective when distance from UV lamp to the sample was minimal (10 cm) and radiation area was maximal (two-sided exposure). All UV intensities significantly (P0.05) different from those of nontreated samples up to 5 min exposure. However, these qualities significantly (Pradiation under optimized conditions could reduce foodborne pathogens without adversely affecting color quality properties of fresh-cut lettuce. © 2013 Elsevier B.V. All rights reserved.

MARKETING RESPONSES TO CHANGING CONSUMER PREFERENCES IN THE FRESH BEEF INDUSTRY

OpenAIRE

Procopio, Mary Elizabeth

1990-01-01

The fresh meat industry is changing the way it markets its products. The decline in red meat consumption that has resulted from greater consumer concerns about the "healthfulness" of red meat, coupled with changes in consumer lifestyles emphasizing a need for convenience is contributing to the diminishment of "commodity selling" in favor of a true "marketing" approach (Pierson and Allen, 1986). In a traditional industry such as meats, the shift from a commodity-selling perspective (i.e., sell...

Lettuce growth and productivity under different types of soil covering = Crescimento e produtividade de alface sob diferentes tipos de cobertura do solo

Directory of Open Access Journals (Sweden)

Natalia Barreto Meneses

2016-07-01

Full Text Available In Brazil, the lettuce is the main vegetable produced and marketed, however, the crop is deficient in technology to optimize production and to ensure environmental sustainability in agricultural areas. This study aimed to verify the effect of different soil covering on soil temperature, and lettuce growth and yield. The experiment was settled adopting a randomized block design with six treatments consisted by different types of soil covering: cover with organic matter (CVe, black polyethylene (0.020 mm (PPt, silver polyethylene (0.020 mm (PPr, white polyethylene (0.020 mm (PBr, transparent polyethylene (0.100 mm (PTr and bare soil (control - T; and with five repetitions per each treatment. The variables analyzed were: total fresh weight, number and fresh weight of commercial leaves, root fresh weight, lettuce head diameter and yield. The soil temperature was monitored during the crop growth. The silver, white and black polyethylene coverings showed similar results. However, they were superior for all the evaluated characteristics compared to other coverings. The soil temperature was influenced by the different types of covering. There was increases of soil temperature for all the plastic coverings. However, the organic material reduced the soil temperature in comparison to the control treatment. = No Brasil, a alface é a principal hortaliça produzida e comercializada, carecendo, contudo, de tecnologias para otimizar a produção e garantir a sustentabilidade ambiental em áreas agrícolas. Objetivou-se com este trabalho verificar o efeito de diferentes coberturas do solo no crescimento, produtividade de plantas de alface e na temperatura do solo. O delineamento experimental utilizado foi em blocos casualizados, com seis tratamentos e cinco repetições. Os tratamentos estudados consistiram de tipos de cobertura do solo, sendo: cobertura com material vegetal (CVe, polietileno preto (0,020 mm (PPt, polietileno prata (0,020 mm (PPr, polietileno

Use of spent mushroom substrates from Agaricus subrufescens (syn. A. blazei, A. brasiliensis) and Lentinula edodes productions in the enrichment of a soil-based potting media for lettuce (Lactuca sativa) cultivation: Growth promotion and soil bioremediation.

Science.gov (United States)

Ribas, L C C; de Mendonça, M M; Camelini, C M; Soares, C H L

2009-10-01

This study aimed to assess physicochemical and microbiological properties of fresh spent mushroom substrates (SMSs)--without post-crop heat treatment--from Agaricus subrufescens and Lentinula edodes production to optimize the use of these residues in the soil enrichment for lettuce growth promotion and soil remediation. Organic matter and C content of both SMSs were high. Fresh A. subrufescens SMS was a good source of N, P and K. On the other hand, L. edodes SMS presented a lower concentration of these nutrients and a high level of immaturity. Both SMSs presented high electric conductivity values (2.5-3.4 mS/cm). Microbiological analysis, based upon enumeration of culturable bacteria (thermophilic and mesophilic) and fungi, and also evolution of CO(2), showed that SMSs played higher microbial diversity than soil control. Laccase activity from A. subrufescens SMS tended to remain constant during a 2-month period, while L. edodes SMS presented low laccase activity throughout the same period. Agaricus subrufescens and L. edodes were able to grow on a PDA (Potato Dextrose Agar) media supplemented with different concentrations of atrazine (1-50 microg/ml), degraded the herbicide, attaining rates of 35% and 26%, respectively. On experiments of lettuce growth promotion using a soil-based potting media with different SMS rates, 5% and 10% (dw) rates of A. subrufescens SMS resulted in higher lettuce aerial dry weights than the rates of 25% and 40%, the chemical fertilization (NPK) and the control (soil). At 10% supplementation, lettuce aerial dry weight increased 2.2 and 1.3 times compared to the control and the NPK treatment, respectively. Protein content increased along with SMS rates. Fresh A. subrufescens SMS was an excellent supplement for lettuce growth promotion and showed potential for remediation of biocides possibly due to improved microbial diversity and enzymatic activity. Fresh L. edodes SMS was not a good fertilizer, at least under the conditions tested

Irradiation of lettuce (Lactuca sativa. L.): microbiological and sensory aspects;Irradiacao de alface (Lactuca sativa. L.): aspectos microbiologicos e sensoriais

Energy Technology Data Exchange (ETDEWEB)

Tsuhako, Vanessa Provenzano

2005-07-01

The increasing demand for fresh foods have stimulated the marketing of minimally processed vegetables. However, these products maintain most of their natural microbiota even after being sanitized, including pathogenic microorganisms. Refrigerated storage allows the growth of psychotropic microorganisms and among them the pathogen Listeria monocytogenes. The ingestion of food contaminated with L. monocytogenes may represent a risk to pregnant women and their fetuses and to immunocompromised people. Non-thermal alternative processes for food preservation, such as irradiation, can reduce pathogenic and spoilage microorganism populations without impairing substantial changes in sensory, physical or chemical attributes. The aims of this research were to evaluate the effect of gamma radiation on L. monocytogenes artificially inoculated on minimally processed lettuce, to evaluate its effect on lettuce leaves through acceptance sensory test and to determine the irradiated vegetable shelf life through sensory and microbiological tests. A mixture of 4 types of lettuce (Iceberg, Boston, Loose-leaf and Red loose-leaf) were artificially inoculated with L. monocytogenes (7 log UFC/g lettuce) and then exposed to 0.3; 0.6; 0.9 and 1.2 kGy, under refrigeration. The DlO values for L. monocytogenes varied fram 0.18 to 0.21 kGy. Sensory and microbiological tests indicated that the shelf life of Iceberg lettuce stored at 7 deg C was 5 and 7 days for the irradiated and non-irradiated samples, respectively, and for the irradiated and non-irradiated Loose-leaf lettuce samples were 10 days. For the non-irradiated Boston sample, the shelf life was 3 days and for the Irradiated 7 days. Red loose-leaf showed 5 and 4 days of shelf lives for the irradiated and non-irradiated, respectively. Irradiated samples presented better microbiological quality than non-irradiated ones. The irradiation is feasible process to improve quality and safety of lettuce leaves. (author)

Analysis of fresh maize marketing in Anambra state, Nigeria ...

African Journals Online (AJOL)

Analysis of fresh maize marketing in Anambra state, Nigeria. ... on marketing income in Anambra State, this study utilized descriptive statistic, Sherpherd-futrel model of determining marketing efficiency ... EMAIL FULL TEXT EMAIL FULL TEXT

Active packaging for fresh-cut iceberg lettuce (Lactuca sativa L. / Embalagem ativa para alface americana (Lactuca sativa L. minimamente processada

Directory of Open Access Journals (Sweden)

Fábio Yamashita

2010-09-01

Full Text Available The minimal processing of horticultural products endears the raw material and is convenient to the consumer due to the facility for preparing and consuming. The objective of this work was to develop an active packaging for fresh-cut iceberg lettuce (Lactuca sativa L. to increase its shelf life. Minimally processing methodology was defined and the product quality was determined by sensorial, physico-chemical and microbiological analysis. The lettuce tree was selected, trimmed, pre-washed, soaked in sanitized water (100ppm of active chlorine for 15 minutes and centrifuged. The lettuce leafs were packed in polypropylene pots with a sachet containing 1-methylcyclopropene (1-MCP and sealed with biodegradable starch film. Soon after the processing, the product was stored at 4oC for 12 days. Periodically samples were evaluated in terms of appearance and purchase intention, soluble solids and vitamin C contents, pH, texture, color, weight loss and total count of mesophilic and psicotrofic microorganisms, lactic bacteria, mould and yeast. Using 1-MCP in sachet format did not increase the lettuce shelf life but the minimal processing combined with packaging sealed with biodegradable film is practicable as the product showed good sensorial acceptance, low microbiological counts and shelf life of 5 days at 4oC.O processamento mínimo de produtos hortícolas agrega valor à matéria-prima e são convenientes ao consumidor, devido à facilidade de preparo e consumo. O objetivo do trabalho foi desenvolver uma embalagem ativa para alface americana (Lactuca sativa L. minimamente processada visando o aumento da vida útil. Foi definida uma metodologia de processamento mínimo e a qualidade do produto foi acompanhada através de avaliação sensorial, físico-química e microbiológica. As cabeças de alface foram desfolhadas, selecionadas, pré-lavadas, sanificadas (100 ppm de cloro ativo por 15 minutos e centrifugadas. As folhas foram acondicionadas em potes de

7 CFR 457.128 - Guaranteed production plan of fresh market tomato crop insurance provisions.

Science.gov (United States)

2010-01-01

... the insured crop directly to consumers without the intervention of an intermediary such as a... Special Provisions. The price election you choose for each type must have the same percentage relationship...: (A) Grown fresh market tomatoes for commercial sales; or (B) Participated in the management of a...

Online hyperspectral imaging system for evaluating quality of agricultural products

Science.gov (United States)

Mo, Changyeun; Kim, Giyoung; Lim, Jongguk

2017-06-01

The consumption of fresh-cut agricultural produce in Korea has been growing. The browning of fresh-cut vegetables that occurs during storage and foreign substances such as worms and slugs are some of the main causes of consumers' concerns with respect to safety and hygiene. The purpose of this study is to develop an on-line system for evaluating quality of agricultural products using hyperspectral imaging technology. The online evaluation system with single visible-near infrared hyperspectral camera in the range of 400 nm to 1000 nm that can assess quality of both surfaces of agricultural products such as fresh-cut lettuce was designed. Algorithms to detect browning surface were developed for this system. The optimal wavebands for discriminating between browning and sound lettuce as well as between browning lettuce and the conveyor belt were investigated using the correlation analysis and the one-way analysis of variance method. The imaging algorithms to discriminate the browning lettuces were developed using the optimal wavebands. The ratio image (RI) algorithm of the 533 nm and 697 nm images (RI533/697) for abaxial surface lettuce and the ratio image algorithm (RI533/697) and subtraction image (SI) algorithm (SI538-697) for adaxial surface lettuce had the highest classification accuracies. The classification accuracy of browning and sound lettuce was 100.0% and above 96.0%, respectively, for the both surfaces. The overall results show that the online hyperspectral imaging system could potentially be used to assess quality of agricultural products.

Detection of Lettuce Discoloration Using Hyperspectral Reflectance Imaging.

Science.gov (United States)

Mo, Changyeun; Kim, Giyoung; Lim, Jongguk; Kim, Moon S; Cho, Hyunjeong; Cho, Byoung-Kwan

2015-11-20

Rapid visible/near-infrared (VNIR) hyperspectral imaging methods, employing both a single waveband algorithm and multi-spectral algorithms, were developed in order to discrimination between sound and discolored lettuce. Reflectance spectra for sound and discolored lettuce surfaces were extracted from hyperspectral reflectance images obtained in the 400-1000 nm wavelength range. The optimal wavebands for discriminating between discolored and sound lettuce surfaces were determined using one-way analysis of variance. Multi-spectral imaging algorithms developed using ratio and subtraction functions resulted in enhanced classification accuracy of above 99.9% for discolored and sound areas on both adaxial and abaxial lettuce surfaces. Ratio imaging (RI) and subtraction imaging (SI) algorithms at wavelengths of 552/701 nm and 557-701 nm, respectively, exhibited better classification performances compared to results obtained for all possible two-waveband combinations. These results suggest that hyperspectral reflectance imaging techniques can potentially be used to discriminate between discolored and sound fresh-cut lettuce.

Uptake and Accumulation of Pharmaceuticals in Lettuce Under Surface and Overhead Irrigations

Science.gov (United States)

Bhalsod, G.; Chuang, Y. H.; Jeon, S.; Gui, W.; Li, H.; Guber, A.; Zhang, W.

2015-12-01

Pharmaceuticals and personal care products are being widely detected in wastewater and surface waters. As fresh water becomes scarcer, interests in using reclaimed water for crop irrigation is intensified. Since reclaimed waters often carry trace levels of pharmaceuticals, accumulation of pharmaceuticals in food crops could increase the risk of human exposure. This study aims to investigate uptake and accumulations of pharmaceuticals in greenhouse-grown lettuce under contrasting irrigation practices (i.e., overhead and surface irrigations). Lettuce was irrigated with water spiked with 11 commonly used pharmaceuticals (acetaminophen, caffeine, carbamazepine, sulfadiazine, sulfamethoxazole, carbadox, trimethoprim, lincomycin hydrochloride, oxytetracycline hydrochloride, monensin sodium, and tylosin). Weekly sampling of lettuce roots, shoots, and soils were continued for 5 weeks, and the samples were freeze dried, extracted for pharmaceuticals and analyzed by LC-MS/MS. Preliminary results indicate that higher concentrations of pharmaceuticals were found in overhead irrigated lettuce compared to surface irrigated lettuce. For carbamezapine, sulfadiazine, trimethoprim, oxytetracycline, and monensin sodium, their concentrations generally increased in lettuce shoots in the overhead treatment over time. However, acetaminophen was found at higher concentrations in both shoots and roots, indicating that acetaminophen can be easily transported in the plant system. This study provides insight on developing better strategies for using reclaimed water for crop irrigations, while minimizing the potential risks of pharmaceutical contamination of vegetables.

77 FR 22467 - Common Crop Insurance Regulations; Fresh Market Tomato (Dollar Plan) Crop Provisions

Science.gov (United States)

2012-04-16

...-0006] RIN 0563-AC32 Common Crop Insurance Regulations; Fresh Market Tomato (Dollar Plan) Crop... Insurance Corporation (FCIC) finalizes the Common Crop Insurance Regulations, Fresh Market Tomato (Dollar... Common Crop Insurance Regulations (7 CFR part 457), Fresh Market Tomato (Dollar Plan) Crop Provisions...

Detailed characterization of Mirafiori lettuce virus-resistant transgenic lettuce.

Science.gov (United States)

Kawazu, Yoichi; Fujiyama, Ryoi; Noguchi, Yuji; Kubota, Masaharu; Ito, Hidekazu; Fukuoka, Hiroyuki

2010-04-01

Lettuce big-vein disease is caused by Mirafiori lettuce virus (MiLV), which is vectored by the soil-borne fungus Olpidium brassicae. A MiLV-resistant transgenic lettuce line was developed through introducing inverted repeats of the MiLV coat protein (CP) gene. Here, a detailed characterization study of this lettuce line was conducted by comparing it with the parental, non-transformed 'Kaiser' cultivar. There were no significant differences between transgenic and non-transgenic lettuce in terms of pollen fertility, pollen dispersal, seed production, seed dispersal, dormancy, germination, growth of seedlings under low or high temperature, chromatographic patterns of leaf extracts, or effects of lettuce on the growth of broccoli or soil microflora. A significant difference in pollen size was noted, but the difference was small. The length of the cotyledons of the transgenic lettuce was shorter than that of 'Kaiser,' but there were no differences in other morphological characteristics. Agrobacterium tumefaciens used for the production of transgenic lettuce was not detected in transgenic seeds. The transgenic T(3), T(4), and T(5) generations showed higher resistance to MiLV and big-vein symptoms expression than the resistant 'Pacific' cultivar, indicating that high resistance to lettuce big-vein disease is stably inherited. PCR analysis showed that segregation of the CP gene was nearly 3:1 in the T(1) and T(2) generations, and that the transgenic T(3) generation was homozygous for the CP gene. Segregation of the neomycin phosphotransferase II (npt II) gene was about 3:1 in the T(1) generation, but the full length npt II gene was not detected in the T(2) or T(3) generation. The segregation pattern of the CP and npt II genes in the T(1) generation showed the expected 9:3:3:1 ratio. These results suggest that the fragment including the CP gene and that including the npt II gene have been integrated into two unlinked loci, and that the T(1) plant selected in our study did

Use of organic acids to inactivate Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on organic fresh apples and lettuce.

Science.gov (United States)

Park, Sang-Hyun; Choi, Mi-Ran; Park, Jeong-Woong; Park, Ki-Hwan; Chung, Myung-Sub; Ryu, Sangryeol; Kang, Dong-Hyun

2011-08-01

This study was undertaken to investigate the antimicrobial effect of organic acids against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on whole red organic apples and lettuce. Several studies have been conducted to evaluate organic acids as sanitizers. However, no studies have compared antimicrobial effects of various organic acids on organic fresh produce, including evaluation of color changes of produce. Apples and lettuce were inoculated with a cocktail of 3 strains each of 3 foodborne pathogens provided above and treated with 1% and 2% organic acids (propionic, acetic, lactic, malic, and citric acid) for 0, 0.5, 1, 5, and 10 min. With increasing treatment time and acid concentration, organic acid treatments showed significant reduction compared to the control treatment (distilled water), and differences in antimicrobial effects between organic acids were observed. After 10 min of treatment with 1% and 2% organic acids in apples, propionic (0.92 to 2.75 log reduction), acetic (0.52 to 2.78 log reduction), lactic (1.69 to >3.42 log reduction), malic (1.48 to >3.42 log reduction), and citric acid (1.52 to >3.42 log reduction) exhibited significant (P acid (1.85 to 2.86 log reduction) showed significant (P acids treatment were not significant during storage. It is suggested that organic acids have a potential as sanitizers for organic fresh produce. These data may help the organic produce industry provide safe fresh produce for consumers. © 2011 Institute of Food Technologists®

Growing patterns to produce 'nitrate-free' lettuce (Lactuca sativa).

Science.gov (United States)

Croitoru, Mircea Dumitru; Muntean, Daniela-Lucia; Fülöp, Ibolya; Modroiu, Adriana

2015-01-01

Vegetables can contain significant amounts of nitrate and, therefore, may pose health hazards to consumers by exceeding the accepted daily intake for nitrate. Different hydroponic growing patterns were examined in this work in order to obtain 'nitrate-free lettuces'. Growing lettuces on low nitrate content nutrient solution resulted in a significant decrease in lettuces' nitrate concentrations (1741 versus 39 mg kg(-1)), however the beneficial effect was cancelled out by an increase in the ambient temperature. Nitrate replacement with ammonium was associated with an important decrease of the lettuces' nitrate concentration (from 1896 to 14 mg kg(-1)) and survival rate. An economically feasible method to reduce nitrate concentrations was the removal of all inorganic nitrogen from the nutrient solution before the exponential growth phase. This method led to lettuces almost devoid of nitrate (10 mg kg(-1)). The dried mass and calcinated mass of lettuces, used as markers of lettuces' quality, were not influenced by this treatment, but a small reduction (18%, p < 0.05) in the fresh mass was recorded. The concentrations of nitrite in the lettuces and their modifications are also discussed in the paper. It is possible to obtain 'nitrate-free' lettuces in an economically feasible way.

Ability of Shiga toxigenic Escherichia coli to survive within dry-surface biofilms and transfer to fresh lettuce.

Science.gov (United States)

Adator, Emelia Hornam; Cheng, Meining; Holley, Rick; McAllister, Tim; Narvaez-Bravo, Claudia

2018-03-23

Biofilms are known to play important roles in bacterial survival and persistence in food-processing environments. This study aimed to determine the ability of the top 7 STEC serotypes to form biofilms on polystyrene (POL) and stainless steel (SS) plates and to quantify their survival and transfer from dry-surface biofilms to lettuce pieces. The ability of 14 STEC strains to form biofilms on these two materials at different exposure times and temperatures was assessed using crystal violet, Congo red and SEM. At 10 °C all serotypes were weak biofilm producers on both surfaces. In contrast, serotypes O45-040, O45-445, O103-102, O103-670 and O157-R508 were strong biofilm producers at 25 °C. Strains O103-102, O103-670, O111-CFS, O111-053 and O157:H7-R508 were expressers of curli. Under scanning electron microscopy, strains O103-670, O111-CFS, O157-R508, and O121-083 formed more discernible multilayer, mature biofilms on SS coupons. Regardless of the surface (POL/SS), all STEC strains were able to transfer viable cells onto fresh lettuce within a short contact time (2 min) to varying degrees (up to 6.35 log cfu/g). On POL, viable cell of almost all serotypes exhibited decreased detachment (p = 0.001) over 6 days; while after 30 days on SS, serotypes O45-040, O103-102, O103-670, O111-053, O111-CFS, O121-083, O145-231 O157:H7-R508 and O157:H7-122 were transferred to lettuce. After enrichment, all 14 STEC strains were recovered from dry-surface biofilms on POL and SS plates after 30 days. Results demonstrated that the top 7 STEC remained viable within dry-surface biofilms for at least 30 days, transferring to lettuce within 2 min of exposure and acting as a source of adulteration. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Phosphorus levels in soil and lettuce production due to phosphorus fertilization

Directory of Open Access Journals (Sweden)

José Ricardo Mantovani

2014-09-01

Full Text Available The leafy vegetables are considered nutrient-demanding, but are scarce in the literature works about phosphorus fertilization. This study aimed to evaluate the effect of phosphate on the production of lettuce, content and amount of P accumulated in leaf plants, and to relate levels of P in the clayey soil with plant production. The experiment was conducted in a greenhouse in pots in a randomized block design with ten treatments and four replications. The treatments were made up of P, corresponding to 0, 50, 100, 150, 200, 300, 400, 500, 600 and 700 mg dm-3, as triple superphosphate powder. Portions of 6 dm3 of the clay soil (420 g kg-1 clay received lime, aimed at raising the V % soil to 70 %, equivalent to 20 t ha-1 of cattle manure, and the phosphate fertilizer according to the treatments, remaining incubated for about 30 days. At the end of incubation, each pot received a change of lettuce cultivar Verônica. The plant harvesting was performed 39 days after transplanting the seedlings. O P gave large increases in growth and production of lettuce, and culture responded positively to the application of high doses of the nutrient. A dose of 350 mg dm-3, equivalent to 800 kg ha-1 P2O5, was the most suitable for growing lettuce in the clay soil. In this work conditions, the phosphorus fertilizations it was necessary when the P-Mehlich contents in the clay soil were less than 75 mg dm-3.

76 FR 24291 - Proposed National Marketing Agreement Regulating Leafy Green Vegetables; Recommended Decision and...

Science.gov (United States)

2011-04-29

... the hearing indicates that the value of leafy green vegetables grown for the United States fresh and... the 2008 production value, lettuce crops accounted for 79 percent, cabbage accounted for 15 percent... Food Safety Guidelines for Lettuce and Leafy Greens Supply Chain''. These guidelines have not been...

Resistance to lettuce aphid (Nasonovia ribisnigri) biotype 0 in wild lettuce accessions PI 491093 and PI 274378

Science.gov (United States)

Lettuce aphid, Nasonovia ribisnigri Mosley (Homoptera : Aphididae), is a major insect pest of lettuce, Lactuca sativa L, in many commercial lettuce productions areas around the world. Resistance to lettuce aphid was first reported in Lactuca virosa L. accession IVT 280 and characterized as complete,...

Genetics of resistance against lettuce downy mildew

Science.gov (United States)

Lettuce (Lactuca sativa) is one of the most valuable vegetable crops in the U.S. Downy mildew (DM), caused by Bremia lactucae, is the most important foliar disease of lettuce worldwide, which decreases the quality of the marketable portion of the crop. The use of resistant varieties carrying dominan...

Quantitative transfer of Escherichia coli O157:H7 to equipment during small-scale production of fresh-cut leafy greens.

Science.gov (United States)

Buchholz, Annemarie L; Davidson, Gordon R; Marks, Bradley P; Todd, Ewen C D; Ryser, Elliot T

2012-07-01

Postharvest contamination and subsequent spread of Escherichia coli O157:H7 can occur during shredding, conveying, fluming, and dewatering of fresh-cut leafy greens. This study quantified E. coli O157:H7 transfer from leafy greens to equipment surfaces during simulated small-scale commercial processing. Three to five batches (22.7 kg) of baby spinach, iceberg lettuce, and romaine lettuce were dip inoculated with a four-strain cocktail of avirulent, green fluorescent protein-labeled, ampicillinresistant E. coli O157:H7 to contain ∼10(6), 10(4), and 10(2) CFU/g, and then were processed after 1 h of draining at ∼23°C or 24 h of storage at 4°C. Lettuce was shredded using an Urschel TransSlicer at two different blade and belt speeds to obtain normal (5 by 5 cm) and more finely shredded (0.5 by 5 cm) lettuce. Thereafter, the lettuce was step conveyed to a flume tank and was washed and then dried using a shaker table and centrifugal dryer. Product (25-g) and water (40-ml) samples were collected at various points during processing. After processing, product contact surfaces (100 cm(2)) on the shredder (n = 14), conveyer (n = 8), flume tank (n = 11), shaker table (n = 9), and centrifugal dryer (n = 8) were sampled using one-ply composite tissues. Sample homogenates diluted in phosphate or neutralizing buffer were plated, with or without prior 0.45- m m membrane filtration, on Trypticase soy agar containing 0.6% yeast extract supplemented with 100 ppm of ampicillin to quantify green fluorescent protein-labeled E. coli O157:H7 under UV light. During leafy green processing, ∼90% of the E. coli O157:H7 inoculum transferred to the wash water. After processing, E. coli O157:H7 populations were highest on the conveyor and shredder (Ptransfer.

Market restructuring and public incentives: the Turkish case of fresh produce marketing cooperatives

OpenAIRE

Lemeilleur, Sylvaine; Bignebat, Celine; Codron, Jean Marie; Humboldt University of Berlin

2006-01-01

Faced to the fast restructuring agrofood markets in Turkey, the Turkish State set up new institutional devices to support agricultural marketing cooperatives. This article analyses the dynamics of these public incentives towards producers’ organizations on the restructuration of the Turkish fresh fruit and vegetable market. The wholesale market law enacted 1995 established brokers on wholesale market halls who collected an atomized supply and guarantee the access of small producers to large s...

Fresh fish ( Clarias gariepinus ) marketing system in major towns of ...

African Journals Online (AJOL)

This study was carried out to investigate marketing system, market channel, nature of costs, market margins and the factors determining the marketing profit of fresh fish (Clarias gariepinus) in major towns in Ibarapa Zone, Oyo state. Data were collected through the use of questionnaire administered to the fish traders.

AND DEVELOPMENT OF LETTUCE ON CHERNOZEM ORDINARY

Directory of Open Access Journals (Sweden)

N. V. Gromakova

2017-01-01

Full Text Available Lettuce is very popular in the Russian consumer market. Special conditions for its cultivation determine the need to select modern, inexpensive elements of agro-technology that promote high yields. At present biochar (bio-coal is considered as a promising organic fertilizer. Its main difference lies in the possibility of using any organic raw material in its production. In Russia, the study on the use of biochar is limited; there is no practice of applying it in the complex of agricultural techniques of various agricultural crops. In the conditions of vegetative experiment, the influence of various doses of biochar in ordinary chernozem on the growth and development of lettuce (Lactuca sativa cultivar was studied in accordance with the developed experiment scheme: control (without biochar, supplemented with 1, 2 and 5 % of biochar. In the experiment, biochar obtained from birch wood was used, by pyrolysis method in fraction of 0.5-5mm. The following observations and determinations were made: the timing of the onset of the phases of plant development, the length of the roots, the number of leaves, the length of the largest leaf, the height of plants, the diameter of the rosette, the mass of 10 plants. The use of biochar contributed to a reduction of beginning period technical ripeness in plants, particularly in variant with the addition of 2%. The increase in root length, the number of leaves of lettuce plants as compared with to control in variants with 2 and 5% of biocar has been observed. The length of the largest leaf, the height of plants and the diameter of the rosette of lettuce are characterized by a significant improvement, even in variant with 1%. Productivity of lettuce was highest in the variant with 2% of biochar applied to the soil.

PRODUCTION OF LETTUCE UNDER GREEN MANURING WITH Calotropis procera IN TWO CULTIVATION SEASONS

Directory of Open Access Journals (Sweden)

ÊNIO GOMES FLÔR SOUZA

2017-01-01

Full Text Available The production of vegetable crops is characterized by intensive land use, high input demands and the requirement of strategic management adoption with an agro - ecological approach. In this study, agronomic indicators were evaluated in lettuce fertilized with different amounts of roostertree biomass; fertilizer was incorporated into the soil at distinct times and seedlings were planted in two cropping seasons (spring and autumn - winter in Serra Talhada, Pernambuco state, Brazil. The experimental design consisted of randomized complete blocks with three replications and treatments arranged in a 4 x 4 factorial scheme. The first factor was the amounts of roostertree biomass (5.4, 8.8, 12.2, and 15.6 t ha - 1 on a dry basis and the second the manure incorporation times (0, 10, 20, and 30 days before lettuce transplanting. The variables evaluated in the lettuce crop were: plant height and diameter, number of leaves per plant, productivity of green mass, and dry shoot mass. Maximum productivity and dry shoot mass were obtained using fertilization with 15.6 t ha - 1 . A synchrony between supply of nutrients by green manure and the period of maximum demand by lettuce was observed in the incorporation times of 10 (spring and 20 (autumn - winter days before transplanting. Cultivation in the spring resulted in higher vegetative growth.

Effects of marketing group on the quality of fresh and cured hams sourced from a commercial processing facility

Science.gov (United States)

The objective was: 1) to characterize the effect of marketing 30 group on fresh and cured ham quality, and 2) to determine which fresh ham traits correlated to cured ham quality traits. Pigs raised in 8 barns representing two seasons (hot and cold) and two production focuses (lean and quality) were ...

Mannanase production by the lettuce endosperm : Control by the embryo.

Science.gov (United States)

Halmer, P; Bewley, J D

1979-01-01

Endo-β-mannanase (EC 3.2.1.78) is produced and secreted by the cells of the endosperm of lettuce (lactuca sativa L.) "seeds" (achenes). In imbibed intact seeds, production is prevented by inhibitors. If the endosperm is incubated alone, these inhibitors can be removed by leaching, allowing mannanase production. Abscisic acid, a component of lettuce seeds, inhibits the production of mannanase in the isolated endosperm, and may be involved in regulation of mannanase production in intact seeds. During germination the inhibition is removed, beginning 4-8 h after red-light irradiation, which was given 4 h from sowing. The cotyledons participate in this process, and are controlled by events occuring in the axis within 4 h from red-light irradiation. This control by the axis apparently depends on the exchange of diffusible substances. Both benzyladenine and gibberellic acid can replace the influence of the axis if the latter is removed, and may therefore be involved in the control by the axis of the rest of the seed.

The evolving fresh market berry industry in Santa Cruz and Monterey counties

Directory of Open Access Journals (Sweden)

Laura Tourte

2016-08-01

Full Text Available The fresh market berry industry in Santa Cruz and Monterey counties has contributed significantly to the agricultural vibrancy of the two counties and the state of California. Dramatic growth in strawberry, raspberry and blackberry production has been documented over the last 50 years, and most notably since the 1980s. Factors influencing this growth include innovations in agricultural practices and heightened consumer demand. Here, we review the historical context for the berry industry in Santa Cruz and Monterey counties. Organic production, production economics and challenges for the future are also discussed.

Robust production of virus-like particles and monoclonal antibodies with geminiviral replicon vectors in lettuce

Science.gov (United States)

Lai, Huafang; He, Junyun; Engle, Michael; Diamond, Michael S.; Chen, Qiang

2011-01-01

Summary Pharmaceutical protein production in plants has been greatly promoted by the development of viral-based vectors and transient expression systems. Tobacco and related Nicotiana species are currently the most common host plants for generation of plant-made pharmaceutical proteins (PMPs). Downstream processing of target PMPs from these plants, however, is hindered by potential technical and regulatory difficulties due to the presence of high levels of phenolics and toxic alkaloids. Here, we explored the use of lettuce, which grows quickly yet produces low levels of secondary metabolites, and viral vector-based transient expression systems to develop a robust PMP production platform. Our results showed that a geminiviral replicon system based on the bean yellow dwarf virus permits high-level expression in lettuce of virus-like particles (VLP) derived from the Norwalk virus capsid protein and therapeutic monoclonal antibodies (mAbs) against Ebola and West Nile viruses. These vaccine and therapeutic candidates can be readily purified from lettuce leaves with scalable processing methods while fully retaining functional activity. Furthermore, this study also demonstrated the feasibility of using commercially produced lettuce for high-level PMP production. This allows our production system to have access to unlimited quantities of inexpensive plant material for large-scale production. These results establish a new production platform for biological pharmaceutical agents that is effective, safe, low-cost, and amenable to large-scale manufacturing. PMID:21883868

Cadmium and chromium effects on seed germination and root elongation in lettuce, spinach and Swiss chard

Directory of Open Access Journals (Sweden)

Oscar V Bautista

2013-04-01

Full Text Available The La Ramada district and the Bogota River are the principal water resources used for horticultural crop production on the Bogota Plateau, which contain channel pollutant materials, including heavy metals due to domestic and industrial activities on the Plateau. These materials have effects on crop production in this zone. The present research, under laboratory conditions, aimed to evaluate the effect of three concentrations (25, 35 and 50 µM L-1 of cadmium (Cd and chromium (Cr on imbibition, seed germination and root elongation in lettuce (Lactuca sativa var. Batavia, Swiss chard (Beta vulgaris var. cicla "White Ribbed", and spinach (Spinacia oleracea Hib. 424, three species widely cultivated on the Plateau. The three species used for evaluation showed a differential susceptibility response to Cd and Cr. In lettuce, fresh weight increase (imbibition was lower with all Cd concentrations at the last day of observation and at 25 µM L-1 of Cd in Swiss chard. Cadmium reduced seed germination by up to 46%, 97% and 8% in Swiss chard, lettuce and spinach, respectively. Also, root elongation decreased in Cd treatments by up to 57%, 89% and 56%, for Swiss chard, lettuce and spinach, respectively. Chromium, which showed fewer negative effects, decreased germination by up to 29% in Swiss chard, 6% in lettuce and 34% in spinach, as compared to the control

Composition of hydroponic lettuce: effect of time of day, plant size, and season.

Science.gov (United States)

Gent, Martin P N

2012-02-01

The diurnal variation of nitrate and sugars in leafy green vegetables may vary with plant size or the ability of plants to buffer the uptake, synthesis, and use of metabolites. Bibb lettuce was grown in hydroponics in a greenhouse and sampled at 3 h intervals throughout one day in August 2007 and another day in November 2008 to determine fresh weight, dry matter, and concentration of nitrate and sugars. Plantings differing in size and age were sampled on each date. The dry/fresh weight ratio increased during the daylight period. This increase was greater for small compared to large plants. On a fresh weight basis, tissue nitrate of small plants was only half that of larger plants. The variation in concentration with time was much less for nitrate than for soluble sugars. Soluble sugars were similar for all plant sizes early in the day, but they increased far more for small compared to large plants in the long days of summer. The greatest yield on a fresh weight basis was obtained by harvesting lettuce at dawn. Although dry matter or sugar content increased later in the day, there is no commercial benefit to delaying harvest as consumers do not buy lettuce for these attributes. Copyright © 2011 Society of Chemical Industry.

Relation between microbiological quality, metabolite production and sensory quality of equilibrium modified atmosphere packaged fresh-cut produce.

Science.gov (United States)

Jacxsens, L; Devlieghere, F; Ragaert, P; Vanneste, E; Debevere, J

2003-06-25

The quality of four types of fresh-cut produce, packaged in consumer-sized packages under an equilibrium modified atmosphere and stored at 7 degrees C, was assessed by establishing the relation between the microbial outgrowth and the corresponding production of nonvolatile compounds and related sensory disorders. In vitro experiments, performed on a lettuce-juice-agar, demonstrated the production of nonvolatile compounds by spoilage causing lactic acid bacteria and Enterobacteriaceae. Pseudomonas fluorescens and yeasts, however, were not able to produce detectable amounts of nonvolatile metabolites. The type of spoilage and quality deterioration in vivo depended on the type of vegetable. Mixed lettuce and chicory endives, leafy tissues, containing naturally low concentrations of sugars, showed a spoilage dominated by Gram-negative microorganisms, which are not producing nonvolatile compounds. Sensory problems were associated with visual properties and the metabolic activity of the plant tissue. Mixed bell peppers and grated celeriac, on the other hand, demonstrated a fast and intense growth of spoilage microorganisms, dominated by lactic acid bacteria and yeasts. This proliferation resulted in detectable levels of organic acids and the rejection by the trained sensory panel was based on the negative perception of the organoleptical properties (off-flavour, odour and taste). The applied microbiological criteria corresponded well with detectable changes in sensory properties and measurable concentrations of nonvolatile compounds, surely in the cases where lactic acid bacteria and yeasts were provoking spoilage. Consequently, the freshness of minimally processed vegetables, sensitive for outgrowth of lactic acid bacteria and yeasts (e.g., carrots, celeriac, bell peppers, mixtures with non-leafy vegetables) can be evaluated via analysis of the produced nonvolatile compounds.

Diversity of Antimicrobial Resistance and Virulence Determinants in Pseudomonas aeruginosa Associated with Fresh Vegetables

Directory of Open Access Journals (Sweden)

Kashina Allydice-Francis

2012-01-01

Full Text Available With the increased focus on healthy eating and consuming raw vegetables, this study assessed the extent of contamination of fresh vegetables by Pseudomonas aeruginosa in Jamaica and examined the antibiotic susceptibility profiles and the presence of various virulence associated determinants of P. aeruginosa. Analyses indicated that vegetables from retail markets and supermarkets were widely contaminated by P. aeruginosa; produce from markets were more frequently contaminated, but the difference was not significant. Lettuce and carrots were the most frequently contaminated vegetables, while tomatoes were the least. Pigment production (Pyoverdine, pyocyanin, pyomelanin and pyorubin, fluorescein and alginate were common in these isolates. Imipenem, gentamicin and ciprofloxacin were the most inhibitory antimicrobial agents. However, isolates were resistant or showed reduced susceptibility to ampicillin, chloramphenicol, sulphamethoxazole/trimethoprim and aztreonam, and up to 35% of the isolates were resistant to four antimicrobial agents. As many as 30% of the isolates were positive for the fpv1 gene, and 13% had multiple genes. Sixty-four percent of the isolates harboured an exoenzyme gene (exoS, exoT, exoU or exoY, and multiple exo genes were common. We conclude that P. aeruginosa is a major contaminant of fresh vegetables, which might be a source of infection for susceptible persons within the community.

PRODUCTIVITY OF LETTUCE CULTURE IN THE FUNCTION OF NITROGEN FERTILIZER MANAGENT

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G. A. Nascimento

2017-12-01

Full Text Available The objective of this work was to evaluate the lettuce yield under the different management of nitrogen fertilization. The ammonium sulfate (NH42 SO4 with 950 kg ha-1 was used as a source of nitrogen. The treatments were constituted: 100% of the N incorporated in the base; 100% of N in single application coverage; 50% of the N incorporated in the base and 50% in cover parceled in 2 times; 25% of the N incorporated in the base and 75% in coverage, divided in 3 times; 100% of N in 3-fold parcel coverage and the control (without N application. The plants were harvested 42 days after transplanting and analyzed the variables weight of the fresh aerial part, aerial dry mass, the number of leaves and height of plant and stem diameter. It was verified that, for all evaluated characteristics, the response to nitrogen application was positive. It was concluded that the treatments 2, 3, 4 and 5 did not difference significantly from each other, and there was no decrease in productivity, the control verified the nitrogen requirement for this crop being below the averages in all variables analyzed.

Lactic acid bacteria and natural antimicrobials to improve the safety and shelf-life of minimally processed sliced apples and lamb's lettuce.

Science.gov (United States)

Siroli, Lorenzo; Patrignani, Francesca; Serrazanetti, Diana I; Tabanelli, Giulia; Montanari, Chiara; Gardini, Fausto; Lanciotti, Rosalba

2015-05-01

Outbreaks of food-borne disease associated with the consumption of fresh and minimally processed fruits and vegetables have increased dramatically over the last few years. Traditional chemical sanitizers are unable to completely eradicate or kill the microorganisms on fresh produce. These conditions have stimulated research to alternative methods for increasing food safety. The use of protective cultures, particularly lactic acid bacteria (LAB), has been proposed for minimally processed products. However, the application of bioprotective cultures has been limited at the industrial level. From this perspective, the main aims of this study were to select LAB from minimally processed fruits and vegetables to be used as biocontrol agents and then to evaluate the effects of the selected strains, alone or in combination with natural antimicrobials (2-(E)-hexenal/hexanal, 2-(E)-hexenal/citral for apples and thyme for lamb's lettuce), on the shelf-life and safety characteristics of minimally processed apples and lamb's lettuce. The results indicated that applying the Lactobacillus plantarum strains CIT3 and V7B3 to apples and lettuce, respectively, increased both the safety and shelf-life. Moreover, combining the selected strains with natural antimicrobials produced a further increase in the shelf-life of these products without detrimental effects on the organoleptic qualities. Copyright © 2014 Elsevier Ltd. All rights reserved.

Genome-wide association study for lettuce cultivars with improved salad processing efficiency

Science.gov (United States)

Lettuce (Lactuca sativa L.) is widely used as the main ingredient of packaged leafy vegetable salads. Salad lettuce can have short shelf life, decaying as early as eight days after harvest and reducing the nutritional quality. Decayed lettuce is not marketable, produces extra waste, and results in t...

Decontamination and survival of Enterobacteriaceae on shredded iceberg lettuce during storage.

Science.gov (United States)

Osaili, Tareq M; Alaboudi, Akram R; Al-Quran, Heba N; Al-Nabulsi, Anas A

2018-08-01

Enterobacteriaceae family can contaminate fresh produce at any stage of production either at pre-harvest or post-harvest stages. The objectives of the current study were to i) identify Enterobacteriaceae species on iceberg lettuce, ii) compare the decontamination efficiency of water, sodium hypochlorite (free chlorine 200 ppm), peroxyacetic acid (PA 80 ppm; Kenocid 2100 ® ) or their combinations and ionizing radiation against Enterobacteriaceae on shredded iceberg lettuce and iii) determine the survival of Enterobacteriaceae post-treatment storage of shredded iceberg lettuce at 4, 10 and 25 °C, for up to 7 days. Klebsiella pneumonia spp. pneumonia, Enterobacter cloacae, Klebsiella oxytoca, Pantoea spp., Leclercia adecarboxylata and Kluyvera ascorbate were identified on iceberg lettuce. No significant difference (P≥ 0.05) among Enterobacteriaceae survival after washing with water or sanitizing with sodium hypochlorite or Kenocid 2100 ® (reduction ≤ 0.6 log CFU/g) were found. Combined sanitizer treatments were more effective against Enterobacteriaceae than single washing/sanitizing treatments. Sanitization of iceberg lettuce with combined washing/sanitizing treatments reduced Enterobacteriaceae by 0.85-2.24 CFU/g. Post-treatment growth of Enterobacteriaceae during storage on samples sanitized with sodium hypochlorite and Kenocid 2100 ® was more than on samples washed with water. The D 10 -value of Enterobacteriaceae on shredded iceberg lettuce was 0.21 KGy. The reduction of Enterobacteriaceae populations on iceberg after gamma radiation (0.6 KGy) was 3 log CFU/g, however, Enterobacteriaceae counts increased post-irradiation storage by 4-5 log CFU/g. Therefore, washing shredded iceberg lettuce with combined sanitizing treatment (sodium hypochlorite/sodium hypochlorite, sodium hypochlorite/Kenocid 2100 ® , or Kenocid 2100 ® /Kenocid 2100 ® ) for total time of 6 min or exposing it to gamma irradiation (0.6 KGy) can decrease the risk of

Application of artificial neural networks in indirect selection: a case study on the breeding of lettuce

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Alcinei Mistico Azevedo

2015-12-01

Full Text Available The efficiency of artificial neural networks (ANN to model complex problems may enable the prediction of characteristics that are hard to measure, providing better results than the traditional indirect selection. Thus, this study aimed to investigate the potential of using artificial neural networks (ANN for indirect selection against early flowering in lettuce, identify the influence of genotype by environment interaction in this strategy and compare your results with the traditional indirect selection. The number of days to anthesis were used as the desired output and the information of six characteristics (fresh weight of shoots, mass of marketable fresh matter of shoots, commercial dry matter of shoots, average diameter of the head, head circumference and leaf number as input file for the training of the ANN-MLP (Perceptron Multi-Layer. The use of ANN has great potential adjustment for indirect selection for genetic improvement of lettuce against early flowering. The selection based on the predicted values by network provided estimates of gain selection largest that traditional indirect selection. The ANN trained with data from an experiment have low power extrapolation to another experiment, due to effect of interaction genotype by environment. The ANNs trained simultaneously with data from different experiments presented greater predictive power and extrapolation.

Marketing System of Fresh Friut and Vegetable: The Role of Modern and Wholesale Market in Jakarta and the Vicinity

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Togar A. Napitupulu

2010-05-01

Full Text Available Marketing system of fresh fruits and vegetable in the context of the rapidly growing dynamic markets in Jakarta and the vicinity was studied. Unstructured interviews and observations of key persons, and panels were conducted, primarily in three main wholesale markets in Jakarta and the vicinity and some supermarkets. It was found that the availability of management services and associated facilities are not yet fully compatible with modern markets. Their role, therefore, in catering to the supermarkets is limited, in particular for vegetables due to requirements on quality and delivery schedules. In general, supermarkets procure their supply directly from production centers through special/dedicated suppliers, which currently amounts to about 1% to 5% of total production from production centers. If policy and conducive economic incentive are available, wholesale markets are not only domain of public investment anymore, but also private investments alike. The newly established wholesale markets show that they now have a higher rate of utilization than in the years before. It is therefore for the local government and the central government to furthers devise conducive policy and regulatory measures, and for the private to take this opportunity in terms of investment in developing the economy of the region. 

