Viscosity changes of probiotic yoghurt with transglutaminase during storage

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Iličić Mirela D.

2008-01-01

Full Text Available The aim of this study was to determine the effect of the quantity of transglutaminase as well as conditions of its application (direct, or after activation by milk heating for 2 h at 40°C and for 1 min at 80°C, on yoghurt viscosity manufactured from two kinds of low fat milk (0.1 % w/w fat and 0.5% w/w fat during 10 days of storage. The fermentation in both series started after the adequate amounts of probiotic starter culture ABT-4 (Chr. Hansen A/S Denmark were added to the milk at 43°C. After milk fermentation at pH 4.5, probiotic yoghurt samples were cooled to 8°C, gently homogenized and packed in plastic containers and stored for 10 days, at +4oC. Viscosity of all samples was measured at 5°C on a Haake Rheostress 600 viscosimeter. On the basis of the obtained results it can be concluded that yoghurt samples produced with low level of transglutaminase activated prior to fermentation have significantly better rheological properties than the samples produced without activation and yoghurt control. Generally, the application of low level transglutaminase in low - fat yoghurt production improves overall rheological properties of the final product.

Functional properties of α-lactalbumin and β-lactoglobulin

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Zoran Herceg

2004-06-01

Full Text Available Whey proteins are commonly used in the food industry due to their nutritive value and functional properties. The most important functional properties of whey proteins are solubility, viscosity, water holding capacity, emulsification and foaming. The aim of this study was to determine functional properties of main whey protein fractions (α-lactalbumin and β-lactoglobulin which have the biggest influence on the functional properties of whey proteins. Particle size analysis and specific area of α-lactalbumin and β-lactoglobulin were performed by «Mie – theory» of «light scatering» using «Malvern Mastersizer X». The results of this analysis have shown that β-lactoglobulin had higher particle size and specific area than α-lactalbumin.By examining functional properties (solubility, dispersibility, emulsifiying properties – emulsion activity index (EAI and emulsion stability index (ESI and foaming properties of α-lactalbumin and β-lactoglobulin, it has been established that β-lactoglobulin has higher solubility, dispersibility, emulsifiying properties as well as foaming properties than α-lactalbumin. Rheological properties of protein suspensions were determined by rotational viscosimeter, Brookfiel DV-III at temperature 25°C. Rheological parameters, flow behavior indeks (n and consistency coefficient (k were determined by the power-law model. The results of investigation have shown that 10% suspenzion of α-lactalbumin and β-lactoglobulin are non-Newtonian fluids and they exhibited pseudoplastic properties.

Properties of retrograded and acetylated starch produced via starch extrusion or starch hydrolysis with pullulanase.

Science.gov (United States)

Kapelko, M; Zięba, T; Gryszkin, A; Styczyńska, M; Wilczak, A

2013-09-12

The aim of the present study was to determine the impact of serial modifications of starch, including firstly starch extrusion or hydrolysis with pullulanase, followed by retrogradation (through freezing and defrosting of pastes) and acetylation (under industrial conditions), on its susceptibility to amylolysis. The method of production had a significant effect on properties of the resultant preparations, whilst the direction and extent of changes depended on the type of modification applied. In the produced starch esters, the degree of substitution, expressed by the per cent of acetylation, ranged from 3.1 to 4.4 g/100 g. The acetylation had a significant impact on contents of elements determined with the atomic emission spectrometry, as it contributed to an increased Na content and decreased contents of Ca and K. The DSC thermal characteristics enabled concluding that the modifications caused an increase in temperatures and a decrease in heat of transition (or its lack). The acetylation of retrograded starch preparations increased their solubility in water and water absorbability. The modifications were found to exert various effects on the rheological properties of pastes determined based on the Brabender's pasting characteristics and flow curves determined with the use of an oscillatory-rotating viscosimeter. All starch acetates produced were characterized by ca. 40% resistance to amylolysis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Rheological changes in irradiated chicken eggs

Science.gov (United States)

Ferreira, Lúcia F. S.; Del Mastro, Nélida L.