Literature Survey on Causes of Spoilage of Fresh Produce - 1959 to 1977

Science.gov (United States)

1982-08-01

handbook discusses 87 different market diseases o< citrus, avocados , bananas, figs, lychees, mangos, papayas, pineapples, and pomegranates, 11 T~’ -A...summary of each refarence is included. In addition, a series of tables was developed from the literature survey listing the market diseases and their...Table 2. Major causes of lettuce losses Table 3. Control of causes of lettuce losses Table 4. List of lettuce market diseases Table 5. List of tomato

Evaluation of Lettuce Genotypes for Seed Thermotolerance

Science.gov (United States)

Thermoinhibition of lettuce (Lactuca sativa L.) seed germination is a common problem associated with lettuce production. Depending on lettuce cultivars, seed germination may be inhibited when temperatures exceed 28oC. The delay or inhibition of seed germination at high temperatures may reduce seedli...

Development of marker-free transgenic lettuce resistant to Mirafiori lettuce big-vein virus.

Science.gov (United States)

Kawazu, Yoichi; Fujiyama, Ryoi; Imanishi, Shunsuke; Fukuoka, Hiroyuki; Yamaguchi, Hirotaka; Matsumoto, Satoru

2016-10-01

Lettuce big-vein disease caused by Mirafiori lettuce big-vein virus (MLBVV) is found in major lettuce production areas worldwide, but highly resistant cultivars have not yet been developed. To produce MLBVV-resistant marker-free transgenic lettuce that would have a transgene with a promoter and terminator of lettuce origin, we constructed a two T-DNA binary vector, in which the first T-DNA contained the selectable marker gene neomycin phosphotransferase II, and the second T-DNA contained the lettuce ubiquitin gene promoter and terminator and inverted repeats of the coat protein (CP) gene of MLBVV. This vector was introduced into lettuce cultivars 'Watson' and 'Fuyuhikari' by Agrobacterium tumefaciens-mediated transformation. Regenerated plants (T0 generation) that were CP gene-positive by PCR analysis were self-pollinated, and 312 T1 lines were analyzed for resistance to MLBVV. Virus-negative plants were checked for the CP gene and the marker gene, and nine lines were obtained which were marker-free and resistant to MLBVV. Southern blot analysis showed that three of the nine lines had two copies of the CP gene, whereas six lines had a single copy and were used for further analysis. Small interfering RNAs, which are indicative of RNA silencing, were detected in all six lines. MLBVV infection was inhibited in all six lines in resistance tests performed in a growth chamber and a greenhouse, resulting in a high degree of resistance to lettuce big-vein disease. Transgenic lettuce lines produced in this study could be used as resistant cultivars or parental lines for breeding.

The market value of freshness: observations from the swordfish and blue shark longline fishery

NARCIS (Netherlands)

Ishimura, G.; Bailey, M.L.

2013-01-01

One important component in determining the market value of fish is freshness, essentially the time period from capture to consumer. By shortening the time from harvest to landing, freshness can be improved and thus the market value may increase. The opportunistic nature of the marine capture

Impact of mulches and growing season on indicator bacteria survival during lettuce cultivation.

Science.gov (United States)

Xu, Aixia; Buchanan, Robert L; Micallef, Shirley A

2016-05-02

In fresh produce production, the use of mulches as ground cover to retain moisture and control weeds is a common agricultural practice, but the influence that various mulches have on enteric pathogen survival and dispersal is unknown. The goal of this study was to assess the impact of different mulching methods on the survival of soil and epiphytic fecal indicator bacteria on organically grown lettuce during different growing seasons. Organically managed lettuce, cultivated with various ground covers--polyethylene plastic, corn-based biodegradable plastic, paper and straw mulch--and bare ground as a no-mulch control, was overhead inoculated with manure-contaminated water containing known levels of generic Escherichia coli and Enterococcus spp. Leaves and soil samples were collected at intervals over a two week period on days 0, 1, 3, 5, 7, 10 and 14, and quantitatively assessed for E. coli, fecal coliforms and Enterococcus spp. Data were analyzed using mixed models with repeated measures and an exponential decline with asymptote survival model. Indicator bacterial concentrations in the lettuce phyllosphere decreased over time under all treatments, with more rapid E. coli declines in the fall than in the spring (plettuce compared to mulches. In fall 2014, the E. coli decline rate on paper mulch-grown lettuce was higher (plettuce phyllosphere, and mulch type was a factor for fecal coliform levels (plettuce production may impact the fate of enteric bacteria in soil or on lettuce, most likely in relation to soil moisture retention, and other weather-related factors, such as temperature and rainfall. The data suggest that the time between exposure to a source of enteric bacteria and harvesting of the crop is season dependent, which has implications for determining best harvest times. Copyright © 2016 Elsevier B.V. All rights reserved.

Test marketing and consumer acceptance of irradiated meat products

International Nuclear Information System (INIS)

Xu Zhicheng; Feng Zhixiong; Jiang Peizhen

2001-01-01

This study consists of two parts: irradiation processing of cooked meat and irradiation preservation of prepackaged chilled fresh cut meats. Irradiation of prepackaged pickled meat products dipped in grains stillage at a dose 6-8 kGy eliminated common food-borne microorganisms, such as E. Coli and other microbial pathogens and extended the shelf life of the product to 10 days at 5 deg. C. Test marketing of 40,000 bags (about 10,000 kg) of the product in more than 100 supermarkets in the city of Shanghai showed no untoward problem with consumer acceptance. Irradiation of prepackaged chilled fresh cut pork at a dose 3 kGy led to inactivation of microbial pathogens and parasites with a concomitant reduction in numbers of common spoilage microorganisms and extension of shelf life of the product for 30 days at 5 deg. C. The cost benefit and marketing applications were evaluated. (author)

Reducing microbial contamination on wastewater-irrigated lettuce by cessation of irrigation before harvesting

DEFF Research Database (Denmark)

Keraita, Bernard; Konradsen, Flemming; Drechsel, Pay

2007-01-01

OBJECTIVE: To assess the effectiveness of cessation of irrigation before harvesting in reducing microbial contamination of lettuce irrigated with wastewater in urban vegetable farming in Ghana. METHODS: Assessment was done under actual field conditions with urban vegetable farmers in Ghana. Trials...... were arranged in completely randomized block design and done both in the dry and wet seasons. Seven hundred and twenty-six lettuce samples and 36 water samples were analysed for thermotolerant coliforms and helminth eggs. RESULTS: On average, 0.65 log units for indicator thermotolerant coliforms and 0.......4 helminth eggs per 100 g of lettuce were removed on each non-irrigated day from lettuce in the dry season. This corresponded to a daily loss of 1.4 tonnes/ha of fresh weight of lettuce. As an input for exposure analysis to make risk estimates, the decay coefficient, k, for thermotolerant coliforms was 0...

Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation.

Science.gov (United States)

Sallach, J Brett; Zhang, Yuping; Hodges, Laurie; Snow, Daniel; Li, Xu; Bartelt-Hunt, Shannon

2015-02-01

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

Listeria monocytogenes internalizes in Romaine Lettuce grown in greenhouse conditions

Science.gov (United States)

Listeria monocytogenes has been implicated in a number of outbreaks involving fresh produce, including an outbreak in 2016 resulting from contaminated packaged salads. The persistence and internalization potential of L. monocytogenes in romaine lettuce was evaluated, and the persistence of two L. mo...

Factors influencing the marketing of fresh fish in Ogun State, Nigeria ...

African Journals Online (AJOL)

Factors influencing the marketing of fresh fish in Ogun State, Nigeria. ... The market prices of Clarias spp. ranged between □250 □400/Kg and the farmers were mostly patronized by retailers. Fish farm ... EMAIL FULL TEXT EMAIL FULL TEXT

Physiological and health quality of commercial lettuce and cabbage seed

Directory of Open Access Journals (Sweden)

Cleyton Teles Contreiras Paiva

2016-08-01

Full Text Available Physiological and sanitary seed quality is essential for rapid and uniform crop establishment at field, a factor which contributes to vegetable crop production success. The aim was to evaluate physiological and sanitary quality of lettuce and cabbage seeds coming three lots acquired in trade. Physiological quality was determined by means of germination test and index of speed germination. Health status was assessed through sanity test in Petri dishes containing BDA medium. The experimental design was completely randomized with four replications and the averages of each lot compared among themselves by Tukey test (5%. No statistical analyzes were performed to health test and samples were evaluated for presence of microorganisms on the plates. Aspergillus spp., Rhizopus spp., cocci and bacillus are associated with lettuce seeds, and Aspergillus spp., cocci and bacillus are associated with cabbage seeds, but this association can not interfere with germination performance at laboratory. Information about germination contained in the package do not always coincide with those examined in situ. Lettuce and cabbage seeds are being marketed carrying pathogens.

Market problems of agricultural products in Albania

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Merita Marku

2017-03-01

Full Text Available The production of fruits and vegetables in our country still faces challenges, including informality in sector of planting material, high costs of inputs purchased and fuel (especially affecting the green houses with heating, low productivity and high losses of post-harvest, especially in the case of fruit. Fresh fruit and vegetable marketing is different in many respects from the marketing of other agricultural and nonagricultural products. Hundreds of individual commodities comprise the total group. Each product has its own special requirements for growing and handling, with its own quality attributes, merchandising methods, and standards of consumer acceptance (How, R. B. 2012, 1. Food safety standards of fruits and vegetables their compliance with key standards and certification as a prerequisite and a challenge to be addressed in order to increase Albanian exports of agricultural products to European markets. Concerning vegetables and fruits, Albanian farmers face important marketing problems. Such problems are encountered at all stages of the production system-provision of inputs, both in terms of processing, promotion and other market incentives, which directly assist in the efficient realization of the sale of fruits and vegetables.

Viabilidade agronômica do consórcio de alface e rúcula, em duas épocas de cultivo Agronomic viability of lettuce-roquette intercropping in two growing periods

Directory of Open Access Journals (Sweden)

Caciana Cavalcanti Costa

2007-03-01

levels: lettuce groups (crisp, cv. Vera; looseleaf, cv. Elisa; and crisphead lettuce, cv. Tainá, cropping systems (intercropping and sole crop and roquette sowing times [0; 7, and 14 days after lettuce transplantating (DAT]. The highest fresh and dry matter production were observed for crisphead lettuce in the Spring. The cropping systems did not affect the lettuce groups productivity. The highest roquette fresh matter production was observed in the Autumn-Winter period at 0 DAT, with the crisp and looseleaf lettuce, and at 7 DAT with crisphead lettuce. For the Spring period the highest roquette fresh matter production was observed at 7 DAT with crisp lettuce and at 0 DAT with looseleaf and the crisphead lettuce. Roquette dry matter was reduced in the intercropping at 14 DAT. The intercropping system yielded 5 to 93% more than the single system according to the land equivalent ratio. The highest land equivalent ratio was observed in the roquette-crisp lettuce intercropping at 0 DAT the crisp variety (1.93 in the Autumn-Winter, while the highest ratio was observed at 7 DAT (1.84 in the Spring.

Agricultural and Management Practices and Bacterial Contamination in Greenhouse versus Open Field Lettuce Production

Science.gov (United States)

Holvoet, Kevin; Sampers, Imca; Seynnaeve, Marleen; Jacxsens, Liesbeth; Uyttendaele, Mieke

2014-01-01

The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production. Information was collected on sources, testing, and monitoring and if applicable, treatment of irrigation and harvest rinsing water. These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples. Enterohemorragic Escherichia coli (EHEC) PCR signals (vt1 or vt2 positive and eae positive), Campylobacter spp., and Salmonella spp. isolates were more often obtained from irrigation water sampled from open field farms (21/45, 46.7%) versus from greenhouse production (9/75, 12.0%). The open field production was shown to be more prone to fecal contamination as the number of lettuce samples and irrigation water with elevated E. coli was significantly higher. Farmers comply with generic guidelines on good agricultural practices available at the national level, but monitoring of microbial quality, and if applicable appropriateness of water treatment, or water used for irrigation or at harvest is restricted. These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards. PMID:25546272

Consumer’s market analysis of products based on cassava

Science.gov (United States)

Unteawati, Bina; Fitriani; Fatih, Cholid

2018-03-01

Cassava product has the important role for enhancing household's income in rural. Cassava as raw material food is plentiful as local food in Lampung. Cassava product is one of strategic value addition activities. Value additional activities are a key to create income source enrichment in rural. The household was product cassava as a snack or additional food. Their product cassava was operated in small-scale, traditional, and discontinuous production. They have been lacked in technology, capital, and market access. Measurement the sustainability of their business is important. The market has driven the business globally. This research aims to (1) describe the cassava demand to locally product cassava in rural and (2) analysis the consumer's perception of cassava product. Research take placed in Lampung Province, involved Bandar Lampung and Metro City, Pringsewu, Pesawaran, Central Lampung, and East Lampung district. It is held in February until April 2017. Data were analyzed by descriptive statistic and multidimensional scaling. Based on the analysis conclude that (1) the demand of product cassava from rural was massive in volume and regularity with the enormous transaction. This fact is very important to role business cycles. Consumers demand continuously will lead the production of cassava product sustain. Producers of product cassava will consume fresh cassava for the farmer. Consumption of fresh cassava for home industry regularly in rural will develop balancing in fresh cassava price in the farming gate (2) The consumer's perception on cassava product in the different market showed that they prefer much to consume cassava chips as cassava product products than other. Next are crackers, opak, and tiwul rice. Urban consumers prefer product products as snacks (chips, crumbs, and opak), with consumption frequency of 2-5 times per week and volume of 1-3 kg purchases. Consumers in rural were more frequent with daily consumption frequency. Multidimensional scaling

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.

Impact of biogas slurry fertilizer on growth, quality and biochemical characteristics of ornamental lettuce 'Biscia Rossa'

International Nuclear Information System (INIS)

Jiaxiang, J.; Khalid, M.; Hong, Z.; Leqi, Y.; Dongqin, T.; Danfeng, H.

2018-01-01

Biogas slurry is a good source of plant nutrients and substituting chemical fertilizers with biogas slurry not only achieve resource utilization of slurry, but also reduce the amount of fertilizer. The present study investigated the influence of different ratios of biogas slurry fertilizer (BSF) on the growth, yield and quality characteristics of ornamental lettuce 'Biscia Rossa'. Results revealed that BSF significantly (p<0.05) improved the growth of ornamental lettuce on treatment with Z1 fertilizer; the plant height was increased by 12.66% and 16.75%, while leaf area was improved by 19.97% and 42.03%, in comparison with control group. The improvement in yield of ornamental lettuce was noted in varying degrees by BSF. The highest dry and fresh weights were observed in case of Z1 treated lettuce plants. The fresh weight was 33.52%, 44.77%, 43.96% and 49.04% higher than that of other 2 fertilizers and 2 control groups, respectively. Whereas the dry weight was 2.7 and 3.17-times greater than that of two control groups. The biogas slurry irrigation also considerably improved the quality of ornamental lettuce. Moreover, it was observed that vitamin C, anthocyanin, soluble sugar and protein were higher than that of control groups. Contrarily, the BSF led to decrease in nitrate-nitrogen content in ornamental lettuce. (author)

Improving “color rendering” of LED lighting for the growth of lettuce

Science.gov (United States)

Han, Tao; Vaganov, Vitaliy; Cao, Shixiu; Li, Qiang; Ling, Lili; Cheng, Xiaoyao; Peng, Lingling; Zhang, Congzhi; Yakovlev, Alexey N.; Zhong, Yang; Tu, Mingjing

2017-04-01

Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve “color rendering” of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 μmol·m-2·s-1 for a 16 hd-1 photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were investigated. We let the absorption spectrum of fresh leaf be the emission spectrum of ideal light and then evaluate the “color rendering” of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates. Under the irradiation of red-yellow-blue light with high correlation coefficient of 0.587, the dry weights and leaf growth rate are 2-3 times as high as the sharp red-blue light. The optimized LED light for lettuce growth can be presumed to be limited to the angle (about 75°) between the vectors passed through the ideal light in the CIE chromaticity coordinates. These findings open up a new idea to assess and find the optimized LED light for plant growth.

Series of Norovirus Outbreaks Caused by Consumption of Green Coral Lettuce, Denmark, April 2016

DEFF Research Database (Denmark)

Müller, Luise; Rasmussen, Lasse Dam; Jensen, Tenna

2016-01-01

In early April 2016, an unusual high number of point-source outbreaks of gastrointestinal disease were reported to occur in Denmark. Outbreaks were individually investigated. Two analytical studies were performed. Patient stool samples collected and analysed; positive stool samples were sequenced...... over the polymerase and/or capsid gene areas. Implicated lettuce heads were collected and analysed for the presence of norovirus. Foods were traced-back and traced-forward and international alert systems applied. A total of 23 linked point-source outbreaks occurred over the course of one week. Fresh...... green coral lettuce (Lollo Bionda lettuce) had been consumed in all settings. In a cohort study including 234 participants a dish containing green lettuce was associated with illness. Norovirus of Genogroup I (GI) was detected in samples from 28 patients comprising eight of the outbreaks. Sequencing...

Effect of solution temperature, light intensity and light in combination with sunlight using mirror duct on growth of leaf lettuce (Lactuca savtiva L. cv. 'Greenwave')

International Nuclear Information System (INIS)

Shimizu, H.; Kushida, M.; Fujinuma, W.; Sekine, M.; Kaiho, K.; Arai, H.; Shibusawa, S.

2004-01-01

Leaf lettuce crops (Lactuca sativa L. cv. 'Greenwave') were grown in a plant production system using a Mirror Duct which intensified sunlight and transferred it to the inside of buildings. This system was expected to reduce the operational energy and lighting cost. The experiments were conducted under four photosynthetic photon flux densities (PPF) of 140,160, 180, and 200 micro mol mE-2 sE-1, in two light conditions, fluorescent light only and fluorescent light plus sunlight transferred with the Mirror Duct, and were repeated five times in total from August 2002 to July 2003. Five different solution temperatures were finally obtained through all the experiments due to temperature changes inside the experiment facility. Variance was analyzed to estimate the effect of these environmental factors on the growth of leaf lettuce. It was found that the fresh weight of leaf lettuce increased as PPF increased and the rate of increase of weight was 0.6 to 1.0 g per unit PPF in both 17.4 deg C and 23.5 deg C solution temperatures; the solution temperature had a significant effect upon the fresh weight; and a difference in fresh weight at harvest of between 40 and 60 g was observed between 17.4 deg C and 23.5 deg C solution temperatures. The light containing 10% sunlight was not effective for increasing fresh weight at harvest compared to the fluorescent lamp

The integrated control concept and its relevance to current integrated pest management in California fresh market grapes.

Science.gov (United States)

Bentley, Walter J

2009-12-01

The foundation of an integrated pest management program involves valid treatment thresholds, accurate and simple monitoring methods, effective natural controls, selective pesticides and trained individuals who can implement the concept. The Integrated Control Concept written by Stern, Smith, van den Bosch and Hagen elucidated each of these points in an alfalfa ecosystem. Alfalfa hay (Medicago sativa L.) has a low per acre value, requires little hand labor and is primarily marketed in the USA. In contrast, fresh market table grape (Vitis vinifera L.) has a high per acre value, requires frequent hand labor operations, suffers unacceptable cosmetic damage and is marketed throughout both the USA and the world. Each of the components of a working IPM program is present in table grape production. Marketing grapes to foreign countries presents special problems with pests considered invasive and where residue tolerances for some selective insecticides are lacking. However, fresh market grape farmers are still able to deal with these special problems and utilize an IPM program that has resulted in a 42% reduction in broad-spectrum insecticide use from 1995 to 2007. (c) 2009 Society of Chemical Industry.

Evaluation of respiratory parameters in minimally processed lettuce grown under organic or conventional system

Directory of Open Access Journals (Sweden)

Júlio César Mello

2010-12-01

Full Text Available The increased preference for minimally processed vegetables has been attributed to the health benefits associated with fresh produce and the demand for ready-to-eat salads. In this paper, lettuce (Lactuca sativa L. was evaluated for the effects of different cropping systems on the respiratory properties. Lettuce was packaged in low density polyethylene bags and stored in a refrigerator at 4 ºC. The concentration of carbon dioxide and oxygen inside the package was monitored during the storage at zero, three, six, eight, ten and twelve days by gas chromatography. Dry matter variation was measured gravimetrically up to day fourteen of storage. Values of respiratory rate for conventional lettuce increased from day 1 to 3 and remained low, while respiratory rate of the organic lettuce increased three-fold up to day 8, stabilizing at a high level. Variation in dry matter during storage also resulted from differences between the two cultivation systems. The highest content of dry matter was achieved by organic lettuce.

Formation of seed productivity in lettuce Lactuca sativa var. secalina L. depending on the form of inflorescence habitus

OpenAIRE

Н. В. Лещук

2009-01-01

It is explained the essence of the formation of seed production of lettuce Lactuca sativa var. secalina L. depending on the form of the inflorescence habitus, which formed during the different areas of plant nutrition. It is substantiated the mechanism of seed formation on different parts of the inflorescence of female plant with identification of it’s sowing quality. It is developed the agrotehnologcal measures aimed at improving the productivity of lettuce seed by overcoming its matrical he...

[The Advances in the Contamination and Detection of Foodborne Pathogen Noroviruses in Fresh Produce].

Science.gov (United States)

Xie, Yajing; Liu, Xianjin

2015-11-01

This article reviewed the researches proceeding on the contamination and detection of the foodborne pathogen noroviruses (NoVs) in fresh produce, which involved the NoVs contaminations in fresh produce, the special attachment of NoVs in fresh produce, the NoVs outbreaks associated with fresh produce and the NoVs detection in fresh produce. There had been an increase in reported infectious disease risks associated with the consumptions of fresh produce for recent 30 years. Because the NoVs, as a primary cause of viral gastroenteritis thoughout the world, were highly contagious, had a low infectious dose, and were persistent in the environment. And also the methods for NoVs detection in food had significantly developed over the last 15 years. Currently NoVs were the most common pathogen accounting for 40% of outbreaks associated with fresh produce (i. e., fruits and vegetables). Data from outbreaks investigations verified fresh produce as the high risk food products for NoVs. The fresh produce were typically eaten raw with no thermal processing, can be contaminated at any step during production and processing from faecally polluted water and fertilizers, the poor hygiene practices by food handlers and the cross-contamination. The attachment of NoVs to the fresh produce was due to the physio-chemical factors of virus protein coat, the special attachment to different fresh produce, and the possibility for internalization of NoVs. It might provide answers to why those high risk foods were more frequently implicated (i. e., lettuce and raspberries). According to the data of foodborne NoVs outbreaks which were associated with fresh produce from EU countries and the USA, the outbreaks in EU countries were mainly associated with NoVs contaminated raspberries and lettuce, while in USA which were associated with NoVs contaminated lettuce. Unfortunately, there were no NoVs detection methods for fresh produce or the data of foodborne NoVs outbreaks which were associated with

Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation

International Nuclear Information System (INIS)

Sallach, J. Brett; Zhang, Yuping; Hodges, Laurie; Snow, Daniel; Li, Xu; Bartelt-Hunt, Shannon

2015-01-01

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce. - Highlights: • Antimicrobial uptake in lettuce is cultivar dependent. • Antimicrobial concentrations in lettuce decrease despite repeated exposure. • Lincomycin is better conserved in the soil-plant system than oxytetracycline or sulfamethoxazole. • Subirrigation resulted in more Salmonella in bottom soil than in top soil. • Internalization frequency of Salmonella in lettuce is low despite repeated exposure. - Cultivar-specific differences in lincomycin and sulfamethazine uptake were observed in lettuce, while uptake of Salmonella was low despite repeated exposure from wastewater

Lettuce contact allergy

DEFF Research Database (Denmark)

Paulsen, Evy; Andersen, Klaus E

2016-01-01

Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present...... person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy.......Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present...... new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22...

Characterization of volatile production during storage of lettuce (Lactuca sativa) seed.

Science.gov (United States)

Mira, Sara; González-Benito, M Elena; Hill, Lisa M; Walters, Christina

2010-09-01

The duration that seeds stay vigorous during storage is difficult to predict but critical to seed industry and conservation communities. Production of volatile compounds from lettuce seeds during storage was investigated as a non-invasive and early detection method of seed ageing rates. Over 30 volatile compounds were detected from lettuce seeds during storage at 35 degrees C at water contents ranging from 0.03 to 0.09 g H(2)O g(-1) dw. Both qualitative and quantitative differences in volatile composition were noted as a function of water content, and these differences were apparent before signs of deterioration were visible. Seeds stored at high water content (L >or=0.06 g H(2)O g(-1) dw) emitted molecular species indicative of glycolysis (methanol+ethanol), and evidence of peroxidation was apparent subsequent to viability loss. Seeds containing less water (0.03-0.05 g H(2)O g(-1) dw) produced volatiles indicative of peroxidation and survived longer compared with seeds stored under more humid conditions. Production of glycolysis-related by-products correlated strongly with deterioration rate when measured as a function of water content. This correlation may provide a valuable non-invasive means to predict the duration of the early, asymptomatic stage of seed deterioration.

Formation of seed productivity in lettuce Lactuca sativa var. secalina L. depending on the form of inflorescence habitus

Directory of Open Access Journals (Sweden)

Н. В. Лещук

2009-12-01

Full Text Available It is explained the essence of the formation of seed production of lettuce Lactuca sativa var. secalina L. depending on the form of the inflorescence habitus, which formed during the different areas of plant nutrition. It is substantiated the mechanism of seed formation on different parts of the inflorescence of female plant with identification of it’s sowing quality. It is developed the agrotehnologcal measures aimed at improving the productivity of lettuce seed by overcoming its matrical heteroquality

Bundle Pricing Decisions for Fresh Products with Quality Deterioration

OpenAIRE

Fang, Yan; Jiang, Yiping; Han, Xingxing

2018-01-01

How to sell fresh products quickly to decrease the storage cost and to meet customer quality requirement is of vital importance in the food supply chain. Bundling fresh products is an efficient strategy to promote sales and reduce storage pressure of retailers. In this paper, we consider the bundle pricing decisions for homogeneous fresh products with quality deterioration. The value of fresh products with quality deterioration is approximated as an exponential function based on which custome...

Ultrasound as an intervention technology for the sanitation of lettuce harvesting knife

Science.gov (United States)

Lettuce field-coring and trimming practices are recent industry developments designed to improve fresh-cut processing yield and reduce shipping and waste disposal costs. Studies showed that the harvesting/coring knives used could be potentially contaminated with pathogens by contact with contaminat...

Evaluation of anti-inflammatory activity and fast UHPLC-DAD-IT-TOF profiling of polyphenolic compounds extracted from green lettuce (Lactuca sativa L.; var. Maravilla de Verano).

Science.gov (United States)

Pepe, Giacomo; Sommella, Eduardo; Manfra, Michele; De Nisco, Mauro; Tenore, Gian Carlo; Scopa, Antonio; Sofo, Adriano; Marzocco, Stefania; Adesso, Simona; Novellino, Tiziana; Campiglia, Pietro

2015-01-15

Fresh cut vegetables represent a widely consumed food worldwide. Among these, lettuce (Lactuca sativa L.) is one of the most popular on the market. The growing interest for this "healthy" food is related to the content of bioactive compounds, especially polyphenols, that show many beneficial effects. In this study, we report the anti-inflammatory and antioxidant potential of polyphenols extracted from lettuce (var. Maravilla de Verano), in J774A.1 macrophages stimulated with Escherichia coli lipopolysaccharide (LPS). Lettuce extract significantly decreased reactive oxygen species, nitric oxide release, inducible nitric oxide synthase and cycloxygenase-2 expression. A detailed quali/quantitative profiling of the polyphenolic content was carried out, obtaining fast separation (10 min), good retention time and peak area repeatability, (RSD% 0.80 and 8.68, respectively) as well as linearity (R(2)⩾ 0.999) and mass accuracy (⩽ 5 ppm). Our results show the importance in the diet of this cheap and popular food for his healthy properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficacy of Peracetic Acid in Inactivating Foodborne Pathogens on Fresh Produce Surface.

Science.gov (United States)

Singh, Prashant; Hung, Yen-Con; Qi, Hang

2018-02-01

Washing treatment with effective sanitizer is one of the critical steps in ensuring fresh produce safety. This study was to evaluate the efficacy of peracetic acid (PAA; VigorOx® 15 F&V), chlorine-based sanitizers (acidic electrolyzed water [AEO], near neutral electrolyzed water and bleach), lactic acid, and deionized (DI) water to reduce Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium DT104 from fresh produce surfaces. A 5-strain cocktail of E. coli O157:H7, L. monocytogenes, and S. Typhimurium DT104 was separately prepared and used for surface inoculation on produce samples (E. coli O157:H7 on romaine lettuce, lemons, tomatoes, and blueberries; L. monocytogenes on romaine lettuce and cantaloupe; S. Typhimurium DT104 on lemons, tomatoes, cantaloupe, and blueberries). PAA at 45, 85, and 100 mg/L; AEO, NNEO, and bleach at 100 mg/L of free chlorine; lactic acid at 2%; and DI water were used for washing inoculated produce in an automated produce washer for 5 min. In general, PAA at 100 mg/L achieved the highest microbial inactivation of E. coli O157:H7 (lettuce, lemon, tomato, and blueberry at 2.2, 5.7, 5.5, and 6.7 log CFU/g, respectively), S. Typhimurium DT104 (lemon, tomato, cantaloupe, blueberry at 5.4, 6.8, 4.5, and 5.9 log CFU/g, respectively), and L. monocytogenes (lettuce and cantaloupe at 2.4 and 4.4 log CFU/g, respectively). Efficacy of sanitizers on produce with coarse surface (for example, lettuce and cantaloupe) was lower than produce with smooth texture (lemon, tomato, and blueberry). Cross-contamination of E. coli O157:H7 among romaine lettuce heads during simulated retail crisping process was greatly reduced by the application of PAA and NNEO. NNEO and PAA showed high efficacy in foodborne pathogen removal from fresh produce. Produce surface texture plays an important role in pathogen removal. NNEO and PAA effectively prevented cross-contamination during the crisping process. © 2018 Institute of Food Technologists®.

Ethylene production by plants in a closed environment

Science.gov (United States)

Wheeler, R. M.; Peterson, B. V.; Sager, J. C.; Knott, W. M.

Ethylene production by 20-m^2 stands of wheat, soybean, lettuce and potato was monitored throughout growth and development in NASA's Controlled Ecological Life Support System (CELSS) Biomass Production Chamber. Chamber ethylene concentrations rose during periods of rapid growth for all four species, reaching 120 parts per billion (ppb) for wheat, 60 ppb for soybean, and 40 to 50 ppb for lettuce and potato. Following this, ethylene concentrations declined during seed fill and maturation (wheat and soybean), or remained relatively constant (potato). Lettuce plants were harvested during rapid growth and peak ethylene production. The highest ethylene production rates (unadjusted for chamber leakage) ranged from 0.04 to 0.06 ml m^-2 day^-1 during rapid growth of lettuce and wheat stands, or approximately 0.8 to 1.1 nl g^-1 fresh weight h^-1 Results suggest that ethylene production by plants is a normal event coupled to periods of rapid metabolic activity, and that ethylene removal or control measures should be considered for growing crops in a tightly closed CELSS.

Regional Markets for Non-timber Forest Products in Eastern Brazilian Amazon

OpenAIRE

Vuola, Matleena

2013-01-01

While export of non-timber forest products (NTFPs) has been promoted as a sustainable development strategy, the literature suggests that local and regional markets are also potentially important, not only for producers but also for traders and consumers (Shackleton et al. 2007). For producers, regional markets are thought to offer more accessible and more stable markets, while for traders, these markets offer employment, and for consumers, reasonably priced, diverse, fresh food. Consumptio...

Postharvest transfer and survival of Salmonella enterica serotype enteritidis on living lettuce.

Science.gov (United States)

Waitt, J A; Kuhn, D D; Welbaum, G E; Ponder, M A

2014-02-01

The potential for postharvest transfer of Salmonella to 'living lettuce' is not well understood. In this study, the transfer of Salmonella enterica Enteritidis (6 log CFU g(-1) ) from worker hands or contaminated roots to leaves of living lettuce was quantified. Transfer rates of Salmonella from contaminated gloves to sequentially handled lettuce heads ranged from 94% to head 1, 82% to head 2 and 69% to head 3. On average, 2.9 ± 0.1 log CFU g(-1) (64%) Salmonella was transferred from inoculated roots to leaves resulting from typical postharvest handling activities for living lettuce. Salmonella persisted on leaves stored at recommended storage temperatures (4°C) and increased 0.5 log CFU g(-1) when stored at temperature abuse conditions (12°C). Salmonella increased 1.6 log CFU g(-1) on roots after 18-day storage at 12°C, emphasizing the need to maintain temperature control to reduce the risk of human illness. Hydroponically grown lettuce packaged in plastic clamshells with intact roots, marketed as 'living lettuce', is increasing in popularity due to its extended shelf life. This study demonstrates the transfer of Salmonella from contaminated worker hands and contaminated roots to leaves where it persisted at 4°C for 18 day. Temperature abuse (12°C) increased Salmonella on roots and leaves. These findings suggest that failure to maintain temperatures below 12°C can pose a risk for consumers purchasing living lettuce at markets where recommended storage temperatures are not maintained. © 2013 The Society for Applied Microbiology.

Effect of Root-Zone Moisture Variations on Growth of Lettuce and Pea Plants

Science.gov (United States)

Ilieva, Iliana; Ivanova, Tania

2008-06-01

Variations in substrate moisture lead to changes in water and oxygen availability to plant roots. Ground experiments were carried out in the laboratory prototype of SVET-2 Space Greenhouse to study the effect of variation of root-zone moisture conditions on growth of lettuce and pea plants. The effect of transient increase (for 1 day) and drastic increase (waterlogging for 10 days) of substrate moisture was studied with 16-day old pea and 21-day old lettuce plants respectively. Pea height and fresh biomass accumulation were not affected by transient substrate moisture increase. Net photosynthetic rate (Pn) of pea plants showed fast response to substrate moisture variation, while chlorophyll content did not change. Drastic change of substrate moisture suppressed lettuce Pn, chlorophyll biosynthesis and plant growth. These parameters slowly recovered after termination of waterlogging treatment but lettuce yield was greatly affected. The results showed that the most sensitive physiological parameter to substrate moisture variations is photosynthesis.

Lettuce breeding

Science.gov (United States)

In the 2016-2017 period, major efforts targeted resistance to lettuce drop caused by Sclerotinia species, Verticillium wilt, Fusarium wilt, bacterial leaf spot, corky root, downy mildew, drought tolerance, lettuce aphid, tipburn, shelf-life of salad-cut lettuce, and multiple disease resistance. Resi...

Comparison of the microbiological quality of environmentally friendly and conventionally grown vegetables sold at retail markets in Korea.

Science.gov (United States)

Ryu, Jee-Hoon; Kim, Minju; Kim, Eun-Gyeong; Beuchat, Larry R; Kim, Hoikyung

2014-09-01

Fresh produce is usually eaten raw without cooking or heating, which may increase the probability of foodborne infection. The microbiological quality of 11 types of fresh, raw vegetables (romaine lettuce, sesame leaves, crown daisy, garlic chives, iceberg lettuce, cabbage, broccoli, leek, chili pepper, capsicum, and zucchini) purchased at retail markets in Iksan, Korea as affected by cultivation method (environmentally friendly vegetables [organic, pesticide-free, and low-pesticide vegetables] and conventionally grown vegetables) and harvest season was determined. Escherichia coli O157:H7 and Salmonella were not detected in all samples of vegetables tested. Aerobic mesophiles (>6 log cfu/g) were detected in environmentally friendly romaine lettuce and crown daisy and environmentally friendly and conventionally grown garlic chives, which also contained coliforms (>3 log cfu/g). Sesame leaf and crown daisy (regardless of cultivation method), as well as conventionally grown romaine lettuce and leek, contained >1 log cfu/g of E. coli. The overall microbiological quality of environmentally friendly and conventionally grown vegetables was not significantly different (P > 0.05). However, there were seasonal effects on populations of coliforms and generic E. coli on vegetables. The greatest numbers of microorganisms were isolated from environmentally friendly or conventionally grown vegetables purchased in winter. The vegetables, regardless of cultivation method or season, should be subjected to appropriate antimicrobial treatment to enhance their microbial safety. © 2014 Institute of Food Technologists®

Challenges with mechanical harvesting of blueberries for the fresh market

Science.gov (United States)

Southern highbush blueberries (SHB) (Vaccinium corymbosum L.) are mostly hand harvested for the fresh market. Hand harvesting of blueberry is labor intensive and costly. Efforts are under way to develop blueberry genotypes that will develop less bruising after impact with hard surfaces on the harv...

Optimal growth condition of earthworms and their vermicompost features during recycling of five different fresh fruit and vegetable wastes.

Science.gov (United States)

Huang, Kui; Xia, Hui; Li, Fusheng; Wei, Yongfen; Cui, Guangyu; Fu, Xiaoyong; Chen, Xuemin

2016-07-01

This study aimed to promote vermicomposting performance for recycling fresh fruit and vegetable wastes (FVWs) and to assess microbial population and community of final products. Five fresh FVWs including banana peels, cabbage, lettuce, potato, and watermelon peels were chosen as earthworms' food. The fate test of earthworms showed that 30 g fresh FVWs/day was the optimal loading and the banana peels was harmful for the survival of Eisenia fetida. The followed vermicomposting test revealed lower contents of total carbon and weaker microbial activity in final vermicomposts, relative to those in compared systems without earthworms worked. The leachate from FVWs carried away great amounts of nutrients from reactors. Additionally, different fresh FVWs displayed dissimilar stabilization process. Molecular biological approaches revealed that earthworms could broaden bacterial diversity in their products, with significant greater populations of actinobacteria and ammonia oxidizing bacteria than in control. This study evidences that vermicomposting efficiency differs with the types and loadings of fresh FVWs and vermicomposts are rich in agricultural probiotics.

Parasitic contamination of fresh vegetables sold at central markets in Khartoum state, Sudan

OpenAIRE

Mohamed, Mona Ali; Siddig, Emmanuel Edwar; Elaagip, Arwa Hassan; Edris, Ali Mahmoud Mohammed; Nasr, Awad Ahmed

2016-01-01

Background Fresh vegetables are considered as vital nutrients of a healthy diet as they supply the body with essential supplements. The consumption of raw vegetables is the main way for transmission of intestinal parasitic organisms. This study was aimed at detecting the parasitic contamination in fresh vegetables sold in two central open-aired markets in Khartoum state, Sudan. Methods In this prospective cross-sectional study, a total of 260 fresh vegetable samples and 50 water samples used ...

Marketing moxie for librarians fresh ideas, proven techniques, and innovative approaches

CERN Document Server

Watson-Lakamp, Paula

2015-01-01

Robust, resilient, and flexible marketing is an absolute necessity for today's libraries. Fortunately, marketing can be fun. Through this savvy guide, you'll discover a wealth of fresh, actionable ideas and approaches that can be combined with tried-and-true marketing techniques to serve any library. Focusing on building platforms rather than chasing trends, the book offers low- and no-budget ideas for those in small libraries as well as information that can be used by libraries that have a staff of professionals. The guide opens with an overview of the basics of marketing and continues throug

Media Effects on Lettuce Growth in "Pillows" Designed for the VEGGIE Spaceflight Growth Chamber

Science.gov (United States)

Massa, Gioia; Newsham, Gerard; McCoy, LaShelle; Stutte, Gary; Wheeler, Raymond

2012-01-01

VEGGIE is a prototype vegetable production unit for space designed by Orbital Technologies Corporation that is being developed to fly on the International Space Station. A modular plant rooting system "pillow" is being designed to support plant growth in VEGGIE under microgravity conditions. VEGGIE pillows are small self-contained packets of media with time-release fertilizer that can wick water passively from a root mat reservoir. Seeds are planted in pillows and the entire root system of a plant is contained as the crop develops, preventing loss into the spacecraft cabin. This study compared five media types and three lettuce cultivars in pillows growing in a VEGGIE analog environment.. Media consisted of a peat-based potting mix (Fafard #2,Conrad Fafard Inc., Agawam, MA), and a calcined clay, (arcillite, 1-2 mm sifted, Turface Proleague, Profile LLC, Buffalo Grove IL) as well as three different blends of the two, 70:30, 50:50, and 30:70. Lettuce cultivars tested were 'Sierra', a bi-colored French crisp Batavia lettuce, 'Outredgeous', a red romaine lettuce and 'Flandria', a green butter head variety. Plants were grown for 28 days, harvested, biometric data was obtained, and tissue mineral analysis was performed. For all cultivars, lettuce plants grown in the media blends were more productive than those in the individual media types. All cultivars showed bell-shaped curves in response to increases in arcillite / decreases in Fafard #2 for leaf area, fresh, and dry mass. Plants in 100% Fafard #2 and in 100% arcillite were stunted, but only those in higher levels of Fafard #2 (70% and 100%) had reduced shoot percent moisture, possibly indicating that mechanisms causing stunting differed. Variation in tissue nutrient content are consistent with this, with Mg and Mn highest in plants grown in 100% Fafard and decreasing as the concentration of arcillite increased. Color also varied with media, especially in the 'Sierra' lettuce, with plants grown in increasing levels

Adaptive Response of Listeria monocytogenes to Heat, Salinity and Low pH, after Habituation on Cherry Tomatoes and Lettuce Leaves.

Science.gov (United States)

Poimenidou, Sofia V; Chatzithoma, Danai-Natalia; Nychas, George-John; Skandamis, Panagiotis N

2016-01-01

Pathogens found on fresh produce may encounter low temperatures, high acidity and limited nutrient availability. The aim of this study was to evaluate the effect of habituation of Listeria monocytogenes on cherry tomatoes or lettuce leaves on its subsequent response to inhibitory levels of acid, osmotic and heat stress. Habituation was performed by inoculating lettuce coupons, whole cherry tomatoes or tryptic soy broth (TSB) with a three-strains composite of L. monocytogenes, which were further incubated at 5°C for 24 hours or 5 days. Additionally, cells grown overnight in TSB supplemented with 0.6% yeast extract (TSBYE) at 30°C were used as control cells. Following habituation, L. monocytogenes cells were harvested and exposed to: (i) pH 3.5 adjusted with lactic acid, acetic acid or hydrochloric acid (HCl), and pH 1.5 (HCl) for 6 h; (ii) 20% NaCl and (iii) 60°C for 150 s. Results showed that tomato-habituated L. monocytogenes cells were more tolerant (P lettuce, and habituation on both foods resulted in more stress resistant cells than prior growth in TSB. On the contrary, the highest resistance to heat stress (P lettuce-habituated L. monocytogenes cells followed by TSB-grown cells at 5°C for 24 h, whereas tomato-habituated cells were highly sensitized. Prolonged starvation on fresh produce (5 days vs. 24 h) increased resistance to osmotic and acid stress, but reduced thermotolerance, regardless of the pre-exposure environment (i.e., tomatoes, lettuce or TSB). These results indicate that L. monocytogenes cells habituated on fresh produce at low temperatures might acquire resistance to subsequent antimicrobial treatments raising important food safety implications.

Exogenous Glycine Nitrogen Enhances Accumulation of Glycosylated Flavonoids and Antioxidant Activity in Lettuce (Lactuca sativa L.

Directory of Open Access Journals (Sweden)

Xiao Yang

2017-12-01

Full Text Available Glycine, the simplest amino acid in nature and one of the most abundant free amino acids in soil, is regarded as a model nutrient in organic nitrogen studies. To date, many studies have focused on the uptake, metabolism and distribution of organic nitrogen in plants, but few have investigated the nutritional performance of plants supplied with organic nitrogen. Lettuce (Lactuca sativa L., one of the most widely consumed leafy vegetables worldwide, is a significant source of antioxidants and bioactive compounds such as polyphenols, ascorbic acid and tocopherols. In this study, two lettuce cultivars, Shenxuan 1 and Lollo Rossa, were hydroponically cultured in media containing 4.5, 9, or 18 mM glycine or 9 mM nitrate (control for 4 weeks, and the levels of health-promoting compounds and antioxidant activity of the lettuce leaf extracts were evaluated. Glycine significantly reduced fresh weight compared to control lettuce, while 9 mM glycine significantly increased fresh weight compared to 4.5 or 18 mM glycine. Compared to controls, glycine (18 mM for Shenxuan 1; 9 mM for Lollo Rossa significantly increased the levels of most antioxidants (including total polyphenols, α-tocopherol and antioxidant activity, suggesting appropriate glycine supply promotes antioxidant accumulation and activity. Glycine induced most glycosylated quercetin derivatives and luteolin derivatives detected and decreased some phenolic acids compared to nitrate treatment. This study indicates exogenous glycine supplementation could be used strategically to promote the accumulation of health-promoting compounds and antioxidant activity of hydroponically grown lettuce, which could potentially improve human nutrition.

Exogenous Glycine Nitrogen Enhances Accumulation of Glycosylated Flavonoids and Antioxidant Activity in Lettuce (Lactuca sativa L.).

Science.gov (United States)

Yang, Xiao; Cui, Xiaoxian; Zhao, Li; Guo, Doudou; Feng, Lei; Wei, Shiwei; Zhao, Chao; Huang, Danfeng

2017-01-01

Glycine, the simplest amino acid in nature and one of the most abundant free amino acids in soil, is regarded as a model nutrient in organic nitrogen studies. To date, many studies have focused on the uptake, metabolism and distribution of organic nitrogen in plants, but few have investigated the nutritional performance of plants supplied with organic nitrogen. Lettuce ( Lactuca sativa L.), one of the most widely consumed leafy vegetables worldwide, is a significant source of antioxidants and bioactive compounds such as polyphenols, ascorbic acid and tocopherols. In this study, two lettuce cultivars, Shenxuan 1 and Lollo Rossa, were hydroponically cultured in media containing 4.5, 9, or 18 mM glycine or 9 mM nitrate (control) for 4 weeks, and the levels of health-promoting compounds and antioxidant activity of the lettuce leaf extracts were evaluated. Glycine significantly reduced fresh weight compared to control lettuce, while 9 mM glycine significantly increased fresh weight compared to 4.5 or 18 mM glycine. Compared to controls, glycine (18 mM for Shenxuan 1; 9 mM for Lollo Rossa) significantly increased the levels of most antioxidants (including total polyphenols, α-tocopherol) and antioxidant activity, suggesting appropriate glycine supply promotes antioxidant accumulation and activity. Glycine induced most glycosylated quercetin derivatives and luteolin derivatives detected and decreased some phenolic acids compared to nitrate treatment. This study indicates exogenous glycine supplementation could be used strategically to promote the accumulation of health-promoting compounds and antioxidant activity of hydroponically grown lettuce, which could potentially improve human nutrition.

Sources of Verticillium dahliae affecting lettuce.