1998-06-01

Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25°C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these results are discussed in terms of possible industrial applications.

Rheological changes in irradiated chicken eggs

International Nuclear Information System (INIS)

Ferreira, Lucia F. S.; Del Mastro, Nelida L.

1998-01-01

Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25 degree sign C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these results are discussed in terms of possible industrial applications

Relationship between blood viscosity and infarct size in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Science.gov (United States)

Cecchi, Emanuele; Liotta, Agatina Alessandriello; Gori, Anna Maria; Valente, Serafina; Giglioli, Cristina; Lazzeri, Chiara; Sofi, Francesco; Gensini, Gian Franco; Abbate, Rosanna; Mannini, Lucia

2009-05-15

Previous studies explored the association between hemorheological alterations and acute myocardial infarction, pointing out the role of hematological components on microvascular flow. The aim of this study was to evaluate the association between blood viscosity and infarct size, estimated by creatine kinase (CK) peak activity and cardiac Troponin I (cTnI) peak concentration in ST-segment elevation myocardial infarction (STEMI) patients after primary percutaneous coronary intervention (PCI). The study population included 197 patients with diagnosis of STEMI undergoing PCI. Hemorheological studies were performed by assessing whole blood viscosity (measured at shear rates of 0.512 s(-1) and 94.5 s(-1)) and plasma viscosity using the Rotational Viscosimeter LS 30 and erythrocyte deformability index by Myrenne filtrometer. Significant correlations between CK peak activity, cTnI peak concentration, left ventricular ejection fraction and hemorheological variables were observed. At linear regression analysis (adjusted for age, gender, traditional cardiovascular risk factors, renal dysfunction, timeliness of reperfusion, pre-PCI TIMI flow, infarct location, multivessel disease and previous coronary artery disease) leukocytes and whole blood viscosity at 0.512 s(-1) and 94.5 s(-1) were independently and positively associated with infarct size. These results demonstrate a significant and independent association between hemorheology and infarct size in STEMI patients after PCI suggesting that blood viscosity, in a condition of low flow, might worsen myocardial perfusion leading to an increased infarct size. The measurement of whole blood viscosity in STEMI patients could help to identify those who may benefit from new therapeutic strategies.

Quality of clay-powders of industrial assortment

Energy Technology Data Exchange (ETDEWEB)

Lityayeva, Z A; Dzetl, B G; Goncharenko, N N; Naurova, I V; Rybchenko, V I; Voyevodin, L I

1979-01-01

Nomenclature was developed for the quality indicators of clay powders which took into consideration the foreign experience, and it is suggested that a suspension of clay powders be viewed as the simplest type of drilling. In this case the technique of preparing the suspensions approaches the maximum to that used in the recommended standard (TU-39-043-074). The output of solution is determined with standardized effective viscosity /eta/ ef =/sup 20/ /SUP cP/ on a series domestic rotary viscosimeter VSN-3 with gradient of shear velocity EPSILON=666 sec/sup -1/; with EPSILON=1022 sec /sup -1//eta/ /SUB ef/ = 15 cP. This makes it possible to obtain data comparable to the foreign standards regarding the output of the fluid from the powders. According to the suggested technique, the clay powder is dispersed for 20-30 minutes in water or saturated solution of NaC1 in a mixing unit ''Voronezh2'' with rotation frequency of 9000 rpm, is left to rest and is again dispersed for 15 minutes. Then the dynamic shear stress (P /SUB k2/ ), plastic viscosity (/eta/ /SUB ef/ ), coefficients of coagulation (K /SUB c/ ) and thyxotropic (K /SUB T/ ) structure-formation are defined. Measurements are made on the instrument FLR-1 of water output with 0.7 (B) or 0.1 (B) MPa. According to this technique, a comparison was made of the domestic powders of industrial assortment with the powder ''Aquagel'' widely used abroad. It was established that only the modified concrete powders with correct selection of reagents can compete with the foreign.