Science.gov (United States)

Atallah, Zahi K; Maruthachalam, Karunakaran; Subbarao, Krishna V

2012-11-01

ABSTRACT Since 1995, lettuce in coastal California, where more than half of the crop in North America is grown, has consistently suffered from severe outbreaks of Verticillium wilt. The disease is confined to this region, although the pathogen (Verticillium dahliae) and the host are present in other crop production regions in California. Migration of the pathogen with infested spinach seed was previously documented, but the geographic sources of the pathogen, as well as the impact of lettuce seed sparsely infested with V. dahliae produced outside coastal California on the pathogen population in coastal California remain unclear. Population analyses of V. dahliae were completed using 16 microsatellite markers on isolates from lettuce plants in coastal California, infested lettuce seed produced in the neighboring Santa Clara Valley of California, and spinach seed produced in four major spinach seed production regions: Chile, Denmark, the Netherlands, and the United States (Washington State). California produces 80% of spinach in the United States and all seed planted with the majority infested by V. dahliae comes from the above four sources. Three globally distributed genetic populations were identified, indicating sustained migration among these distinct geographic regions with multiple spinach crops produced each year and repeated every year in coastal California. The population structure of V. dahliae from coastal California lettuce plants was heavily influenced by migration from spinach seed imported from Denmark and Washington. Conversely, the sparsely infested lettuce seed had limited or no contribution to the Verticillium wilt epidemic in coastal California. The global trade in plant and seed material is likely contributing to sustained shifts in the population structure of V. dahliae, affecting the equilibrium of native populations, and likely affecting disease epidemiology.

Effect of variety, processing, and storage on the flavonoid glycoside content and composition of lettuce and endive.

Science.gov (United States)

DuPont, M S; Mondin, Z; Williamson, G; Price, K R

2000-09-01

Eight varieties of lettuce (Lactuca sativum) and three varieties of endive (Cichorium endivia) were analyzed for flavonoid composition and content. Total flavonoid contents, expressed as units of aglycon for fresh material, were in the ranges of 0.3-229 microg/g for lettuce and 44-248 microg/g for endive. Five quercetin conjugates [quercetin 3-O-galactoside, quercetin 3-O-glucoside, quercetin 3-O-glucuronide, quercetin 3-O-(6-O-malonyl)glucoside, and quercetin 3-O-rhamnoside] and luteolin 7-O-glucuronide were measured in the green-leafed lettuce and an additional two cyanidin conjugates [cyanidin 3-O-glucoside and cyanidin 3-O-[(6-O-malonyl)glucoside

In-package inhibition of E. coli O157:H7 on bulk Romaine lettuce using cold plasma.

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Min, Sea C; Roh, Si Hyeon; Niemira, Brendan A; Boyd, Glenn; Sites, Joseph E; Uknalis, Joseph; Fan, Xuetong

2017-08-01

Dielectric barrier discharge atmospheric cold plasma (DACP) treatment was evaluated for the inactivation of Escherichia coli O157:H7, surface morphology, color, carbon dioxide generation, and weight loss of bulk Romaine lettuce in a commercial plastic clamshell container. The lettuce samples were packed in a model bulk packaging configuration (three rows with either 1, 3, 5, or 7 layers) in the container and treated by DACP (42.6 kV, 10 min). DACP treatment reduced the number of E. coli O157:H7 in the leaf samples in the 1-, 3-, and 5-layer configurations by 0.4-0.8 log CFU/g lettuce, with no significant correlation to the sample location (P > 0.05). In the largest bulk stacking with 7 layers, a greater degree of reduction (1.1 log CFU/g lettuce) was observed at the top layer, but shaking the container increased the uniformity of the inhibition. DACP did not significantly change the surface morphology, color, respiration rate, or weight loss of the samples, nor did these properties differ significantly according to their location in the bulk stack. DACP treatment inhibited E. coli O157:H7 on bulk lettuce in clamshell containers in a uniform manner, without affecting the physical and biological properties and thus holds promise as a post-packaging process for fresh and fresh-cut fruits and vegetables. Published by Elsevier Ltd.

Vertical farming increases lettuce yield per unit area compared to conventional horizontal hydroponics.

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Touliatos, Dionysios; Dodd, Ian C; McAinsh, Martin

2016-08-01

Vertical farming systems (VFS) have been proposed as an engineering solution to increase productivity per unit area of cultivated land by extending crop production into the vertical dimension. To test whether this approach presents a viable alternative to horizontal crop production systems, a VFS (where plants were grown in upright cylindrical columns) was compared against a conventional horizontal hydroponic system (HHS) using lettuce ( Lactuca sativa L . cv. "Little Gem") as a model crop. Both systems had similar root zone volume and planting density. Half-strength Hoagland's solution was applied to plants grown in perlite in an indoor controlled environment room, with metal halide lamps providing artificial lighting. Light distribution (photosynthetic photon flux density, PPFD) and yield (shoot fresh weight) within each system were assessed. Although PPFD and shoot fresh weight decreased significantly in the VFS from top to base, the VFS produced more crop per unit of growing floor area when compared with the HHS. Our results clearly demonstrate that VFS presents an attractive alternative to horizontal hydroponic growth systems and suggest that further increases in yield could be achieved by incorporating artificial lighting in the VFS.

Variability, plot size and border effect in lettuce trials in protected environment

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Daniel Santos

2018-03-01

Full Text Available ABSTRACT The variability within rows of cultivation may reduce the accuracy of experiments conducted in a complete randomized block design if the rows are considered as blocks, however, little is known about this variability in protected environments. Thus, our aim was to study the variability of the fresh mass in lettuce shoot, growing in protected environment, and to verify the border effect and size of the experimental unit in minimizing the productive variability. Data from two uniformity trials carried out in a greenhouse in autumn and spring growing seasons were used. In the statistical analyses, it was considered the existence of parallel cultivation rows the lateral openings of the greenhouse and of columns perpendicular to these openings. Different scenarios were simulated by excluding rows and columns to generate several borders arrangements and also to use different sizes of the experimental unit. For each scenario, homogeneity test of variances between remaining rows and columns was performed, and it was calculated the variance and coefficient of variation. There is variability among rows in trials with lettuce in plastic greenhouses and the border use does not bring benefits in terms of reduction of the coefficient of variation or minimizing the cases of heterogeneous variances among rows. In experiments with lettuce in a plastic greenhouse, the use of an experimental unit size greater than or equal to two plants provides homogeneity of variances among rows and columns and, therefore, allows the use of a completely randomized design.

Contamination by intestinal parasites in vegetables marketed in an area of Jequitinhonha Valley, Minas Gerais, Brazil

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João Gabriel Guimarães LUZ

Full Text Available ABSTRACT Objective: The present study aimed to evaluate the presence of helminthes and intestinal protozoa in vegetables commercialized in Diamantina, a municipality located at Jequitinhonha Valley, one of the poorest regions of the world. Methods: A total of 108 specimens, including lettuce, green onion and rocket, were monthly collected from the most popular open street market, green grocery and supermarket of the municipality. The samples were processed by a concentration method and evaluated by light microscopy for parasitological identification. Results: The percentage of contamination was 50.9% (55/108, with predominance of nematode larvae (36.5%, cysts of Entamoeba coli (26.0% and eggs of hookworms/Strongyloides spp. (12.9%. Lettuce showed greater contamination rate (61.1% and samples from the open street market were more contaminated (77.8%. Information collected at each point of sale pointed the field cultivation as the critical step for such contaminations. Conclusion: Vegetables marketed in Diamantina presents a wide variety of intestinal parasites, which may represent a potential risk to the health of consumers of fresh vegetables.

Evidence of Protaphorura fimata (Collembola: Poduromorpha: Onychiuridae) feeding on germinating lettuce in the Salinas Valley of California.

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Joseph, Shimat V; Bettiga, Christopher; Ramirez, Christian; Soto-Adames, Felipe N

2015-02-01

A series of experiments were conducted to determine the impact of Protaphorura fimata Gisin (Family: Onychiuridae) feeding on seeds and germinating seedlings of lettuce, Lactuca sativa L. (Asteraceae). First, various densities of P. fimata were incubated with 25 lettuce seeds for 7 d and feeding injury was evaluated in three soilless arena experiments. As a second step, 100 P. fimata were incubated with 25 lettuce seeds in three arena experiments with soil media. Finally, in a commercial field the incidence and impact of P. fimata on recently planted lettuce was assessed following applications of pyrethroid-insecticides: 2 d before planting, at planting, and 20 d later. In experiments without soil, the number of ungerminated seeds, feeding injury sites, and plants with injury were significantly greater in arenas with P. fimata than without. Similarly, the number of germinated seedlings, shoot fresh, and dry weights, and the length and width of fully opened-leaves were greater in arenas without than with P. fimata in assays with soil. In the field, P. fimata densities were significantly lower in beds that received insecticides at 2 d before and at planting than in untreated beds. Also, the fresh and dry weights of lettuce plants were significantly greater in the beds that received insecticide than in untreated. The results clearly show that P. fimata is a pest of lettuce and can cause severe feeding injury to germinating seeds or seedlings, thereby reducing their growth rate. The potential implications of P. fimata feeding and feeding injury characteristics are discussed. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Phyllosphere Microbiota Composition and Microbial Community Transplantation on Lettuce Plants Grown Indoors

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Williams, Thomas R.

2014-01-01

ABSTRACT The aerial surfaces of plants, or phyllosphere, are microbial habitats important to plant and human health. In order to accurately investigate microbial interactions in the phyllosphere under laboratory conditions, the composition of the phyllosphere microbiota should be representative of the diversity of microorganisms residing on plants in nature. We found that Romaine lettuce grown in the laboratory contained 10- to 100-fold lower numbers of bacteria than age-matched, field-grown lettuce. The bacterial diversity on laboratory-grown plants was also significantly lower and contained relatively higher proportions of Betaproteobacteria as opposed to the Gammaproteobacteria-enriched communities on field lettuce. Incubation of field-grown Romaine lettuce plants in environmental growth chambers for 2 weeks resulted in bacterial cell densities and taxa similar to those on plants in the field but with less diverse bacterial populations overall. In comparison, the inoculation of laboratory-grown Romaine lettuce plants with either freshly collected or cryopreserved microorganisms recovered from field lettuce resulted in the development of a field-like microbiota on the lettuce within 2 days of application. The survival of an inoculated strain of Escherichia coli O157:H7 was unchanged by microbial community transfer; however, the inoculation of E. coli O157:H7 onto those plants resulted in significant shifts in the abundance of certain taxa. This finding was strictly dependent on the presence of a field-associated as opposed to a laboratory-associated microbiota on the plants. Phyllosphere microbiota transplantation in the laboratory will be useful for elucidating microbial interactions on plants that are important to agriculture and microbial food safety. PMID:25118240

Developing lettuce with improved quality for processed salads.

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Lettuce is increasingly consumed as minimally processed salads. Cultivars grown for this market may require breeding for improved shelf-life and resistance to physiological defects such as tipburn (TB). Tipburn is a calcium deficiency related defect causing necrosis on the leaf margins, typically on...

Estratégias de uso de água salobra na produção de alface em hidroponia NFT Strategies for use of brackish water in NFT hydroponic lettuce production

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Márcio S. Alves

2011-05-01

Full Text Available Plantas de alface crespa 'Verônica' foram cultivadas em condições hidropônicas, objetivando avaliar três diferentes estratégias de emprego de águas salobras: 1 águas salobras para reposição das perdas por evapotranspiração (ETc e água doce para o preparo da solução nutritiva (SN; 2 águas salobras para o preparo da SN e água doce para reposição da ETc; 3 águas salobras para o preparo da SN e reposição da ETc. Os níveis de salinidade da água foram obtidos pela adição de NaCl à água doce (0,27 dS m-1: 1,45; 2,51; 3,6; 5,41 e 7,5 dS m-1. O experimento foi conduzido em quatro blocos aleatorizados, com quatro repetições por tratamento. Uma estrutura de pesquisa foi construída com 72 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT. O uso de água salobra apenas para repor a ETc não produziu efeito sobre a produção da alface. Por outro lado, o uso de águas salobras para o preparo da SN e água doce para reposição da ETc, reduziu o rendimento da alface (massa de matéria fresca da parte aérea em 4,99% por (dS m-1. O rendimento foi reduzido em 7% por dS m-1 quando águas salobras foram usadas tanto para o preparo da SN quanto para reposição da ETc. Apesar da redução linear da produção da alface com o aumento da salinidade da água, sintomas depreciativos para a qualidade da alface hidropônica não foram registrados.Plants of crisphead lettuce cv. 'Verônica' were grown under hydroponic conditions aiming to evaluate three different strategies of brackish waters utilization: 1 brackish waters to replace the evapotranspiration loss (ETc and fresh water to prepare nutrient solution (NS; 2 brackish waters to prepare NS and fresh water to replace the ETc; 3 brackish waters to prepare NS and replace ETc. The levels of water salinity were obtained by addition of NaCl to fresh water (0.27 dS m-1: 1.45; 2.51; 3.6; 5.41 and 7.5 dS m-1. The experiment was conducted in randomized blocks with four

Effects of Abiotic and Biotic Stresses on the Internalization and Dissemination of Human Norovirus Surrogates in Growing Romaine Lettuce.

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DiCaprio, Erin; Purgianto, Anastasia; Li, Jianrong

2015-07-01

Human norovirus (NoV) is the major causative agent of fresh-produce-related outbreaks of gastroenteritis; however, the ecology and persistence of human NoV in produce systems are poorly understood. In this study, the effects of abiotic and biotic stresses on the internalization and dissemination of two human NoV surrogates (murine norovirus 1 [MNV-1] and Tulane virus [TV]) in romaine lettuce were determined. To induce abiotic stress, romaine lettuce was grown under drought and flood conditions that mimic extreme weather events, followed by inoculation of soil with MNV-1 or TV. Independently, lettuce plants were infected with lettuce mosaic virus (LMV) to induce biotic stress, followed by inoculation with TV. Plants were grown for 14 days, and viral titers in harvested tissues were determined by plaque assays. It was found that drought stress significantly decreased the rates of both MNV-1 and TV internalization and dissemination. In contrast, neither flood stress nor biotic stress significantly impacted viral internalization or dissemination. Additionally, the rates of TV internalization and dissemination in soil-grown lettuce were significantly higher than those for MNV-1. Collectively, these results demonstrated that (i) human NoV surrogates can be internalized via roots and disseminated to shoots and leaves of romaine lettuce grown in soil, (ii) abiotic stress (drought) but not biotic stress (LMV infection) affects the rates of viral internalization and dissemination, and (iii) the type of virus affects the efficiency of internalization and dissemination. This study also highlights the need to develop effective measures to eliminate internalized viruses in fresh produce. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Development of a Chlorine Dosing Strategy for Fresh Produce Washing Process to Maintain Microbial Food Safety and Minimize Residual Chlorine.

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Chen, Xi; Hung, Yen-Con

2018-05-22

The residual free chlorine level in fresh produce wash solution is closely correlated to the chemical and microbial safety of produce. Excess amount of free chlorine can quickly react with organic matters to form hazardous disinfection by-products (DBPs) above EPA-permitted levels, whereas deficiency of residual chlorine in produce wash solution may result in incompletely removing pathogens on produce. The purpose of this study was to develop a chlorine dosing strategy to optimize the chlorine dosage during produce washing process without impacting the microbial safety of fresh produce. Prediction equations were developed to estimate free chlorine needed to reach targeted residual chlorine at various sanitizer pH and organic loads, and then validated using fresh-cut iceberg lettuce and whole strawberries in an automated produce washer. Validation results showed that equations successfully predicted the initial chlorine concentration needed to achieve residual chlorine at 10, 30, 60, and 90 mg/L for both lettuce and strawberry washing processes, with the root mean squared error at 4.45 mg/L. The Escherichia coli O157:H7 reductions only slightly increased on iceberg lettuce and strawberries with residual chlorine increasing from 10 to 90 mg/L, indicating that lowering residual chlorine to 10 mg/L would not compromise the antimicrobial efficacy of chlorine-based sanitizer. Based on the prediction equations and E. coli O157:H7 reduction results, a chlorine dosing strategy was developed to help the produce industry to maintain microbial inactivation efficacy without adding excess amount of free chlorine. The chlorine dosing strategy can be used for fresh produce washing process to enhance the microbial food safety and minimize the DBPs formation potential. © 2018 Institute of Food Technologists®.

Use of Propolis in the Sanitization of Lettuce

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Xesús Feás

2014-07-01

Full Text Available The present study aimed to determine the effectiveness of propolis in reducing the microbial load in ready-to-eat (RTE and fresh whole head (FWH lettuces (Lactuca sativa L. type Batavia. Two sanitizing solutions were employed: sodium hypochlorite (SH and propolis (PS, during 15 and 30 min. Tap water (TW was used as a control. Regarding the mean reduction on aerobic mesophiles, psychrotrophic and fecal coliforms, the SH and PS treatments showed the same pattern of variation. In all cases, PS was slightly more effective in the microbiological reduction in comparison with commercial SH. Reductions between two and three log cycles were obtained with PS on aerobic mesophiles and psychrotrophic counts. The information obtained in the present study can be used to evaluate the potential use of propolis as product for sanitizing other vegetables and for developing other food preservation technologies, with impact on human health.

Impact of phytopathogen infection and extreme weather stress on internalization of Salmonella Typhimurium in lettuce.

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Ge, Chongtao; Lee, Cheonghoon; Nangle, Ed; Li, Jianrong; Gardner, David; Kleinhenz, Matthew; Lee, Jiyoung

2014-01-03

Internalization of human pathogens, common in many types of fresh produce, is a threat to human health since the internalized pathogens cannot be fully inactivated/removed by washing with water or sanitizers. Given that pathogen internalization can be affected by many environmental factors, this study was conducted to investigate the influence of two types of plant stress on the internalization of Salmonella Typhimurium in iceberg lettuce during pre-harvest. The stresses were: abiotic (water stress induced by extreme weather events) and biotic (phytopathogen infection by lettuce mosaic virus [LMV]). Lettuce with and without LMV infection were purposefully contaminated with green fluorescence protein-labeled S. Typhimurium on the leaf surfaces. Lettuce was also subjected to water stress conditions (drought and storm) which were simulated by irrigating with different amounts of water. The internalized S. Typhimurium in the different parts of the lettuce were quantified by plate count and real-time quantitative PCR and confirmed with a laser scanning confocal microscope. Salmonella internalization occurred under the conditions outlined above; however internalization levels were not significantly affected by water stress alone. In contrast, the extent of culturable S. Typhimurium internalized in the leafy part of the lettuce decreased when infected with LMV under water stress conditions and contaminated with high levels of S. Typhimurium. On the other hand, LMV-infected lettuce showed a significant increase in the levels of culturable bacteria in the roots. In conclusion, internalization was observed under all experimental conditions when the lettuce surface was contaminated with S. Typhimurium. However, the extent of internalization was only affected by water stress when lettuce was infected with LMV. © 2013.

Yield and nutritional quality of greenhouse lettuce (Lactuca sativa L. as affected by genotype and production methods

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Govedarica-Lučić Aleksandra

2014-01-01

Full Text Available Greenhouse experiments were conducted in winter growing seasons in order to evaluate the effects of genotype and production methods on yield and nutritional quality of lettuce (Lactuca sativa L.. A three-year (2009-2011 study was conducted by randomized block system in a greenhouse without additional heating. The trial included three genotypes of lettuce (Archimedes RZ, Santoro RZ, Kibou RZ. Each row with these genotypes was exposed to the following variants of covering: control-planting on bare soil, mulching before sowing with PE-black foil, agro textile-covering plants after planting with agro textile (17 g, a combination of mulching + agro textile. Throughout of all the three years of the trial, it was continuously evidenced that the genotype “Santoro RZ” had the biggest heads and the highest yield (15.33 kg 10 m-2, which leads to conclusion that the yield of lettuce is a genotype characteristics. Moreover, the nutritional value (ascorbic acid concentration has shown that, depending on the method of production, in average, the combination of mulching + agro textile (26.77 mg 100 g-1 had the highest content while the control variant had significantly lower vitamin C content (21.10 mg 100 g-1. The three-year researches have shown that the production method and genotype significantly affect the nitrate content. An average nitrate content was 2196.33 mg kg-1 on the control variant, and 2526.24 mg kg-1 on agro textile. Leafy lettuce of genotyp „Kibou RZ“ had lower nitrate content (2176.85 mg kg-1 compared to „Archimedes RZ“ (2843.05 mg kg-1 and „Santoro RZ“ (2221.37 mg kg-1. However nitrate concentration in all treatments remained within the European Union’s permissible levels.

Parasitic Contamination of Commonly Consumed Fresh Leafy Vegetables in Benha, Egypt

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Maysa Ahmad Eraky

2014-01-01

Full Text Available This study evaluated the degree of parasitic contamination of vegetables which are commercialized and consumed fresh in Benha, Egypt. It included 530 vegetables: lettuce, watercress, parsley, green onion, and leek. Vegetables were collected randomly from markets within Benha. Samples were washed in saline, and the resulting washing solution was filtered and centrifuged to concentrate the parasitic stages. Sediments and supernatants were examined by iodine and modified Ziehl-Neelsen stained smears. Intestinal parasites were detected in 157/530 (29.6% samples. Giardia lamblia cysts were the most prevalent parasite (8.8% followed by Entamoeba spp. cysts (6.8%, Enterobius vermicularis eggs (4.9%, various helminth larvae (3.6%, Hymenolepis nana eggs (2.8%, Hymenolepis diminuta eggs (2.1%, and Ascaris lumbricoides eggs (0.6%. The highest contaminated vegetable was lettuce (45.5% followed by watercress (41.3%, parsley (34.3%, green onion (16.5%, and leek (10.7%. These results indicate a significant seasonal variation (P<0.05, with highest prevalence in summer (49% and the lowest in winter (10.8%. These findings provide evidence for the high risk of acquiring parasitic infection from the consumption of raw vegetables in Benha, Egypt. Effective measures are necessary to reduce parasitic contamination of vegetables.

Increasing plant density in eastern United States broccoli production systems to maximize marketable head yields

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Increased demand for fresh market broccoli (Brassica oleracea L. var. italica) has led to increased production along the eastern seaboard of the United States. Maximizing broccoli yields is a primary concern for quickly expanding eastern commercial markets. Thus, a plant density study was carried ...

Semi-high throughput screening for potential drought-tolerance in lettuce (Lactuca sativa) germplasm collections

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This protocol describes a method by which a large collection of the leafy green vegetable lettuce (Lactuca sativa L.) germplasm was screened for likely drought-tolerance traits. Fresh water availability for agricultural use is a growing concern across the United States as well as many regions of th...

Recurring off-types in lettuce: Their significance in plant breeding and seed production.

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Maxon Smith, J W

1977-03-01

The lettuce cv. Valentine regularly produces non-heading off-type plants at the relatively high frequency of 4 × 10(-3). They result from mutation to the dominant condition. A similar propensity has been reported twice before in lettuce; it is highly heritable.The propensity to produce off-types was not present in the parents of Valentine so it must have arisen during the pedigree breeding programme. Closely related cultivars do not carry the character but it was subsequently transmitted to Dandie a new cultivar of which Valentine was one of the parents. Allelism tests to relate Valentine off-types to those in crisphead cultivars were not successful.The elimination of off-types in breeding programmes is discussed. Contrary to the findings in day-neutral crisphead cultivars, mutant phenotypes in long-day butterhead cultivars have no selective advantage for seed production. Consequently, strict roguing ensures adequate varietal stability.

Stable plastid transformation in lettuce (Lactuca sativa L.).

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Lelivelt, Cilia L C; McCabe, Matthew S; Newell, Christine A; Desnoo, C Bastiaan; van Dun, Kees M P; Birch-Machin, Ian; Gray, John C; Mills, Kingston H G; Nugent, Jacqueline M

2005-08-01

Although plastid transformation in higher plants was first demonstrated in the early 1990s it is only recently that the technology is being extended to a broader range of species. To date, the production of fertile transplastomic plants has been reported for tobacco, tomato, petunia, soybean, cotton and Lesquerella fendleri (Brassicaceae). In this study we demonstrate a polyethylene glycol-mediated plastid transformation system for lettuce that generates fertile, homoplasmic, plastid-transformed lines. Transformation was achieved using a vector that targets genes to the trnA/trnI intergenic region of the lettuce plastid genome employing the aadA gene as a selectable marker against spectinomycin. Spectinomycin resistance and heterologous gene transcription were shown in T(1) plants derived from self-pollinated primary regenerants demonstrating transmission of the plastid-encoded transgene to the first seed generation. Crossing with male sterile wild-type lettuce showed that spectinomycin resistance was not transmitted via pollen. Constructs containing the gfp gene showed plastid-based expression of green fluorescent protein. The lettuce plastid could have potential both as a production and a delivery system for edible human therapeutic proteins.

Ionising energy treatment of fresh fruit

International Nuclear Information System (INIS)

Rigney, C.J.

1985-01-01

The main purposes of the ionising energy treatment of fresh fruit are: the extension of shelf life of the commodity due to a direct physiological effect on the particular product; the extension of shelf life of the commodity due to a reduction in the development of moulds and rots which would normally render the product worthless; and the killing of insect pests of quarantine significance, to allow for normal marketing of fresh fruit without the risk of introducing insect pests to previously pest-free areas

Evaluation of Combined Disinfection Methods for Reducing Escherichia coli O157:H7 Population on Fresh-Cut Vegetables

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Eva Petri

2015-07-01

Full Text Available Most current disinfection strategies for fresh-cut industry are focused on the use of different chemical agents; however, very little has been reported on the effectiveness of the hurdle technology. The effect of combined decontamination methods based on the use of different sanitizers (peroxyacetic acid and chlorine dioxide and the application of pressure (vacuum/positive pressure on the inactivation of the foodborne pathogen E. coli O157:H7 on fresh-cut lettuce (Lactuca sativa and carrots (Daucus carota was studied. Fresh produce, inoculated with E. coli O157:H7, was immersed (4 °C, 2 min in tap water (W, chlorine water (CW, chlorine dioxide (ClO2: 2 mg/L and peroxyacetic acid (PAA: 100 mg/L in combination with: (a vacuum (V: 10 mbar or (b positive pressure application (P: 3 bar. The product quality and antimicrobial effects of the treatment on bacterial counts were determined both in process washing water and on fresh-cut produce. Evidence obtained in this study, suggests that the use of combined methods (P/V + sanitizers results in a reduction on the microorganism population on produce similar to that found at atmospheric pressure. Moreover, the application of physical methods led to a significant detrimental effect on the visual quality of lettuce regardless of the solution used. Concerning the process water, PAA proved to be an effective alternative to chlorine for the avoidance of cross-contamination.

Evaluation of Combined Disinfection Methods for Reducing Escherichia coli O157:H7 Population on Fresh-Cut Vegetables.

Science.gov (United States)

Petri, Eva; Rodríguez, Mariola; García, Silvia

2015-07-23

Most current disinfection strategies for fresh-cut industry are focused on the use of different chemical agents; however, very little has been reported on the effectiveness of the hurdle technology. The effect of combined decontamination methods based on the use of different sanitizers (peroxyacetic acid and chlorine dioxide) and the application of pressure (vacuum/positive pressure) on the inactivation of the foodborne pathogen E. coli O157:H7 on fresh-cut lettuce (Lactuca sativa) and carrots (Daucus carota) was studied. Fresh produce, inoculated with E. coli O157:H7, was immersed (4 °C, 2 min) in tap water (W), chlorine water (CW), chlorine dioxide (ClO2: 2 mg/L) and peroxyacetic acid (PAA: 100 mg/L) in combination with: (a) vacuum (V: 10 mbar) or (b) positive pressure application (P: 3 bar). The product quality and antimicrobial effects of the treatment on bacterial counts were determined both in process washing water and on fresh-cut produce. Evidence obtained in this study, suggests that the use of combined methods (P/V + sanitizers) results in a reduction on the microorganism population on produce similar to that found at atmospheric pressure. Moreover, the application of physical methods led to a significant detrimental effect on the visual quality of lettuce regardless of the solution used. Concerning the process water, PAA proved to be an effective alternative to chlorine for the avoidance of cross-contamination.

Agronomic efficiency of intercropping tomato and lettuce

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Arthur B. Cecílio Filho

2011-09-01

Full Text Available Four experiments were carried out at the São Paulo State University, Brazil, with the aim of determining the agronomic viability of intercropping tomato and lettuce, under greenhouse conditions. The studied intercropping systems were established by transplanting lettuce at 0, 10, 20 and 30 days after transplanting (DAT tomato and by transplanting tomato at 0, 10, 20 and 30 DAT lettuce. Intercropped tomato and lettuce were evaluated during two seasons and compared to their sole cropping. The experimental design was a randomized complete block with nine treatments. The productivity and the classification of the tomato fruits were not influenced by having lettuce intercropped with it, but lettuce production was lowered when tomato was intercropped with it. The longer the delay in lettuce transplanting, the greater the reduction in its productivity. There was an effect of cropping season on the extent of the agronomic advantage of intercropping over sole cropping. In the first cropping season, intercropping established by transplanting lettuce during the interval between 30 days before up to 20 DAT tomato yielded land use efficiency (LUE indices of 1.63 to 2.22. In the second period, intercropping established with the transplanting of lettuce up to 30 days before tomato yielded LUE indices of 1.57 to 2.05.Quatro experimentos foram conduzidos na Unesp, Brasil, com o objetivo de determinar a viabilidade agronômica de cultivos consorciados de alface e tomate em ambiente protegido. Consórcios estabelecidos por transplantes da alface aos 0, 10, 20 e 30 dias após o transplante (DAT do tomate e de tomate aos 0, 10, 20 e 30 DAT da alface, foram avaliados em duas épocas e comparados às suas monoculturas. Cada experimento foi conduzido em delineamento de blocos ao acaso, com nove tratamentos. Verificou-se que a produtividade do tomate e a classificação dos frutos não foram influenciadas pela alface, mas a produção da alface foi menor em cons

Microbiological Quality and Safety of Fresh Fruits and Vegetables at Retail Levels in Korea.

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Tango, Charles Nkufi; Wei, Shuai; Khan, Imran; Hussain, Mohammad Shakhawat; Kounkeu, Paul-François Ngnitcho; Park, Joong-Hyun; Kim, Se-Hun; Oh, Deog Hwan

2018-02-01

The aim of this study was to evaluate the microbiological quality and safety of fresh produce at retail level in Korea in order to periodically update information and establish available risks associated with consumption of fresh fruits and vegetables. The samples from different markets located in 3 provinces of South Korea were collected. The protocol in the Korean Food Standards Codex was applied and generic Escherichia coli, coliforms, aerobic mesophilic bacteria (AMB), and yeast and mold (YM) in 360 packaged and unpackaged fresh fruits and vegetables were analyzed. Presence of pathogens was examined using real-time polymerase chain reaction (q-PCR) after enrichment of samples. For all, the microbial counts ranged from 1.7 to 10.6 log cfu/g for AMB, 2.2 to 7.9 log cfu/g for coliforms, and 5.5 to 7.9 log cfu/g for YM. Three lettuce samples were contaminated by E. coli with a bacterial load ranging from 2 to 4 log cfu/g. Salmonella spp. were not detected in any fresh produce. Listeria monocytogenes, E. coli O157:H7, and Staphylococcus aureus were found in 1 (0.6%), 3 (0.8%), and 5 (1.4%) fresh produce samples, respectively. Bacillus cereus (50.3%) and Clostridium perfringens (13.3%) had the highest prevalence. These results indicate the need for employing strict control measures and developing preventive strategies to improve the quality and safety of fresh produce in Korea. © 2018 Institute of Food Technologists®.

Doses de nitrogênio no acúmulo de nitrato e na produção da alface em hidroponia Nitrogen rates on nitrate accumulation and lettuce production in hydroponic system

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Mônica LA Pôrto

2012-09-01

Full Text Available A produção da alface em hidroponia apresenta crescente expansão no Brasil, mas ainda ocorrem problemas de qualidade e risco de acúmulo de nitrato. O objetivo desse trabalho foi avaliar a produção da alface (cv. Elba e acúmulo de nitrato em hidroponia em função de níveis crescentes de N na solução nutritiva. Plantas de alface foram cultivadas em estufa telada da UFPB em Areia (PB, em solução nutritiva que continha níveis crescentes de N (11, 13, 15, 17, 19 e 21 mmol L-1 por 25 dias. O delineamento utilizado foi inteiramente casualizado com quatro repetições. Foram avaliadas a produção total (PTT, produção comercial (PCM e os teores de nitrato na matéria fresca da raiz, caule e folhas da alface. Não foram verificados efeitos significativos do incremento dos níveis de N na solução sobre a PTT e PCM, sendo obtidos valores médios de 357,3 e 352,5 g/planta, respectivamente. A elevação dos níveis de N em solução resultou em incrementos nos teores de nitrato em todas as partes da alface, obtendo-se na dose máxima teores de 659, 623 e 615 mg kg-1 de matéria fresca, para raiz, caule e folhas, respectivamente. Os máximos teores foliares de nitrato obtidos se encontraram abaixo do limite de risco para saúde humana.Lettuce production in hydroponic system presents growing expansion in Brazil, but still there are problems of quality and risk of nitrate accumulation. This work was carried out to evaluate the lettuce production and nitrate accumulation in hydroponic system depending on the increasing levels of nitrogen in the nutrient solution. The experiment was conducted in greenhouse of the Universidade Federal da Paraíba, Brazil. The lettuce plants were grown in nutrient solution containing increasing levels of N (11, 13, 15, 17, 19 and 21 mmol L-1 during a 25-day period. An entirely randomized design with four replications was used. Plant total yield (PTT, plant commercial yield (PCM and nitrate contents in the fresh

Atividade respiratória e evolução de etileno em alface crespa minimamente processada armazenada sob duas temperaturas Respiratory activity and ethylene evolution of fresh-cut crisphead lettuce stored under two temperatures

Directory of Open Access Journals (Sweden)

Leonora Mansur Mattos

2008-12-01

process in which organic compounds are oxidized to carbon dioxide and water, with energy release. Ethylene evolution is also very important and can be observed in fresh-cut vegetables crops. In the present work we studied the physiological effects associated with fresh-cut lettuce (Lactuca sativa L. searching the best temperature for storage as well as how the stress caused by processing affects the product. It was observed that right after processing respiratory rates of the materials sliced at 5 and 10mm thick were statistically different from the lettuce processed for both 5 ºC and 10 ºC storage temperatures. Storage at 5 ºC was capable of reducing the metabolism faster when compared to the storage at 10 ºC. The respiratory activity and ethylene evolution curves profile for the lettuce processed at 10 mm were the same for both the studied temperatures, differing only for the values, that were higher, as expected, for 10 ºC. Ethylene evolution reduced for the material processed at 10 mm and stored at 5 ºC, but did not reduce for the material processed at 5 mm at the first two hours after processing. The best temperature for fresh-cut lettuce storage was 5 ºC and the material processed as whole leaves showed the lowest levels of carbon dioxide and ethylene evolution.

Effects of environmental factors on the morphometric characteristics of cultivated lettuce (Lactuca sativa L.

Directory of Open Access Journals (Sweden)

Antonio D Ojeda

2012-09-01

Full Text Available We evaluated the phenotypic response of three varieties of lettuce Batavia Colwart, Lisa Elisa and Crespa Verde Cassabella in three growing environments: plastic greenhouse, glass greenhouse and open field on the Bogota Plateau (Chia, Cundinamarca, in order to generate useful information to improve the quality of plants grown by farmers, ensuring a healthy product with characteristics that meet market demands. The three agroecosystems were constantly monitored for the environmental variables of temperature, relative humidity and solar radiation; which showed a significant variation between the three agroecosystems. To assess the phenotypic response, we examined the effect of the environmental variables mentioned on seven morphometric variables of agronomic interest. The study showed that, for the variables germination percentage and fresh weight, the environmental effect reached a variance percentage of 79 and 44%, respectively. On the contrary, it was established that the average phenotypic response of the variables clean weight and percentage of dry mass corresponds especially to the effect of genetic varieties with a variance percentage of 35 and 45%, respectively. Similarly, for the variables specific leaf area and total leaf area, it was established that both the effects of environmental and genetic variables explain 87% (50 genetic, 37 environmental and 56% (31 genetic, 25 environmental, respectively, of the total variability observed

Pre-Harvest light intensity affects shelf-Life of fresh-cut lettuce

NARCIS (Netherlands)

Witkowska, I.M.; Woltering, E.J.

2010-01-01

The industry of fresh-cut produce is continuously growing due to increasing demand for fresh, healthy and convenient foods. However, processing of vegetables accelerates quality deterioration due to structural, physiological and biochemical changes. Therefore, the value of the produce to the

Assessing nitrogen supply potential and influence on growth of lettuce and amaranthus of different aged composts

International Nuclear Information System (INIS)

Akhtar, M.J.; Young, I.; Irvine, R.J.; Sturrock, C.

2010-01-01

This study assessed the potential of different composts at different maturity stages to supply N and their effect on the vegetative growth of lettuce and Amaranthus. Five composts aged 1, 3, 6, 9, and 12 months, were mixed with soil at the rate of 5%, 10% and 15% then seeded with lettuce and Amaranthus. Results showed that 1, 3 and 6 month aged composts had a negative effect on plant height of lettuce and Amaranthus as 1-15.78% and 4.78 to 29.45% decrease in plant height over control was recorded respectively. On the other hand 9 and 12 month aged composts had a significant positive effect on plant height of lettuce and Amaranthus where 43.48% and 34.8% increase over control was recorded with the application of 15% of 12 month aged compost respectively. A similar effect was observed on fresh biomass of both lettuce and Amaranthus where a 386% and 59.43% increase over control was recorded with the application of 15% of 12 month aged compost respectively. One and three month aged composts revealed a negative effect on N absorption by lettuce whereas 1, 3, 6 and 9 month aged composts had a negative effect on N absorption by Amaranthus. 30.39% and 21.48% increases over control in N absorption by lettuce and Amaranthus respectively were recorded with the application of 15% of 12 month aged compost. (author)

Semi-High Throughput Screening for Potential Drought-tolerance in Lettuce (Lactuca sativa) Germplasm Collections.

Science.gov (United States)

Knepper, Caleb; Mou, Beiquan

2015-04-17

This protocol describes a method by which a large collection of the leafy green vegetable lettuce (Lactuca sativa L.) germplasm was screened for likely drought-tolerance traits. Fresh water availability for agricultural use is a growing concern across the United States as well as many regions of the world. Short-term drought events along with regulatory intervention in the regulation of water availability coupled with the looming threat of long-term climate shifts that may lead to reduced precipitation in many important agricultural regions has increased the need to hasten the development of crops adapted for improved water use efficiency in order to maintain or expand production in the coming years. This protocol is not meant as a step-by-step guide to identifying at either the physiological or molecular level drought-tolerance traits in lettuce, but rather is a method developed and refined through the screening of thousands of different lettuce varieties. The nature of this screen is based in part on the streamlined measurements focusing on only three water-stress indicators: leaf relative water content, wilt, and differential plant growth following drought-stress. The purpose of rapidly screening a large germplasm collection is to narrow the candidate pool to a point in which more intensive physiological, molecular, and genetic methods can be applied to identify specific drought-tolerant traits in either the lab or field. Candidates can also be directly incorporated into breeding programs as a source of drought-tolerance traits.

Uptake and Accumulation of Pharmaceuticals in Overhead- and Surface-Irrigated Greenhouse Lettuce.

Science.gov (United States)

Bhalsod, Gemini D; Chuang, Ya-Hui; Jeon, Sangho; Gui, Wenjun; Li, Hui; Ryser, Elliot T; Guber, Andrey K; Zhang, Wei

2018-01-31

Understanding the uptake and accumulation of pharmaceuticals in vegetables under typical irrigation practices is critical to risk assessment of crop irrigation with reclaimed water. This study investigated the pharmaceutical residues in greenhouse lettuce under overhead and soil-surface irrigations using pharmaceutical-contaminated water. Compared to soil-surface irrigation, overhead irrigation substantially increased the pharmaceutical residues in lettuce shoots. The increased residue levels persisted even after washing for trimethoprim, monensin sodium, and tylosin, indicating their strong sorption to the shoots. The postwashing concentrations in fresh shoots varied from 0.05 ± 0.04 μg/kg for sulfadiazine to 345 ± 139 μg/kg for carbamazepine. Root concentration factors ranged from 0.04 ± 0.14 for tylosin to 19.2 ± 15.7 for sulfamethoxazole. Translocation factors in surface-irrigated lettuce were low for sulfamethoxalzole, trimethoprim, monensin sodium, and tylosin (0.07-0.15), but high for caffeine (4.28 ± 3.01) and carbamazepine (8.15 ± 2.87). Carbamazepine was persistent in soil and hyperaccumulated in shoots.

Sensitivity of Pseudomonas fluorescens to gamma irradiation following surface inoculations on romaine lettuce and baby spinach

Science.gov (United States)

Irradiation of fresh fruits and vegetables is a post-harvest intervention measure often used to inactivate pathogenic food-borne microbes. We evaluated the sensitivity of Pseudomonas fluorescens strains (2-79, Q8R1, Q287) to gamma irradiation following surface inoculations on romaine lettuce and spi...

Effect of nitrogen nutrition on growth and nitrate accumulation in lettuce (Lactuca sativa L.), under various conditions of radiation and temperature

International Nuclear Information System (INIS)

Dapoigny, L.; Tourdonnet, S. de; Roger-Estrade, G.; Jeuffroy, M.H.; Fleury, A.

2000-01-01

A better understanding of the effect of environmental factors on growth and nitrate accumulation in plants is necessary to develop cultivation practices, and in particular for providing lettuces with a low nitrate content. This study was conducted to analyse the effect of nitrogen supply on the interception and conversion of the PAR in dry matter, and on the nitrate and water accumulations in fresh tissues of the lettuce, for various conditions of temperature and radiation. The growth, and water and nitrate concentrations of two soilless cultures of lettuce (summer and autumn) were measured for two levels of radiation and two levels of nitrogen supply. RUE ranged from 2.12 to 3.50 gMJ -1 , being higher for a low radiation level and for a high nitrogen supply. There was a positive correlation between the lettuce nitrate and water contents. The slope of this relationship was not affected by environmental conditions, indicating a strong interdependance between nitrate and water accumulation in lettuce. (author) [fr

Variability of phenolic content and antioxidant activity of two lettuce varieties under Fe deficiency.

Science.gov (United States)

Msilini, Najoua; Oueslati, Samia; Amdouni, Thouraya; Chebbi, Mohamed; Ksouri, Riadh; Lachaâl, Mokhtar; Ouerghi, Zeineb

2013-06-01

Fe deficiency affects food growth and quality in calcareous soils. In this study, the effect of Fe deficiency on growth parameters, phenolic content and antioxidant capacities of two lettuce shoots varieties (Romaine and Vista) were investigated. Fresh matter production, pigment (chlorophyll and carotenoid) and Fe2+ content were significantly reduced by Fe deficiency in both varieties. However, restriction of these parameters was particularly pronounced in Romaine variety as compared to Vista. Moreover, Fe deficiency caused decreases in the activity of antioxidant enzymes such as catalase and guaiacol peroxidase, whereas ascorbate peroxidase and malondialdehyde concentrations were not significantly affected. On the other hand, Fe deficiency in Vista variety induced an increase in polyphenol and flavonoid content as compared to Romaine variety. In addition, total antioxidant capacity and antiradical test against DPPH radical decreased in leaves of Romaine variety after 15 days of treatment. These results suggest that the higher polyphenol content in Vista variety supports the involvement of these components in the stability of antioxidant capacities and then in its protection against oxidative damage generated by Fe deficiency in lettuce plants. © 2012 Society of Chemical Industry.

Simple method for the determination of personal care product ingredients in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by GC-MS.

Science.gov (United States)

Cabrera-Peralta, Jerónimo; Peña-Alvarez, Araceli

2018-05-01

A simple method for the simultaneous determination of personal care product ingredients: galaxolide, tonalide, oxybenzone, 4-methylbenzyliden camphor, padimate-o, 2-ethylhexyl methoxycinnamate, octocrylene, triclosan, and methyl triclosan in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by gas chromatography with mass spectrometry was developed. Lettuce was directly extracted by ultrasound-assisted extraction with methanol, this extract was combined with water, extracted by solid-phase microextraction in immersion mode, and analyzed by gas chromatography with mass spectrometry. Good linear relationships (25-250 ng/g, R 2  > 0.9702) and low detection limits (1.0-25 ng/g) were obtained for analytes along with acceptable precision for almost all analytes (RSDs < 20%). The validated method was applied for the determination of personal care product ingredients in commercial lettuce and lettuces grown in soil and irrigated with the analytes, identifying the target analytes in leaves and roots of the latter. This procedure is a miniaturized and environmentally friendly proposal which can be a useful tool for quality analysis in lettuce. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lettuce seeds production in hydroponic system

OpenAIRE

Menezes, Nilson Lemos de; Santos, Osmar Souza dos; Schmidt, Denise

2001-01-01

Sementes de alface das cultivares Deyse e Regina foram produzidas em estufa, no sistema hidropônico, com elevados rendimentos por planta e boa qualidade de sementes, quando comparados a resultados de sistema convencional, de canteiros em campo. Esses dados sugerem estudos de produção de sementes de alface em cultivo protegido.Lettuce seeds of Deyse and Regina cultivars were produced in greenhouse, in hydroponic system, with excelents rendiments per plant and seed quality, when compared to con...

Chemical qualities of oils from some fresh and market vegetable ...

African Journals Online (AJOL)

JTEkanem

production was examined by evaluating the oil yield and chemical qualities of oil extracted from fresh ... oil may be considered as Nigeria potential asset for biofuel and oleochemical production. Keywords: ..... standards for edible Arachis oil.

Pesticide Residues in Commercial Lettuce, Onion, and Potato Samples From Bolivia—A Threat to Public Health?

DEFF Research Database (Denmark)

Skovgaard, Marlene; Renjel, Susana; Jensen, Olaf Chresten

2017-01-01

lettuce samples from La Paz were sampled on August 15, 2015 at a local market and screened for 283 pesticides. Residues of cypermethrin, chlorpyrifos, difenoconazol, or/and λ-cyhalothrin were detected in 50% of the lettuce samples, whereas no pesticides were found in potatoes and onions. In 20......% of the lettuce samples, the measurements were above the maximum residue limits, and 2 or 3 pesticides were identified simultaneously. Washing almost halved the pesticide levels, but still 20% of the samples showed measurements above the limits. No samples contained concentrations of pesticides which alone...

A model for multiseasonal spread of verticillium wilt of lettuce.

Science.gov (United States)

Wu, B M; Subbarao, K V

2014-09-01

Verticillium wilt, caused by Verticillium dahliae, is a destructive disease in lettuce, and the pathogen is seedborne. Even though maximum seed infestation rates of lettuce seed lots, it is necessary to establish acceptable contamination thresholds to prevent introduction and establishment of the pathogen in lettuce production fields. However, introduction of inoculum into lettuce fields for experimental purposes to determine its long term effects is undesirable. Therefore, we constructed a simulation model to study the spread of Verticillium wilt following pathogen introduction from seed. The model consists of four components: the first for simulating infection of host plants, the second for simulating reproduction of microsclerotia on diseased plants, the third for simulating the survival of microsclerotia, and the fourth for simulating the dispersal of microsclerotia. The simulation results demonstrated that the inoculum density-disease incidence curve parameters and the dispersal gradients affect disease spread in the field. Although a steep dispersal gradient facilitated the establishment of the disease in a new field with a low inoculum density, a long-tail gradient allowed microsclerotia to be dispersed over greater distances, promoting the disease spread in fields with high inoculum density. The simulation results also revealed the importance of avoiding successive lettuce crops in the same field, reducing survival rate of microsclerotia between crops, and the need for breeding resistance against V. dahliae in lettuce cultivars to lower the number of microsclerotia formed on each diseased plant. The simulation results, however, suggested that, even with a low seed infestation rate, the pathogen would eventually become established if susceptible lettuce cultivars were grown consecutively in the same field for many years. A threshold for seed infestation can be established only when two of the three drivers of the disease-(i) low microsclerotia production per

Effect of residual monomer from polyacrylamide on head lettuce grown in peat substrate.

Science.gov (United States)

Mroczek, Ewelina; Kleiber, Tomasz; Konieczny, Piotr; Waśkiewicz, Agnieszka

2015-01-01

The paper investigates the migration of the acrylamide monomer (AMD) to lettuce chosen as a test plant growing in an organic medium (peat substrate). Polyacrylamide (PAM)-based flocculant added to the growing medium contained no more than 1000 mg kg(-1) of AMD. Plants were grown with varied doses of PAM preparation (0.5-3.0 mg dm(-3) of peat substrate) to compare the results with the control sample. The determination of AMD content, chlorophyll content, weight of the lettuce head, and also analysis of macro- and micro-elements in lyophilised test material was made under the same analytical conditions. The results showed that lettuce plants absorb AMD to the leaves from the peat substrate. The AMD uptake has a negative impact on the growth of lettuce. It reduces the average fresh weight of heads and destabilises the mineral composition of the plant. Therefore, concern related to the transfer risk of the residual AMD from sludge used for organic fertilisation of edible plants still remains a crucial question from a food and consumer safety point of view. To ensure consumer safety, the fate of the AMD following the application of PAM to cropland should be carefully monitored in the whole food chain.

The use of lytic bacteriophages to reduce E. coli O157:H7 on fresh cut lettuce introduced through cross-contamination

Science.gov (United States)

The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield) at 108 PFU/ml or a control (phosphate buffered saline, PBS) was applied to lettuce by either 1) spraying on to lettuce piec...

Improving Water Use Efficiency of Lettuce (Lactuca sativa L.) Using Phosphorous Fertilizers.

Science.gov (United States)

Alkhader, Asad M F; Abu Rayyan, Azmi M

2013-01-01

A greenhouse pot experiment was conducted to evaluate the effect of phosphorous (P) fertilizers application to an alkaline calcareous soil on the water use efficiency (WUE) of lettuce cultivar "robinson" of iceberg type. Head fresh and dry weights, total water applied and WUE were affected significantly by the P fertilizer type and rate. P fertilizers addition induced a significant enhancement in the WUE and fresh and dry weights of the crop. A local phosphate rock (PR) applied directly was found to be inferior to the other types of P fertilizers (Mono ammonium phosphate (MAP), Single superphosphate (SSP), and Di ammonium phosphate ((DAP)). MAP fertilizer at 375 and 500 kg P2O5/ha application rates recorded the highest significant values of head fresh weight and WUE, respectively.

Plastid transformation in lettuce (Lactuca sativa L.) by biolistic DNA delivery.

Science.gov (United States)

Ruhlman, Tracey A

2014-01-01

The interest in producing pharmaceutical proteins in a nontoxic plant host has led to the development of an approach to express such proteins in transplastomic lettuce (Lactuca sativa L.). A number of therapeutic proteins and vaccine antigen candidates have been stably integrated into the lettuce plastid genome using biolistic DNA delivery. High levels of accumulation and retention of biological activity suggest that lettuce may provide an ideal platform for the production of biopharmaceuticals.

The Effect of Plant Growth Promoting Bacteria on Transplants Growth and Lettuce Yield in Organic Production

Directory of Open Access Journals (Sweden)

Szczech Magdalena

2016-12-01

Full Text Available Application of beneficial bacterial strain B125 (Enterobacter sp. and strain PZ9 (Bacillus sp. in lettuce transplants production significantly enhanced seed germination and plant biomass. The best effect was obtained when the mixture of B125 and PZ9 was used. Combined application of these bacteria significantly increased transplants biomass, which was about 45% higher than that in the control. However, after planting these transplants in organic field, generally, there were no differences in yield and nutrient content in plants treated and not treated with the bacteria, except for nitrogen and vitamin C. The lettuce grown from transplants treated with bacterial mixture B125 + PZ9 contained significantly higher nitrogen than plants from other treatments. Opposite to nitrogen, bacterial applications decreased the amount of vitamin C. The growth and organic lettuce composition was affected by planting time. The yield was higher in spring, but the concentration of nutrients in these plants was lower than that in plants harvested in autumn. Climatic and light conditions in the late season were the reasons for increased dry matter content, minerals, phenolic compounds, and vitamin C, as well as high concentration of nitrates.

Different Seed Selection and Conservation Practices for Fresh Market and Dried Chile Farmers in Aguascalientes, Mexico.

Science.gov (United States)

Kraft, Kraig H; de Jesús Luna-Ruíz, José; Gepts, Paul

2010-12-01

Different Seed Selection and Conservation Practices for Fresh Market and Dried Chile Farmers in Aguascalientes, Mexico. The process of selecting and saving seed is the most basic and oldest of agricultural practices. In today's modern and highly capital-intensive agriculture, seeds are often treated like another chemical input. This study sought to examine seed selection and saving practices among chile farmers in Aguascalientes, Mexico, where both industrial and traditional agriculture are practiced. We observed a clear division among farmers who plant chile peppers commercially. Sixty-eight chile pepper farmers were surveyed in order to document seed selection and saving practices. Fifteen respondents (22%) planted chile peppers destined for the fresh market and all utilized purchased commercial seed of F1 hybrid varieties. Fifty-three farmers (78%) planted chiles to be dried and either saved their own or purchased seeds that others had saved and selected. Farmers who saved their own seed sought to maintain an ideotype, rather than directionally select for certain traits, much like Cleveland et al. (2000) chronicled in central Mexican maize farmers. Farmers would benefit from a participatory plant-breeding program in order to maintain productive seed stock for the continued cultivation of dried chile pepper in the state.

Incidence of Lettuce mosaic virus in lettuce and its detection by polyclonal antibodies produced against recombinant coat protein expressed in Escherichia coli.

Science.gov (United States)

Sharma, Prachi; Sharma, Susheel; Singh, Jasvir; Saha, Swati; Baranwal, V K

2016-04-01

Lettuce mosaic virus (LMV), a member of the genus Potyvirus of family Potyviridae, causes mosaic disease in lettuce has recently been identified in India. The virus is seed borne and secondary infection occurs through aphids. To ensure virus freedom in seeds it is important to develop diagnostic tools, for serological methods the production of polyclonal antibodies is a prerequisite. The coat protein (CP) gene of LMV was amplified, cloned and expressed using pET-28a vector in Escherichia coli BL21DE3 competent cells. The LMV CP was expressed as a fusion protein containing a fragment of the E. coli His tag. The LMV CP/His protein reacted positively with a commercial antiserum against LMV in an immunoblot assay. Polyclonal antibodies purified from serum of rabbits immunized with the fusion protein gave positive results when LMV infected lettuce (Lactuca sativa) was tested at 1:1000 dilution in PTA-ELISA. These were used for specific detection of LMV in screening lettuce accessions. The efficacy of the raised polyclonal antiserum was high and it can be utilized in quarantine and clean seed production. Copyright © 2016 Elsevier B.V. All rights reserved.

Oxygenated phosphine fumigation for control of Nasonovia ribisnigri (Homoptera: Aphididae) on harvested lettuce.

Science.gov (United States)

Liu, Yong-Biao

2012-06-01

Low temperature regular phosphine fumigations under the normal oxygen level and oxygenated phosphine fumigations under superatmospheric oxygen levels were compared for efficacy against the aphid, Nasonovia ribisnigri (Mosley), and effects on postharvest quality of romaine and head lettuce. Low temperature regular phosphine fumigation was effective against the aphid. However, a 3 d treatment with high phosphine concentrations of > or = 2,000 ppm was needed for complete control of the aphid. Oxygen greatly increased phosphine toxicity and significantly reduced both treatment time and phosphine concentration for control of N. ribisnigri. At 1,000 ppm phosphine, 72 h regular fumigations at 6 degrees C did not achieve 100% mortality of the aphid. The 1,000 ppm phosphine fumigation under 60% O2 killed all aphids in 30 h. Both a 72 h regular fumigation with 2,200 ppm phosphine and a 48 h oxygenated fumigation with 1,000 ppm phosphine under 60% O2 were tested on romaine and head lettuce at 3 degrees C. Both treatments achieved complete control of N. ribisnigri. However, the 72 h regular fumigation resulted in significantly higher percentages of lettuce with injuries and significantly lower lettuce internal quality scores than the 48 h oxygenated phosphine fumigation. Although the oxygenated phosphine fumigation also caused injuries to some treated lettuce, lettuce quality remained very good and the treatment is not expected to have a significant impact on marketability of the lettuce. This study demonstrated that oxygenated phosphine fumigation was more effective and less phytotoxic for controlling N. ribisnigri on harvested lettuce than regular phosphine fumigation and is promising for practical use.

Is There a Relation between the Microscopic Leaf Morphology and the Association of Salmonella and Escherichia coli O157:H7 with Iceberg Lettuce Leaves?

Science.gov (United States)

VAN der Linden, Inge; Eriksson, Markus; Uyttendaele, Mieke; Devlieghere, Frank

2016-10-01

To prevent contamination of fresh produce with enteric pathogens, more insight into mechanisms that may influence the association of these pathogens with fresh produce is needed. In this study, Escherichia coli O157:H7 and Salmonella were chosen as model pathogens, and fresh cut iceberg lettuce was chosen as a model fresh produce type. The morphological structure of iceberg lettuce leaves (stomatal density and length of cell margins per leaf area) was quantified by means of leaf peels and light microscopy of leaves at different stages of development (outer, middle, and inner leaves of the crop) on both leaf sides (abaxial and adxial) and in three leaf regions (top, center, and bottom). The morphology of the top region of the leaves was distinctly different from that of the center and base, with a significantly higher stomatal density (up to five times more stomata), different cell shape, and longer cell margins (two to three times longer). Morphological differences between the same regions of the leaves at different stages of development were smaller or nonsignificant. An attachment assay with two attenuated E. coli O157:H7 strains (84-24h11-GFP and BRMSID 188 GFP) and two Salmonella strains (serovars Thompson and Typhimurium) was performed on different regions of the middle leaves. Our results confirmed earlier reports that these pathogens have a higher affinity for the base of the lettuce leaf than the top. Differences of up to 2.12 log CFU/g were seen ( E. coli O157:H7 86-24h11-GFP). Intermediate attachment occurred in the central region. The higher incidence of preferential bacterial attachment sites such as stomata and cell margins or grooves could not explain the differences observed in the association of the tested pathogens with different regions of iceberg lettuce leaves.

Governance of market-oriented fresh food value chains

NARCIS (Netherlands)

Trienekens, Jacques; Velzen, van Mariska; Lees, Nic; Saunders, Caroline; Pascucci, Stefano

2018-01-01

The competition in international food markets is increasingly moving towards products with higher levels of added value and higher degrees of differentiation, requiring companies to become more market-oriented. Market orientation is 'the extent to which an actor in the marketplace uses knowledge

Retrospectiva e tendência da alfacicultura brasileira Retrospective and trends of Brazilian lettuce crop

Directory of Open Access Journals (Sweden)

Fernando Cesar Sala

2012-06-01

for hot and high rainfall summer season. Brazilian preference for the Grand Rapids type is a unique event in the world market of lettuce. Crisp head lettuce had increased its preference, but there are many limitations to grow this type outdoors in our rainy hot summer. Thicker leaves of iceberg have a better flavor, crispness and long shelf live under refrigeration for its post-harvest management. Crispness is an important and mandatory quality for the fresh cut market which is a growing tendency. Considerations on breeding focus to get tropical-adapted varieties with crispness and resistance to specific Brazilian diseases which are limiting to lettuce are discussed.

Increasing Community Access to Fresh Fruits and Vegetables: A Case Study of the Farm Fresh Market Pilot Program in Cobb County, Georgia, 2014.

Science.gov (United States)

Woodruff, Rebecca C; Coleman, Anne-Marie; Hermstad, April K; Honeycutt, Sally; Munoz, Jennifer; Loh, Lorna; Brown, Agnes F; Shipley, Rebecca; Kegler, Michelle C

2016-03-10

Ecological models of health suggest that to effectively prevent chronic disease, community food environments must support healthy eating behaviors. However, disparities in access to healthy foods persist in the United States. The Farm Fresh Market (FFM) was a fruit and vegetable market that sold low-cost fresh produce in Cobb County, Georgia in 2014. This case study describes the development of the FFM through a community engagement process and presents evaluation results from the project's pilot implementation. Community engagement strategies included forming a community advisory board, conducting a needs assessment, and contracting with a community-based organization to implement the FFM. In the pilot year, the FFM served an average of 28.7 customers and generated an average of $140.20 in produce sales per market day. Most returning customers lived in the local community and reported a range of socioeconomic backgrounds. Most returning customers strongly agreed that the FFM made it easier (69.0%) and less expensive (79.0%) for them to buy fresh fruits and vegetables, reported that they ate more vegetables (65.0%) and fruit (55.0%) as a result of the FFM, and reported that they were very satisfied with the FFM overall (92.0%). Results from this community case study underscore the importance of engaging communities in the development of community food environment interventions. Results also suggest that the FFM initiative was a feasible and acceptable way to respond to the community-identified public health priority of increasing access to healthy foods.

L'agriculture périurbaine à Yaoundé: ses rapports avec le réduction de la pauvreté, le développement économique, la conservation de la biodiversité et de l'environnement

Directory of Open Access Journals (Sweden)

Awono, LDK.

2005-01-01

Full Text Available Peri-urban Agriculture in Yaounde: Its Relation to Poverty Alleviation, Economic Development, Biodiversity Conservation and the Environment. Rapid urbanization coupled with economic stagnation and the underdevelopment of transportation and food marketing systems have increased the importance of peri-urban agriculture production for employment and food security in Yaounde. Peri-urban agriculture is particularly important in terms of urban food supply for highly perishable products like traditional leaf vegetables and lettuce, and products that are bulky and costly to transport over long distances like fresh cassava and certain fruits. Intensive and semi-intensive peri-urban poultry and pig production is significant in terms of urban supply. Marketing of traditional leafy vegetables and fresh cassava offers employment to over four thousand women. The production of poultry and pigs is also a source of employment and revenue for a great part of urban population. Intensive production systems using organic manure and agrochemicals have been developed for traditional leafy vegetables and lettuce in inland valleys during the dry season. The abundance of labor relative to land availability in conjunction with nearly immediate access to agricultural markets for outputs and inputs have engendered these intensification processes. By concentrating intensification within the urban periphery of Yaounde, indirect environmental benefits include the reduced pressure on forest margins and thereby the slowing of deforestation due to slash and burn agriculture. Major constraints peri-urban agriculture in Yaounde is facing include pests and diseases, a lack of producer credit and inadequate extension services.

The Numerical Analysis of Monopolistically Competitive Markets: The Case of a New York Fresh Apple Packer

OpenAIRE

Starbird, Sterling A.; Milligan, Robert A.

1987-01-01

The hypothesis is adduced that in some monopolistically competitive markets a firm's demand schedule evolves faster than the firm's marketing policies can adjust. A probabilistic model of this phenomenon is introduced. The numerical analysis of a New York fresh apple packer's inventory control policies illustrates the model's usefulness.

Ultralow oxygen treatment for postharvest control of Nasonovia ribisnigri (Homoptera: Aphididae) on iceberg lettuce.

Science.gov (United States)

Liu, Yong-Biao

2005-12-01

The aphid Nasonovia ribisnigri (Mosley) is a common pest of lettuce in the United States. It hinders export of U.S. lettuce to the overseas market such as Japan where it is a quarantined pest. Ultralow oxygen treatments were studied for control of the insect on iceberg lettuce. Small-scale ultralow oxygen treatments in plastic jars were conducted at 1, 5, and 10 degrees C for different durations to determine effective treatment against nymphs and alates of N. ribisnigri. At oxygen levels of 0.015-0.025%, N. ribisnigri can be controlled in 3 d at 1 degrees C, 2 d at 5 degrees C, and 1 d at 10 degrees C. Large-scale ultralow oxygen treatments were conducted in bulk container treatment chambers with commercial iceberg lettuce heads for 2 d at 6 degrees C with oxygen levels of 0.015 and 0.025% and for 3 d at 3 degrees C with oxygen level of 0.015%. All treatments achieved complete control of N. ribisnigri. No negative impact on lettuce quality was detected after 2 wk of posttreatment storage. Therefore, the selected treatments have potential to be commercially developed for postharvest control of N. ribisnigri on iceberg lettuce.

Consumer attitudes and preferences for fresh market tomatoes.

Science.gov (United States)

Oltman, A E; Jervis, S M; Drake, M A

2014-10-01

This study established attractive attributes and consumer desires for fresh tomatoes. Three focus groups (n = 28 participants) were conducted to explore how consumers perceived tomatoes, including how they purchased and consumed them. Subsequently, an Adaptive Choice Based Conjoint (ACBC) survey was conducted to understand consumer preferences toward traditional tomatoes. The ACBC survey with Kano questions (n = 1037 consumers in Raleigh, NC) explored the importance of color, firmness, size, skin, texture, interior, seed presence, flavor, and health benefits. The most important tomato attribute was color, then juice when sliced, followed by size, followed by seed presence, which was at parity with firmness. An attractive tomato was red, firm, medium/small sized, crisp, meaty, juicy, flavorful, and with few seeds. Deviations from these features resulted in a tomato that was rejected by consumers. Segmentations of consumers were determined by patterns in utility scores. External attributes were the main drivers of tomato liking, but different groups of tomato consumers exist with distinct preferences for juiciness, firmness, flavor, and health benefits. Conjoint analysis is a research technique that collects a large amount of data from consumers in a format designed to be reflective of a real life market setting and can be combined with qualitative insight from focus groups to gain information on consumer consumption and purchase behaviors. This study established that the most important fresh tomato attributes were color, amount of juice when sliced, and size. Distinct consumer clusters were differentiated by preference for color/appearance, juiciness and firm texture. Tomato growers can utilize the results to target attributes that drive consumer choice for fresh tomatoes. © 2014 Institute of Food Technologists®

Effects of marketing group and production focus on quality and variability of adipose tissue and bellies sourced from a commercial processing facility.

Science.gov (United States)

Overholt, M F; Arkfeld, E K; Wilson, K B; Mohrhauser, D A; King, D A; Wheeler, T L; Dilger, A C; Shackelford, S D; Boler, D D

2016-12-01

Objectives were to determine the effects of marketing group on quality and variability of belly and adipose tissue quality traits of pigs sourced from differing production focuses (lean vs. quality). Pigs ( = 8,042) raised in 8 barns representing 2 seasons (cold and hot) were used. Three groups were marketed from each barn with 2 barns per production focus marketed per season. Data were collected on 7,684 carcasses at a commercial abattoir. Fresh belly characteristics, American Oil Chemists' Society iodine value (AOCS-IV), and near-infrared iodine value were measured on a targeted 50, 10, and 100% of carcasses, respectively. Data were analyzed as a split-plot design in the MIXED procedure of SAS 9.4 with production focus as the whole-plot factor and marketing group as the split-plot factor. Barn (block), season, and sex were random variables. A multivariance model was fit using the REPEATED statement with the marketing group × production focus interaction as the grouping variable. Variances for production focus and marketing groups were calculated using the MEANS procedure. Homogeneity of variance was tested on raw data using the Levene's test of the GLM procedure. Among quality focus carcasses, marketing group 3 bellies weighed less ( ≤ 0.03) than those from either marketing group 1 or 2, but there was no difference ( ≥ 0.99) among marketing groups of the lean focus carcasses. There was no effect ( ≥ 0.11) of production focus on fresh belly measures, SFA, or iodine value (IV), but lean focus carcasses had decreased ( = 0.04) total MUFA and increased ( Marketing group did not affect ( ≥ 0.10) fresh belly dimensions, total SFA, total MUFA, total PUFA, or IV. Belly weight, flop score, width, and all depth measurements were less variable ( ≤ 0.01); whereas, belly length, total SFA, and total MUFA were more variable ( marketing groups. Belly weight, length, width, and depth measurements; SFA; or IV variance did not differ ( ≥ 0.06) among marketing groups

Characterization and Application of Autochthonous Starter Cultures for Fresh Cheese Production

Directory of Open Access Journals (Sweden)

Andreja Leboš Pavunc

2012-01-01

Full Text Available The use of commercial starter cultures in fresh cheese production from pasteurized milk results in the loss of typical characteristics of artisan fresh cheese due to the replacement of complex native microbiota with a defined starter culture. Hence, the aim of this research is to isolate and characterize dominant lactic acid bacteria (LAB in artisan fresh cheese and to evaluate their capacity as autochthonous starter cultures for fresh cheese production. Fifteen most prevalent Gram-positive, catalase-negative and asporogenous bacterial strains were selected for a more detailed characterization. Eleven lactic acid bacterial strains were determined to be homofermentative cocci and four heterofermentative lactobacilli. Further phenotypic and genotypic analyses revealed that those were two different LAB strains with high acidifying and proteolytic activity, identified as Lactobacillus fermentum A8 and Enterococcus faecium A7. These two autochthonous strains, alone or in combination with commercial starter, were used to produce different types of fresh cheese, which were evaluated by a panel. Conventional culturing, isolation, identification and PCR-denaturing gradient gel electrophoresis (PCR-DGGE procedures, applied to the total fresh cheese DNA extracts, were employed to define and monitor the viability of the introduced LAB strains and their effect on the final product characteristics. Production of fresh cheese using a combination of commercial starter culture and selected autochthonous strains resulted in improved sensorial properties, which were more similar to the ones of spontaneously fermented fresh cheese than to those of cheese produced with only starter culture or selected strains. After 10 days of storage, that cheese retained the best sensorial properties in comparison with all other types of cheese. The presence of inoculated autochthonous and starter cultures and their identification was demonstrated by DGGE analysis. The obtained

The use of nile tilapia ( Oreochromis niloticus) cultivation wastewater for the production of romaine lettuce ( Lactuca sativa L. var. longifolia) in water recirculation system

Science.gov (United States)

Effendi, Hefni; Wahyuningsih, Sri; Wardiatno, Yusli

2017-10-01

In the recirculation aquaponic system (RAS), fish farming waste was utilized as a nutrient for plant, minimizing the water need, reducing the waste disposal into the environment, and producing the fish and plant as well. The study aimed to examine the growth of romaine lettuce ( Lactuca sativa L. var. Longifolia) in aquaponic system without the addition of artificial nutrient. The nutrient relies solely on wastewater of nile tilapia ( Oreochromis niloticus) cultivation circulated continuously on the aquaponic system. The results showed that tilapia weight reached 48.49 ± 3.92 g of T3 (tilapia, romaine lettuce, and inoculated bacteria), followed by T2 (tilapia and romaine lettuce) and T1 (tilapia) of 47.80 ± 1.97 and 45.89 ± 1.10 g after 35 days of experiment. Tilapia best performance in terms of growth and production occurred at T3 of 3.96 ± 0.44 g/day, 12.10 ± 0.63 %/day, 96.11 ± 1.44 % and 1.60 ± 0.07 for GR, SGR, SR, and FCR, respectively. It is also indicated by better water quality characteristic in this treatment. Romaine lettuce harvests of T2 and T3 showed no significant difference, with the final weight of 61.87 ± 5.59 and 57.74 ± 4.35 g. Overall, the integration of tilapia fish farming and romaine lettuce is potentially a promising aquaponic system for sustainable fish and horticulture plant production.

Composted slaughterhouse sludge as a substitute for chemical fertilizers in the cultures of lettuce (Lactuca sativa L. and radish (Raphanus sativus L.

Directory of Open Access Journals (Sweden)

José Juscelino de OLIVEIRA

Full Text Available Abstract Flotation sludge (FS is produced in huge amounts at slaughterhouses in western Santa Catarina, Brazil. This waste is rich in plant nutrients and a valuable resource for soil amendments. Five FS composts were tested as a replacement for chemical fertilizers (QF, namely T1 (75% poultry manure (PM and 25% sawdust (SD; T2 (50% PM and 50% SD; T3 (25% PM and 75% SD; T4 (100% PM and 0% SD; and T5 (0% PM x 100% SD. For lettuce plants, treatments containing composted FS resulted in an increased number of leaves, leaf area and leaf fresh weight (LFW. T1 presented the best results with increases of 1.4 fold in LFW compared to plants supplemented with QF. T2 was the most effective treatment for radish with the best results of root fresh weight and root diameter. Although T4 had the highest nitrogen content, it did not present the best results in growth performance for lettuce or radish. The presence of higher proportions of SD in composts (25% for lettuce and 50% for radish improved the physical characteristics of the soil and proved to be a more balanced compost.

Determination of the level of parasitic infection (Cryptosporidium and Giardia of the vegetables marketed in Ilam city

Directory of Open Access Journals (Sweden)

Moyad Avazpoor

2015-01-01

Full Text Available Background: Infected with intestinal parasites is one of the most important health and economical problems, which could have different effects, such as diarrheal diseases or death associated. The purpose of this study was to determine the level of prevalence of Cryptosporidium and Giardia parasites in the vegetable marketed in Ilam city. Methods: This study was performed on 280 samples of fresh vegetables and lettuce in Ilam. The samples were taken at the level of 500 grams from the places where vegetables and lettuce are sold. Micro liters of each sample was placed on the slide using automatic micropipette, and Logel and Zyl-Nelson stainings were performed in order to identify Cryptosporidium and Giardia. Results: From 200 samples, 54 samples were contaminated to Cryptosporidium oocyte and 13 samples to Giardia cysts. From 80 lettuce samples also 32 samples were contaminated to Cryptosporidium oocyte, and 6 samples contaminated to Giardia cysts. The results showed that the overall infection was 37%. Infection with Giardia cysts was 6.8% and infection with Cryptosporidium oocyte was 30.7%, and Cryptosporidium infection rates in vegetables and lettuce were different. This difference was statistically significant (P<0.05. Conclusion: As a result of this research it is determined that the prevalence of Giardia and Cryptosporidium in Ilam vegetables is significantly higher, and the contamination of lettuce is far greater. Therefore, authorities should be more attentive to the field of education and the control of parasitic diseases.

Marketing experience with radurised products in South Africa

International Nuclear Information System (INIS)

Van der Linde, H.J.

1983-01-01

The South African food irradiation program is a joint undertaking of the Nuclear Development Corporation and the Department of Agriculture. After almost a decade of research and development, it was decided to proceed to the commercialisation stage. A private company erected a commercial bath irradiator for the radurisation of, especially, subtropical fruits. There are now three commercial irradiators involved in the radurisation of fresh and processed food products in South Africa. The outcome of the marketing trials and ensuing factors found to be most important in the commercialisation of radurisation are discussed

Influence of nitrogen and phosphorus sources on mycorrhizal lettuces under organic farming

Science.gov (United States)

Scotti, Riccardo; Seguel, Alex; Cornejo, Pablo; Rao, Maria A.; Borie, Fernando

2010-05-01

Arbuscular mycorrhizal fungi (AMF) develop symbiotic associations with plants roots. These associations are very common in the natural environment and can provide a range of benefits to the host plant. AMF improve nutrition, enhance resistance to soil-borne pests and disease, increase resistance to drought and tolerance to heavy metals, and contribute to a better soil structure. However, agricultural intensive managements, such as the use of mineral fertilizes, pesticides, mouldboard tillage, monocultures and use of non-mycorrhizal crops, are detrimental to AMF. As a consequence, agroecosystems are impoverished in AMF and may not provide the full range of benefits to the crop. Organic farming systems may be less unfavourable to AMF because they exclude the use of water-soluble fertilisers and most pesticides, and generally they plan diverse crop rotations. The AMF develop the most common type of symbiosis in nature: about 90% of the plants are mycorrhizal and many agricultural crops are mycorrhizal. One of more mycorrhizal crops is lettuce, that is very widespread in intensive agricultural under greenhouse. Therefore, cultivated lettuce is know to be responsive to mycorrhizal colonization which can reach 80% of root length and contribute to phosphorus and nitrogen absorption by this plant specie. For this work four different lettuce cultivars (Romana, Milanesa, Grande Lagos and Escarola) were used to study mycorrhization under organic agricultural system, supplying compost from agricultural waste (1 kg m-2) as background fertilization for all plots, red guano as phosphorus source (75 U ha-1 and 150 U ha-1 of P2O5), lupine flour as nitrogen source (75 and 150 U/ha of N) and a combination of both. Lettuce plants were cultivated under greenhouse and after two months of growing, plants were harvested and dried and fresh weight of lettuce roots and shoots were evaluated. The number of spores, percentage of colonization, total mycelium and glomalin content were also

Bacterial diversity and community structure in lettuce soil are shifted by cultivation time

Science.gov (United States)

Liu, Yiqian; Chang, Qing; Guo, Xu; Yi, Xinxin

2017-08-01

Compared with cereal production, vegetable production usually requires a greater degree of management and larger input of nutrients and irrigation, but these systems are not sustainable in the long term. This study aimed to what extent lettuce determine the bacterial community composition in the soil, during lettuce cultivation, pesticides and fertilizers were not apply to soil. Soil samples were collected from depths of 0-20cm and 20-40cm. A highthroughput sequencing approach was employed to investigate bacterial communities in lettuce-cultivated soil samples in a time-dependent manner. The dominant bacteria in the lettuce soil samples were mainly Proteobacteria, Actinobacteria, Chloroflexi, Nitrospirae, Firmicutes, Acidobacteria, Bacteroidetes, Verrucomicrobia, Planctomycetes, Gemmatimo nadetes, Cyanobacteria. Proteobacteria was the most abundant phylum in the 6 soil samples. The relative abundance of Acidobacteria, Firmicutes, Bacteroidetes, Verrucomicrobia and Cyanobacteria decreased through time of lettuce cultivation, but the relative abundance of Proteobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi, Planctomycetes and Nitrospirae increased over time. In the 0-20cm depth group and the 20-40cm depth soil, a similar pattern was observed that the percentage number of only shared OTUs between the early and late stage was lower than that between the early and middle stage soil, the result showed that lettuce growth can affect structure of soil bacterial communities.

Minimal processing of iceberg lettuce has no substantial influence on the survival, attachment and internalization of E. coli O157 and Salmonella.

Science.gov (United States)

Van der Linden, Inge; Avalos Llano, Karina R; Eriksson, Markus; De Vos, Winnok H; Van Damme, Els J M; Uyttendaele, Mieke; Devlieghere, Frank

2016-12-05

The influence of a selection of minimal processing techniques (sanitizing wash prior to packaging, modified atmosphere, storage conditions under light or in the dark) was investigated in relation to the survival of, attachment to and internalization of enteric pathogens in fresh produce. Cut Iceberg lettuce was chosen as a model for fresh produce, Escherichia coli O157:H7 (E. coli O157) and Salmonella enterica were chosen as pathogen models. Care was taken to simulate industrial post-harvest processing. A total of 50±0.1g of fresh-cut Iceberg lettuce was packed in bags under near ambient atmospheric air with approximately 21% O 2 (NAA) conditions or equilibrium modified atmosphere with 3% O 2 (EMAP). Two lettuce pieces inoculated with E. coli O157 BRMSID 188 or Salmonella Typhimurium labeled with green fluorescent protein (GFP) were added to each package. The bags with cut lettuce were stored under either dark or light conditions for 2days at 7°C. The pathogens' capacity to attach to the lettuce surface and cut edge was evaluated 2days after inoculation using conventional plating technique and the internalization of the bacteria was investigated and quantified using confocal microscopy. The effect of a sanitizing wash step (40mg/L NaClO or 40mg/L peracetic acid+1143mg/L lactic acid) of the cut lettuce prior to packaging was evaluated as well. Our results indicate that both pathogens behaved similarly under the investigated conditions. Pathogen growth was not observed, nor was there any substantial influence of the investigated atmospheric conditions or light/dark storage conditions on their attachment/internalization. The pathogens attached to and internalized via cut edges and wounds, from which they were able to penetrate into the parenchyma. Internalization through the stomata into the parenchyma was not observed, although some bacteria were found in the substomatal cavity. Washing the cut edges with sanitizing agents to reduce enteric pathogen numbers was not

Escherichia coli transfer from simulated wildlife feces to lettuce during foliar irrigation: A field study in the Northeastern United States.

Science.gov (United States)

Weller, Daniel L; Kovac, Jasna; Kent, David J; Roof, Sherry; Tokman, Jeffrey I; Mudrak, Erika; Kowalcyk, Barbara; Oryang, David; Aceituno, Anna; Wiedmann, Martin

2017-12-01

Wildlife intrusion has been associated with pathogen contamination of produce. However, few studies have examined pathogen transfer from wildlife feces to pre-harvest produce. This study was performed to calculate transfer coefficients for Escherichia coli from simulated wildlife feces to field-grown lettuce during irrigation. Rabbit feces inoculated with a 3-strain cocktail of non-pathogenic E. coli were placed in a lettuce field 2.5-72 h before irrigation. Following irrigation, the E. coli concentration on the lettuce was determined. After exclusion of an outlier with high E. coli levels (Most Probable Number = 5.94*10 8 ), the average percent of E. coli in the feces that transferred to intact lettuce heads was 0.0267% (Standard Error [SE] = 0.0172). Log-linear regression showed that significantly more E. coli transferred to outer leaves compared to inner leaves (Effect = 1.3; 95% Confidence Interval = 0.4, 2.1). Additionally, the percent of E. coli that transferred from the feces to the lettuce decreased significantly with time after fecal placement, and as the distance between the lettuce and the feces, and the lettuce and the sprinklers increased. These findings provide key data that may be used in future quantitative risk assessments to identify potential intervention strategies for reducing food safety risks associated with fresh produce. Copyright © 2017 Elsevier Ltd. All rights reserved.

Flavor characteristics of the juices from fresh market tomatoes differentiated from those from processing tomatoes by combined analysis of volatile profiles with sensory evaluation.

Science.gov (United States)

Iijima, Yoko; Iwasaki, Yumi; Otagiri, Yuji; Tsugawa, Hiroshi; Sato, Tsuneo; Otomo, Hiroe; Sekine, Yukio; Obata, Akio

2016-12-01

Various commercial tomato juices with different flavors are available at markets worldwide. To clarify the marker compounds related to the flavor characteristics of tomato juice, we analyzed 15 pure commercial tomato juices by a combination of volatile profiling and sensory evaluation. The correlations among volatiles and the relationship between volatiles and sensory descriptors were elucidated by multivariate analyses. Consequently, the tomato juices made from fresh market tomatoes (including the popular Japanese tomato variety "Momotaro") were clearly separated from other juices made from processing tomatoes, by both the volatile composition and sensory profiles. cis-3-Hexenol, hexanal, and apocarotenoids negatively contributed to the juices from fresh market tomatoes, whereas Strecker aldehydes and furfural showed positive contributions to the juices. Accordingly, the sensory characteristics of juices from fresh market tomatoes were related to cooked and fruity flavors but not to green or fresh notes.

Low cost industrial production of coagulation factor IX bioencapsulated in lettuce cells for oral tolerance induction in hemophilia B

Science.gov (United States)

Su, Jin; Zhu, Liqing; Sherman, Alexandra; Wang, Xiaomei; Lin, Shina; Kamesh, Aditya; Norikane, Joey H.; Streatfield, Stephen J.; Herzog, Roland W.; Daniell, Henry

2015-01-01

Antibodies (inhibitors) developed by hemophilia B patients against coagulation factor IX (FIX) are challenging to eliminate because of anaphylaxis or nephrotic syndrome after continued infusion. To address this urgent unmet medical need, FIX fused with a transmucosal carrier (CTB) was produced in a commercial lettuce (Simpson Elite) cultivar using species specific chloroplast vectors regulated by endogenous psbA sequences. CTB-FIX (~1mg/g) in lyophilized cells was stable with proper folding, disulfide bonds and pentamer assembly when stored ~2 years at ambient temperature. Feeding lettuce cells to hemophilia B mice delivered CTB-FIX efficiently to the gut immune system, induced LAP+ regulatory T cells and suppressed inhibitor/IgE formation and anaphylaxis against FIX. Lyophilized cells enabled 10-fold dose escalation studies and successful induction of oral tolerance was observed in all tested doses. Induction of tolerance in such a broad dose range should enable oral delivery to patients of different age groups and diverse genetic background. Using Fraunhofer cGMP hydroponic system, ~870 kg fresh or 43.5 kg dry weight can be harvested per 1000 ft2 per annum yielding 24,000–36,000 doses for 20-kg pediatric patients, enabling first commercial development of an oral drug, addressing prohibitively expensive purification, cold storage/transportation and short shelf life of current protein drugs. PMID:26302233

Requirement analysis for the one-stop logistics management of fresh agricultural products

Science.gov (United States)

Li, Jun; Gao, Hongmei; Liu, Yuchuan

2017-08-01

Issues and concerns for food safety, agro-processing, and the environmental and ecological impact of food production have been attracted many research interests. Traceability and logistics management of fresh agricultural products is faced with the technological challenges including food product label and identification, activity/process characterization, information systems for the supply chain, i.e., from farm to table. Application of one-stop logistics service focuses on the whole supply chain process integration for fresh agricultural products is studied. A collaborative research project for the supply and logistics of fresh agricultural products in Tianjin was performed. Requirement analysis for the one-stop logistics management information system is studied. The model-driven business transformation, an approach uses formal models to explicitly define the structure and behavior of a business, is applied for the review and analysis process. Specific requirements for the logistic management solutions are proposed. Development of this research is crucial for the solution of one-stop logistics management information system integration platform for fresh agricultural products.

A Research on Online Shopping of Fresh Agricultural Products in China%我国生鲜农产品网购研究

Institute of Scientific and Technical Information of China (English)

彭礼

2015-01-01

With the development of information technology,e-commerce market is changing rapidly,since consumers have more shopping way,online shopping is becoming increasingly attractive.This paper summarized the development status,existing problems and factors affecting fresh agricultural product,and put forward countermeasures and suggestions,so as to provide ideas for online market extension of fresh agricultural products.%随着信息技术的发展,电子商务市场变化很快,当消费者有更多的购物方法时,在线购物网站的吸引力越来越大.从生鲜农产品网购发展现状与问题、网购行为影响因素等方面进行归纳,并提出对策建议,以期为生鲜农产品网购市场的开拓提供思路.

Responses of Nasonovia ribisnigri (Homoptera: Aphididae) to susceptible and resistant lettuce.

Science.gov (United States)

Liu, Yong-Biao; McCreight, James D

2006-06-01

Nymphs and alates of aphid Nasonovia ribisnigri (Mosley) (Homoptera: Aphididae) were tested on 10 lettuce cultivars with N. ribisnigri resistance gene Nr and 18 cultivars without the resistance gene in various bioassays. Bioassays used whole plants, leaf discs, or leaf cages to determine susceptibility of commercial lettuce cultivars to N. ribisnigri infestation and to evaluate screening methods for breeding lettuce resistance to N. ribisnigri. Resistant and susceptible plants were separated in 3 d when using whole plant bioassays. Long-term (> or =7 d) no-choice tests using leaf cages or whole plants resulted in no survival of N. ribisnigri on resistant plants, indicating great promise of the Nr gene for management of N. ribisnigri. Effective screening was achieved in both no-choice tests where resistant or susceptible intact plants were tested separately in groups or individually and in choice tests where susceptible and resistant plants were intermixed. Leaf discs bioassays were not suitable for resistance screening. All lettuce cultivars without the resistance gene were suitable hosts for N. ribisnigri, indicating the great importance of this pest to lettuce production and the urgency in developing resistant lettuce cultivars to manage N. ribisnigri.

Sources and persistence of human noroviruses in fresh produce chains and associated public health risks

NARCIS (Netherlands)

Verhaelen, K.

2014-01-01

Human norovirus is a frequent cause of gastroenteritis worldwide, and viewed as the most common cause of foodborne disease. Numerous norovirus outbreaks associated with fresh produce, especially soft-berries and lettuce are described. Risk management strategies need to be improved in order to reduce

Jatropha press cake as organic fertilizer in lettuce cultivation

Directory of Open Access Journals (Sweden)

José R. Mantovani

Full Text Available ABSTRACT In biodiesel production, vegetable press cake is obtained as waste, and a suitable destination for jatropha press cake would be the use in agriculture as organic fertilizer. This study aimed to evaluate the effect of jatropha press cake on soil fertility attributes and on lettuce production and accumulation of nutrients in the shoots. The experiment was conducted in pots in a greenhouse, in a randomized block design with eight treatments and five replicates. The treatments consisted of doses of jatropha press cake equivalent to 0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 and 32.0 t ha-1. Portions of 5.5 dm3 of soil received limestone, phosphate fertilizer and the doses of jatropha press cake, and remained incubated for 30 days. After incubation, soil samples were collected, each pot received one lettuce seedling and the experiment was carried out for 45 days. The organic fertilization with jatropha press cake increased the contents of nutrients in the soil, especially K+, but caused increment in soil acidity and electrical conductivity. The use of jatropha press cake as organic fertilizer decreased lettuce production and accumulation of nutrients in the shoots.

The market chain of fruit production in Serbia: A case study of raspberry and sour cherry cultivation

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Radosavljević Katica

2008-01-01

Full Text Available The trade in fresh and frozen fruit is complex and fragmentary. Currently producers are forced to use a variety of marketing channels - farmers' markets, processing industries, trade companies and brokers. To increase quality, production, profitability and exports, it is essential to maximize cooperation between producers, processors, wholesalers and retailers. Vertically and laterally integrated fruit marketing channels demand the smallest number of intermediaries and direct relations with consumers. In past decades, fruit production in Serbia was characterized by irrational resource allocation. Neglect of the agribusiness marketing concept led to supply shortages. As a result, prices increased while quality decreased. Only integrated marketing concepts can boost quality, yields, profitability and competitiveness.

Toward a semi-mechanical harvesting platform system for harvesting blueberries with fresh-market quality

Science.gov (United States)

Major concerns related to harvesting blueberries for fresh market with over-the-row (OTR) harvesters are that the quality of the fruit harvested with OTR machines is generally low and ground loss is excessive. Machine-harvested blueberries have more internal bruise and usually soften rapidly in col...

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.

Effect of different substrates in aquaponic lettuce production associated with intensive tilapia farming with water recirculation systems

OpenAIRE

Geisenhoff, Luciano O.; Jordan, Rodrigo A.; Santos, Rodrigo C.; Oliveira, Fabricio C. de; Gomes, Eder P.

2016-01-01

ABSTRACT The integration of fish farming in intensive system and plant production, called "aquaponics" is practiced successfully in countries like the USA, Australia and Europe. In Brazil, this integration has attracted the attention of researchers and producers. In this context, the aim of this study was to evaluate the effect of two substrates (crushed stone number 3, CS III and flexible polyurethane foam, FPF) on the production of aquaponic lettuce, moreover, to show that the residual wate...

78 FR 41259 - Importation of Fresh Citrus Fruit From Uruguay, Including Citrus

Science.gov (United States)

2013-07-10

... therefore opposed importation of fresh citrus fruit from Uruguay until its effectiveness could be validated...'' imports. The commenter stated that this argument is invalid due to the year-round marketing of citrus... metric tons, which is less than 3 percent of U.S. production. Uruguay's total fresh orange and lemon...

Isolation, molecular identification and quinolone-susceptibility testing of Arcobacter spp. isolated from fresh vegetables in Spain.

Science.gov (United States)

González, Ana; Bayas Morejón, Isidro Favián; Ferrús, María Antonia

2017-08-01

Some species of the Arcobacter genus are considered emerging foodborne and waterborne enteropathogens. However, the presence of Arcobacter spp. in vegetables very little is known, because most studies have focused on foods of animal origin. On the other hand, quinolones are considered as first-line drugs for the treatment of infection by campylobacteria in human patients, but few data are currently available about the resistance levels to these antibiotics among Arcobacter species. Therefore, the aim of this study was to investigate the presence and diversity of arcobacters isolated from fresh vegetables such as lettuces, spinaches, chards and cabbages. Resistance to quinolones of the isolates was also investigated. One hundred fresh vegetables samples purchased from seven local retail markets in Valencia (Spain) during eight months were analysed. The study included 41 lettuces, 21 spinaches, 34 chards and 4 cabbages. Samples were analysed by culture and by molecular methods before and after enrichment. By culture, 17 out of 100 analysed samples were Arcobacter positive and twenty-five isolates were obtained from them. Direct detection by PCR was low, with only 4% Arcobacter spp. positive samples. This percentage increased considerably, up 20%, after 48 h enrichment. By polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), 17 out of the 25 isolates were identified as A. butzleri and 8 as A. cryaerophilus. Only two A. butzleri isolates showed resistance to levofloxacin and ciprofloxacin. The sequencing of a fragment of the QRDR region of the gyrA gene from the quinolones-resistant isolates revealed the presence of a mutation in position 254 of this gene (C-T transition). This study is the first report about the presence of pathogenic species of Arcobacter spp. in chards and cabbages and confirms that fresh vegetables can act as transmission vehicle to humans. Moreover, the presence of A. butzleri quinolone resistant in vegetables could

Nondestructive phenotyping of lettuce plants in early stages of development with optical sensors

Science.gov (United States)

Rapid development of plants is important for the production of ‘baby-leaf’ lettuce that is harvested when plants reach the four- to eight-leaf stage of growth. However, environmental factors, such as high or low temperature, or elevated concentrations of salt, inhibit lettuce growth. Therefore, nond...

The effects of irrigation timing on growth, yield, and physiological traits of hydroponic lettuce

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Md. Jahedur Rahman

2018-01-01

Full Text Available Crop-specific timing of irrigation is necessary to conserve irrigation water and improve yield of vegetables. Therefore, the experiment was conducted to identify the optimum irrigation timings for hydroponic lettuce plants. Three nutrient solution timings, T1(once a day at 0900 hours, T2(once on alternative days at 0900 hours, and T3(once at two-day intervals, and three varieties, ‘Legacy’ (V1, ‘Red fire’ (V2, and ‘Green wave’ (V3 were evaluated. Growth and yield parameters, including number of leaves, leaf length, leaf diameter, and fresh weight of leaves, and growth parameters, including leaf area (LA, leaf area ratio (LAR, leaf mass ratio (LMR, root weight ratio (RWR, relative growth rate (RGR, and net assimilation rate (NAR were determined. The values of growth parameters were the highest for T1. The highest and lowest NAR and RGR values were obtained for T1 and T3, respectively. The values of most growth traits, including fresh weight, NAR, and RGR were higher for V1 than other varieties. T1 provides high yield with comparatively less irrigation water and nutrient solution so it can be used to culture lettuce using aggregate hydroponics as.

Technological innovations to preserve quality and safety of fresh-cut horticultural products

OpenAIRE

Artés-Hernández, Francisco; Gómez, Perla; Aguayo, Encarna; Artés-Hernández, Francisco

2010-01-01

Proceedings of the International Conference “Environmentally friendly and safe technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro, Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924. Fresh-cut or minimally processed fruit and vegetables have strongly increased their market share all over the industrialized countries. For that reason this market is currently very competitive, and forces the specialized ...

Effects of microcystin-LR, cylindrospermopsin and a microcystin-LR/cylindrospermopsin mixture on growth, oxidative stress and mineral content in lettuce plants (Lactuca sativa L.).

Science.gov (United States)

Freitas, Marisa; Azevedo, Joana; Pinto, Edgar; Neves, Joana; Campos, Alexandre; Vasconcelos, Vitor

2015-06-01

Toxic cyanobacterial blooms are documented worldwide as an emerging environmental concern. Recent studies support the hypothesis that microcystin-LR (MC-LR) and cylindrospermopsin (CYN) produce toxic effects in crop plants. Lettuce (Lactuca sativa L.) is an important commercial leafy vegetable that supplies essential elements for human nutrition; thus, the study of its sensitivity to MC-LR, CYN and a MC-LR/CYN mixture is of major relevance. This study aimed to assess the effects of environmentally relevant concentrations (1, 10 and 100 µg/L) of MC-LR, CYN and a MC-LR/CYN mixture on growth, antioxidant defense system and mineral content in lettuce plants. In almost all treatments, an increase in root fresh weight was obtained; however, the fresh weight of leaves was significantly decreased in plants exposed to 100 µg/L concentrations of each toxin and the toxin mixture. Overall, GST activity was significantly increased in roots, contrary to GPx activity, which decreased in roots and leaves. The mineral content in lettuce leaves changed due to its exposure to cyanotoxins; in general, the mineral content decreased with MC-LR and increased with CYN, and apparently these effects are time and concentration-dependent. The effects of the MC-LR/CYN mixture were almost always similar to the single cyanotoxins, although MC-LR seems to be more toxic than CYN. Our results suggest that lettuce plants in non-early stages of development are able to cope with lower concentrations of MC-LR, CYN and the MC-LR/CYN mixture; however, higher concentrations (100 µg/L) can affect both lettuce yield and nutritional quality. Copyright © 2015 Elsevier Inc. All rights reserved.

Consumer’s attitude and perception of fresh seafood products: cognitive effects on behaviour buying

OpenAIRE

Gouin, Stéphane; Mesnildrey, Lucile; Lesueur, Marie

2010-01-01

Since 2004, the French fishery field has had to cope with a levelling off of consumption of fresh seafood products whereas the consumption of processed seafood products is increasing. Nowadays, consumers prefer easier products: fresh deli products, easy to cook or ready to consume. Therefore, fresh seafood products do not seem to fulfil current consumer demand intrinsically (aspect, taste) and extrinsically (cooking methods, use, origin, brand and price). In order to understand the evolution ...

Non-destructive monitoring of agricultural product (lettuce [Lactuca sativa]) based on laser-induced fluorescence

International Nuclear Information System (INIS)

Ishizawa, H.; Saito, Y.; Amemiya, T.; Komatu, K.

2002-01-01

Quality control of agricultural products in process of cultivation and distribution has become an important problem. This paper describes a field measuring method of lettuce based on laser induced fluorescence (LIF) spectroscopy for growth monitoring. Intensity at 460nm of LIF spectra showed characteristic variations of near harvest time. The results of chemical analysis confirmed that sucrose and chlorogenic acid are origins of the 460nm fluorescence. The prediction of harvest time and the possibility of quality monitoring are discussed based on the experimental data

Simulation of gamma-ray irradiation of lettuce leaves in a 137Cs irradiator using MCNP

International Nuclear Information System (INIS)

Kim, Jongsoon; Moreira, Rosana G.; Braby, Leslie A.

2010-01-01

Ionizing radiation effectively reduces the number of common microbial pathogens in fresh produce. However, the efficacy of the process for pathogens internalized into produce tissue is unknown. The objective of this study was to understand gamma irradiation of lettuce leaf structure exposed in a 137 Cs irradiator using MCNP. The simulated 137 Cs irradiator is a self-shielded device, and its geometry and sources are described in the MCNP input file. When the irradiation chamber is filled with water, lower doses are found at the center of the irradiation volume and the dose uniformity ratio (maximum dose/minimum dose) is 1.76. For randomly oriented rectangular lettuce leaf segments in the irradiation chamber, the dose uniformity ratio is 1.25. It shows that dose uniformity in the Cs irradiator is strongly dependent of the density of the sample. To understand dose distribution inside the leaf, we divided a lettuce leaf into a low density (flat) region (0.72 g/cm 3 ) and high density (rib) region (0.86 g/cm 3 ). Calculated doses to the rib are 61% higher than doses to the flat region of the leaf. This indicates that internalized microorganisms can be inactivated more easily than organisms on the surface. This study shows that irradiation can effectively reduce viable microorganism internalized in lettuce. (author)

Possible Internalization of an Enterovirus in Hydroponically Grown Lettuce

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Annalaura Carducci

2015-07-01

Full Text Available Several studies have shown that enteric viruses can be transferred onto the surface of vegetables and fruits through spray irrigation, but, recently, reports have suggested viral contamination of vegetables sub-irrigated with reused wastewater. Hydroponic cultures, used to grow ready to eat fresh lettuce, have also been used to study the possibility of viral absorption through roots. This study was conducted to assess a possible risk of viral contamination in lettuce from contaminated water. The leaves of lettuce plants grown in hydroponic cultures where the roots were exposed to water containing Coxsakievirus B2, were analysed for evidence of the virus. The plants and water were sampled at different times and virus was measured using quantitative RT-PCR and infectivity assay. In leaf samples, the lowest observed infective data were lower than the qRT-PCR detection limits, suggesting that free viral RNA or damaged viruses are eliminated rapidly while infectious particles remain stable for a longer time. The obtained data revealed that the leaves were contaminated at a water concentration of 4.11 ± 1 Log Most Probable Number/L (8.03 ± 1 Log GC/L a concentration observed in contaminated untreated water of wastewater treatment plants. However, the absorption dynamics and whether the virus is inactive in the leaves still remains to be clarified. Nevertheless, this work has practical implications for risk management in using reclaimed water for agricultural use; when irrigated vegetables are destined for raw consumption, virological contamination in water sources should be evaluated.

Possible Internalization of an Enterovirus in Hydroponically Grown Lettuce.

Science.gov (United States)

Carducci, Annalaura; Caponi, Elisa; Ciurli, Adriana; Verani, Marco

2015-07-17

Several studies have shown that enteric viruses can be transferred onto the surface of vegetables and fruits through spray irrigation, but, recently, reports have suggested viral contamination of vegetables sub-irrigated with reused wastewater. Hydroponic cultures, used to grow ready to eat fresh lettuce, have also been used to study the possibility of viral absorption through roots. This study was conducted to assess a possible risk of viral contamination in lettuce from contaminated water. The leaves of lettuce plants grown in hydroponic cultures where the roots were exposed to water containing Coxsakievirus B2, were analysed for evidence of the virus. The plants and water were sampled at different times and virus was measured using quantitative RT-PCR and infectivity assay. In leaf samples, the lowest observed infective data were lower than the qRT-PCR detection limits, suggesting that free viral RNA or damaged viruses are eliminated rapidly while infectious particles remain stable for a longer time. The obtained data revealed that the leaves were contaminated at a water concentration of 4.11 ± 1 Log Most Probable Number/L (8.03 ± 1 Log GC/L) a concentration observed in contaminated untreated water of wastewater treatment plants. However, the absorption dynamics and whether the virus is inactive in the leaves still remains to be clarified. Nevertheless, this work has practical implications for risk management in using reclaimed water for agricultural use; when irrigated vegetables are destined for raw consumption, virological contamination in water sources should be evaluated.

Efficient and stable transformation of Lactuca sativa L. cv. Cisco (lettuce) plastids.

Science.gov (United States)

Kanamoto, Hirosuke; Yamashita, Atsushi; Asao, Hiroshi; Okumura, Satoru; Takase, Hisabumi; Hattori, Masahira; Yokota, Akiho; Tomizawa, Ken-Ichi

2006-04-01

Transgenic plastids offer unique advantages in plant biotechnology, including high-level foreign protein expression. However, broad application of plastid genome engineering in biotechnology has been largely hampered by the lack of plastid transformation systems for major crops. Here we describe the development of a plastid transformation system for lettuce, Lactuca sativa L. cv. Cisco. The transforming DNA carries a spectinomycin-resistance gene (aadA) under the control of lettuce chloroplast regulatory expression elements, flanked by two adjacent lettuce plastid genome sequences allowing its targeted insertion between the rbcL and accD genes. On average, we obtained 1 transplastomic lettuce plant per bombardment. We show that lettuce leaf chloroplasts can express transgene-encoded GFP to approximately 36% of the total soluble protein. All transplastomic T0 plants were fertile and the T1 progeny uniformly showed stability of the transgene in the chloroplast genome. This system will open up new possibilities for the efficient production of edible vaccines, pharmaceuticals, and antibodies in plants.

Genetics of the partial resistance against race 2 of Verticillium dahliae in lettuce

Science.gov (United States)

Lettuce (Lactuca sativa L.) production on the Coastal California is threatened by Verticillium wilt, a soil borne fungal disease caused by Verticillium dahliae that diminishes yield and quality. Two races of V. dahliae were identified on lettuce, race 1 and race 2. Complete resistance to race 1 is c...

Modeling the contamination of lettuce with Escherichia coli 157:H7 from manure-amended soil and the effect of intervention strategies

NARCIS (Netherlands)

Franz, E.; Semenov, A.V.; Bruggen, van A.H.C.

2008-01-01

Aims: A growing number of foodborne illnesses has been associated with the consumption of fresh produce. In this study, the probability of lettuce contamination with Escherichia coli O157:H7 from manure-amended soil and the effect of intervention strategies was determined. Methods and Results:

Effect of single or combined chemical and natural antimicrobial interventions on Escherichia coli O157:H7, total microbiota and color of packaged spinach and lettuce.

Science.gov (United States)

Poimenidou, Sofia V; Bikouli, Vasiliki C; Gardeli, Chryssavgi; Mitsi, Christina; Tarantilis, Petros A; Nychas, George-John; Skandamis, Panagiotis N

2016-03-02

Aqueous extract of Origanum vulgare (oregano), sodium hypochlorite (60 and 300 ppm of free chlorine), Citrox® (containing citric acid and phenolic compounds [bioflavonoids] as active ingredients), vinegar, lactic acid, and double combinations of Citrox, lactic acid and oregano were evaluated against Escherichia coli O157:H7 and total mesophilic microbiota on fresh-cut spinach and lettuce and for their impact on color of treated vegetables. Spinach and lettuce leaves were inoculated with E. coli O157:H7 to a level of 5-6 log CFU/g and immersed in washing solutions for 2 or 5 min at 20 °C, followed by rinsing with ice water (30s). Bacterial populations on vegetables were enumerated immediately after washing and after storage of the samples at 5 °C for 7 days under 20% CO2: 80% N2. No significant post-washing microbial reductions were achieved by chlorinated water, whereas after storage total microbiota was increased by 2.4 log CFU/g on lettuce. Vinegar wash was the most effective treatment causing E. coli O157:H7 reductions of 1.8-4.3 log CFU/g. During storage, pathogen was further decreased to below the detection limit level (lettuce during storage. Washing lettuce samples with oregano for 2 min resulted in 2.1 log CFU/g reduction of E. coli O157:H7. When Citrox was combined with oregano, 3.7-4.0 log CFU/g reduction was achieved on spinach and lettuce samples, with no significant effect on color parameters. Additionally, rinsing with ice water after decontamination treatments contributed to maintenance of color of the treated vegetables. In conclusion, the results indicated that vinegar, lactic acid or oregano aqueous extract alone or in combination, as alternative washing solutions to chlorine, may be effectively used to control E. coli O157:H7 and sustain acceptable appearance of fresh cut spinach and lettuce. Copyright © 2016 Elsevier B.V. All rights reserved.

Phosphorus rates on yield and quality of lettuce seeds

OpenAIRE

Kano,Cristiaini; Cardoso,Antonio Ismael Inácio; Bôas,Roberto L Villas

2012-01-01

Because of lack of information about phosphorus fertilization in lettuce from the standpoint of seed production, this study was undertaken. The work was carried out in Botucatu, São Paulo state, Brazil, from September 25, 2003 to February 19, 2004, in order to study the influence of crescents phosphorus rates on yield and quality of lettuce seeds, cultivar Verônica. The experimental design was randomized blocks with five treatments (0; 200; 400; 600 and 800 kg ha-1 of P2O5) and five replicati...

Association analysis of bacterial leaf spot resistance and SNP markers derived from expressed sequence tags (ESTs) in lettuce (Lactuca sativa L.)

Science.gov (United States)

Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A total of 179 lettuce ge...

76 FR 71271 - Common Crop Insurance Regulations; Fresh Market Tomato (Dollar Plan) Crop Provisions

Science.gov (United States)

2011-11-17

... to add ``strawberries'' in section 9(b)(3) to the list of crops that require soil fumigation before planting fresh market tomatoes. Strawberries are susceptible to nematode damage and pose the same risk of... sections 9(b)(1) and (2)), peppers, eggplants, strawberries or tobacco have been grown and the soil was not...

Production and efficiency of organic compost generated by millipede activity

Directory of Open Access Journals (Sweden)

Luiz Fernando de Sousa Antunes

2016-05-01

Full Text Available ABSTRACT: The putrefactive activity of organisms such as diplopods in the edaphic macrof auna can be leveraged to promote the transformation of agricultural and urban waste into a low-cost substrate for the production of vegetable seedlings. This research aimed to evaluate: (1 the quantity of Gervais millipedes ( Trigoniulus corallinus needed to produce an acceptable quantity of organic compost; (2 the main physical and chemical characteristics of different compost types; and (3 compost efficiency in the production of lettuce seedlings. The first experiment lasted 90 days and was conducted using 6.5L of Gliricidia, 6.5L of Flemingia, 13.5L of grass cuttings, 4.5L of cardboard, 4.5L of coconut husk, and 4.5L of corncob. Treatments consisting of 0, 0.10, 0.30, 0.50, and 0.90L of millipedes were applied. This experiment compared millicompost and vermicompost, using four repetitions. After 23 days, the heights of grown lettuce plants and the weights of the fresh and dry mass of above ground lettuce and of the roots were assessed. A millipede volume of 0.1L proved to be sufficient for the production of an acceptable volume of organic compost. However, the addition of greater volumes leads to increased calcium, magnesium, and phosphorous content. Millicompost has similar physicochemical characteristics those of vermicompost, and both are equally efficient as a substrate for the production of lettuce seedlings.

Wild lettuce (Lactuca virosa) toxicity.

Science.gov (United States)

Besharat, Sima; Besharat, Mahsa; Jabbari, Ali

2009-01-01

Wild lettuce (Lactuca virosa) can cause toxic effects when eaten. Wild lettuce grows in the north of Iran and some natives consume it unaware of its adverse side effects. We describe eight patients with manifestations of wild lettuce toxicity, admitted to a general hospital affiliated to the Golestan University of Medical Sciences. All the patients recovered (although one had to spend 48 h in the intensive care unit) and no chronic complications were reported. A clinical suspicion of toxicity caused by wild lettuce intake and an accurate history formed the basis of the diagnosis. Conservative treatment, vital sign monitoring, control of patient intake and output, and reducing patient agitation provided the basis for treatment.

Consumers’ attitude and opinion towards different types of fresh cheese: an exploratory study

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Cássia Pereira de BARROS

2016-01-01

Full Text Available Abstract Fresh cheese stands out for its tradition and widespread consumption in Brazil. However, there is a lack of information on motivation towards the consumption of available fresh cheeses in the Brazilian market. Focus group sessions were used to explore consumers’ attitude and opinion about fresh cheese. Products with different characteristics were used to stimulate discussion among participants including cheese with “no added salt”, the claim “contains probiotic microorganisms” and products processed with goat milk. The salt content played an important role on the consumer intention to purchase of fresh cheese. Participants stated that they would consume cheese without salt only by following a medical prescription. However, the subjects declared that they would buy reduced salt cheese if such reduction would not compromise the flavor. The meaning of the claim “contains probiotic microorganisms” was often declared as unknown during the discussion. However, they would buy a probiotic product. In addition, it was mentioned that a premium price would be paid for such functional cheese. Participants declared that would buy goat cheese. Nevertheless, to pay a higher price over the conventional one was a controversial and debatable issue among consumers. Results revealed important implications for the development of marketing strategies for fresh cheese.

Bio-hydrogen Production Potential from Market Waste

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Lanna Jaitalee

2010-07-01

Full Text Available This research studied bio-hydrogen production from vegetable waste from a fresh market in order to recover energy. A series of batch experiments were conducted to investigate the effects of initial volatile solids concentration on the bio-hydrogen production process. Lab bench scale anaerobic continuous stirred-tank reactors (CSTR were used to study the effect of substrate and sludge inoculation on hydrogen production. Three different concentrations of initial total volatile solids (TVS of organic waste were varied from 2%, 3% and 5% respectively. The pH was controlled at 5.5 for all batches in the experiment. The results showed that bio-hydrogen production depended on feed-substrate concentration. At initial TVS content of 3%, the highest hydrogen production was achieved at a level of 0.59 L-H2/L at pH 5.5. The maximum hydrogen yield was 15.3 ml H2/g TVS or 8.5 ml H2/g COD. The composition of H2 in the biogas ranged from 28.1-30.9% and no CH4 was detected in all batch tests.

Biofortification of lettuce (Lactuca sativa L.) with iodine: the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce grown in water culture.

Science.gov (United States)

Voogt, Wim; Holwerda, Harmen T; Khodabaks, Rashied

2010-04-15

Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture. In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 microg iodine L(-1), applied as iodate (IO(3)(-)) or iodide (I(-)), did not affect plant biomass, produce quality or water uptake. Increases in iodine concentration significantly enhanced iodine content in the plant. Iodine contents in plant tissue were up to five times higher with I(-) than with IO(3)(-). Iodine was mainly distributed to the outer leaves. The highest iodide dose rates in both trials resulted in 653 and 764 microg iodine kg(-1) total leaf fresh weight. Biofortification of lettuce with iodine is easily applicable in a hydroponic growing system, both with I(-) and IO(3)(-). I(-) was more effective than IO(3)(-). Fifty grams of iodine-biofortified lettuce would provide, respectively, 22% and 25% of the recommended daily allowance of iodine for adolescents and adults. (c) 2010 Society of Chemical Industry.

Factors influencing the microbial safety of fresh produce: a review.

Science.gov (United States)

Olaimat, Amin N; Holley, Richard A

2012-10-01

Increased consumption, larger scale production and more efficient distribution of fresh produce over the past two decades have contributed to an increase in the number of illness outbreaks caused by this commodity. Pathogen contamination of fresh produce may originate before or after harvest, but once contaminated produce is difficult to sanitize. The prospect that some pathogens invade the vascular system of plants and establish "sub-clinical" infection needs to be better understood to enable estimation of its influence upon risk of human illness. Conventional surface sanitation methods can reduce the microbial load, but cannot eliminate pathogens if present. Chlorine dioxide, electrolyzed water, UV light, cold atmospheric plasma, hydrogen peroxide, organic acids and acidified sodium chlorite show promise, but irradiation at 1 kGy in high oxygen atmospheres may prove to be the most effective means to assure elimination of both surface and internal contamination of produce by pathogens. Pathogens of greatest current concern are Salmonella (tomatoes, seed sprouts and spices) and Escherichia coli O157:H7 on leafy greens (spinach and lettuce). This review considers new information on illness outbreaks caused by produce, identifies factors which influence their frequency and size and examines intervention effectiveness. Research needed to increase our understanding of the factors influencing microbial safety of fresh produce is addressed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Genetic investigation of the nonhost resistance of wild lettuce, Lactuca saligna, to lettuce downy mildew, Bremia lactucae

NARCIS (Netherlands)

Boer, den E.

2014-01-01

Abstract

Downy mildew (Bremia lactucae) in lettuce (Lactuca sativa) is a devastating foliar disease causing high losses in lettuce cultivation. The wild lettuce and nonhost species, Lactuca saligna, is absolute resistant to downy mildew and

Effects of household washing on bacterial load and removal of Escherichia coli from lettuce and "ready-to-eat" salads.

Science.gov (United States)

Uhlig, Elisabeth; Olsson, Crister; He, Jiayi; Stark, Therese; Sadowska, Zuzanna; Molin, Göran; Ahrné, Siv; Alsanius, Beatrix; Håkansson, Åsa

2017-11-01

Customer demands for fresh salads are increasing, but leafy green vegetables have also been linked to food-borne illness due to pathogens such as Escherichia coli O157:H7. As a safety measure, consumers often wash leafy vegetables in water before consumption. In this study, we analyzed the efficiency of household washing to reduce the bacterial content. Romaine lettuce and ready-to-eat mixed salad were washed several times in flowing water at different rates and by immersing the leaves in water. Lettuce was also inoculated with E. coli before washing. Only washing in a high flow rate (8 L/min) resulted in statistically significant reductions ( p  < .05), "Total aerobic count" was reduced by 80%, and Enterobacteriaceae count was reduced by 68% after the first rinse. The number of contaminating E. coli was not significantly reduced. The dominating part of the culturable microbiota of the washed lettuce was identified by rRNA 16S sequencing of randomly picked colonies. The majority belonged to Pseudomonadaceae , but isolates from Enterobacteriaceae and Staphylococcaceaceae were also frequently found. This study shows the inefficiency of tap water washing methods available for the consumer when it comes to removal of bacteria from lettuce. Even after washing, the lettuce contained high levels of bacteria that in a high dose and under certain circumstances may constitute a health risk.

Frequency of Verticillium Species in Commercial Spinach Fields and Transmission of V. dahliae from Spinach to Subsequent Lettuce Crops.

Science.gov (United States)

Short, D P G; Gurung, S; Koike, S T; Klosterman, S J; Subbarao, K V

2015-01-01

Verticillium wilt caused by V. dahliae is a devastating disease of lettuce in California (CA). The disease is currently restricted to a small geographic area in central coastal CA, even though cropping patterns in other coastal lettuce production regions in the state are similar. Infested spinach seed has been implicated in the introduction of V. dahliae into lettuce fields but direct evidence linking this inoculum to wilt epidemics in lettuce is lacking. In this study, 100 commercial spinach fields in four coastal CA counties were surveyed to evaluate the frequency of Verticillium species recovered from spinach seedlings and the area under spinach production in each county was assessed. Regardless of the county, V. isaacii was the most frequently isolated species from spinach followed by V. dahliae and, less frequently, V. klebahnii. The frequency of recovery of Verticillium species was unrelated to the occurrence of Verticillium wilt on lettuce in the four counties but was related to the area under spinach production in individual counties. The transmission of V. dahliae from infested spinach seeds to lettuce was investigated in microplots. Verticillium wilt developed on lettuce following two or three plantings of Verticillium-infested spinach, in independent experiments. The pathogen recovered from the infected lettuce from microplots was confirmed as V. dahliae by polymerase chain reaction assays. In a greenhouse study, transmission of a green fluorescence protein-tagged mutant strain of V. dahliae from spinach to lettuce roots was demonstrated, after two cycles of incorporation of infected spinach residue into the soil. This study presents conclusive evidence that V. dahliae introduced via spinach seed can cause Verticillium wilt in lettuce.

Low cost industrial production of coagulation factor IX bioencapsulated in lettuce cells for oral tolerance induction in hemophilia B.

Science.gov (United States)

Su, Jin; Zhu, Liqing; Sherman, Alexandra; Wang, Xiaomei; Lin, Shina; Kamesh, Aditya; Norikane, Joey H; Streatfield, Stephen J; Herzog, Roland W; Daniell, Henry

2015-11-01

Antibodies (inhibitors) developed by hemophilia B patients against coagulation factor IX (FIX) are challenging to eliminate because of anaphylaxis or nephrotic syndrome after continued infusion. To address this urgent unmet medical need, FIX fused with a transmucosal carrier (CTB) was produced in a commercial lettuce (Simpson Elite) cultivar using species specific chloroplast vectors regulated by endogenous psbA sequences. CTB-FIX (∼1 mg/g) in lyophilized cells was stable with proper folding, disulfide bonds and pentamer assembly when stored ∼2 years at ambient temperature. Feeding lettuce cells to hemophilia B mice delivered CTB-FIX efficiently to the gut immune system, induced LAP(+) regulatory T cells and suppressed inhibitor/IgE formation and anaphylaxis against FIX. Lyophilized cells enabled 10-fold dose escalation studies and successful induction of oral tolerance was observed in all tested doses. Induction of tolerance in such a broad dose range should enable oral delivery to patients of different age groups and diverse genetic background. Using Fraunhofer cGMP hydroponic system, ∼870 kg fresh or 43.5 kg dry weight can be harvested per 1000 ft(2) per annum yielding 24,000-36,000 doses for 20-kg pediatric patients, enabling first commercial development of an oral drug, addressing prohibitively expensive purification, cold storage/transportation and short shelf life of current protein drugs. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Reduction of Escherichia coli 0157:H7 in shredded iceberg lettuce by chlorination and gamma irradiation

Energy Technology Data Exchange (ETDEWEB)

Foley, D.M. E-mail: dfoley@chapman.edu; Dufour, A.; Rodriguez, L.; Caporaso, F.; Prakash, A

2002-03-01

Lettuce was inoculated with a six-strain cocktail of acid-adapted Escherichia coli 0157:H7 at a level of 1x10{sup 7} CFU/g. Following chlorination at 200 {mu}g/ml, the lettuce was irradiated at 0.15, 0.38, or 0.55 kGy using a {sup 60}Co source. Survival of E. coli 0157:H7, aerobic mesophiles and yeast and molds were measured over a period of 10 days. For quality analysis, chlorinated lettuce was subjected to irradiation at 0.33 and 0.53 kGy and stored at 1.0 deg. C, 4.0 deg. C or 7.0 deg. C. Changes in texture and color were determined by instrumental means and changes in flavor, odor, and visual quality were determined by sensory testing. Chlorination plus irradiation at 0.55 kGy produced a 5.4-log reduction in E. coli 0157:H7 levels. Chlorination alone reduced the E. coli 0157:H7 counts by 1-2 logs. Irradiation at 0.55 kGy was also effective in reducing standard plate counts and yeast and mold counts. Irradiation at this level did not cause softening of lettuce and sensory attributes were not adversely affected. In general, appearance and flavor were affected more by the length of storage than by temperature conditions. The 5+log reduction in E. coli counts and lack of adverse effects on sensory attributes indicate that low-dose irradiation can improve the safety and shelf-life of fresh-cut iceberg lettuce for retail sale or food service.

Reduction of Escherichia coli 0157:H7 in shredded iceberg lettuce by chlorination and gamma irradiation

International Nuclear Information System (INIS)

Foley, D.M.; Dufour, A.; Rodriguez, L.; Caporaso, F.; Prakash, A.

2002-01-01

Lettuce was inoculated with a six-strain cocktail of acid-adapted Escherichia coli 0157:H7 at a level of 1x10 7 CFU/g. Following chlorination at 200 μg/ml, the lettuce was irradiated at 0.15, 0.38, or 0.55 kGy using a 60 Co source. Survival of E. coli 0157:H7, aerobic mesophiles and yeast and molds were measured over a period of 10 days. For quality analysis, chlorinated lettuce was subjected to irradiation at 0.33 and 0.53 kGy and stored at 1.0 deg. C, 4.0 deg. C or 7.0 deg. C. Changes in texture and color were determined by instrumental means and changes in flavor, odor, and visual quality were determined by sensory testing. Chlorination plus irradiation at 0.55 kGy produced a 5.4-log reduction in E. coli 0157:H7 levels. Chlorination alone reduced the E. coli 0157:H7 counts by 1-2 logs. Irradiation at 0.55 kGy was also effective in reducing standard plate counts and yeast and mold counts. Irradiation at this level did not cause softening of lettuce and sensory attributes were not adversely affected. In general, appearance and flavor were affected more by the length of storage than by temperature conditions. The 5+log reduction in E. coli counts and lack of adverse effects on sensory attributes indicate that low-dose irradiation can improve the safety and shelf-life of fresh-cut iceberg lettuce for retail sale or food service

Soil Contamination With Heavy Metals and Its Effect on Growth, Yield and Physiological Responses of Vegetable Crop Plants (Turnip and Lettuce

Directory of Open Access Journals (Sweden)

Raifa Ahmed Hassanein

2013-11-01

Full Text Available The present study was conducted to investigate the impact of irrigation with industrial wastewater on soil and plant. For these purpose turnip and lettuce plants were cultivated in soil irrigated with wastewater then heavy metals content of the soil, plant growth, yield and the subsequent changes in biochemical constituents of plant were examined. Irrigation with wastewater was found to load the soil with heavy metals (Pb, Co, Ni and Cd that were not detected in soil before irrigation. The magnitude of Cd in soils after irrigation with industrial wastewater exceeds the maximum allowable limit (3 mg Kg-1. Both turnip and lettuce exhibited significant decreases in leaf area, fresh weight and dry weight of shoots and roots as well as all the measured yield components in response to wastewater irrigation. The magnitude of decrease was positively correlated with the amounts of heavy metals detected in the soil and the inhibitory effect on turnip was much more pronounced than in lettuce. Furthermore, heavy metals accumulation in soil resulted in an oxidative damage to turnip and lettuce as indicated by the significant increase in lipid peroxidation and H2O2 levels in both plants comparing to control values. The significant increases in putrescine in lettuce and turnip shoots and roots and spermidine in lettuce roots as well as total phenolics and flavonoids in plants cultivated in soil enriched with heavy metals are believed to be defense mechanisms in turnip and lettuce plants to counteract the oxidative stress resulted from heavy metals contamination generated from irrigation with wastewater.

Eat fresh vegetables, fruit, and whole grain products | NIH MedlinePlus the Magazine

Science.gov (United States)

... please turn Javascript on. Feature: Diverticulitis "Eat fresh vegetables, fruit, and whole grain products." Past Issues / Winter 2010 ... or the diverticulitis. I once again eat fresh vegetables and fruit and whole grain products. My two episodes of ...

What determines fresh fish consumption in Croatia?

Science.gov (United States)

Tomić, Marina; Matulić, Daniel; Jelić, Margareta

2016-11-01

Although fresh fish is widely available, consumption still remains below the recommended intake levels among the majority of European consumers. The economic crisis affects consumer food behaviour, therefore fresh fish is perceived as healthy but expensive food product. The aim of this study was to determine the factors influencing fresh fish consumption using an expanded Theory of Planned Behaviour (Ajzen, 1991) as a theoretical framework. The survey was conducted on a heterogeneous sample of 1151 Croatian fresh fish consumers. The study investigated the relationship between attitudes, perceived behavioural control, subjective norm, moral obligation, involvement in health, availability, intention and consumption of fresh fish. Structural Equation Modeling by Partial Least Squares was used to analyse the collected data. The results indicated that attitudes are the strongest positive predictor of the intention to consume fresh fish. Other significant predictors of the intention to consume fresh fish were perceived behavioural control, subjective norm, health involvement and moral obligation. The intention to consume fresh fish showed a strong positive correlation with behaviour. This survey provides valuable information for food marketing professionals and for the food industry in general. Copyright © 2015 Elsevier Ltd. All rights reserved.

Wild lettuce (Lactuca virosa) toxicity

OpenAIRE

Besharat, Sima; Besharat, Mahsa; Jabbari, Ali

2009-01-01

Wild lettuce (Lactuca virosa) can cause toxic effects when eaten. Wild lettuce grows in the north of Iran and some natives consume it unaware of its adverse side effects. We describe eight patients with manifestations of wild lettuce toxicity, admitted to a general hospital affiliated to the Golestan University of Medical Sciences. All the patients recovered (although one had to spend 48 h in the intensive care unit) and no chronic complications were reported. A clinical suspicion of toxicity...

Liquid humus and microorganisms to promote the production of Lettuce (Lactuca sativa var. Crespa in hydroponic crop

Directory of Open Access Journals (Sweden)

Velasco José

2016-11-01

Full Text Available In an initial phase, a trial with growing hydroponic lettuce was installed, considering all the macro and micronutrients necessary and sufficient for growth, where treatments were applied with and without liquid humus, combining separately with inoculation of mycorrhiza and bacteria Bacillus type, observing that the significant effect by the individual use of the liquid humus is up to 50%. Subsequently, in a Phase II, different doses of only liquid humus with only mycorrhizae were evaluated, where applying of 8 L of pure liquid humus per 36 L of stock solution of hydroponics crop, the plants had the highest weight (40.7%, the highest altitude (39% and the longest (42% compared to the witness. Instead, the combination of liquid humus plus mycorrhizal is 6 L per 36 L of stock solution, which stimulated a further growth and weight of growing lettuce in hydroponics conditions. In general, the use of liquid humus decreased the production time from 60 to 52 days.

Micropropagation of transgenic lettuce containing HBsAg as a method of mass-scale production of standardised plant material for biofarming purposes.

Science.gov (United States)

Pniewski, Tomasz; Czyż, Marcin; Wyrwa, Katarzyna; Bociąg, Piotr; Krajewski, Paweł; Kapusta, Józef

2017-01-01

Micropropagation protocol of transgenic lettuce bearing S-, M- and L-HBsAg was developed for increased production of uniformised material for oral vaccine preparation. Effective manufacturing of plant-based biopharmaceuticals, including oral vaccines, depends on sufficient content of a protein of interest in the initial material and its efficient conversion into an administrable formulation. However, stable production of plants with a uniformised antigen content is equally important for reproducible processing. This can be provided by micropropagation techniques. Here, we present a protocol for micropropagation of transgenic lettuce lines bearing HBV surface antigens: S-, M- and L-HBsAg. These were multiplied through axillary buds to avoid the risk of somaclonal variation. Micropropagation effectiveness reached 3.5-5.7 per passage, which implies potential production of up to 6600 plant clones within a maximum 5 months. Multiplication and rooting rates were statistically homogenous for most transgenic and control plants. For most lines, more than 90 % of clones obtained via in vitro micropropagation had HBsAg content as high as reference plants directly developed from seeds. Clones were also several times more uniform in HBsAg expression. Variation coefficients of HBsAg content did not exceed 10 % for approximately 40-85 % of clones, or reached a maximum 20 % for 90 % of all clones. Tissue culture did not affect total and leaf biomass yields. Seed production for clones was decreased insignificantly and did not impact progeny condition. Micropropagation facilitates a substantial increase in the production of lettuce plants with high and considerably equalised HBsAg contents. This, together with the previously reported optimisation of plant tissue processing and its long-term stability, constitutes a successive step in manufacturing of a standardised anti-HBV oral vaccine of reliable efficacy.

Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods.

Science.gov (United States)

Barbosa, Guilherme Lages; Gadelha, Francisca Daiane Almeida; Kublik, Natalya; Proctor, Alan; Reichelm, Lucas; Weissinger, Emily; Wohlleb, Gregory M; Halden, Rolf U

2015-06-16

The land, water, and energy requirements of hydroponics were compared to those of conventional agriculture by example of lettuce production in Yuma, Arizona, USA. Data were obtained from crop budgets and governmental agricultural statistics, and contrasted with theoretical data for hydroponic lettuce production derived by using engineering equations populated with literature values. Yields of lettuce per greenhouse unit (815 m2) of 41 ± 6.1 kg/m2/y had water and energy demands of 20 ± 3.8 L/kg/y and 90,000 ± 11,000 kJ/kg/y (±standard deviation), respectively. In comparison, conventional production yielded 3.9 ± 0.21 kg/m2/y of produce, with water and energy demands of 250 ± 25 L/kg/y and 1100 ± 75 kJ/kg/y, respectively. Hydroponics offered 11 ± 1.7 times higher yields but required 82 ± 11 times more energy compared to conventionally produced lettuce. To the authors' knowledge, this is the first quantitative comparison of conventional and hydroponic produce production by example of lettuce grown in the southwestern United States. It identified energy availability as a major factor in assessing the sustainability of hydroponics, and it points to water-scarce settings offering an abundance of renewable energy (e.g., from solar, geothermal, or wind power) as particularly attractive regions for hydroponic agriculture.

Characterization of lettuce big-vein associated virus and Mirafiori lettuce big-vein virus infecting lettuce in Saudi Arabia.

Science.gov (United States)

Umar, M; Amer, M A; Al-Saleh, M A; Al-Shahwan, I M; Shakeel, M T; Zakri, A M; Katis, N I

2017-07-01

During 2014 and 2015, 97 lettuce plants that showed big-vein-disease-like symptoms and seven weed plants were collected from the Riyadh region. DAS-ELISA revealed that 25% and 9% of the lettuce plants were singly infected with LBVaV and MiLBVV, respectively, whereas 63% had a mixed infection with both viruses. The results were confirmed by multiplex reverse transcription polymerase chain reaction using primers specific for LBVaV and MiLBVV. LBVaV and MiLBVV were also detected in Sonchus oleraceus and Eruca sativa, respectively. The nucleotide sequence of LBVaV and MiLBVV Saudi isolates ranged from 94.3-100%, and their similarities to isolates with sequences in the GenBank database ranged from 93.9 to 99.6% and 93.8 to 99.3%, respectively. Olpidium sp. was present in the roots of lettuce plants with big-vein disease and it was shown to facilitate transmission of both viruses.

Lettuce (Lactuca sativa L.) leaf-proteome profiles after exposure to cylindrospermopsin and a microcystin-LR/cylindrospermopsin mixture: a concentration-dependent response.

Science.gov (United States)

Freitas, Marisa; Campos, Alexandre; Azevedo, Joana; Barreiro, Aldo; Planchon, Sébastien; Renaut, Jenny; Vasconcelos, Vitor

2015-02-01

The intensification of agricultural productivity is an important challenge worldwide. However, environmental stressors can provide challenges to this intensification. The progressive occurrence of the cyanotoxins cylindrospermopsin (CYN) and microcystin-LR (MC-LR) as a potential consequence of eutrophication and climate change is of increasing concern in the agricultural sector because it has been reported that these cyanotoxins exert harmful effects in crop plants. A proteomic-based approach has been shown to be a suitable tool for the detection and identification of the primary responses of organisms exposed to cyanotoxins. The aim of this study was to compare the leaf-proteome profiles of lettuce plants exposed to environmentally relevant concentrations of CYN and a MC-LR/CYN mixture. Lettuce plants were exposed to 1, 10, and 100 μg/l CYN and a MC-LR/CYN mixture for five days. The proteins of lettuce leaves were separated by two-dimensional electrophoresis (2-DE), and those that were differentially abundant were then identified by matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF/TOF MS). The biological functions of the proteins that were most represented in both experiments were photosynthesis and carbon metabolism and stress/defense response. Proteins involved in protein synthesis and signal transduction were also highly observed in the MC-LR/CYN experiment. Although distinct protein abundance patterns were observed in both experiments, the effects appear to be concentration-dependent, and the effects of the mixture were clearly stronger than those of CYN alone. The obtained results highlight the putative tolerance of lettuce to CYN at concentrations up to 100 μg/l. Furthermore, the combination of CYN with MC-LR at low concentrations (1 μg/l) stimulated a significant increase in the fresh weight (fr. wt) of lettuce leaves and at the proteomic level resulted in the increase in abundance of a high number of proteins. In

Partial aphid resistance in lettuce negatively affects parasitoids.

Science.gov (United States)

Lanteigne, Marie-Eve; Brodeur, Jacques; Jenni, Sylvie; Boivin, Guy

2014-10-01

This study investigated the effects of partial plant resistance on the lettuce aphid Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae), a major pest of cultivated lettuce (Lactuca sativa L.), and one of its parasitoids, Aphidius ervi Haliday (Hymenoptera: Braconidae). Aphids were reared on susceptible (L. sativa variety Estival; S) or partially resistant (Lactuca serriola L. PI 491093; PR) lettuce, and next parasitized by A. ervi females. Fitness proxies were measured for both aphids and parasitoids. Developmental time to adult stage took longer for alate and apterous aphids (an average of 3.5 and 1.5 additional days, respectively) on PR than on S lettuce, and fecundity of alate aphids reared on PR lettuce was reduced by 37.8% relative to those reared on S lettuce. Size (tibia length) and weight of aphids reared on PR lettuce were lower than for aphids reared on S lettuce from the third and second instar onward, respectively. Parasitism of aphids reared on PR plants resulted in lower parasitoid offspring emergence (-49.9%), lower adult female (-30.3%) and male (-27.5%) weight, smaller adult female (-17.5%) and male (-11.9%) size, and lower female fecundity (37.8% fewer eggs) than when parasitoids developed from aphids reared on S plants. Our results demonstrate that partial aphid resistance in lettuce negatively affects both the second and third trophic levels. Host plant resistance in cultivated lettuce may therefore create an ecological sink for aphid parasitoids.

Inhibitory effects of ambient levels of solar UV-A and UV-B radiation in growth of cv. New Red Fire lettuce

International Nuclear Information System (INIS)

Krizek, D.T.; Britz, S.J.; Mirecki, R.M.

1998-01-01

The influence of solar UV-A and UV-B radiation at Beltsville, MD, USA, on growth of Lactuca sativa L. (cv. New Red Fire lettuce) was examined during early summer of 1996 and 1997. Plants were grown from seed in plastic window boxes covered with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or tefzel (1996) or teflon (1997) to transmit UV-A and UV-B radiation. After 31-34 days, plants grown in the absence of solar UV-B radiation (polyester) had 63 and 57% greater fresh weight and dry weight of tops, respectively, and 57, 72 and 47% greater dry weight of leaves, stems and roots, respectively, as compared to those grown under ambient UV-B (tefzel or teflon). Plants protected from UV-A radiation as well (Llumar) showed an additional 43 and 35% increase, respectively, in fresh and dry weight of tops and a 33 and 33% increase, respectively, in dry weight of leaves and stems, but no difference in root biomass over those grown under polyester. Excluding ambient UV-B (polyester) significantly reduced the UV absorbance of leaf extracts at 270, 300 and 330 nm (presumptive flavonoids) and the concentration of anthocyantins at 550 nm as compared to those of leaf extract from plants grown under ambient UV-A and UV-B. Additional removal of ambient UV-A (Llumar) reduced the concentration of anthocyanins, but had no further effect on UV absorbance at 270, 300 or 330 nm. These findings provide evidence that UV-B radiation is more important than UV-A radiation for flavonoid induction in this red-pigmented lettuce cultivar. Although previous workers have obtained decreases in lettuce yield under enhanced UV-B, this is the first evidence for inhibitory effects of solar UV-A and UV-B radiation on lettuce growth. (au)

Inhibitory effects of ambient levels of solar UV-A and UV-B radiation in growth of cv. New Red Fire lettuce

Energy Technology Data Exchange (ETDEWEB)

Krizek, D.T.; Britz, S.J.; Mirecki, R.M. [Climate Stress Laboratory, Beltsville, MD (United States)

1998-05-01

The influence of solar UV-A and UV-B radiation at Beltsville, MD, USA, on growth of Lactuca sativa L. (cv. New Red Fire lettuce) was examined during early summer of 1996 and 1997. Plants were grown from seed in plastic window boxes covered with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or tefzel (1996) or teflon (1997) to transmit UV-A and UV-B radiation. After 31-34 days, plants grown in the absence of solar UV-B radiation (polyester) had 63 and 57% greater fresh weight and dry weight of tops, respectively, and 57, 72 and 47% greater dry weight of leaves, stems and roots, respectively, as compared to those grown under ambient UV-B (tefzel or teflon). Plants protected from UV-A radiation as well (Llumar) showed an additional 43 and 35% increase, respectively, in fresh and dry weight of tops and a 33 and 33% increase, respectively, in dry weight of leaves and stems, but no difference in root biomass over those grown under polyester. Excluding ambient UV-B (polyester) significantly reduced the UV absorbance of leaf extracts at 270, 300 and 330 nm (presumptive flavonoids) and the concentration of anthocyantins at 550 nm as compared to those of leaf extract from plants grown under ambient UV-A and UV-B. Additional removal of ambient UV-A (Llumar) reduced the concentration of anthocyanins, but had no further effect on UV absorbance at 270, 300 or 330 nm. These findings provide evidence that UV-B radiation is more important than UV-A radiation for flavonoid induction in this red-pigmented lettuce cultivar. Although previous workers have obtained decreases in lettuce yield under enhanced UV-B, this is the first evidence for inhibitory effects of solar UV-A and UV-B radiation on lettuce growth. (au) 34 refs.

Product-Marketing Innovation, Skills, and Firm Productivity Growth

DEFF Research Database (Denmark)

Junge, Martin; Severgnini, Battista; Sørensen, Anders

2016-01-01

The role of product and marketing innovation for productivity growth is addressed using survey and register data for the Danish economy. It is hypothesized that product and marketing innovation are complementary inputs and that innovation activities are skill-intensive. It is established...... that product and marketing innovation in skill-intensive firms results in significantly faster productivity growth. Moreover, product and marketing innovation have independent roles in productivity growth, which cannot be attributed to organizational changes. Finally, we apply an instrument variable approach...... for firms, innovation choices to study endogeneity. The results strongly support the idea that product–marketing innovation leads to faster productivity growth in skill-intensive firms....

Classification and coding of commercial fishing injuries by work processes: an experience in the Danish fresh market fishing industry

DEFF Research Database (Denmark)

Jensen, Olaf Chresten; Stage, Søren; Noer, Preben

2005-01-01

BACKGROUND: Work-related injuries in commercial fishing are of concern internationally. To better identify the causes of injury, this study coded occupational injuries by working processes in commercial fishing for fresh market fish. METHODS: A classification system of the work processes was deve......BACKGROUND: Work-related injuries in commercial fishing are of concern internationally. To better identify the causes of injury, this study coded occupational injuries by working processes in commercial fishing for fresh market fish. METHODS: A classification system of the work processes...... to working with the gear and nets vary greatly in the different fishing methods. Coding of the injuries to the specific working processes allows for targeted prevention efforts....

Microbiological Quality of Fresh Produce from Open Air Markets and Supermarkets in the Philippines

Directory of Open Access Journals (Sweden)

Pierangeli G. Vital

2014-01-01

Full Text Available This study is the first in the Philippines to conduct a comprehensive assessment of the prevalence of bacterial pathogens and somatic phages in retailed fresh produce used in salad preparation, namely, bell pepper, cabbage, carrot, lettuce, and tomato, using culture and molecular methods. Out of 300 samples from open air and supermarkets, 16.7% tested positive for thermotolerant Escherichia coli, 24.7% for Salmonella spp., and 47% for somatic phages. Results show that counts range from 0.30 to 4.03 log10 CFU/g for E. coli, 0.66 to ≥2.34 log10 MPN/g for Salmonella spp., and 1.30 to ≥3.00 log10 PFU/g for somatic phages. Statistical analyses show that there was no significant difference in the microbial counts between open air and supermarkets (α=0.05. TaqMan and AccuPower Plus DualStar real-time polymerase chain reaction (RT-PCR was used to confirm the presence of these organisms. The relatively high prevalence of microorganisms observed in produce surveyed signifies reduction in shelf-life and a potential hazard to food safety. This information may benefit farmers, consumers, merchants, and policy makers for foodborne disease detection and prevention.

Fate of [14C]-zineb on lettuce plants

International Nuclear Information System (INIS)

Vonk, J.W.

1976-01-01

[1,2- 14 C]-zinc ethylenebisdithiocarbamate (zineb) was prepared and applied in droplets to leaves of lettuce plants. In aqueous suspension zineb decomposes mainly into ethylenethiourea (ETU) and 5,6-dihydro-3H-imidazo[2,1-C]-1,2,4-dithiazole-3-thione (DIDT). Lettuce plants were harvested 0,1,3,7,14 and 21 days after treatment and analysed. A high proportion of radioactivity remained on the surface of the plant and could be washed off. The following identified products were present: unchanged zineb, ETU, DIDT, 2-imidazoline and ethyleneurea. The ETU residue disappeared within 7 days, while 2-imidazoline and ethyleneurea were formed gradually. Radioactivity inside the plant consisted mostly of ethyleneurea: no ETU was present. (author)

The main new driver of customer experience in Grocery retail - the Fresh opportunity

Directory of Open Access Journals (Sweden)

ISMANĂ -ILISAN Camelia -Maria

2018-01-01

Full Text Available The main challenge of a modern retailer is how to delight customers in fresh products without risking profitability. To compete effectively, businesses must focus on the customer's shopping experience. To manage a customer's experience, retailers should understand what “customer experience” actually means. Customer experience includes every point of contact at which the customer interacts with the business, product, or service. Customer experience management represents a business strategy designed to manage the customer experience. This paper presents the results of a marketing research study conducted for reviewing perception versus reality of customer experience delivery in fresh products and product availability.

Inflorescence Development and the Role of LsFT in Regulating Bolting in Lettuce (Lactuca sativa L.)

Science.gov (United States)

Chen, Zijing; Han, Yingyan; Ning, Kang; Ding, Yunyu; Zhao, Wensheng; Yan, Shuangshuang; Luo, Chen; Jiang, Xiaotang; Ge, Danfeng; Liu, Renyi; Wang, Qian; Zhang, Xiaolan

2018-01-01

Lettuce (Lactuca sativa L.) is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT) gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce. PMID:29403510

Inflorescence Development and the Role of LsFT in Regulating Bolting in Lettuce (Lactuca sativa L.).

Science.gov (United States)

Chen, Zijing; Han, Yingyan; Ning, Kang; Ding, Yunyu; Zhao, Wensheng; Yan, Shuangshuang; Luo, Chen; Jiang, Xiaotang; Ge, Danfeng; Liu, Renyi; Wang, Qian; Zhang, Xiaolan

2017-01-01

Lettuce ( Lactuca sativa L.) is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT) gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce.

A PCR procedure for the detection of Giardia intestinalis cysts and Escherichia coli in lettuce.

Science.gov (United States)

Ramirez-Martinez, M L; Olmos-Ortiz, L M; Barajas-Mendiola, M A; Giono Cerezo, S; Avila, E E; Cuellar-Mata, P

2015-06-01

Giardia intestinalis is a pathogen associated with foodborne outbreaks and Escherichia coli is commonly used as a marker of faecal contamination. Implementation of routine identification methods of G. intestinalis is difficult for the analysis of vegetables and the microbiological detection of E. coli requires several days. This study proposes a PCR-based assay for the detection of E. coli and G. intestinalis cysts using crude DNA isolated from artificially contaminated lettuce. The G. intestinalis and E. coli PCR assays targeted the β-giardin and uidA genes, respectively, and were 100% specific. Forty lettuces from local markets were analysed by both PCR and light microscopy and no cysts were detected, the calculated detection limit was 20 cysts per gram of lettuce; however, by PCR, E. coli was detected in eight of ten randomly selected samples of lettuce. These data highlight the need to validate procedures for routine quality assurance. These PCR-based assays can be employed as alternative methods for the detection of G. intestinalis and E. coli and have the potential to allow for the automation and simultaneous detection of protozoa and bacterial pathogens in multiple samples. Significance and impact of the study: There are few studies for Giardia intestinalis detection in food because methods for its identification are difficult for routine implementation. Here, we developed a PCR-based method as an alternative to the direct observation of cysts in lettuce by light microscopy. Additionally, Escherichia coli was detected by PCR and the sanitary quality of lettuce was evaluated using molecular and standard microbiological methods. Using PCR, the detection probability of Giardia cysts inoculated onto samples of lettuce was improved compared to light microscopy, with the advantage of easy automation. These methods may be employed to perform timely and affordable detection of foodborne pathogens. © 2015 The Society for Applied Microbiology.

Laboratory and semi-field evaluation of Beauveria bassiana (Ascomycota: Hypocreales) against the lettuce aphid, Nasonovia ribisnigri (Hemiptera: Aphididae)

DEFF Research Database (Denmark)

Shrestha, Govinda; Enkegaard, Annie; Steenberg, Tove

2015-01-01

The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. The entomopathogenic fungus Beauveria bassiana strain GHA has recently been reported as a potential biocontrol candidate for use against the lettuce aphid. This study provides information...... on the mortality inflicted by B. bassiana when applied against different life stages of the lettuce aphid under laboratory conditions and how fungus infection affects the aphid fecundity. In addition, temporal changes in persistence of fungus inoculum applied to foliage of young lettuce plants under semi......-field conditions was analysed. Immature life stages were generally the least susceptible to fungal infection and the susceptibility of all stages was dose-dependent, with the highest mortality occurring at the highest dose. B. bassiana significantly affected the rate of nymph production by the lettuce aphid...

The economics of managing Verticillium wilt, an imported disease in California lettuce

OpenAIRE

Carroll, Christine L; Carter, Colin A; Goodhue, Rachael E; Lin Lawell, C.-Y. Cynthia; Subbarao, Krishna V

2017-01-01

Verticillium dahliae is a soilborne fungus that is introduced to the soil via infested spinach seeds and that causes lettuce to be afflicted with Verticillium wilt. This disease has spread rapidly through the Salinas Valley, the prime lettuce production region of California. Verticillium wilt can be prevented or controlled by the grower by fumigating, planting broccoli, or not planting spinach. Because these control options require long-term investment for future gain, renters might not take ...

Effects of soil texture and drought stress on the uptake of antibiotics and the internalization of Salmonella in lettuce following wastewater irrigation.

Science.gov (United States)

Zhang, Yuping; Sallach, J Brett; Hodges, Laurie; Snow, Daniel D; Bartelt-Hunt, Shannon L; Eskridge, Kent M; Li, Xu

2016-01-01

Treated wastewater is expected to be increasingly used as an alternative source of irrigation water in areas facing fresh water scarcity. Understanding the behaviors of contaminants from wastewater in soil and plants following irrigation is critical to assess and manage the risks associated with wastewater irrigation. The objective of this study was to evaluate the effects of soil texture and drought stress on the uptake of antibiotics and the internalization of human pathogens into lettuce through root uptake following wastewater irrigation. Lettuce grown in three soils with variability in soil texture (loam, sandy loam, and sand) and under different levels of water stress (no drought control, mild drought, and severe drought) were irrigated with synthetic wastewater containing three antibiotics (sulfamethoxazole, lincomycin and oxytetracycline) and one Salmonella strain a single time prior to harvest. Antibiotic uptake in lettuce was compound-specific and generally low. Only sulfamethoxazole was detected in lettuce with increasing uptake corresponding to increasing sand content in soil. Increased drought stress resulted in increased uptake of lincomycin and decreased uptake of oxytetracycline and sulfamethoxazole. The internalization of Salmonella was highly dependent on the concentration of the pathogen in irrigation water. Irrigation water containing 5 Log CFU/mL Salmonella resulted in limited incidence of internalization. When irrigation water contained 8 Log CFU/mL Salmonella, the internalization frequency was significantly higher in lettuce grown in sand than in loam (p = 0.009), and was significantly higher in lettuce exposed to severe drought than in unstressed lettuce (p = 0.049). This work demonstrated how environmental factors affected the risk of contaminant uptake by food crops following wastewater irrigation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of soil texture and drought stress on the uptake of antibiotics and the internalization of Salmonella in lettuce following wastewater irrigation

International Nuclear Information System (INIS)

Zhang, Yuping; Sallach, J. Brett; Hodges, Laurie; Snow, Daniel D.; Bartelt-Hunt, Shannon L.; Eskridge, Kent M.; Li, Xu

2016-01-01

Treated wastewater is expected to be increasingly used as an alternative source of irrigation water in areas facing fresh water scarcity. Understanding the behaviors of contaminants from wastewater in soil and plants following irrigation is critical to assess and manage the risks associated with wastewater irrigation. The objective of this study was to evaluate the effects of soil texture and drought stress on the uptake of antibiotics and the internalization of human pathogens into lettuce through root uptake following wastewater irrigation. Lettuce grown in three soils with variability in soil texture (loam, sandy loam, and sand) and under different levels of water stress (no drought control, mild drought, and severe drought) were irrigated with synthetic wastewater containing three antibiotics (sulfamethoxazole, lincomycin and oxytetracycline) and one Salmonella strain a single time prior to harvest. Antibiotic uptake in lettuce was compound-specific and generally low. Only sulfamethoxazole was detected in lettuce with increasing uptake corresponding to increasing sand content in soil. Increased drought stress resulted in increased uptake of lincomycin and decreased uptake of oxytetracycline and sulfamethoxazole. The internalization of Salmonella was highly dependent on the concentration of the pathogen in irrigation water. Irrigation water containing 5 Log CFU/mL Salmonella resulted in limited incidence of internalization. When irrigation water contained 8 Log CFU/mL Salmonella, the internalization frequency was significantly higher in lettuce grown in sand than in loam (p = 0.009), and was significantly higher in lettuce exposed to severe drought than in unstressed lettuce (p = 0.049). This work demonstrated how environmental factors affected the risk of contaminant uptake by food crops following wastewater irrigation. - Highlights: • Higher sand content in soil caused higher internalization of sulfamethoxazole and Salmonella in lettuce. • Drought

Synergies between renewable energy and fresh water production. Scoping study

Energy Technology Data Exchange (ETDEWEB)

Geurts, F.; Noothout, P.; Schaap, A. [Ecofys Netherlands, Utrecht (Netherlands)

2011-02-15

The IEA Implementing Agreement for Renewable Energy Technology Deployment (IEA-RETD) investigated the opportunities for coupling renewable energy systems with fresh water supply systems. The four main conclusions of the scoping study, carried out by Ecofys, are: (1) Fresh water production based on desalination technologies provide most options for synergies with renewable energy production; (2) Linking desalination to renewable sources is currently not economically viable; (3) There is a large potential for small scale (decentralised) desalination plants; (4) Current commercially-sized desalination technologies are in need of a constant operation point. Reverse osmosis and thermal membrane technologies might give future synergies as deferrable load.

Produção de alface hidropônica em três ambientes de cultivo Production of hydroponic lettuce in three environments

Directory of Open Access Journals (Sweden)

Edílson Costa

2009-09-01

tested the following systems: (A1 without evaporative cooling air CO2 aerial injection, (A2 with CO2 aerial injection and without evaporative cooling and (A3 with CO2 aerial injection and pad-fan evaporative cooling system. The fresh and dry mass of leaves in grams, number of leaves and leaf area in square millimeter were evaluated. The completely randomized statistical analysis was used. The cycle C1 were used 48 replications, for cycles C2, C3 and C5 were used 64 replications and C5 were used 24 replications. The results showed that greenhouse with evaporative cooling system and CO2 allow better development and greater lettuce yield. It was possible to conclude that the aerial injection of CO2, in the absence of evaporative cooling system, did not lead increasing the lettuce productivity to most cycles. Bigger lettuce leaf areas were found in periods with higher temperatures.

Reduction of radiation injury of fresh agricultural products by saccharide

International Nuclear Information System (INIS)

Todoroki, Setsuko; Hayashi, Toru

1999-01-01

Radiation exposure has been paid attention as an alternative technique of methylbromide to protect agricultural products against insects. However, it has been pointed out that radiation at a dose lower than 300-400 Gy necessary for insecticidal effects might produce damages in fresh agricultural products. To reduce such radiation damages, radiation sensitivities of various fresh products were determined to clarify whether sugar treatment is effective for reduction of damages. Further, the timing of the treatment and its influence on the metabolism of agricultural product were investigated. When sucrose was added to a cut flower of chrysanthemum via water before and during irradiation, the withering time of its leaves and flowers was earlier than that of the untreated product, whereas continuous administration of sucrose after radiation exposure caused to lengthen the flower's life and delay the leave's yellowing. Thus, it was indicated that continuous sugar supply after irradiation was effective for prevention of radiation damages. (M.N.)

Quantitative assessment of human exposure to extended spectrum and AmpC β-lactamases bearing E. coli in lettuce attributable to irrigation water and subsequent horizontal gene transfer.

Science.gov (United States)

Njage, P M K; Buys, E M

2017-01-02

The contribution of the fresh produce production environment to human exposure with bacteria bearing extended spectrum β-lactamases and AmpC β-lactamases (ESBL/AmpC) has not been reported. High prevalence of ESBLs/AmpC bearing E. coli as well as a high gene transfer efficiency of lettuce and irrigation water E. coli isolates was previously reported. This stochastic modeling was aimed at quantitatively assessing human exposure to ESBL/AmpC bearing E. coli through lettuce attributable to irrigation water and subsequent horizontal gene transfer. Modular process risk approach was used for the quantitative exposure assessment and models were constructed in Ms. Excel spreadsheet with farm to consumption chain accounted for by primary production, processing, retail and consumer storage. Probability distributions were utilised to take into account the variability of the exposure estimates. Exposure resulting from ESBL/AmpC positive E. coli and gene transfer was taken into account. Monte Carlo simulation was carried out using @Risk software followed by sensitivity and scenario analysis to assess most effective single or combinations of mitigation strategies for the ESBL/AmpC positive E. coli events from farm to fork. Three percent of South African lettuce consumers are exposed to lettuce contaminated with about 10 6.4 ±10 6.7 (95% CI: 10 5.1 -10 7 ) cfu of ESBL/AmpC positive E. coli per serving. The contribution of originally positive isolates and conjugative genetic transfer was 10 6 ±10 6.7 (95% CI: 10 5 -10 7 ) and 10 5.2 ±10 5.6 (95% CI: 10 3.9 -10 5.8 ) cfu per serving respectively. Proportion of ESBL/AmpC positive E. coli (Spearman's correlation coefficient (ρ)=0.85), conjugative gene transfer (ρ=0.05-0.14), washing in chlorine water (ρ=0.18), further rinsing (ρ=0.15), and prevalence of E. coli in irrigation water (ρ=0.16) had highest influence on consumer exposure. The most effective single methods in reducing consumer exposure were reduction in irrigation

[Willingness and influencing factors related to "centralized slaughtering, fresh poultry listing and marketing" strategy among the household chefs in Guangzhou].

Science.gov (United States)

Liu, W H; Ma, Y; Lu, J Y; Yan, H C; Zhou, J H; Liao, X L; Zeng, J H; Lin, W Q; Wu, D; Zhang, Z B; Yang, Z C; Chen, Z Q; Chen, J D; Li, T G

2018-02-10

Objective: To study the willingness and influence factors related to "centralized slaughtering, fresh poultry listing and marketing" strategy, among the household chefs, and provide reference for government to adjust and optimize the strategy on avian influenza prevention. Methods: According to the geographical characteristics and regional functions, 6 'monitoring stations' were selected from 12 residential districts of Guangzhou, respectively. Another 21 meat markets which selling live poultry, were selected in each station and 5 household chefs of each market were invited to attend a face to face interview. Basic information, personal cognitive, willingness and influencing factors to the policy were under study. Univariate and multivariate logistic regression methods were used. Results: A total of 664 household chefs underwent the survey and results showed that the rate of support to the "centralized slaughtering, fresh poultry listing and marketing" strategy was 44.6% (296/664). Results from the multi-factor logistic regression showed that those household chefs who were males ( OR =1.618, 95% CI : 1.156-2.264, P =0.005), having received higher education ( OR =1.814, 95% CI : 1.296-2.539, P =0.001), or believing that the existence of live poultry stalls was related to the transmission of avian influenza ( OR =1.918, 95% CI : 1.341-2.743, P marketing" strategy. Conclusion: Detailed study on this subject and, setting up pilot project in some areas as well as prioritizing the education programs for household chefs seemed helpful to the implementation of the 'freezing-fresh poultry' policy.

Silencing the lettuce homologs of small rubber particle protein does not influence natural rubber biosynthesis in lettuce (Lactuca sativa).

Science.gov (United States)

Chakrabarty, Romit; Qu, Yang; Ro, Dae-Kyun

2015-05-01

Natural rubber, cis-1,4-polyisoprene, is an important raw material in chemical industries, but its biosynthetic mechanism remains elusive. Natural rubber is known to be synthesized in rubber particles suspended in laticifer cells in the Brazilian rubber tree (Hevea brasiliensis). In the rubber tree, rubber elongation factor (REF) and its homolog, small rubber particle protein (SRPP), were found to be the most abundant proteins in rubber particles, and they have been implicated in natural rubber biosynthesis. As lettuce (Lactuca sativa) can synthesize natural rubber, we utilized this annual, transformable plant to examine in planta roles of the lettuce REF/SRPP homologs by RNA interference. Among eight lettuce REF/SRPP homologs identified, transcripts of two genes (LsSRPP4 and LsSRPP8) accounted for more than 90% of total transcripts of REF/SRPP homologs in lettuce latex. LsSRPP4 displays a typical primary protein sequence as other REF/SRPP, while LsSRPP8 is twice as long as LsSRPP4. These two major LsSRPP transcripts were individually and simultaneously silenced by RNA interference, and relative abundance, polymer molecular weight, and polydispersity of natural rubber were analyzed from the LsSRPP4- and LsSRPP8-silenced transgenic lettuce. Despite previous data suggesting the implications of REF/SRPP in natural rubber biosynthesis, qualitative and quantitative alterations of natural rubber could not be observed in transgenic lettuce lines. It is concluded that lettuce REF/SRPP homologs are not critically important proteins in natural rubber biosynthesis in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

Key plants preserve elements of culture: a study over distance and time of fresh crops in Puerto Rican markets in Hartford, Connecticut, "A moveable feast".

Science.gov (United States)

Taylor, David W; Anderson, Gregory J

2014-04-01

People retain culinary customs when they migrate. We tested this commitment via the study of Puerto Rican fresh produce markets in the continental United States over time, 18 yr, and space, by comparisons with source markets in Puerto Rico (PR). A survey of Puerto Rican markets in Hartford (HT), Connecticut in 1993-1994 was repeated in 2009-2010. A comparative study was made at open-air markets in PR in 2009. Surveys recorded fresh crops, and interviews with vendors and Hartford Puerto Rican residents provided context. We recorded 84 plant crops (64 species; 32 families) for seven categories. The largest category was viandas (fresh, starchy "root" crops and immature fruits), followed by saborizantes (flavorings). In the second HT survey, 80% of the crops were still present. And ∼90% of the HT 1993-1994 crops and ∼75% of the HT 2009-2010 crops were shared with markets in PR. On the basis of our results, we suggest two new concepts. The persistence of these largely tropical foods in a temperate market far removed from tropical PR shows the importance of basic foods as an element of cultural identification. We recognize this stability as an example of "culinary cultural conservation". Second, analysis of these fresh produce markets leads to the conclusion that viandas are the most prominent in diversity, persistence over time and distance, volume, and in terms of consumers' "willingness to pay". Accordingly, we consider the viandas a good example of a "cultural keystone food group", a food group that is emblematic of a community's culinary conservation.

An Investigation of Potential Fraud in Commercial Orange Juice Products in Malaysian Market by Cluster Analysis and Principal Component Analysis

International Nuclear Information System (INIS)

Keng, S.E.; Abbas Fadhl Mubarek Al-Karkhi; Mohd Khairuddin Mohd Talib; Azhar Mat Easa; Hoong, C.L.

2015-01-01

This study was triggered by Malaysia Ministry of Health to monitor quality of commercial orange juice products sold in Malaysia market. A total of 19 orange juice samples from 14 different brands of packed orange juice products and 5 different brands of fresh orange fruit juices were analyzed for total soluble solids content, total titratable acidity, sugar composition and amino acid profiles. Hierarchical Cluster analysis (HCA) and Principal component analysis (PCA) on amino acid composition alone allowed visual discrimination between fresh squeezed orange juices and commercial packed orange juices. Suspicion of mislabel was raised in cases of miss-classification. (author)

Product-Marketing Innovation, Skills and Firm Productivity Growth

DEFF Research Database (Denmark)

Junge, Martin; Severgnini, Battista; Sørensen, Anders

The role of product and marketing innovation for productivity growth is addressed using survey and register data for the Danish economy. It is argued that marketing and product innovation are complementary inputs and that innovation activities are skill-intensive. It is found that product...... and marketing innovation in skill-intensive firms results in significantly faster productivity growth than in unskilled-intensive firms that introduce this combination of innovation activities. More precisely, an increase in the share of educated workers of one percentage point, increases productivity growth...... by around 0.1 percentage point in firms with product and marketing innovation. In addition, it is found that firms that engage in product innovation but not in marketing innovation or the other way around do not demonstrate a growth effect from their innovation activities. It is also found that product...

Selection for resistance to Verticillium wilt caused by race 2 isolates of Verticillium dahliae in accessions of lettuce (Lactuca sativa L.).

Science.gov (United States)

Verticillium wilt of lettuce caused by Verticillium dahliae can cause severe economic damage to lettuce producers. The pathogen exists as two races (races 1 and 2) in lettuce, and complete resistance to race 1 is known. Resistance to race 2 isolates has not been reported, and production of race 1 re...

Consórcios alface-cenoura e alface-rabanete sob manejo orgânico Intercropping of lettuce-carrot and lettuce-radish under organic management

Directory of Open Access Journals (Sweden)

Ailena Sudo Salgado

2006-07-01

lettuce, with crisp or smooth leaf, presented land equivalent ratios of 1.54 and 1.27, respectively. Besides, the amounts of nutrients extracted by harvested products were lower than the inputs, pointing out the viability of the tested intercroppings.

Detection of live Salmonella enterica in fresh-cut vegetables by a TaqMan-based one-step reverse transcription real-time PCR.

Science.gov (United States)

Miao, Y J; Xiong, G T; Bai, M Y; Ge, Y; Wu, Z F

2018-05-01

Fresh-cut produce is at greater risk of Salmonella contamination. Detection and early warning systems play an important role in reducing the dissemination of contaminated products. One-step Reverse Transcription Polymerase Chain Reaction (RT-qPCR) targeting Salmonella tmRNA with or without a 6-h enrichment was evaluated for the detection of Salmonella in fresh-cut vegetables after 6-h storage. LOD of one-step RT-qPCR was 1·0 CFU per ml (about 100 copies tmRNA per ml) by assessed 10-fold serially diluted RNA from 10 6 CFU per ml bacteria culture. Then, one-step RT-qPCR assay was applied to detect viable Salmonella cells in 14 fresh-cut vegetables after 6-h storage. Without enrichment, this assay could detect 10 CFU per g for fresh-cut lettuce, cilantro, spinach, cabbage, Chinese cabbage and bell pepper, and 10 2 CFU per g for other vegetables. With a 6-h enrichment, this assay could detect 10 CFU per g for all fresh-cut vegetables used in this study. Moreover, this assay was able to discriminate viable cells from dead cells. This rapid detection assay may provide potential processing control and early warning method in fresh-cut vegetable processing to strengthen food safety assurance. Significance and Impact of the Study: Fresh-cut produce is at greater risk of Salmonella contamination. Rapid detection methods play an important role in reducing the dissemination of contaminated products. One-step RT-qPCR assay used in this study could detect 10 CFU per g Salmonella for 14 fresh-cut vegetables with a 6-h short enrichment. Moreover, this assay was able to discriminate viable cells from dead cells. This rapid detection assay may provide potential processing control and early warning method in fresh-cut vegetable processing to strengthen food safety assurance. © 2018 The Society for Applied Microbiology.

The influence of the microbial quality of wastewater, lettuce cultivars and enumeration technique when estimating the microbial contamination of wastewater-irrigated lettuce.

Science.gov (United States)

Makkaew, P; Miller, M; Cromar, N J; Fallowfield, H J

2017-04-01

This study investigated the volume of wastewater retained on the surface of three different varieties of lettuce, Iceberg, Cos, and Oak leaf, following submersion in wastewater of different microbial qualities (10, 10 2 , 10 3 , and 10 4 E. coli MPN/100 mL) as a surrogate method for estimation of contamination of spray-irrigated lettuce. Uniquely, Escherichia coli was enumerated, after submersion, on both the outer and inner leaves and in a composite sample of lettuce. E. coli were enumerated using two techniques. Firstly, from samples of leaves - the direct method. Secondly, using an indirect method, where the E. coli concentrations were estimated from the volume of wastewater retained by the lettuce and the E. coli concentration of the wastewater. The results showed that different varieties of lettuce retained significantly different volumes of wastewater (p 0.01) were detected between E. coli counts obtained from different parts of lettuce, nor between the direct and indirect enumeration methods. Statistically significant linear relationships were derived relating the E. coli concentration of the wastewater in which the lettuces were submerged to the subsequent E. coli count on each variety the lettuce.

Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite.

Science.gov (United States)

Bachelli, Mara Lígia Biazotto; Amaral, Rívia Darla Álvares; Benedetti, Benedito Carlos

2013-01-01

Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L(-1)/10 min), peracetic acid (100 mg L(-1)/15 min) and ozonated water (1.2 mg L(-1)/1 min) as alternative sanitizers to sodium hypochlorite (150 mg L(-1) free chlorine/15 min) were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 °C with the product packaged on LDPE bags of 60 μm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days.

Advancements in utilizing molecular markers in lettuce breeding

Science.gov (United States)

Lettuce (Lactuca sativa L.) is globally the most popular commercially produced, leafy vegetable, farmed in moderate climates. Cultivated lettuce is a self-fertilizing, diploid (2n = 2x = 18) species from the family Compositae (Asteraceae). New cultivars of lettuce are developed by combining desirabl...

Evidence for Lettuce big-vein associated virus as the causal agent of a syndrome of necrotic rings and spots in lettuce

NARCIS (Netherlands)

Verbeek, M.; Dullemans, A.M.; Bekkum, van P.J.; Vlugt, van der R.A.A.

2013-01-01

Lettuce big-vein associated virus (LBVaV, genus Varicosavirus) was shown to be responsible for characteristic necrotic symptoms observed in combination with big-vein symptoms in lettuce breeding lines when tested for their susceptibility to lettuce big-vein disease (BVD) using viruliferous Olpidium

Growth and gas exchange by lettuce stands in a closed, controlled environment.

Science.gov (United States)

Wheeler, R M; Mackowiak, C L; Sager, J C; Yorio, N C; Knott, W M; Berry, W L

1994-05-01

Two studies were conducted in which 'Waldmann's Green' lettuce (Lactuca sativa L.) was grown hydroponically from seed to harvest in a large (20-m2), atmospherically closed growth chamber for the National Aeronautics and Space Administration's controlled ecological life support system (CELSS) program. The first study used metal-halide (MH) lamps [280 micromoles m-2 s-1 photosynthetic photon flux (PPF)], whereas the second used high-pressure sodium (HPS) lamps (293 micromoles m-2 s-1). Both studies used a 16-hour photoperiod, a constant air temperature (22 to 23C), and 1000 micromoles mol-1 CO2 during the light period. In each study, canopy photosynthesis and evapotranspiration (ET) rates were highly correlated to canopy cover, with absolute rates peaking at harvest (28 days after planting ) at 17 micromoles CO2/m2 per sec and 4 liters m-2 day-1, respectively. When normalized for actual canopy cover, photosynthesis and ET rates per unit canopy area decreased with age (between 15 and 28 days after planting). Canopy cover increased earlier during the study with HPS lamps, and final shoot yields averaged 183 g fresh mass (FM)/plant 8.8 g dry mass (DM)/plant. Shoot yields in the first study with MH lamps averaged 129 g FM/plant and 6.8 g DM/plant. Analysis of leaf tissue showed that ash levels from both studies averaged 22% and K levels ranged from 15% to 17% of tissue DM. Results suggest that lettuce should be easily adaptable to a CELSS with moderate lighting and that plant spacing or transplant schemes are needed to maximize canopy light interception and sustained efficient CO2 removal and water production.

Produção e indicadores fisiológicos de alface sob hidroponia com água salina Production and physiologic indicators of lettuce grown in hydroponics with saline water

Directory of Open Access Journals (Sweden)

Dalva Paulus

2010-03-01

at the moment an essential activity, facing the rising demand of fresh water, as for the agricultural activity as for the urban and industrial supplying. This study aimed to evaluate production and physiologic indicators of lettuce in hydroponic system with the use of saline waters. The experiment was carried out in a greenhouse in the period from December 2007 to January 2008, in Piracicaba, Brazil. The experimental design was randomized blocks in factorial scheme - five salinity levels obtained with the addition of NaCl, which resulted in different water electrical conductivity levels (dS m-1: 0,42, 1,53, 3,52, 5,55, 7,43 - and two cultivars of lettuce - Veronica and Pira Roxa. It was determined the fresh and dry mass of leaves, stem, roots and shoot and the content of nitrate, proline and chlorophyll. The increase of water salinity reduced lineally the fresh and dry mass of leaves, stem, roots and shoot. The cv Verônica produced 36% and 57% more shoot fresh and dry mass, respectively, than Pira Roxa. The cv. Pira Roxa accumulated 25% more nitrate (3008 mg L-1, presented 50% more total chlorophyll (1,46 mg g-1fresh mass and 71,43% more proline (0,21 µM g fresh mass- 1 than the cv Verônica, showing a mechanism of avoiding salinity stress. Cultivars Pira Roxa and Veronica presented loss of 69% and 64% of commercial productivity, respectively, when the most saline water (7,43 dS m-1 was used. In the other hand dry matter was reduced in 53% and 44%, respectively, for cv. Pira Roxa and Verônica in the most saline water. The results obtained in this study can indicate the possibility of using saline water as an alternative for the production of vegetables, specially for growers that have saline water available but restricted fresh water, even with reduction of productivity.

Genetic resources collections of leafy vegetables (lettuce, spinach, chicory, artichoke, asparagus, lamb’s lettuce, rhubarb and rocket salad): composition and gaps

NARCIS (Netherlands)

Treuren, van R.; Coquin, P.; Lohwasser, U.

2012-01-01

Lettuce, spinach and chicory are generally considered the main leafy vegetables, while a fourth group denoted by ‘minor leafy vegetables’ includes, amongst others, rocket salad, lamb’s lettuce, asparagus, artichoke and rhubarb. Except in the case of lettuce, central crop databases of leafy

Marketing research: Pathway to optimal market oriented products ...

African Journals Online (AJOL)

This paper examines the role of marketing research as pathway to developing optimal market oriented products. The objectives of this paper among others are to (i) Establish whether the use of marketing research has effect on new product adoption process by consumers (ii) Find out if there is any relationship between the ...

Effect of ionizing radiation on fresh vegetables artificially contaminated with Vibrio cholerae

Energy Technology Data Exchange (ETDEWEB)

Rubio, T; Espinoza, J; Vargas, M [Comision Chilena de Energia Nuclear (Chile); Araya, E [Facultad de Ciencias Agrarias y Forestales, Universidad de Chile (Chile); Avendano, S; Lopez, L [Facultad de Quimica y Farmacia, Universidad de Chile (Chile)

2001-04-01

Lettuce, cabbage and celery were artificially contaminated with Vibrio cholerae El Tor 01 Inaba, and irradiated at 0.50, 0.75 and 1.00 kGy. Non-irradiated samples were used as controls. The effect of irradiation was measured during 7-days storage under refrigeration, from the viewpoints of microbiological (MPN), nutritional (Vitamin C content), and sensory quality. Irradiation proved to be an effective technique to eliminate V. cholerae in fresh vegetables. Doses of less than 0.75 kGy were sufficient to eliminate an initial contamination of 10{sup 5} cells/g of V. cholerae; neither sensory properties or nutritional quality (Vitamin C content) were adversely affected by the treatment. The cost of irradiating the vegetables at 0.5 kGy under the conditions of the study was US$ 0.131, 0.067 and 0.445 per unit of lettuce, cabbage and celery, respectively. (author)

Effect of ionizing radiation on fresh vegetables artificially contaminated with Vibrio cholerae

International Nuclear Information System (INIS)

Rubio, T.; Espinoza, J.; Vargas, M.; Araya, E.; Avendano, S.; Lopez, L.

2001-01-01

Lettuce, cabbage and celery were artificially contaminated with Vibrio cholerae El Tor 01 Inaba, and irradiated at 0.50, 0.75 and 1.00 kGy. Non-irradiated samples were used as controls. The effect of irradiation was measured during 7-days storage under refrigeration, from the viewpoints of microbiological (MPN), nutritional (Vitamin C content), and sensory quality. Irradiation proved to be an effective technique to eliminate V. cholerae in fresh vegetables. Doses of less than 0.75 kGy were sufficient to eliminate an initial contamination of 10 5 cells/g of V. cholerae; neither sensory properties or nutritional quality (Vitamin C content) were adversely affected by the treatment. The cost of irradiating the vegetables at 0.5 kGy under the conditions of the study was US$ 0.131, 0.067 and 0.445 per unit of lettuce, cabbage and celery, respectively. (author)

Requirement Analysis for the Collaborative Supply and Logistics Management of Fresh Agricultural Products

Directory of Open Access Journals (Sweden)

Li Jun

2017-01-01

Full Text Available Issues and concerns for food safety, agro-processing, and the environmental and ecological impact of food production have been attracted many research interests. Traceability and logistics management of fresh agricultural products is faced with the technological challenges including food product label and identification, activity/process characterization, information systems for the supply chain, i.e., from farm to table. Application of information technologies for food processing and logistics industry in the fields of smart packaging and materials, automation and control technology, standards and their application scenarios, and production management principles were wildly studied. A collaborative research project for the supply and logistics of fresh agricultural products in Tianjin was performed. System analysis for the logistics management information system is studied. The model-driven business transformation, an approach uses formal models to explicitly define the structure and behavior of a business, is applied for the review and analysis process. Requirements for the logistic management solutions are proposed. Development of this research is crucial for the solution integration of supply and logistic management information system for fresh agricultural products.

Product Market Integration, Comparative Advantages and Labour Market Performance

DEFF Research Database (Denmark)

Andersen, Torben M.; Rose Skaksen, Jan

2003-01-01

Product Market Integration, Comparative Advantages andLabour Market Performance@*In a two-country model with trade driven by comparative advantages, it is considered howimperfectly competitive labour markets are affected by lower frictions in international goodstrade. Easier goods trading...... is equivalent to increased mobility of employment acrosscountries and thus a change in the trade-off between wages and employment faced by wagesetters. While the effects of product market integration on the trade-off between wages andemployment in general is ambiguous, it is shown that product market...... integration works like ageneral improvement in productivity via the specialization it allows through trade.Unambiguously, real wages and employment and welfare improve upon reductions in tradefrictions, and therefore workers are better off irrespective of whether the market power ofunions is enhanced or muted...

Allelopathic activity of medicinal plant essential oils on seed germination and vigor of lettuce achenes

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Cíntia Alvarenga Santos Fraga de Miranda

2015-07-01

Full Text Available In recent years, essential oils have gained commercial interest in the agricultural area, mainly for their allelopathic, insecticidal, antifungal, antimicrobial and antioxidant properties, and, also for their natural compounds, which have generally displayed low toxicity, relatively low cost and rapid degradation in the environment. Medicinal plants have emerged as potential suppliers of essential oils because of their ethnopharmacological utility. The aim of this study was to evaluate the allelopathic potential of essential oils extracted from fresh leaves of lemon grass (Cymbopogon citratus, wild basil (Ocimum gratissimum L. and sweet basil (Ocimum basilicum L. with regard to their major constituents (citral, eugenol and cineol, respectively in different application forms (direct contact and the effect of volatile constituents on the germination and vigor of lettuce seeds (cultivar Regina SF 3500. The effects of the oils and their major components were evaluated with regard to the variables: first germination count, total germination, GVI (germination velocity index, seedling dry weight and average lengths of shoots and lettuce roots. The essential oils from lemon grass and basil displayed allelopathic potentials on seed germination and vigor of lettuce achenes that can be assigned to their respective major constituents citral and eugenol. On the other hand, the allelopathic effect of the essential oil from basil was a consequence of the combined effect of all the components, regardless the application method.

Chitin mixed in potting soil alters lettuce growth, the survival of zoonotic bacteria on the leaves and associated rhizosphere microbiology.

Directory of Open Access Journals (Sweden)

Jane eDebode

2016-04-01

Full Text Available Chitin is a promising soil amendment for improving soil quality, plant growth and plant resilience. The objectives of this study were twofold. First, to study the effect of chitin mixed in potting soil on lettuce growth and on the survival of two zoonotic bacterial pathogens, Escherichia coli O157:H7 and Salmonella enterica on the lettuce leaves. Second, to assess the related changes in the microbial lettuce rhizosphere, using phospholipid fatty acid (PLFA analysis and amplicon sequencing of a bacterial 16S rRNA gene fragment and the fungal ITS2. As a result of chitin addition, lettuce fresh yield weight was significantly increased. S. enterica survival in the lettuce phyllosphere was significantly reduced. The E. coli O157:H7 survival was also lowered, but not significantly. Moreover, significant changes were observed in the bacterial and fungal community of the lettuce rhizosphere. PLFA analysis showed a significant increase in fungal and bacterial biomass. Amplicon sequencing showed no increase in fungal and bacterial biodiversity, but relative abundances of the bacterial phyla Acidobacteria, Verrucomicrobia, Actinobacteria, Bacteroidetes, and Proteobacteria and the fungal phyla Ascomycota, Basidiomycota, and Zygomycota were significantly changed. More specifically, a more than tenfold increase was observed for operational taxonomic units (OTUs belonging to the bacterial genera Cellvibrio, Pedobacter, Dyadobacter, and Streptomyces and to the fungal genera Lecanicillium and Mortierella. These genera include several species previously reported to be involved in biocontrol, plant growth promotion, the nitrogen cycle and chitin degradation. These results enhance the understanding of the response of the rhizosphere microbiome to chitin amendment. Moreover, this is the first study to investigate the use of soil amendments to control the survival of S. enterica on plant leaves.

Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce

Science.gov (United States)

Tang, Yongkang; Guo, Shuangsheng; Dong, Wenping; Qin, Lifeng; Ai, Weidang; Lin, Shan

2010-09-01

The objectives of this research were to determine photosynthesis, evapotranspiration and growth of lettuce at long-term low atmospheric pressure. Lettuce ( Lactuca sativa L . cv. Youmaicai) plants were grown at 40 kPa total pressure (8.4 kPa p) or 101 kPa total pressure (20.9 kPa p) from seed to harvest for 35 days. Germination rate of lettuce seeds decreased by 7.6% at low pressure, although this was not significant. There was no significant difference in crop photosynthetic rate between hypobaria and ambient pressure during the 35-day study. The crop evapotranspiration rate was significantly lower at low pressure than that at ambient pressure from 20 to 30 days after planting (DAP), but it had no significant difference before 20 DAP or after 30 DAP. The growth cycle of lettuce plants at low pressure was delayed. At low pressure, lettuce leaves were curly at the seedling stage and this disappeared gradually as the plants grew. Ambient lettuce plants were yellow and had an epinastic growth at harvest. The shoot height, leaf number, leaf length and shoot/root ratio were lower at low pressure than those at ambient pressure, while leaf area and root growth increased. Total biomass of lettuce plants grown at two pressures had no significant difference. Ethylene production at low pressure decreased significantly by 38.8% compared with ambient pressure. There was no significant difference in microelements, nutritional phytochemicals and nitrate concentrations at the two treatments. This research shows that lettuce can be grown at long-term low pressure (40 kPa) without significant adverse effects on seed germination, gas exchange and plant growth. Furthermore, ethylene release was reduced in hypobaria.

Application of water-assisted ultraviolet light in combination of chlorine and hydrogen peroxide to inactivate Salmonella on fresh produce.

Science.gov (United States)

Guo, Shuanghuan; Huang, Runze; Chen, Haiqiang

2017-09-18

With the demand for fresh produce increases in recent decades, concerns for microbiological safety of fresh produce are also raised. To identify effective ultraviolet (UV) light treatment for fresh produce decontamination, we first determined the effect of three forms of UV treatment, dry UV (samples were treated by UV directly), wet UV (samples were dipped in water briefly and then exposed to UV), and water-assisted UV (samples were treated by UV while being immersed in agitated water) on inactivation of Salmonella inoculated on tomatoes and fresh-cut lettuce. In general, the water-assisted UV treatment was found to be the most effective for both produce items. Chlorine and hydrogen peroxide were then tested to determine whether they could be used to enhance the decontamination efficacy of water-assisted UV treatment and prevent transfer of Salmonella via wash water by completely eliminating it. Neither of them significantly enhanced water-assisted UV inactivation of Salmonella on tomatoes. Chlorine significantly improved the decontamination effectiveness of the water-assisted UV treatment for baby-cut carrots and lettuce, but not for spinach. In general, the single water-assisted UV treatment and the combined treatment of water-assisted UV and chlorine were similar or more effective than the chlorine washing treatment. In most of the cases, no Salmonella was detected in the wash water when the single water-assisted UV treatment was used to decontaminate tomatoes. In a few cases when Salmonella was detected in the wash water, the populations were very low,≤2CFU/mL, and the wash water contained an extremely high level of organic load and soil level. Therefore, the single water-assisted UV treatment could potentially be used as an environmentally friendly and non-chemical alternative to chlorine washing for tomatoes after validation in industrial scale. For lettuce, spinach and baby-cut carrots, the combined treatment of water-assisted UV treatment and chlorine

Environmental assessment of Ultra-High Pressure Homogenisation for milk and fresh cheese production

DEFF Research Database (Denmark)

Valsasina, Lucia; Pizzol, Massimo; Smetana, Sergiy

2015-01-01

Temperature (UHT) treatment and, at the same time, to lower energy consumptions through the combination of pasteurisation and homogenisation in a single process. Furthermore, the use of UHPH treated milk for the production of fresh cheese has been proven to increase shelf life days and increase yield...... This study provides an LCA of UHPH and UHT processing of milk and fresh cheese production from processing to end-of-life....

Cowpea fresh pods - a new legume for the market: assessment of their quality and dietary characteristics of 37 cowpea accessions grown in southern Europe.

Science.gov (United States)

Karapanos, Ioannis; Papandreou, Anastasia; Skouloudi, Marianna; Makrogianni, Despoina; Fernández, Juan A; Rosa, Eduardo; Ntatsi, Georgia; Bebeli, Penelope J; Savvas, Dimitrios

2017-10-01

Cowpea is traditionally cultivated in some regions of southern Europe for its dried seeds; however, there is a scarcity of information on the quality and dietary characteristics of fresh pods, which are occasionally used in folk diets. This paper aims at covering this gap in knowledge, thereby contributing to the dissemination of fresh cowpea pods as a novel product for the market. The quality and dietary characteristics of pods from 37 accessions (Vigna unguiculata ssp. unguiculata and ssp. sesquipedalis) grown in southern Europe were assessed in an attempt to provide information on pod quality and nutritional properties and to identify relationships between quality traits and accession origin. Pods from the sesquipedalis accessions were heavier and larger, and reached commercial maturity 2 days later, than those from the unguiculata accessions. There were also large differences in the quality and dietary characteristics of the accessions. The pods of most accessions were rich in proteins, chlorophylls, carotenoids and phenolics, and showed high antioxidant activity and low concentrations of nitrates and raffinose-family oligosaccharides. Cluster analysis based on quality, dietary or antinutritional traits did not reveal any apparent grouping among the accessions. All the quality characteristics were independent of accession origin and subspecies. Most of the accessions produced fresh pods of good quality and high dietary value, suitable for introduction in the market and/or for use as valuable genetic material for the development of new improved varieties. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Farmers’ Market Expands to Offer Products in Winter | Poster

Science.gov (United States)

By Carolynne Keenan, Contributing Writer The 2013 National Cancer Institute (NCI) at Frederick Farmers’ Market regular season may have closed, but that doesn’t mean customers who want fresh produce, handmade crafts, and other homemade goodies from local vendors are out of luck. Winter Markets, which began Jan. 7, will be held every other Tuesday, from 11 a.m. to 1 p.m., in

Efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate Escherichia coli O157:H7 from lettuce leaves.

Science.gov (United States)

Keskinen, Lindsey A; Burke, Angela; Annous, Bassam A

2009-06-30

This study compared the efficacy of chlorine (20-200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20-200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20-200 ppm chlorite ion concentration, TriNova) washes in reducing populations of Escherichia coli O157:H7 on artificially inoculated lettuce. Fresh-cut leaves of Romaine or Iceberg lettuce were inoculated by immersion in water containing E. coli O157:H7 (8 log CFU/ml) for 5 min and dried in a salad spinner. Leaves (25 g) were then washed for 2 min, immediately or following 24 h of storage at 4 degrees C. The washing treatments containing chlorite ion concentrations of 100 and 200 ppm were the most effective against E. coli O157:H7 populations on Iceberg lettuce, with log reductions as high as 1.25 log CFU/g and 1.05 log CFU/g for TriNova and Sanova wash treatments, respectively. All other wash treatments resulted in population reductions of less than 1 log CFU/g. Chlorine (200 ppm), TriNova, Sanova, and acidic electrolyzed water were all equally effective against E. coli O157:H7 on Romaine, with log reductions of approximately 1 log CFU/g. The 20 ppm chlorine wash was as effective as the deionized water wash in reducing populations of E. coli O157:H7 on Romaine and Iceberg lettuce. Scanning electron microscopy indicated that E. coli O157:H7 that was incorporated into biofilms or located in damage lettuce tissue remained on the lettuce leaf, while individual cells on undamaged leaf surfaces were more likely to be washed away.

DETERMINATION OF MINERAL CONTAIN AND BACTERIA CONTAMINANT ON ORGANIC AND NONORGANIC FRESH VEGETABLES

Directory of Open Access Journals (Sweden)

Harsojo Harsojo

2010-06-01

Full Text Available The determination of mineral content and bacteria contaminant on fresh vegetable of long bean (Vegan ungulate Wall., white cabbage (Basic tolerance L., and lettuce (Lectuca sativa L. that cultivated by organic and nonorganic system have been done. The mineral content has been analyzed using neutron activation analysis and atomic absorption spectroscopy method, while bacteria contaminant by total plate count number using Nutrient Agar, Mac Conkey Agar, Baird Parker medium, and Salmonella using selective medium. The results showed that there are some essential mineral such as Fe, Zn, Ca, Co, and nonessential mineral Cd. There is tendency that fresh vegetable that cultivated by organic system contained Fe, Zn, Ca, Co and Cd mineral less than nonorganic. The Zn mineral content in nonorganic of fresh vegetable were higher than the limit of threshold number from Health Department, Republic of Indonesia (2004, while Cd mineral in organic or nonorganic of fresh vegetable were greater then threshold number from Codex Alimentarius Commision. The measurement of bacteria contaminant on organic and nonorganic of fresh vegetables contained aerob, coli, and Staphylococcus bacteria in organic of fresh vegetables were less compared to nonorganic of fresh vegetables.   Keywords: mineral, bacteria aerob, coli, Staphylococcus, Salmonella, organic, and nonorganic vegetable, neutron activation

Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite

Directory of Open Access Journals (Sweden)

Mara Lígia Biazotto Bachelli

2013-09-01

Full Text Available Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L-1/10 min, peracetic acid (100 mg L-1/15 min and ozonated water (1.2 mg L-1 /1 min as alternative sanitizers to sodium hypochlorite (150 mg L-1 free chlorine/15 min were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 ºC with the product packaged on LDPE bags of 60 µm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days.

PLANT PROTECTION PRODUCT RESIDUES IN APPLES, CAULIFLOWER, CEREALS, GRAPE, LETTUCE, PEAS, PEPPERS, POTATOES AND STRAWBERRIES OF THE SLOVENE ORIGIN IN 2006

Directory of Open Access Journals (Sweden)

Helena BAŠA ČESNIK

2010-02-01

Full Text Available In the year 2006, 181 apple, cauliflower, cereal, grape, lettuce, pea, pepper, potato and strawberry samples from Slovene producers were analysed for plant protection product residues. The samples were analysed for the presence of 86 different active compounds using four analytical methods. In nine samples (5.0 % exceeded maximum residue levels (MRLs were determined which is comparable with the results of the monitoring of plant protection product residues in products of plant origin in the European union, Norway, Iceland and Liechtenstein in 2005 (4.9 %.

Health effect of vegetable-based diet: lettuce consumption improves cholesterol metabolism and antioxidant status in the rat.

Science.gov (United States)

Nicolle, Catherine; Cardinault, Nicolas; Gueux, Elyett; Jaffrelo, Lydia; Rock, Edmond; Mazur, Andrzej; Amouroux, Pierre; Rémésy, Christian

2004-08-01

It is often assumed that fruits and vegetables contribute to protect against degenerative pathologies such as cardiovascular diseases. Besides epidemiological observations, scientific evidences for their mechanism of action are scarce. In the present study, we investigated the mean term and post-prandial effects of lettuce ingestion on lipid metabolism and antioxidant protection in the rat. Feeding rats a 20% lettuce diet for 3 weeks resulted in a decrease cholesterol LDL/HDL ratio and a marked decrease of liver cholesterol levels (-41%). Concurrently, fecal total steroid excretion increased (+44%) and apparent absorption of dietary cholesterol was significantly depressed (-37%) by the lettuce diet. Lettuce diet also displayed an improvement of vitamin E/TG ratio in plasma and limited lipid peroxidation in heart as evidenced by TBARS. In post-prandial experiment, lettuce intake significantly increased both ascorbic acid and alpha-tocopherol plasma levels which contribute to improve plasma antioxidant capacity within 2 h of consumption. Other lipid-soluble antioxidants (lutein and vitamin E) may also improve the plasma antioxidant capacity. Lettuce consumption increases the total cholesterol end-products excretion and improves antioxidant status due to the richness in antioxidants (vitamins C, E and carotenoids). In our model, lettuce clearly shows a beneficial effect on lipid metabolism and on tissue oxidation. Therefore regular consumption of lettuce should contribute to improve protection against cardiovascular diseases. Copyright 2003 Elsevier Ltd.

Citrus fruits freshness assessment using Raman spectroscopy.

Science.gov (United States)

Nekvapil, Fran; Brezestean, Ioana; Barchewitz, Daniel; Glamuzina, Branko; Chiş, Vasile; Cintă Pinzaru, Simona

2018-03-01

The freshness of citrus fruits commonly available in the market was non-destructively assessed by Raman spectroscopy. Intact clementine, mandarin and tangerine species were characterised concerning their carotenoids skin Raman signalling in a time course from the moment they were acquired as fresh stock, supplying the market, to the physical degradation, when they were no longer attractive to consumers. The freshness was found to strongly correlate to the peel Raman signal collected from the same area of the intact fruits in a time course of a maximum of 20days. We have shown that the intensity of the carotenoid Raman signal is indeed a good indicator of fruit freshness and introduced a Raman coefficient of freshness (C Fresh ), whose time course is linearly decreasing, with different slope for different citrus groups. Additionally, we demonstrated that the freshness assessment could be achieved using a portable Raman instrument. The results could have a strong impact for consumer satisfaction and the food industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

7 CFR 319.56-24 - Lettuce and peppers from Israel.

Science.gov (United States)

2010-01-01

... 7 Agriculture 5 2010-01-01 2010-01-01 false Lettuce and peppers from Israel. 319.56-24 Section 319... Lettuce and peppers from Israel. (a) Lettuce may be imported into the United States from Israel without... protected with sticky traps and prophylactic sprays approved for the crop by Israel; (v) The lettuce must be...

Changes in spectral signatures of red lettuce regards to Zinc uptake

Science.gov (United States)

Shin, J.; Yu, J.; Koh, S. M.; Park, G.; Kim, S.

2017-12-01

Heavy metal contaminations caused by human activities such as mining and industrial activities caused serious soil contamination. Soil contaminations causes secondary impact on vegetation by uptake processes. Intakes of vegetables harvested from heavy metal contaminated soil may cause serious health problems. It would be very effective if screening tool could be developed before the vegetables are distributed over the market. This study investigated spectral response of red lettuce regards to Zn uptake from the treated soil in a laboratory condition. Zn solutions at different levels of concentration are injected to potted lettuce. The chemical composition and spectral characteristics of the leaves are analyzed every 2 days and the correlation between the Zn concentration and spectral reflectance is investigated. The experiment reveals that Zn uptake of red lettuce is significantly higher for the leaves from treated pot compared to untreated pot showing highly contaminated concentrations beyond the standard Zn concentrations for food. The spectral response regards to Zn is manifested at certain level of concentration threshold. Below the threshold, reflectance at NIR regions increases regards to increase in Zn concentration. On the other hand, above the threshold, IR reflectance decreases and slope of NIR shoulder increases regards to higher Zn concentration. We think this result may contribute for development of screening tools for heavy metal contaminations in vegetables.

Combination of minimal processing and irradiation to improve the microbiological safety of lettuce (Lactuca sativa, L.)

International Nuclear Information System (INIS)

Goularte, L.; Martins, C.G.; Morales-Aizpurua, I.C.; Destro, M.T.; Franco, B.D.G.M.; Vizeu, D.M.; Hutzler, B.W.; Landgraf, M.

2004-01-01

The feasibility of gamma radiation in combination with minimal processing (MP) to reduce the number of Salmonella spp. and Escherichia coli O157:H7 in iceberg lettuce (Lactuca sativa, L.) (shredded) was studied in order to increase the safety of the product. The reduction of the microbial population during the processing, the D 10 -values for Salmonella spp. and E. coli O157:H7 inoculated on shredded iceberg lettuce as well as the sensory evaluation of the irradiated product were evaluated. The immersion in chlorine (200 ppm) reduced coliform and aerobic mesophilic microorganisms by 0.9 and 2.7 log, respectively. D-values varied from 0.16 to 0.23 kGy for Salmonella spp. and from 0.11 to 0.12 kGy for E. coli O157:H7. Minimally processed iceberg lettuce exposed to 0.9 kGy does not show any change in sensory attributes. However, the texture of the vegetable was affected during the exposition to 1.1 kGy. The exposition of MP iceberg lettuce to 0.7 kGy reduced the population of Salmonella spp. by 4.0 log and E. coli by 6.8 log without impairing the sensory attributes. The combination of minimal process and gamma radiation to improve the safety of iceberg lettuce is feasible if good hygiene practices begins at farm stage

Combination of minimal processing and irradiation to improve the microbiological safety of lettuce (Lactuca sativa, L.)

Energy Technology Data Exchange (ETDEWEB)

Goularte, L.; Martins, C.G.; Morales-Aizpurua, I.C.; Destro, M.T.; Franco, B.D.G.M.; Vizeu, D.M.; Hutzler, B.W.; Landgraf, M. E-mail: landgraf@usp.br

2004-10-01

The feasibility of gamma radiation in combination with minimal processing (MP) to reduce the number of Salmonella spp. and Escherichia coli O157:H7 in iceberg lettuce (Lactuca sativa, L.) (shredded) was studied in order to increase the safety of the product. The reduction of the microbial population during the processing, the D{sub 10}-values for Salmonella spp. and E. coli O157:H7 inoculated on shredded iceberg lettuce as well as the sensory evaluation of the irradiated product were evaluated. The immersion in chlorine (200 ppm) reduced coliform and aerobic mesophilic microorganisms by 0.9 and 2.7 log, respectively. D-values varied from 0.16 to 0.23 kGy for Salmonella spp. and from 0.11 to 0.12 kGy for E. coli O157:H7. Minimally processed iceberg lettuce exposed to 0.9 kGy does not show any change in sensory attributes. However, the texture of the vegetable was affected during the exposition to 1.1 kGy. The exposition of MP iceberg lettuce to 0.7 kGy reduced the population of Salmonella spp. by 4.0 log and E. coli by 6.8 log without impairing the sensory attributes. The combination of minimal process and gamma radiation to improve the safety of iceberg lettuce is feasible if good hygiene practices begins at farm stage.

Combination of minimal processing and irradiation to improve the microbiological safety of lettuce ( Lactuca sativa, L.)

Science.gov (United States)

Goularte, L.; Martins, C. G.; Morales-Aizpurúa, I. C.; Destro, M. T.; Franco, B. D. G. M.; Vizeu, D. M.; Hutzler, B. W.; Landgraf, M.

2004-09-01

The feasibility of gamma radiation in combination with minimal processing (MP) to reduce the number of Salmonella spp. and Escherichia coli O157:H7 in iceberg lettuce ( Lactuca sativa, L.) (shredded) was studied in order to increase the safety of the product. The reduction of the microbial population during the processing, the D10-values for Salmonella spp. and E. coli O157:H7 inoculated on shredded iceberg lettuce as well as the sensory evaluation of the irradiated product were evaluated. The immersion in chlorine (200 ppm) reduced coliform and aerobic mesophilic microorganisms by 0.9 and 2.7 log, respectively. D-values varied from 0.16 to 0.23 kGy for Salmonella spp. and from 0.11 to 0.12 kGy for E. coli O157:H7. Minimally processed iceberg lettuce exposed to 0.9 kGy does not show any change in sensory attributes. However, the texture of the vegetable was affected during the exposition to 1.1 kGy. The exposition of MP iceberg lettuce to 0.7 kGy reduced the population of Salmonella spp. by 4.0 log and E. coli by 6.8 log without impairing the sensory attributes. The combination of minimal process and gamma radiation to improve the safety of iceberg lettuce is feasible if good hygiene practices begins at farm stage.

The resistance of lettuce to the aphid Nasonovia ribisnigri

NARCIS (Netherlands)

Helden, van M.

1995-01-01

The resistance of lettuce to the aphid Nasonovia ribisnigri is based on a single, dominant gene, the Nr-gene. On the resistant plant aphids died within a few days, without any honeydew production. Transfer-experiments with a short stay on a resistant plant followed by a

Sequential disinfection of E. coli O157:H7 on shredded lettuce leaves by aqueous chlorine dioxide, ozonated water, and thyme essential oil

Science.gov (United States)

Singh, Nepal; Singh, Rakesh K.; Bhunia, Arun K.; Stroshine, Richard L.; Simon, James E.

2001-03-01

There have been numerous studies on effectiveness of different sanitizers for microbial inactivation. However, results obtained from different studies indicate that microorganism cannot be easily removed from fresh cut vegetables because of puncture and cut surfaces with varying surface topographies. In this study, three step disinfection approach was evaluated for inactivation of E. coli O157:H7 on shredded lettuce leaves. Sequential application of thyme oil, ozonated water, and aqueous chlorine dioxide was evaluated in which thyme oil was applied first followed by ozonated water and aqueous chlorine dioxide. Shredded lettuce leaves inoculated with cocktail culture of E. coli O157:H7 (C7927, EDL 933 and 204 P), were washed with ozonated water (15 mg/l for 10min), aqueous chlorine dioxide (10 mg/l,for 10min) and thyme oil suspension (0.1%, v/v for 5min). Washing of lettuce leaves with ozonated water, chlorine dioxide and thyme oil suspension resulted in 0.44, 1.20, and 1.46 log reduction (log10 cfu/g), respectively. However, the sequential treatment achieved approximately 3.13 log reductions (log10 cfu/g). These results demonstrate the efficacy of sequential treatments in decontaminating shredded lettuce leaves containing E. coli O157:H7.

Sensory shelf life estimation of minimally processed lettuce considering two stages of consumers' decision-making process.

Science.gov (United States)

Ares, Gastón; Giménez, Ana; Gámbaro, Adriana

2008-01-01

The aim of the present work was to study the influence of context, particularly the stage of the decision-making process (purchase vs consumption stage), on sensory shelf life of minimally processed lettuce. Leaves of butterhead lettuce were placed in common polypropylene bags and stored at 5, 10 and 15 degrees C. Periodically, a panel of six assessors evaluated the appearance of the samples, and a panel of 40 consumers evaluated their appearance and answered "yes" or "no" to the questions: "Imagine you are in a supermarket, you want to buy a minimally processed lettuce, and you find a package of lettuce with leaves like this, would you normally buy it?" and "Imagine you have this leaf of lettuce stored in your refrigerator, would you normally consume it?". Survival analysis was used to calculate the shelf lives of minimally processed lettuce, considering both decision-making stages. Shelf lives estimated considering rejection to purchase were significantly lower than those estimated considering rejection to consume. Therefore, in order to be conservative and assure the products' quality, shelf life should be estimated considering consumers' rejection to purchase instead of rejection to consume, as traditionally has been done. On the other hand, results from logistic regressions of consumers' rejection percentage as a function of the evaluated appearance attributes suggested that consumers considered them differently while deciding whether to purchase or to consume minimally processed lettuce.

Effectiveness of two-sided UV-C treatments in inhibiting natural microflora and extending the shelf-life of minimally processed 'Red Oak Leaf' lettuce.

Science.gov (United States)

Allende, Ana; McEvoy, James L; Luo, Yaguang; Artes, Francisco; Wang, Chien Y

2006-05-01

The use of UV-C radiation treatments to inhibit the microbial growth and extend the shelf-life of minimally processed 'Red Oak Leaf' lettuce was investigated. Initially, UV-C resistance of 20 bacterial strains from different genera often associated with fresh produce (Enterobacter, Erwinia, Escherichia, Leuconostoc, Pantoea, Pseudomonas, Rahnela, Salmonella, Serratia and Yersinia) were tested in vitro. Most of the bacterial strains were inhibited with the minimum dose (30 J m(-2)). Erwinia carotovora, Leuconostoc carnosum, Salmonella typhimurium, and Yersinia aldovae were the most resistant strains requiring a UV-C dose of 85 J m(-2) to completely inhibit growth. An in vivo study consisted of treating minimally processed 'Red Oak Leaf' lettuce (Lactuca sativa) with UV-C at three radiation doses (1.18, 2.37 and 7.11 kJ m(-2)) on each side of the leaves and storing the product under passive MAP conditions at 5 degrees C for up to 10 days. The gas composition inside packages varied significantly among the treatments, with CO2 concentrations positively and O2 concentrations negatively correlating with the radiation dose. All the radiation doses were effective in reducing the natural microflora of the product, although the highest doses showed the greatest microbial inhibitions. Taking into account the microbial limit set by Spanish legislation [Boletín Oficial del Estado (BOE), 2001. Normas de higiene para la elaboración, distribución y comercio de comidas preparadas, Madrid, Spain, Real Decreto 3484/2000, pp. 1435-1441], all UV-C treatments extended the shelf-life of the product. However, the 7.11 kJ m(-2) dose induced tissue softening and browning after 7 days of storage at 5 degrees C. Therefore, the use of two sided UV-C radiation, at the proper dose, is effective in reducing the natural microflora and extending the shelf-life of minimally processed 'Red Oak Leaf' lettuce.

Water lettuce

African Journals Online (AJOL)

Nutritive values, Mineral and Antioxidant properties of Pistia stratiotes (Water lettuce). 1R .S.U. Wasagu ... The use of plants as medicines predates written human history and some of ... used to maintain health, as well as to prevent, diagnose ...

Ethylene production throughout growth and development of plants

Science.gov (United States)

Wheeler, Raymond M.; Peterson, Barbara V.; Stutte, Gary W.

2004-01-01

Ethylene production by 10 or 20 m2 stands of wheat, soybean, lettuce, potato, and tomato was monitored throughout growth and development in an atmospherically closed plant chamber. Chamber ethylene levels varied among species and rose during periods of canopy expansion and rapid growth for all species. Following this, ethylene levels either declined during seed fill and maturation for wheat and soybean, or remained relatively constant for potato and tomato (during flowering and early fruit development). Lettuce plants were harvested during rapid growth and peak ethylene production. Chamber ethylene levels increased rapidly during tomato ripening, reaching concentrations about 10 times that measured during vegetative growth. The highest ethylene production rates during vegetative growth ranged from 1.6 to 2.5 nmol m-2 d-1 during rapid growth of lettuce and wheat stands, or about 0.3 to 0.5 nmol g-1 fresh weight per hour. Estimates of stand ethylene production during tomato ripening showed that rates reached 43 nmol m-2 d-1 in one study and 93 nmol m-2 d-1 in a second study with higher lighting, or about 50x that of the rate during vegetative growth of tomato. In a related test with potato, the photoperiod was extended from 12 to 24 hours (continuous light) at 58 days after planting (to increase tuber yield), but this change in the environment caused a sharp increase in ethylene production from the basal rate of 0.4 to 6.2 nmol m-2 d-1. Following this, the photoperiod was changed back to 12 h at 61 days and ethylene levels decreased. The results suggest three separate categories of ethylene production were observed with whole stands of plants: 1) production during rapid vegetative growth, 2) production during climacteric fruit ripening, and 3) production from environmental stress.

Allelopathic effects of aqueous extracts of Duranta repens on the germination and early growth of Lactuca sativa and Lycopersicum esculentum

Directory of Open Access Journals (Sweden)

Junior Borella

2010-04-01

effect by one plant on another through production of chemical compounds released into the environment. In this work, the effects of aqueous extracts of Duranta repens fresh, dried leaves and fruit on the germination and early growth of lettuce and tomato were investigated. Aqueous extracts at concentrations of 1%, 2% and 4% (w/v were prepared and characterized as to pH and osmotic potential. Phytochemical analysis of leaves and fruits was also carried out. Germination parameters consisted of the percentage of germination (PG, speed of germination (VG and speed of germination index (IVG. Initial growth was evaluated through length (root and shoot and mass (fresh, dried and water content. Extracts of fresh and dry leaves altered the tomato PG and lettuce and tomato VG and IVG. All extracts affected the root length of the lettuce and tomato, as well as the length of the shoots and mass (dry and fresh of the lettuce. The phytochemical analysis revealed the presence of saponins and flavonoids. The action of the extracts was disassociated from any effect of osmotic potential and pH, indicating allelopathic activity.

Application of Phase Change Materials (PCM's) to Preserve the Freshness of Seafood Products

OpenAIRE

Pudjiastuti, Wiwik; Listyarini, Arie; Riyanto, Arief

2015-01-01

The application of Phase Change Materials (PCMs) as one of latent heat energy storage materials in smart cold system has been investigated for preserving a freshness of seafood products. In this investigation, PCMs was installed on Expanded Polystyrene (EPS) box system as insulated container. The freshness of the seafood product was shown by the time of keeping temperature during storage or distribution. Keeping temperature time of smart cold system using PCMs was compared to conventional col...

Improvement of the growth and yield of lettuce plants by elf sinusoidal non-uniform magnetic fields

International Nuclear Information System (INIS)

Souzal, A. De; Gonzalez, L.M.; Sueirol, L.; Peralta, O.; Liceal, L.; Porras, E.; Gilart, F.

2008-01-01

Influence of pre-sowing magnetic treatments on plant growth and final yield of lettuce (cv. Black Seeded Simpson) were studied under organoponic conditions. Lettuce seeds were exposed to full-wave rectified sinusoidal non-uniform magnetic fields (MFs) induced by an electromagnet at 120 mT(rms) for 3 min, 160 mT(rms) for 1 min and to 160 mT (rms) for 5 min. Non-treated seeds were considered as controls. Plants were grown in experimental stonemasons (25.2 m2) of an organoponic and cultivated according to standard agricultural practices. During nursery and vegetative growth stages, samples were collected at regular intervals for seedling growth assessment and growth rate analyses. At physiological maturity, the plants were harvested from each stonemason and the final yield and yield parameters were determined. In the nursery stage, the magnetic treatments induced a significant increase of root length and shoot height in plants derived from magnetically-treated seeds. In the vegetative stage, the relative growth rates of plants derived from magnetically-exposed seeds were greater than those shown by the control plants. At maturity stage, all magnetic treatments increased significantly (p<0.05) the plant height, the leaf area per plant, the final yield per area and the fresh mass per plant in comparison with the controls. Pre-sowing magnetic treatments would enhance the growth and final yield of lettuce crop

Purification, characterization and immunomodulatory activity of polysaccharides from stem lettuce.

Science.gov (United States)

Nie, Chenzhipeng; Zhu, Peilei; Ma, Shuping; Wang, Mingchun; Hu, Youdong

2018-05-15

Stem lettuce has a long history of cultivation in China and possesses high nutritional and medicinal value. In our previous studies, extraction optimization, characterization, and bioactivities of stem lettuce polysaccharides (SLP) were investigated. In this study, SLP were further separated into two purified polysaccharides, SLP-1 and SLP-2, by anion exchange chromatography followed by size exclusion chromatography. SLP-1, with a molecular weight of 90 KDa, was mainly composed of galacturonic acid, galactose and arabinose in a molar ratio of 17.6:41.7:33.9. SLP-2, with a molecular weight of 44 KDa, was mainly composed of mannose, galacturonic acid, galactose and arabinose in a molar ratio of 11.5:69.5:9.3:8.2. In addition, both purified polysaccharides contain sulphate radicals, have triple helical structures and can promote macrophage proliferation without cytotoxicity. SLP-2 was better able to stimulate phagocytic and nitric oxide production than SLP-1. The results suggest that polysaccharides from stem lettuce could be explored as immunomodulatory agents in the field of pharmaceuticals and functional foods. Copyright © 2018 Elsevier Ltd. All rights reserved.

Virus diseases in lettuce in the Mediterranean basin.

Science.gov (United States)

Moreno, Aranzazu; Fereres, Alberto

2012-01-01

Lettuce is frequently attacked by several viruses causing disease epidemics and considerable yield losses along the Mediterranean basin. Aphids are key pests and the major vectors of plant viruses in lettuce fields. Lettuce mosaic virus (LMV) is probably the most important because it is seed-transmitted in addition to be transmissible by many aphid species that alight on the crop. Tomato spotted wilt virus (TSWV) is another virus that causes severe damage since the introduction of its major vector, the thrips Frankliniella occidentalis. In regions with heavy and humid soils, Lettuce Mirafiori big-vein virus (LMBVV) can also produce major yield losses. Copyright © 2012 Elsevier Inc. All rights reserved.

Biological Control of Lettuce Drop and Host Plant Colonization by Rhizospheric and Endophytic Streptomycetes

Science.gov (United States)

Chen, Xiaoyulong; Pizzatti, Cristina; Bonaldi, Maria; Saracchi, Marco; Erlacher, Armin; Kunova, Andrea; Berg, Gabriele; Cortesi, Paolo

2016-01-01

Lettuce drop, caused by the soil borne pathogen Sclerotinia sclerotiorum, is one of the most common and serious diseases of lettuce worldwide. Increased concerns about the side effects of chemical pesticides have resulted in greater interest in developing biocontrol strategies against S. sclerotiorum. However, relatively little is known about the mechanisms of Streptomyces spp. as biological control agents against S. sclerotiorum on lettuce. Two Streptomyces isolates, S. exfoliatus FT05W and S. cyaneus ZEA17I, inhibit mycelial growth of Sclerotinia sclerotiorum by more than 75% in vitro. We evaluated their biocontrol activity against S. sclerotiorum in vivo, and compared them to Streptomyces lydicus WYEC 108, isolated from Actinovate®. When Streptomyces spp. (106 CFU/mL) were applied to S. sclerotiorum inoculated substrate in a growth chamber 1 week prior lettuce sowing, they significantly reduced the risk of lettuce drop disease, compared to the inoculated control. Interestingly, under field conditions, S. exfoliatus FT05W and S. cyaneus ZEA17I protected lettuce from drop by 40 and 10% respectively, whereas S. lydicus WYEC 108 did not show any protection. We further labeled S. exfoliatus FT05W and S. cyaneus ZEA17I with the enhanced GFP (EGFP) marker to investigate their rhizosphere competence and ability to colonize lettuce roots using confocal laser scanning microscopy (CLSM). The abundant colonization of young lettuce seedlings by both strains demonstrated Streptomyces' capability to interact with the host from early stages of seed germination and root development. Moreover, the two strains were detected also on 2-week-old roots, indicating their potential of long-term interactions with lettuce. Additionally, scanning electron microscopy (SEM) observations showed EGFP-S. exfoliatus FT05W endophytic colonization of lettuce root cortex tissues. Finally, we determined its viability and persistence in the rhizosphere and endorhiza up to 3 weeks by quantifying its

Biological control of lettuce drop and host plant colonization by rhizospheric and endophytic streptomycetes

Directory of Open Access Journals (Sweden)

Xiaoyulong eChen

2016-05-01

Full Text Available Lettuce drop, caused by the soil borne pathogen Sclerotinia sclerotiorum, is one of the most common and serious diseases of lettuce worldwide. Increased concerns about the side effects of chemical pesticides have resulted in greater interest in developing biocontrol strategies against S. sclerotiorum. However, relatively little is known about the mechanisms of Streptomyces spp. as biological control agents against S. sclerotiorum on lettuce. Two Streptomyces isolates, S. exfoliatus FT05W and S. cyaneus ZEA17I, inhibit mycelial growth of Sclerotinia sclerotiorum by more than 75% in vitro. We evaluated their biocontrol activity against S. sclerotiorum in vivo, and compared them to Streptomyces lydicus WYEC 108, isolated from Actinovate®. When Streptomyces spp. (106 CFU/mL were applied to S. sclerotiorum inoculated substrate in a growth chamber one week prior lettuce sowing, they significantly reduced the risk of lettuce drop disease, compared to the inoculated control. Interestingly, under field conditions, S. exfoliatus FT05W and S. cyaneus ZEA17I protected lettuce from drop by 40% and 10% respectively, whereas S. lydicus WYEC 108 did not show any protection. We further labeled S. exfoliatus FT05W and S. cyaneus ZEA17I with the enhanced GFP (EGFP marker to investigate their rhizosphere competence and ability to colonize lettuce roots using confocal laser scanning microscopy (CLSM. The abundant colonization of young lettuce seedlings by both strains demonstrated Streptomyces’ capability to interact with the host from early stages of seed germination and root development. Moreover, the two strains were detected also on two-week-old roots, indicating their potential of long-term interactions with lettuce. Additionally, scanning electron microscopy (SEM observations showed EGFP-S. exfoliatus FT05W endophytic colonization of lettuce root cortex tissues. Finally, we determined its viability and persistence in the rhizosphere and endorhiza up to

Assessing genetic variation in lettuce for traits related to nitrogen use efficiency using susceptibility and relative efficiency indices

Science.gov (United States)

Lettuce is a high value commodity in the USA with annual value of ~$2.5 billion. California produces ~75 percent of all lettuce in the country. Overuse of agricultural inputs for crop production can cause detrimental effects to the health of Californians as well as on agricultural and natural resour...

"Lettuce" Learn Math: Teaching Mathematics with Seeds and Centimeters

Science.gov (United States)

Rickard, Laura N.; Wilson, Colette

2006-01-01

"Lettuce Learn Math" is an interdisciplinary program that has effectively linked a small-scale agricultural production system to a sixth-grade mathematics and science curriculum. The mathematical concepts and skills, including measurement and geometry, taught in this project met and often exceeded the standards set by New York state for…

Oil palm waste and synthetic zeolite: an alternative soil-less growth substrate for lettuce production as a waste management practice

Energy Technology Data Exchange (ETDEWEB)

Jayasinghe, G.Y.; Tokashiki, Y.; Kitou, M.; Kinjo, K. [Kagoshima University, Kagoshima (Japan). United Graduate School of Agricultural Science

2008-12-15

A study was conducted to assess the characteristics and the prospective utilization of oil palm waste (OP) and synthetic zeolite (SZ) developed by coal fly ash, as an alternative substrate to peat and commercial perlite for lettuce (Lactuca sativa L.) production. The SZ, OP, sphagnum peat (PE), perlite (PL) and two different SZ-OP mixtures (v/v) at the ratio of 1 : 3 and 1 : 10 were utilized as the substrates under this study. The substrates formulated by mixing SZ with OP at the ratio of 1 : 3 and 1 : 10 showed improved substrate physical and chemical properties such as air space, bulk density, particle density, water-holding capacity, pH and electrical conductivity (EC), which were in the ideal substrate range when compared with PL. Furthermore, the water-holding capacity of the substrate having a 1 : 10 mixing ratio of SZ with OP was higher than that of the PL by 28.23%, whereas the bulk density was lower than that of PL by 35%. A greenhouse experiment was carried out to assess the influence of the substrates on the growth and development of lettuce. The results of the study suggest that the SZ-OP-based substrates and OP can be successfully utilized as alternatives to the commercial perlite and to substitute the conventional peat substrate for lettuce cultivation. In addition, this can be proposed as an alternative waste management practice.

Marketing technologically advanced products

NARCIS (Netherlands)

Bender, Horst

1989-01-01

This paper calls for a merger of technology and marketing under a customer value perspective; for an enhancement of the traditional technological innovation orientation of the technology-based firm with a market thrust. It establishes technology-based products as product-service offerings that are

Control of spoiler Pseudomonas spp. on fresh cut vegetables by neutral electrolyzed water.

Science.gov (United States)

Pinto, Loris; Ippolito, Antonio; Baruzzi, Federico

2015-09-01

In the present study, we evaluated the antimicrobial activity of neutral electrolyzed water (NEW) against 14 strains of spoilage Pseudomonas of fresh cut vegetables under cold storage. The NEW, produced from solutions of potassium and sodium chloride, and sodium bicarbonate developed up to 4000 mg/L of free chlorine, depending on the salt and relative concentration used. The antimicrobial effect of the NEW was evaluated against different bacterial strains at 10(5) cells/ml, with different combinations of free chlorine concentration/contact time; all concentrations above 100 mg/L, regardless of the salt used, were found to be bactericidal already after 2 min. When catalogna chicory and lettuce leaves were dipped for 5 min in diluted NEW, microbial loads of mesophilic bacteria and Enterobacteriaceae were reduced on average of 1.7 log cfu/g. In addition, when lettuce leaves were dipped in a cellular suspension of the spoiler Pseudomonas chicorii I3C strain, diluted NEW was able to reduce Pseudomonas population of about 1.0 log cfu/g. Thanks to its high antimicrobial activity against spoilage microorganisms, and low cost of operation, the application of cycles of electrolysis to the washing water looks as an effective tool in controlling fresh cut vegetable microbial spoilage contamination occurring during washing steps. Copyright © 2015 Elsevier Ltd. All rights reserved.

Growth of Three Lettuce Cultivars in NASA's HDU PEM During the 2010 DRATS Test

Science.gov (United States)

Stutte, Gary W.; Newsham, Gerard; Wheeler, Raymond

2011-01-01

NASA's 2010 Desert Research and Technology Studies (DRATS) of the VEGGIE Food Production System in the Habitat Demonstration Unit (HDU) Pressurized Excursion Module (PEM) was the first operational evaluation of salad crop production technology in a NASA analog test. Rooting media and slow release fertilizers were evaluated for three lettuce cultivars that had shown promise as candidates for a surface based food production system. These tests involved comparing growth, color and quality of the lettuce cultivars grown under VEGGIE LED array (Orbitec, Madison, WI) or Biomass Production System for Education ((BSEe), Orbitec, Madison, WI) compact fluorescent lamps using a gravity feed water delivery system. Mission relevant conditions of CO2, temperature and RH were maintained using controlled environment chambers (EGC, Chagrin Falls, OH). Growth data was obtained for the two red leaf lettuce cultivars, Outredgeous and Firecracker, and the green Bibb lettuce cultivar, Flandria. Growth and quality was evaluated using different concentrations (7.5 g/L and 15 g/L) of commercial slow release fertilizer (Osmocote Plus 15-9-12, Scotts, Maryville, OH) and Nutricote 18-6-8 (Florikan, Sarasota, FL) in either a peat/vermiculite media (sunshine LP5 MiX, Sungro, Bellview, WA) or calcined montmorillonite clay [(arcillite,)Turface Proleague, Profile LLC, Buffalo Grove, IL]. The commercial peat/vermiculite mix generally resulted in larger plants than those grown in arcillite. Increasing the concentration of Osmocote from 7.5 to 15 g/L increased the height, dry mass, and leaf area of lettuce cultivars. In contrast, there was a decrease in growth parameters when concentration of Nutricote was increased from 7.5 to 15 g/L. The best growth was obtained with the 7.5 g/L Nutricote using a commercial peat/vermiculite mixture. This media was used for field testing VEGGIE plant system in the 2010 DRAT test. The VEGGIE nutrient delivery system worked well, was able to be maintained by multiple

Effect of vanadium on germination and seedling growth of lettuce (Lactuca sativa L. C. V. salad bowl)

Energy Technology Data Exchange (ETDEWEB)

Lepp, N.W.

1977-01-01

The effect of vanadium, applied as VOSO/sub 4/, on germination and subsequent seedling growth of Lettuce has been studied. No differences in germination were observed at any of the applied vanadium concentrations, when compared to a vanadium-free control. Subsequent seedling growth, however, was significantly inhibited by all vanadium treatments. Reductions in shoot growth, root growth and fresh weight were apparent. Similar, but less dramatic effects were observed when 3 day old seedlings were transferred to vanadium enriched media. 13 references, 2 tables.

Product Market Integration, Comparative Advantages and Labour Market Performance

DEFF Research Database (Denmark)

Andersen, Torben M.; Rose Skaksen, Jan

2004-01-01

of the specialization gains are similar to anincrease in labour productivity, whereas the labour market reform effectis similar to an increase in the degree of competition in the labourmarket. Wages, employment and welfare increase as a result of furtherproduct market integration. It is interesting to note......In this paper, we set up a two-country general equilibrium modelwhere trade unions have wage bargaining power. We show that adecrease in trade distortions inducing further product market integrationgives rise to specialization gains as well as a labour market reformeffect. The implications...... that the labourmarket reform effect of product market integration is achieved despitean increase in the wage level.JEL Classification: F15, J30, J50.Keywords: Trade frictions, wage formation, employment, welfaregains....

Bioactive compounds from flesh and by-product of fresh-cut watermelon cultivars.

Science.gov (United States)

Tarazona-Díaz, Martha Patricia; Viegas, Joana; Moldao-Martins, Margarida; Aguayo, Encarna

2011-03-30

The fresh-cut industry produces thousands of tons of waste in non-edible portions that present an environmental and management problem. These by-products could be reused, in particular, to obtain bioactive compounds. In this study, five different fresh-cut watermelon cultivars were assessed for their flesh and by-product bioactive contents. The amount of by-product varied between 31.27 and 40.61% of initial fresh weight (f.w.) depending on the cultivar. Watermelon cultivars were poor sources of total antioxidant, and the content was similar between rind and flesh samples (46.96 vs 43.46 mg ascorbic acid equivalent antioxidant capacity kg(-1) f.w.). However, the rind had a moderate total phenolic content higher than that of the flesh (458 vs 389 mg chlorogenic acid equivalent kg(-1) f.w.) and a much higher content of the amino acid citrulline (3.34 vs 2.33 g kg(-1) f.w.), which has potential bioactive properties. Watermelon rind offers quantitative interest as a natural source of citrulline, particularly Fashion, a dark-skinned, seedless cultivar. More research is required on the efficient extraction of citrulline from watermelon rind and its suitability as an additive to drinks, juices or others products to produce new functional food products with valid health claims. Copyright © 2010 Society of Chemical Industry.

Chemical composition of essential oils and in vitro antioxidant activity of fresh and dry leaves crude extracts of medicinal plant of Lactuca Sativa L. native to Sultanate of Oman.

Science.gov (United States)

Al Nomaani, Rahma Said Salim; Hossain, Mohammad Amzad; Weli, Afaf Mohammed; Al-Riyami, Qasim; Al-Sabahi, Jamal Nasser

2013-05-01

To isolate and analyse the chemical composition in the essential oils and free radical scavenging activity of different crude extracts from the fresh and dry leaves of vegetable plants of Lactuca sativa L. (L. sativa). The essential oils and volatile chemical constituents were isolated from the fresh and dry leaves of L. sativa (lettuce) grown in Sultanate of Oman by hydro distillation method. The antioxidant activity of the crude extracts was carried out by well established free radical scavenging activity (DPPH) method. About 20 chemical compounds of different concentration representing 83.07% and 79.88% respectively were isolated and identified by gas chromatography-mass spectroscopy in the essential oils isolated from the fresh and dry leaves as α-pinene (5.11% and 4.05%), γ-cymene (2.07% and 1.92%), thymol (11.55% and 10.73%), durenol (52.00% and 49.79%), α-terpinene (1.66% and 1.34%), thymol acetate (0.99% and 0.67%), caryophyllene (2.11% and 1.98%), spathulenol (3.09% and 2.98%), camphene (4.11% and 3.65%), limonene (1.28% and 1.11%) representing these major chemical compounds. However, some other minor chemical constituents were also isolated and identified from the essential oil of lettuce including β-pinene, α-terpinolene, linalool, 4-terpineol, α-terpineol, o-methylthymol, L-alloaromadendrene and viridiflorene. The chemical constituents in the essential oils from the locally grown lettuce were identified in the following classes or groups of chemical compounds such as monoterpenes, sesquiterpenes volatile organic compounds and their oxygenated hydrocarbons. Therefore, the essential oils and the crude extracts from Omani vegetable species of lettuce are active candidates which would be used as antioxidant, antifungal or antimicrobial agents in new drugs preparation for therapy of infectious diseases.

Determination of nitrate in lettuce by ion chromatography after microwave water extraction

Directory of Open Access Journals (Sweden)

Humberto Brevilato Novaes

2009-01-01

Full Text Available Lettuce is worldwide known as the most important vegetable. In this context, most farmers are searching new techniques for best quality products including hydropony. However, nitrate is of great concern, since it has a negative impact on human metabolism. The main objective of the present work was to evaluate the nitrate content of lettuce produced by conventional and hydroponic systems. The determination was conducted by ion chromatography and a new method of extraction was tested using microwave oven digestion. The results indicated that nitrate level produced in the conventional system was lower than in the hydroponic system.

Produção de alface em NFT e Floating aproveitando água salobra e o rejeito da dessalinização Lettuce production under NFT and Floating using brackish groundwater and the reject from its desalination

Directory of Open Access Journals (Sweden)

Alexandre Nascimento dos Santos

2011-06-01

Full Text Available Plantas de alface cv. Elba foram cultivadas em dois sistemas hidropônicos, Floating e NFT, com o objetivo de avaliar três tipos de água: a água salobra natural (2,47 dS m-1 obtida a partir de um poço profundo; água doce (0,11 dS m-1 produzido por dessalinização por osmose inversa, e o rejeito salino (5,15 dS m-1, um efluente do processo de dessalinização. Estas águas foram combinadas em seis tratamentos resultantes da sua utilização alternada para preparar a solução nutritiva (SN e/ou substituir as perdas por evapotranspiração (ETc. O experimento foi conduzido em casa de vegetação na região semiárida de Pernambuco, utilizando 48 unidades experimentais em blocos casualizados em esquema fatorial 6x2 com quatro repetições. O rendimento da alface (massa de matéria fresca foi maior nas condições do Floating. O uso exclusivo da água do poço profundo e do rejeito de dessalinizadores diminuiu 22,7 e 39,6% a produção de alface, respectivamente. Para uma melhor combinação de águas doces e salobras, o uso de água salobra para repor a perda por ETc pode aumentar a produção de alface em relação ao uso dessas águas para preparar a SN, estes resultados foram registrados para a água do poço profundo e o rejeito.Plants of lettuce cv. Elba were grown under two hydroponic systems, Floating and NFT, aiming to evaluate three water resources: natural brackish water (2,47 dS m-1 obtained from a deep well; fresh water (0,11 dS m-1 produced by reverse osmosis desalination; and reject brine (5,15 dS m-1, a wastewater from desalination process. These waters were combined in six treatments resulted from their alternated use to prepare nutrient solution (NS and/or replace the evapotranspiration loss (ETc. The experiment was carried out under a greenhouse condition in the semiarid region of Pernambuco State, Brazil; 48 experimental units were used for both hydroponic systems. The lettuce yield (shoot fresh matter was higher under

Shelf-life prediction models for ready-to-eat fresh cut salads: Testing in real cold chain.

Science.gov (United States)

Tsironi, Theofania; Dermesonlouoglou, Efimia; Giannoglou, Marianna; Gogou, Eleni; Katsaros, George; Taoukis, Petros

2017-01-02

The aim of the study was to develop and test the applicability of predictive models for shelf-life estimation of ready-to-eat (RTE) fresh cut salads in realistic distribution temperature conditions in the food supply chain. A systematic kinetic study of quality loss of RTE mixed salad (lollo rosso lettuce-40%, lollo verde lettuce-45%, rocket-15%) packed under modified atmospheres (3% O 2 , 10% CO 2 , 87% N 2 ) was conducted. Microbial population (total viable count, Pseudomonas spp., lactic acid bacteria), vitamin C, colour and texture were the measured quality parameters. Kinetic models for these indices were developed to determine the quality loss and calculate product remaining shelf-life (SL R ). Storage experiments were conducted at isothermal (2.5-15°C) and non-isothermal temperature conditions (T eff =7.8°C defined as the constant temperature that results in the same quality value as the variable temperature distribution) for validation purposes. Pseudomonas dominated spoilage, followed by browning and chemical changes. The end of shelf-life correlated with a Pseudomonas spp. level of 8 log(cfu/g), and 20% loss of the initial vitamin C content. The effect of temperature on these quality parameters was expressed by the Arrhenius equation; activation energy (E a ) value was 69.1 and 122.6kJ/mol for Pseudomonas spp. growth and vitamin C loss rates, respectively. Shelf-life prediction models were also validated in real cold chain conditions (including the stages of transport to and storage at retail distribution center, transport to and display at 7 retail stores, transport to and storage in domestic refrigerators). The quality level and SL R estimated after 2-3days of domestic storage (time of consumption) ranged between 1 and 8days at 4°C and was predicted within satisfactory statistical error by the kinetic models. T eff in the cold chain ranged between 3.7 and 8.3°C. Using the validated models, SL R of RTE fresh cut salad can be estimated at any point of

Lettuce facing microcystins-rich irrigation water at different developmental stages: Effects on plant performance and microcystins bioaccumulation.

Science.gov (United States)

Levizou, Efi; Statiris, George; Papadimitriou, Theodoti; Laspidou, Chrysi S; Kormas, Konstantinos Ar

2017-09-01

This study investigated the microcystins (MCs)-rich irrigation water effect on lettuce of different developmental stages, i.e. during a two months period, covering the whole period from seed germination to harvest at marketable size of the plant. We followed four lettuce plant groups receiving MCs-rich water (1.81μgl -1 of dissolved MCs), originating from the Karla Reservoir, central Greece: 1) from seeds, 2) the cotyledon, 3) two true leaves and 4) four true leaves stages, all of which were compared to control plants that received tap water. Lettuce growth, photosynthetic performance, biochemical and mineral characteristics, as well as MCs accumulation in leaves, roots and soil were measured. The overall performance of lettuce at various developmental stages pointed to increased tolerance since growth showed minor alterations and non-enzymatic antioxidants remained unaffected. Plants receiving MCs-rich water from the seed stage exhibited higher photosynthetic capacity, chlorophylls and leaf nitrogen content. Nevertheless, considerable MCs accumulation in various plant tissues occurred. The earlier in their development lettuce plants started receiving MCs-rich water, the more MCs they accumulated: roots and leaves of plants exposed to MCs-rich water from seeds and cotyledons stage exhibited doubled MCs concentrations compared to respective tissues of the 4 Leaves group. Furthermore, roots accumulated significantly higher MCs amounts than leaves of the same plant group. Concerning human health risk, the Estimated Daily Intake values (EDI) of Seed and Cotyledon groups leaves exceeded Tolerable Daily Intake (TDI) by a factor of 6, while 2 Leaves and 4 Leaves groups exceeded TDI by a factor of 4.4 and 2.4 respectively. Our results indicate that irrigation of lettuce with MCs-rich water may constitute a serious public health risk, especially when contaminated water is received from the very early developmental stages (seed and cotyledon). Finally, results obtained for

Enhanced Removal of a Human Norovirus Surrogate from Fresh Vegetables and Fruits by a Combination of Surfactants and Sanitizers▿

Science.gov (United States)

Predmore, Ashley; Li, Jianrong

2011-01-01

Fruits and vegetables are major vehicles for transmission of food-borne enteric viruses since they are easily contaminated at pre- and postharvest stages and they undergo little or no processing. However, commonly used sanitizers are relatively ineffective for removing human norovirus surrogates from fresh produce. In this study, we systematically evaluated the effectiveness of surfactants on removal of a human norovirus surrogate, murine norovirus 1 (MNV-1), from fresh produce. We showed that a panel of surfactants, including sodium dodecyl sulfate (SDS), Nonidet P-40 (NP-40), Triton X-100, and polysorbates, significantly enhanced the removal of viruses from fresh fruits and vegetables. While tap water alone and chlorine solution (200 ppm) gave only <1.2-log reductions in virus titer in all fresh produce, a solution containing 50 ppm of surfactant was able to achieve a 3-log reduction in virus titer in strawberries and an approximately 2-log reduction in virus titer in lettuce, cabbage, and raspberries. Moreover, a reduction of approximately 3 logs was observed in all the tested fresh produce after sanitization with a solution containing a combination of 50 ppm of each surfactant and 200 ppm of chlorine. Taken together, our results demonstrate that the combination of a surfactant with a commonly used sanitizer enhanced the efficiency in removing viruses from fresh produce by approximately 100 times. Since SDS is an FDA-approved food additive and polysorbates are recognized by the FDA as GRAS (generally recognized as safe) products, implementation of this novel sanitization strategy would be a feasible approach for efficient reduction of the virus load in fresh produce. PMID:21622782

Lettuce seed production in Colombia Producción de semilla de lechuga en Colombia

Directory of Open Access Journals (Sweden)

Pinzón Hernán

1993-12-01

Full Text Available Inorder to study letluce seed production locally under
greenhouse conditions, four experiments were conducted using Simpson 100and Great Lakes 118, as imported varieties. To describe flowering and seed formation, estimate seed production per plant and per hectare and to evaluate inIhe laboratoryand in the field the locally produced seed. Results show clearly that it is possible to produce lettuce seed
locally under greenhouse conditions, getting yields as high as 247 and 172 Kg/ha for Simpson and Great Lakes, respectively. Germination data for bolh varieties provedthat fresh letluce seeds aredormant, but it decreases notoriously to the tenlh week after harvest. However, when the seed is treated for 10 days with 5°C, the dormancy is broken and the
germination increases. When both seed types (local and imported were compared under greenhouse conditions, it was found that the imported seed was slightly superior to the locally produced one with respect to emergence and seedlings dry weight, bul theywere uniform independentlyofvarietyand origin.
Con el objeto de estudiar la producción de semilla de lechuga a nivel local bajo invernadero, se realizaron cuatro experimentos con las variedades Simpson 100 y Great lakes 118 para describir la floración y formación de semilla, cuantificar la producción por planta y por hectárea y evaluar, en laboratorio y en campo, la semilla producida. Los resultados muestran que es posible producir semilla de lechuga localmente y de una manera rentable con rendimientos para las variedades Simpson y Great Lakes, que
alcanzan 247 y 172 Kg de semilla/ha, respectivamente. Las curvas de germinación para ambas variedades confirmaron que las semillas frescas de lechuga presentan latencia, la cual disminuye notoriamente hacia la décima semana después de cosecha. Sin embargo, cuando la semilla es sometida a
5°C por 10 días, la latencia se rompe y se obtienen porcentajes de germinación del

Genetic characterization of resistance to Sclerotinia in lettuce cultivar Eruption

Science.gov (United States)

Lettuce drop caused by the fungal pathogens Sclerotinia minor and S. sclerotiorum is a serious disease of lettuce. The use of genetic resistance as part of an integrated lettuce drop management strategy should have a significant economic advantage in mitigating yield loss. Sclerotinia resistance is ...

Colonization of lettuce rhizosphere and roots by tagged Streptomyces.

Science.gov (United States)

Bonaldi, Maria; Chen, Xiaoyulong; Kunova, Andrea; Pizzatti, Cristina; Saracchi, Marco; Cortesi, Paolo

2015-01-01

Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plasmid harboring an enhanced green fluorescent protein marker and resistance to apramycin. The fitness of transformants was compared to the wild-type strains and all of them grew and sporulated at similar rates and retained the production of enzymes and selected secondary metabolites as well as in vitro inhibition of S. sclerotiorum. The tagged ZEA17I strain was selected to study the dynamics of lettuce roots and rhizosphere colonization in non-sterile growth substrate. The transformed strain was able to colonize soil, developing roots, and rhizosphere. When the strain was inoculated directly on the growth substrate, significantly more t-ZEA17I was re-isolated both from the rhizosphere and the roots when compared to the amount obtained after seed coating. The re-isolation from the rhizosphere and the inner tissues of surface-sterilized lettuce roots demonstrated that t-ZEA17I is both rhizospheric and endophytic.

Effectiveness of Active Packaging on Control of Escherichia Coli O157:H7 and Total Aerobic Bacteria on Iceberg Lettuce.

Science.gov (United States)

Lu, Haixia; Zhu, Junli; Li, Jianrong; Chen, Jinru

2015-06-01

Contaminated leafy green vegetables have been linked to several outbreaks of human gastrointestinal infections. Antimicrobial interventions that are adoptable by the fresh produce industry for control of pathogen contamination are in great demand. This study was undertaken to evaluate the efficacy of sustained active packaging on control of Escherichia coli O157:H7 and total aerobic bacteria on lettuce. Commercial Iceberg lettuce was inoculated with a 3-strain mixture of E. coli O157:H7 at 10(2) or 10(4) CFU/g. The contaminated lettuce and un-inoculated controls were placed respectively in 5 different active packaging structures. Traditional, nonactive packaging structure was included as controls. Packaged lettuce was stored at 4, 10, or 22 °C for 3 wk and sampled weekly for the population of E. coli O157:H7 and total aerobic bacteria. Results showed that packaging structures with ClO2 generator, CO2 generator, or one of the O2 scavengers effectively controlled the growth of E. coli O157:H7 and total aerobic bacteria under all storage conditions. Packaging structure with the ClO2 generator was most effective and no E. coli O157:H7 was detected in samples packaged in this structure except for those that were inoculated with 4 log CFU/g of E. coli O157:H7 and stored at 22 °C. Packaging structures with an oxygen scavenger and the allyl isothiocyanate generator were mostly ineffective in control of the growth of the bacteria on Iceberg lettuce. The research suggests that some of the packaging structures evaluated in the study can be used to control the presence of foodborne pathogens on leafy green vegetables. © 2015 Institute of Food Technologists®

Monitoring programme on nitrates in vegetables and vegetable-based baby foods marketed in the Region of Valencia, Spain: levels and estimated daily intake.

Science.gov (United States)

Pardo-Marín, O; Yusà-Pelechà, V; Villalba-Martín, P; Perez-Dasí, J A

2010-04-01

This study was carried out to determine the current levels of nitrates in vegetables and vegetable-based baby foods (a total of 1150 samples) marketed in the Region of Valencia, Spain, over the period 2000-2008, and to estimate the toxicological risk associated with their intake. Average (median) levels of nitrate in lettuce, iceberg-type lettuce and spinach (1156, 798 and 1410 mg kg(-1) w/w, respectively) were lower than the maximum limits established by European Union legislation. Thirteen fresh spinach samples exceeded the regulatory limits. Median nitrate values in other vegetables for which a maximum limit has not been fixed by the European Commission were 196, 203, 1597, 96, 4474 and 2572 mg kg(-1) w/w (for potato, carrot, chard, artichoke, rucola and lamb's lettuce, respectively). The estimated nitrate daily intakes through vegetables consumption for adult, extreme consumers and children were found to be about 29%, 79.8% and 15.1%, respectively, of the acceptable daily intake (3.7 mg kg(-1)). The levels (median = 60.4 mg kg(-1) w/w) found in vegetable-based baby foods were, in all cases, lower the maximum level proposed by European Union legislation. The estimated nitrate daily intake through baby foods for infants between 0-1 and 1-2 years of age were 13% and 18%, respectively, of the acceptable daily intake.

Sustainable mobility for fresh goods in city: field test in Rome

International Nuclear Information System (INIS)

Lioi, Antonio

2015-01-01

Companies that transport and deliver daily fresh products to final consumers or retailers in urban areas, can achieve a reduction in operating costs and environmental impact with greater energy efficiency, thanks to the use of vehicles as the prototype prepared by ENEA. The article describes the main requirements of the vehicle and reports the results obtained in an experimental campaign lasted 5 months. During the campaign the vehicle has traveled 8,500 kilometers and performed 85 deliveries of fresh merchandise from three Roman farms to bars, restaurants and street markets in the center of Rome. [it

Season, Irrigation, Leaf Age, and Escherichia coli Inoculation Influence the Bacterial Diversity in the Lettuce Phyllosphere

Science.gov (United States)

Williams, Thomas R.; Moyne, Anne-Laure; Harris, Linda J.; Marco, Maria L.

2013-01-01

The developmental and temporal succession patterns and disturbance responses of phyllosphere bacterial communities are largely unknown. These factors might influence the capacity of human pathogens to persist in association with those communities on agriculturally-relevant plants. In this study, the phyllosphere microbiota was identified for Romaine lettuce plants grown in the Salinas Valley, CA, USA from four plantings performed over 2 years and including two irrigation methods and inoculations with an attenuated strain of Escherichia coli O157:H7. High-throughput DNA pyrosequencing of the V5 to V9 variable regions of bacterial 16S rRNA genes recovered in lettuce leaf washes revealed that the bacterial diversity in the phyllosphere was distinct for each field trial but was also strongly correlated with the season of planting. Firmicutes were generally most abundant in early season (June) plantings and Proteobacteria comprised the majority of bacteria recovered later in the year (August and October). Comparisons within individual field trials showed that bacterial diversity differed between sprinkler (overhead) and drip (surface) irrigated lettuce and increased over time as the plants grew. The microbiota were also distinct between control and E. coli O157:H7-inoculated plants and between E. coli O157:H7-inoculated plants with and without surviving pathogen cells. The bacterial inhabitants of the phyllosphere therefore appear to be affected by seasonal, irrigation, and biological factors in ways that are relevant for assessments of fresh produce food safety. PMID:23844230

Acidovorax valerianellae sp. nov., a novel pathogen of lamb's lettuce [Valerianella locusta (L.) Laterr].

Science.gov (United States)

Gardan, Louis; Stead, David E; Dauga, Catherine; Gillis, Moniek

2003-05-01

Bacterial spot disease of lamb's lettuce [Valerianella locusta (L.) Laterr.] was first observed in fields in 1991. This new bacterial disease is localized in western France in high-technology field production of lamb's lettuce for the preparation of ready-to-use salad. Nineteen strains isolated in 1992 and 1993 from typical black leaf spots of naturally infected lamb's lettuce were characterized and compared with reference strains of Acidovorax and Delftia. The pathogenicity of the 19 strains was confirmed by artificial inoculation. Biochemical and physiological tests, fatty acid profiles, DNA-DNA hybridization and other nucleic acid-based tests were performed. A numerical taxonomic analysis of the 19 lamb's lettuce strains showed a single homogeneous phenon closely related to previously described phytopathogenic taxa of the genus Acidovorax. DNA-DNA hybridization studies showed that the lamb's lettuce strains were 91-100% related to a representative strain, strain CFBP 4730(T), and constituted a discrete DNA hybridization group, indicating that they belong to the same novel species. Results from DNA-rRNA hybridization, 16S rRNA sequence analysis and fatty acid analysis studies confirmed that this novel species belongs to the beta-subclass of the Proteobacteria and, more specifically, to the family Comamonadaceae and the genus Acidovorax. The name Acidovorax valerianellae sp. nov. is proposed for this novel taxon of phytopathogenic bacteria. The type strain is strain CFBP 4730(T) (= NCPPB 4283(T)).

Biodegradable films of starch/PVOH/alginate in packaging systems for minimally processed lettuce (Lactuca sativa L.

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Renata Paula Herrera Brandelero

Full Text Available ABSTRACT Biodegradable packaging may replace non-biodegradable materials when the shelf life of the packaged product is relatively short, as in minimally processed foods. The objective of this work was to evaluate the efficiency of biodegradable films comprising starch/polyvinyl alcohol (PVOH/alginate with the addition of 0 or 0.5% of essential oil of copaiba (EOCP or lemongrass (EOLM compared to poly-vinyl chloride (PVC films in the storage of minimally processed lettuce. Lettuce samples cut into 1-cm strips were placed in polypropylene trays wrapped with biodegradable films and stored at 6 ± 2 °C for 8 days. PVC films were used as controls. The biofilms presented 11.43-8.11 MPa resistance and 11.3-13.22% elongation, with water vapor permeability (WVP of 0.5-4.04 x 10-12 g. s-1.Pa-1.m-1; thus, the films' properties were considered suitable for the application. The lettuce stored in PVC presented minor total soluble solids (TSS, less luminosity (L, higher intensity of yellow color (b, and eight times less mass loss than that stored in biodegradable films. Multivariate analysis showed that the lettuce lost quality after 2 days of storage in PVC films, representing a different result from the other treatments. Lettuce stored in biodegradable films for 2 and 4 days showed a greater similarity with newly harvested lettuce (time zero. The films with or without the addition of essential oil showed similar characteristics. Biodegradable films were considered viable for the storage of minimally processed lettuce.

Gibberellins producing Bacillus methylotrophicus KE2 supports plant growth and enhances nutritional metabolites and food values of lettuce.

Science.gov (United States)

Radhakrishnan, Ramalingam; Lee, In-Jung

2016-12-01

The nutritional quality of green leafy vegetables can be enhanced by application of plant beneficial micro-organisms. The present study was aimed to increase the food values of lettuce leaves by bacterial treatment. We isolated bacterial strain KE2 from Kimchi food and identified as Bacillus methylotrophicus by phylogenetic analysis. The beneficial effect of B. methylotrophicus KE2 on plants was confirmed by increasing the percentage of seed germination of Lactuca sativa L., Cucumis melo L., Glycine max L. and Brassica juncea L. It might be the secretion of array of gibberellins (GA 1 , GA 3 , GA 7 , GA 8 , GA 9 , GA 12 , GA 19 , GA 20 , GA 24 , GA 34 and GA 53 ) and indole-acetic acid from B. methylotrophicus KE2. The mechanism of plant growth promotion via their secreted metabolites was confirmed by a significant increase of GA deficient mutant rice plant growth. Moreover, the bacterial association was favor to enhance shoot length, shoot fresh weight and leaf width of lettuce. The higher concentration of protein, amino acids (Asp, Thr, Ser, Glu, Gly, Ala, Leu, Tyr and His), gama-aminobutric acid and fructose was found in bacterial culture (KE2) applied plants. The macro and micro minerals such as K, Mg, Na, P, Fe, Zn and N were also detected as significantly higher quantities in bacteria treated plants than untreated control plants. In addition, the carotenoids and chlorophyll a were also increased in lettuce at bacterial inoculation. The results of this study suggest that B. methylotrophicus KE2 application to soil helps to increase the plant growth and food values of lettuce. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Nutritional value, bioactive compounds, and health benefits of lettuce (Lactuca sativa L.)

Science.gov (United States)

Lettuce is one of the most popularly consumed vegetables worldwide but its nutritional value has been underestimated. Lettuce is low in calories and fat but high in fiber. Moreover, lettuce is high in potassium but low in sodium. Lettuce is also a good source of health-beneficial bioactive compounds...

Determination of low levels of perchlorate in lettuce and spinach using ion chromatography-electrospray ionization mass spectrometry (IC-ESI-MS).

Science.gov (United States)

Seyfferth, Angelia L; Parker, David R

2006-03-22

A sample preparation method was developed to quantify environmentally relevant (low micrograms per liter) concentrations of perchlorate (ClO4(-)) in leafy vegetables using IC-ESI-MS. Lettuce and spinach were macerated, centrifuged, and filtered, and the aqueous extracts were rendered water-clear using a one-step solid-phase extraction method. Total time for extraction and sample preparation was 6 h. Ion suppression was demonstrated and was likely due to unknown organics still present in the extract solution after cleanup. However, this interference was readily eliminated using a Cl(18)O4(-) internal standard at 1 microg/L in all standards and samples. Hydroponically grown perchlorate-free butterhead lettuce was spiked to either 10.3 or 37.7 microg/kg of fresh weight (FW), and recoveries were between 91 and 98% and between 93 and 101%, respectively. Five types of lettuce and spinach from a local grocery store were then analyzed; they contained from 0.6 to 6.4 microg/kg of FW. Spike recoveries using the store-bought samples ranged from 89 to 100%. The method detection limit for perchlorate in plant extracts is 40 ng/L, and the corresponding minimum reporting limit is 200 ng/L or 0.8 microg/kg of FW.

Changes in the flavonoid and phenolic acid contents and antioxidant activity of red leaf lettuce (Lollo Rosso) due to cultivation under plastic films varying in ultraviolet transparency.

Science.gov (United States)

García-Macías, Paulina; Ordidge, Matthew; Vysini, Eleni; Waroonphan, Saran; Battey, Nicholas H; Gordon, Michael H; Hadley, Paul; John, Philip; Lovegrove, Julie A; Wagstaffe, Alexandra

2007-12-12

Red leaf lettuce (Lollo Rosso) was grown under three types of plastic films that varied in transparency to UV radiation (designated as UV block, UV low, and UV window). Flavonoid composition was determined by high-performance liquid chromatography (HPLC), total phenolics by the Folin-Ciocalteu assay, and antioxidant capacity by the oxygen radical absorbance capacity (ORAC) assay. Exposure to increased levels of UV radiation during cultivation caused the leaves to redden and increased concentrations of total phenols and the main flavonoids, quercetin and cyanidin glycosides, as well as luteolin conjugates and phenolic acids. The total phenol content increased from 1.6 mg of gallic acid equivalents (GAE)/g of fresh weight (FW) for lettuce grown under UV block film to 2.9 and 3.5 mg of GAE/g of FW for lettuce grown under the UV low and UV window films. The antioxidant activity was also higher in lettuce exposed to higher levels of UV radiation with ORAC values of 25.4 and 55.1 micromol of Trolox equivalents/g of FW for lettuce grown under the UV block and UV window films, respectively. The content of phenolic acids, quantified as caffeic acid, was also different, ranging from 6.2 to 11.1 micromol/g of FW for lettuce cultivated under the lowest and highest UV exposure plastic films, respectively. Higher concentrations of the flavonoid glycosides were observed with increased exposure to UV radiation, as demonstrated by the concentrations of aglycones after hydrolysis, which were cyanidin (ranging from 165 to 793 microg/g), quercetin (ranging from 196 to 880 microg/g), and luteolin (ranging from 19 to 152 microg/g). The results demonstrate the potential of the use of UV-transparent plastic as a means of increasing beneficial flavonoid content of red leaf lettuce when the crop is grown in polytunnels.

Allelopathic effects of aqueous extracts of Duranta repens on the germination and early growth of Lactuca sativa and Lycopersicum esculentum

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Celia Maria Tur

2010-06-01

Full Text Available Allelopathy can be efined as any stimulatory or inhibitory effect by one plant on another through production of chemical compounds released into the environment. In this work, the effects of aqueous extracts of Duranta repens fresh, dried leaves and fruit on the germination and early growth of lettuce and tomato were investigated. Aqueous extracts at concentrations of 1%, 2% and 4% (w/v were prepared and characterized as to pH and osmotic potential. Phytochemical analysis of leaves and fruits was also carried out. Germination parameters consisted of the percentage of germination (PG, speed of germination (VG and speed of germination index (IVG. Initial growth was evaluated through length (root and shoot and mass (fresh, dried and water content. Extracts of fresh and dry leaves altered the tomato PG and leaf lettuce and tomato VG and IVG. All extracts affected the root length of the lettuce and tomato, as well as the length of the shoots and mass (dry and fresh of the lettuce. The phytochemical analysis revealed the presence of saponins and flavonoids. The action of the extracts was disassociated from any effect of osmotic potential and pH, indicating allelopathic activity.

Preservation of fresh avocados by irradiation

International Nuclear Information System (INIS)

Karmelic, J.

1985-01-01

Avocado is the fifth most important fruit in Chile, which exports fruits to Europe. The production of avocado has increased from 14,000 metric tons in 1978 to a projected 70,000 metric tons in 1985. The main problem of shipping fresh Chilean avocado to Europe has been its short shelf life, being around 24 days with a maximum of 30 days. To market fresh Chilean avocados in Europe, adequate keeping quality must be assured for 40 or more days. A project on the preservation of fresh Chilean avocados supported by the International Atomic Energy Agency (IAEA) takes the approach of combining mild heat and low-dose gamma-radiation. Two varieties of avocados were studied (Hass and Fuerte) and two batches of each were treated: one at the beginning and the other at the end of the picking season. In each case a combination of heat treatment (46 0 C for 10 minutes) and irradiation was applied. Fruits were individually wrapped with flexible PVC and placed in cardboard boxes containing 20 each. Fruits treated with 25,50, and 100 Gy were compared with two controls: one with and another without individual wrapping

Feeling Fresh

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Feeling Fresh KidsHealth / For Teens / Feeling Fresh Print en español La higiene femenina As ... the other products that claim to make women feel cleaner and fresher. But do these work? And ...

Sensory characteristics and consumer acceptance and purchase intention toward fresh-cut potatoes.

Science.gov (United States)

Montouto-Graña, Mónica; Cabanas-Arias, Sonia; Porto-Fojo, Silvia; Vázquez-Odériz, Ma Lourdes; Romero-Rodríguez, Ma Angeles

2012-01-01

For a new product to succeed in the market, it must be accepted by consumers. This study investigates consumer opinions on fresh-cut potatoes packaged under vacuum and under a modified atmosphere using home use tests. The data obtained were related to demographic characteristics and patterns of consumption and to purchase intention toward potatoes and other vegetables. The sensory characteristics evaluated by a panel of assessors trained in the sensory evaluation of potato were also considered. The results indicate that although both products were accepted by the consumer, vacuum-packed potatoes received slightly higher ratings and more consumers intended to purchase this product. The fresh-cut potato packaged under vacuum is a product with all the sensory characteristics that will be accepted by the consumers. The adaptation to the productive process at the industrial level, it can be performed with enough guarantees that the product will definitely be purchased by the consumers. © 2011 Institute of Food Technologists®

Gooseberry (Physalis peruviana L processing alternatives for the profit of the fruits unsuitable for the marketing fresh

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Adriana María Castro Sánchez

2014-05-01

Full Text Available The use of unsuitable fruits for marketing in fresh, represents an area with great economic potential. In the regions of Colombia where is produced cape gooseberry it is necessary to consider and develop processing alternatives of this fruit, because the losses in harvest and postharvest of gooseberry in the country, can reach up to 45% of the total production. In this research, it was developed pulp, jam and nectar of cape gooseberry ecotype Colombia with cracked and soft fruits, from Ventaquemada and Cienega, municipalities of the department of Boyaca. The results of this research have applications for the producing regions of cape gooseberry in Colombia that suffer from loss of fruit by cracking and softening. There were three formulations of each by-product, by varying the content of pulp in the final product and the physiochemical characterization, microbiological and sensorial. Finally, it was calculated the cost of each most accepted by-product by the panel. The results showed that at a microbiological l and physic-chemical level, the sub-products meet the regulations. At sensory level, the most widely accepted pulp pasteurized with sugar, the most accepted nectar was the formulation with 20% of pulp and the most widely accepted jam was the formulation with 50% of pulp. The cost to process 1 kg of fruit was 3,11 USD for pulp, 3,36 USD for nectar and 3,66 USD for jam.

Viabilidade da consorciação de pimentão com repolho, rúcula, alface e rabanete Feasibility of intercropping pepper with cabbage, rocket, lettuce and radish

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Bráulio Luciano A Rezende

2006-03-01

to their monocultives. The experiment consisted of 15 treatments, corresponding to 10 intercropping and five monocultives. The experimental design was a radomized block with six replications. The hybrid Magali R and Kenzan were used, respectively, for pepper and cabbage; and cultivars Vera, Cultivada and Crimson Gigante, respectively, for lettuce, rocket and radish. Yields of pepper and cabbage in intercropping did not differ significantly to that obtained in monocultive. The largest fresh mass of the aerial part of lettuce (438.86 g/plant was observed in lettuce and pepper intercropping cultivation. In the other cultivations, 323.05 g/plant was obtained of lettuce. Increase in yield of commercial roots of radish was observed in radish and pepper intercropping, however, it was significantly larger to the intercropping cultivation of the pepper+cabbage+radish only. The fresh mass of the aerial part of the rocket showed statistical difference between pepper+rocket+lettuce and pepper+rocket+cabbage intercropping. Except for pepper+cabbage intercropping with land efficient use (LEU of 1.92, all the intercropping cultives showed LEU higher than 2.0, with highwest LEU (2.64 obtained with pepper+lettuce intercropping. The better results obtained with intercropping in relation to production of food per area, demonstrate the viability of policultives and better land efficient use.

Pesticide contamination of fruits and vegetables - A market basket survey from selected regions in Ghana

International Nuclear Information System (INIS)

Asiedu, Eric

2013-07-01

A market - basket survey was carried out with the aim of determining the concentration levels of pesticides, in lettuce, garden eggs, pineapple and mango from some selected regions in Ghana and to assess the potential health risk associated with exposure to the pesticide residues from fruits and vegetables consumption. A total of 192 fresh samples of fruits and vegetables were randomly collected under normal purchase conditions from 12 major towns and cities in the three regions of Ghana. The samples were extracted and analyzed for organophosphates, synthetic pyrethroids and organo chlorine pesticides. The percentage of samples of fruits and vegetables with pesticide residues in Lettuce, Garden eggs, Pineapple and Mango were 52%, 40%, 45%, 48% respectively and concentrations of pesticides did not vary significantly in samples as well as the sampling areas (p>0.05) even though there were differences in residual concentrations of pesticides . The differences in residual concentrations of pesticides could be due to different agricultural practices adopted by farmers and also accessibility of the pesticides. The average residue concentrations range from 0.01-0.45 mg/kg, 0.01-0.30 mg/kg and 0.01-1.27 mg/kg for organophosphates, synthetic pyrethroids and organo chlorine pesticides respectively. Lindane, chloropyrifos and cypermethrin were the most frequent organo chlorine, organophosphate and synthetic pyrethroid pesticides respectively while lettuce was the most frequently contaminated sample. Comparing the concentration levels of organo chlorine pesticides residue with the maximum residue limits (MRLs) adopted by the FAO/WHO Codex Alimentarious Commission shows that some of the fruits and vegetables sold on Ghanaian markets are contaminated even though the levels are generally low. Health risk analysis indicates that heptachlor in particular may be of public concern since its concentration levels exceeded the reference dose in all the four different types of samples

Marketing research of consumer preferences in juice products market in Kemerovo

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T. F. Kiseleva

2017-01-01

Full Text Available In this paper, studies on juice products market in Kemerovo, preferences of Kemerovo residents buying juice products were conducted. With the help of the data obtained, the characteristics of juice products market in Kemerovo with the identification of the main suppliers of products were given. The object of the study in thiswork was the residents of Kemerovo. The purpose of the work was to study juice products market in Kemerovo, to investigate the preferences of Kemerovo residents buying juice products. The objectives of this work werethe following: characteristics of juice products market in Kemerovo, determining of the potential of the juice products market, analysis of the division of the market between producers, processing of the data obtained concerning the state of the juice products market in Kemerovo. The survey method was used to study the goals. Questioning is a method of collecting primary material in the form of a written survey of a large number of respondents to collect information on the state of certain aspects of the process under study. The questionnaire can cover a wide range of people, which makes it possible to minimize atypical manifestations, while personal contact with the respondent is not necessary. Another important advantage of the method is the convenience of performing mathematical processing of questionnaires. According to the processed questionnaires, advice of recommendation character, which is not mandatory for use, was given to the producers of juice products. Taking these recommendations into account, the manufacturer will be able to determine the characteristic and inherent features of the juice market in Kemerovo. Kemerovo residents were asked to answer a number of questions. The survey was conducted anonymously. The answers are informative and will be used for further study.

Over fertilization limits lettuce productivity because of osmotic stress

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Francisco Albornoz

2015-09-01

Full Text Available It is customary that growers apply high doses of nutrients to the soil in order to achieve high yields, with detrimental consequences for the environment; but no information exists with regards to the crop response to high fertilization levels. To evaluate the physiological response of lettuce (Lactuca sativa L. to various root zone nutrient concentrations (expressed as electrical conductivity, from 0.6 to 10 dS m-1, a replicated experiment was conducted using increasing concentrations of macronutrients applied to the root zone in an aeroponic system. Leaf photosynthesis and chlorophyll fluorescence were measured using a portable infrared gas analyzer attached with a fluorometer. Leaf nutrient content was analyzed by mass spectrometry and NO3-N was determined by flow injection analysis. Leaf photosynthetic rates increased when the solution concentration was raised from 0.6 to 4.8 dS m-1, but further increases in solution concentration did not result in any differences. The enhancement in photosynthetic rates was related to higher concentrations of N, P, Mg, and S in leaves. Leaf K content was correlated with stomatal conductance. Maximum growth was achieved with solution concentrations between 1.2 and 4.8 dS m-1 while at 10.0 dS m-1 leaf production was reduced by 30%. It is concluded that at high concentration of nutrients supplied in the root zone, yield reduces because of a combination of decreased stomatal conductance and leaf area.

Logistics Management Strategies to Improve Food Safety of Fresh Fruits at Retail Outlets: The Case of Year-Round Sourcing of Strawberries.

NARCIS (Netherlands)

Rijpkema, W.A.; Rossi, R.; Vorst, van der J.G.A.J.

2013-01-01

The quality of most fresh products deteriorates as a function of environmental conditions and time, resulting in reduced market value and ultimately in product waste. Although product spoilage significantly impacts the performance of perishable supply chains often supply chain design strategies do

Activity of aphids associated with lettuce and broccoli in Spain and their efficiency as vectors of Lettuce mosaic virus.

Science.gov (United States)

Nebreda, M; Moreno, A; Pérez, N; Palacios, I; Seco-Fernández, V; Fereres, A

2004-03-01

This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed.

Linkages between the markets for crude oil and the markets for refined products

International Nuclear Information System (INIS)

Didziulis, V.S.

1990-01-01

To understand the crude oil price determination process it is necessary to extend the analysis beyond the markets for petroleum. Crude oil prices are determined in two closely related markets: the markets for crude oil and the markets for refined products. An econometric-linear programming model was developed to capture the linkages between the markets for crude oil and refined products. In the LP refiners maximize profits given crude oil supplies, refining capacities, and prices of refined products. The objective function is profit maximization net of crude oil prices. The shadow price on crude oil gives the netback price. Refined product prices are obtained from the econometric models. The model covers the free world divided in five regions. The model is used to analyze the impacts on the markets of policies that affect crude oil supplies, the demands for refined products, and the refining industry. For each scenario analyzed the demand for crude oil is derived from the equilibrium conditions in the markets for products. The demand curve is confronted with a supply curve which maximizes revenues providing an equilibrium solution for both crude oil and product markets. The model also captures crude oil price differentials by quality. The results show that the demands for crude oil are different across regions due to the structure of the refining industries and the characteristics of the demands for refined products. Changes in the demands for products have a larger impact on the markets than changes in the refining industry. Since markets for refined products and crude oil are interrelated they can't be analyzed individually if an accurate and complete assessment of a policy is to be made. Changes in only one product market in one region affect the other product markets and the prices of crude oil

USE OF PELLETED LETTUCE SEEDS IN BIOAVAILABILITY STUDIES

Science.gov (United States)

Lettuce (Latuca sativa L., cv. Buttercrunch) is one of the most common and sensitive test organisms, among plants, used in toxicology and bioavailability studies. Much of the available lettuce seeds in commercial channels are pelleted to allow for precision machine planting. Th...

USE OF PELLETED LETTUCE SEEDS IN BIOABAILABILITY STUDIES

Science.gov (United States)

Lettuce (Latuca sativa L., cv. Buttercrunch) is one of the most common and sensitive test organisms, among plants, used in toxicology and bioavailability studies. Much of the available lettuce seeds in commercial channels are pelleted to allow for precision machine planting. Th...

Lettuce achene invigoration through osmopriming at supraoptimal temperature

International Nuclear Information System (INIS)

Jahangir, M.M.; Amjad, M.; Iqbal, Q.; Nawaz, A.; Afzal, I.

2009-01-01

The effect of osmopriming on lettuce achene invigoration at supra optimal temperature (35degreeC) was investigated in the present study. Osmopriming of lettuce achene with KNO/sub 3/ (0.25%, 0.5% and 1%), CaCl/sub 2/ (15 mM, 25 mM, 50 mM) and PEG 8000 (0.1 g/ml H/sub 2/O, 0.2 g/ml H/sub 2/O, 0.3g/ml H/sub 2/O) alleviated thermodormancy and improved lettuce achene's vigor. Moreover, priming significantly improved final germination % age, energy of germination, germination index, shoot length, root length, vigor index and reduced mean germination time and time taken to 50% germination, as compared to control, when seeds were subjected to supra-optimal germination environments. It can be concluded that osmopriming can act as effective tool to invigorate lettuce seeds at supra optimal temperature. (author)

Prospects and challenges of radiation processing of meats and meat products in India

International Nuclear Information System (INIS)

Chander, Ramesh

2014-01-01

In India goat, lamb and chicken meat are widely preferred, while, bovine meat and pork are consumed only by a small segment of the population. Meats in the country are mainly marketed fresh or in frozen state. Recently chilled poultry has been introduced in Indian market. In addition to fresh meats, several other ready to eat or ready to cook meat products like chicken chilly, chicken tikka, mutton shammi kababs, mutton seekh kababs etc are available in urban Indian market. These products are marketed only in the frozen state and have limited market due to expensive and inadequate freezing facilities. Major share of domestic fresh meat and poultry market is by unorganized sector and only a few corporate houses like Godrej and Venkey's are marketing poultry products. The time has come to benefit from radiation processing for safe, chilled meat and poultry in India. Shelf-stable, nutritious meat and meat products can also be produced by the process. Radiation processing of these foods will be of great economic and health significance and give boost to exports. This radiation processing can meet the needs of services of convenient and ready-to-eat meat and meat products

Agronomic aspects of strip intercropping lettuce with alyssum for biological control of aphids

OpenAIRE

Brennan, Eric B.

2013-01-01

Organic lettuce growers in California typically use insectary strips of alyssum (Lobularia maritima (L.) Desv.) to attract hoverflies (Syrphidae) that provide biological control of aphids. A two year study with transplanted organic romaine lettuce in Salinas, California investigated agronomic aspects of lettuce monoculture and lettuce-alyssum strip intercropping on beds in replacement intercropping treatments where alyssum transplants replaced 2 to 8% of the lettuce transplants, and in additi...

Colonization of lettuce rhizosphere and roots by tagged Streptomyces

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Maria eBonaldi

2015-02-01

Full Text Available Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plasmid harboring an enhanced green fluorescent protein marker and resistance to apramycin. The fitness of transformants was compared to the wild-type strains and all of them grew and sporulated at similar rates and retained the production of enzymes and selected secondary metabolites as well as in vitro inhibition of S. sclerotiorum. The tagged ZEA17I strain was selected to study the dynamics of lettuce roots and rhizosphere colonization in non-sterile growth substrate. The transformed strain was able to colonize soil, developing roots and rhizosphere. When the strain was inoculated directly on the growth substrate, significantly more t-ZEA17I was re-isolated both from the rhizosphere and the roots when compared to the amount obtained after seed coating. The re-isolation from the rhizosphere and the inner tissues of surface-sterilized lettuce roots demonstrated that t-ZEA17I is both rhizospheric and endophytic.

Fate and Phytotoxicity of CeO2 Nanoparticles on Lettuce Cultured in the Potting Soil Environment.

Science.gov (United States)

Gui, Xin; Zhang, Zhiyong; Liu, Shutong; Ma, Yuhui; Zhang, Peng; He, Xiao; Li, Yuanyuan; Zhang, Jing; Li, Huafen; Rui, Yukui; Liu, Liming; Cao, Weidong

2015-01-01

Cerium oxide nanoparticles (CeO2 NPs) have been shown to have significant interactions in plants. Previous study reported the specific-species phytotoxicity of CeO2 NPs by lettuce (Lactuca sativa), but their physiological impacts and vivo biotransformation are not yet well understood, especially in relative realistic environment. Butterhead lettuce were germinated and grown in potting soil for 30 days cultivation with treatments of 0, 50, 100, 1000 mg CeO2 NPs per kg soil. Results showed that lettuce in 100 mg·kg-1 treated groups grew significantly faster than others, but significantly increased nitrate content. The lower concentrations treatment had no impact on plant growth, compared with the control. However, the higher concentration treatment significantly deterred plant growth and biomass production. The stress response of lettuce plants, such as Superoxide dismutase (SOD), Peroxidase (POD), Malondialdehyde(MDA) activity was disrupted by 1000 mg·kg-1 CeO2 NPs treatment. In addition, the presence of Ce (III) in the roots of butterhead lettuce explained the reason of CeO2 NPs phytotoxicity. These findings demonstrate CeO2 NPs modification of nutritional quality, antioxidant defense system, the possible transfer into the food chain and biotransformation in vivo.

Fate and Phytotoxicity of CeO2 Nanoparticles on Lettuce Cultured in the Potting Soil Environment.

Directory of Open Access Journals (Sweden)

Xin Gui

Full Text Available Cerium oxide nanoparticles (CeO2 NPs have been shown to have significant interactions in plants. Previous study reported the specific-species phytotoxicity of CeO2 NPs by lettuce (Lactuca sativa, but their physiological impacts and vivo biotransformation are not yet well understood, especially in relative realistic environment. Butterhead lettuce were germinated and grown in potting soil for 30 days cultivation with treatments of 0, 50, 100, 1000 mg CeO2 NPs per kg soil. Results showed that lettuce in 100 mg·kg-1 treated groups grew significantly faster than others, but significantly increased nitrate content. The lower concentrations treatment had no impact on plant growth, compared with the control. However, the higher concentration treatment significantly deterred plant growth and biomass production. The stress response of lettuce plants, such as Superoxide dismutase (SOD, Peroxidase (POD, Malondialdehyde(MDA activity was disrupted by 1000 mg·kg-1 CeO2 NPs treatment. In addition, the presence of Ce (III in the roots of butterhead lettuce explained the reason of CeO2 NPs phytotoxicity. These findings demonstrate CeO2 NPs modification of nutritional quality, antioxidant defense system, the possible transfer into the food chain and biotransformation in vivo.

Unravelling the resistance mechanism of lettuce against Nasonovia ribisnigri

OpenAIRE

Broeke, ten, C.J.M.

2013-01-01

Aphids are serious pests of crop plant species, and host plant resistance is often the most effective and environmentally friendly control strategy to control these pests. One of these aphid pests is the black currant - lettuce aphid, Nasonovia ribisnigri (Mosely), an economically important pest of cultivated lettuce, Lactuca sativa L. Host plant resistance has been used since 1982 to control this aphid species and is mediated by the Nr-gene, originating from wild lettuce Lactuca virosa L. H...

Internalization and Dissemination of Human Norovirus and Animal Caliciviruses in Hydroponically Grown Romaine Lettuce

Science.gov (United States)

DiCaprio, Erin; Ma, Yuanmei; Purgianto, Anastasia; Hughes, John

2012-01-01

Fresh produce is a major vehicle for the transmission of human norovirus (NoV) because it is easily contaminated during both pre- and postharvest stages. However, the ecology of human NoV in fresh produce is poorly understood. In this study, we determined whether human NoV and its surrogates can be internalized via roots and disseminated to edible portions of the plant. The roots of romaine lettuce growing in hydroponic feed water were inoculated with 1 × 106 RNA copies/ml of a human NoV genogroup II genotype 4 (GII.4) strain or 1 × 106 to 2 × 106 PFU/ml of animal caliciviruses (Tulane virus [TV] and murine norovirus [MNV-1]), and plants were allowed to grow for 2 weeks. Leaves, shoots, and roots were homogenized, and viral titers and/or RNA copies were determined by plaque assay and/or real-time reverse transcription (RT)-PCR. For human NoV, high levels of viral-genome RNA (105 to 106 RNA copies/g) were detected in leaves, shoots, and roots at day 1 postinoculation and remained stable over the 14-day study period. For MNV-1 and TV, relatively low levels of infectious virus particles (101 to 103 PFU/g) were detected in leaves and shoots at days 1 and 2 postinoculation, but virus reached a peak titer (105 to 106 PFU/g) at day 3 or 7 postinoculation. In addition, human NoV had a rate of internalization comparable with that of TV as determined by real-time RT-PCR, whereas TV was more efficiently internalized than MNV-1 as determined by plaque assay. Taken together, these results demonstrated that human NoV and animal caliciviruses became internalized via roots and efficiently disseminated to the shoots and leaves of the lettuce. PMID:22729543

Marker-assisted selection for disease resistance in lettuce

Science.gov (United States)

Lettuce (Lactuca sativa L.) is the most popular leafy vegetable that is cultivated mainly in moderate climate. Consumers demand lettuce with good visual appearance and free of disease. Improved disease resistance of new cultivars is achieved by combining desirable genes (or alleles) from existing cu...

Validation of a Method for Cylindrospermopsin Determination in Vegetables: Application to Real Samples Such as Lettuce (Lactuca sativa L.

Directory of Open Access Journals (Sweden)

Ana I. Prieto

2018-02-01

Full Text Available Reports on the occurrence of the cyanobacterial toxin cylindrospermopsin (CYN have increased worldwide because of CYN toxic effects in humans and animals. If contaminated waters are used for plant irrigation, these could represent a possible CYN exposure route for humans. For the first time, a method employing solid phase extraction and quantification by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS of CYN was optimized in vegetables matrices such as lettuce (Lactuca sativa. The validated method showed a linear range, from 5 to 500 ng CYN g−1 of fresh weight (f.w., and detection and quantitation limits (LOD and LOQ of 0.22 and 0.42 ng CYN g−1 f.w., respectively. The mean recoveries ranged between 85 and 104%, and the intermediate precision from 12.7 to 14.7%. The method showed to be robust for the three different variables tested. Moreover, it was successfully applied to quantify CYN in edible lettuce leaves exposed to CYN-contaminated water (10 µg L−1, showing that the tolerable daily intake (TDI in the case of CYN could be exceeded in elderly high consumers. The validated method showed good results in terms of sensitivity, precision, accuracy, and robustness for CYN determination in leaf vegetables such as lettuce. More studies are needed in order to prevent the risks associated with the consumption of CYN-contaminated vegetables.

Validation of a Method for Cylindrospermopsin Determination in Vegetables: Application to Real Samples Such as Lettuce (Lactuca sativa L.).

Science.gov (United States)

Prieto, Ana I; Guzmán-Guillén, Remedios; Díez-Quijada, Leticia; Campos, Alexandre; Vasconcelos, Vitor; Jos, Ángeles; Cameán, Ana M

2018-02-01

Reports on the occurrence of the cyanobacterial toxin cylindrospermopsin (CYN) have increased worldwide because of CYN toxic effects in humans and animals. If contaminated waters are used for plant irrigation, these could represent a possible CYN exposure route for humans. For the first time, a method employing solid phase extraction and quantification by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) of CYN was optimized in vegetables matrices such as lettuce ( Lactuca sativa ). The validated method showed a linear range, from 5 to 500 ng CYN g -1 of fresh weight (f.w.), and detection and quantitation limits (LOD and LOQ) of 0.22 and 0.42 ng CYN g -1 f.w., respectively. The mean recoveries ranged between 85 and 104%, and the intermediate precision from 12.7 to 14.7%. The method showed to be robust for the three different variables tested. Moreover, it was successfully applied to quantify CYN in edible lettuce leaves exposed to CYN-contaminated water (10 µg L -1 ), showing that the tolerable daily intake (TDI) in the case of CYN could be exceeded in elderly high consumers. The validated method showed good results in terms of sensitivity, precision, accuracy, and robustness for CYN determination in leaf vegetables such as lettuce. More studies are needed in order to prevent the risks associated with the consumption of CYN-contaminated vegetables.

Application Of Phase Change Materials (PCM’s To Preserve The Freshness Of Seafood Products

Directory of Open Access Journals (Sweden)

Wiwik Pudjiastuti

2015-04-01

Full Text Available The application of Phase Change Materials (PCMs as one of latent heat energy storage materials in smart cold system has been investigated for preserving a freshness of seafood products. In this investigation, PCMs was installed on Expanded Polystyrene (EPS box system as insulated container. The freshness of the seafood product was shown by the time of keeping temperature during storage or distribution. Keeping temperature time of smart cold system using PCMs was compared to conventional cold system using ice cubes. The result shows that EPS box system using PCMs can prolonged the keeping temperature time and reached colder temperature than the conventional one. Microbiology test of products was monitored to prove that products occured no changes in quality.

Nitrogen utilization and environmental losses in organic greenhouse lettuce amended with two distinct biochars.

Science.gov (United States)

Pereira, Engil Isadora Pujol; Conz, Rafaela Feola; Six, Johan

2017-11-15

The potential of biochar to prevent nitrogen (N) losses and improve plant performance were studied across various levels of N input for two growing seasons in mesocosms simulating an organic lettuce production system. A silt loam soil was amended with pine chip (PC) and walnut shell (WS) biochar (10tha -1 ) in combination with five organic N fertilization rates (0, 56, 112, 168, and 225kgNha -1 ). The N output through harvest, leachate, and N 2 O emissions were measured to assess N utilization and environmental losses of biochar-amended soils. For both biochars, only at the 100% N fertilization rate was lettuce biomass production improved with significant increases in N use efficiency (NUE); however, only PC biochar decreased N losses via leaching (at 100% N fertilization rate) and seasonal N 2 O emissions (at 50% N fertilization rate). Thus, due to increases in plant biomass and decreases in N losses, PC biochar significantly decreased the ratio of N lost over N exported in biomass. Findings from this study suggest that both WS and PC biochars can improve organic lettuce production but only at 225kgNha -1 . Decreases in N losses via leachate and N 2 O emissions vary with fertilization level and biochar type. Copyright © 2017 Elsevier B.V. All rights reserved.