Behaviour of a new material for the oil well cementing. Relations between particle structure and rheological properties; Comportement d'un nouveau materiau pour la cimentation de puits de petrole. Relations entre la structure particulaire et les proprietes rheologiques

Energy Technology Data Exchange (ETDEWEB)

Dubois, N

1999-12-16

This work focuses on the control and the characterization of the rheological behaviour of Ultra High Performances Concretes (UHPC) for oil well during the dormant period, in the first moments following malaxation. Cement, sand, silica fume, water and a super-plasticizer were principally used in this study. We sought to control their rheological behaviour with simple macroscopic data, such as dry compactness and diameters of the particles. Viscosity and yield stress measurements were determined with controlled stress or controlled rotational speed viscosimeters, by using parallel plates, concentric cylinders, or a vane. We highlight the experimental difficulties generated by the characterization of such mixtures and describe the precautions to take in order to carry out significant measurements. First, we explain the rheological behaviour by traditional granular interactions, such as wall and loosening effects. These interactions allow to predict dry compactness and the rheological behaviour of certain granular mixtures, whose diameters ratio of two successive classes n-1 and n satisfies D{sub n-1}/D{sub n}<0,2 with D{sub n}>D{sub n-1}. The introduction of another concept, named 'spacing', enabled us to evaluate the viscosity of suspension whose diameters ratio of two successive size ranges are large (D{sub n-1}/D{sub n}>0,2), and to predict the behaviour of hollow mixtures. We show moreover that it is possible to lower the viscosity and the yield stress of BUHP, by modifying the granulometric distribution of the components, while preserving the same quantity of water. Finally we highlight the particular action of the silica fume, consisted of welded spherical particles and forming not easily breakable clusters, onto the rheological behaviour of BUHP. (author)

Blood viscosity during coagulation at different shear rates

Science.gov (United States)

Ranucci, Marco; Laddomada, Tommaso; Ranucci, Matteo; Baryshnikova, Ekaterina

2014-01-01

Abstract During the coagulation process, blood changes from a liquid to a solid gel phase. These changes are reflected by changes in blood viscosity; however, blood viscosity at different shear rates (SR) has not been previously explored during the coagulation process. In this study, we investigated the viscosity changes of whole blood in 10 subjects with a normal coagulation profile, using a cone‐on‐plate viscosimeter. For each subject, three consecutive measurements were performed, at a SR of 20, 40, 80 sec−1. On the basis of the time‐dependent changes in blood viscosity, we identified the gel point (GP), the time‐to‐gel point (TGP), the maximum clot viscosity (MCV), and the clot lysis half‐time (CLH). The TGP significantly (P = 0.0023) shortened for increasing SR, and was significantly associated with the activated partial thromboplastin time at a SR of 20 sec−1 (P = 0.038) and 80 sec−1 (P = 0.019). The MCV was significantly lower at a SR of 80 sec−1 versus 40 sec−1 (P = 0.027) and the CLH significantly (P = 0.048) increased for increasing SR. These results demonstrate that measurement of blood viscosity during the coagulation process offers a number of potentially useful parameters. In particular, the association between the TGP and the activated partial thromboplastin time is an expression of the clotting time (intrinsic and common pathway), and its shortening for increasing SR may be interpreted the well‐known activating effects of SR on platelet activation and thrombin generation. Further studies focused on the TGP under conditions of hypo‐ or hypercoagulability are required to confirm its role in the clinical practice. PMID:24994896

Behaviour of a new material for the oil well cementing. Relations between particle structure and rheological properties; Comportement d'un nouveau materiau pour la cimentation de puits de petrole. Relations entre la structure particulaire et les proprietes rheologiques

Energy Technology Data Exchange (ETDEWEB)

Dubois, N.

1999-12-16

This work focuses on the control and the characterization of the rheological behaviour of Ultra High Performances Concretes (UHPC) for oil well during the dormant period, in the first moments following malaxation. Cement, sand, silica fume, water and a super-plasticizer were principally used in this study. We sought to control their rheological behaviour with simple macroscopic data, such as dry compactness and diameters of the particles. Viscosity and yield stress measurements were determined with controlled stress or controlled rotational speed viscosimeters, by using parallel plates, concentric cylinders, or a vane. We highlight the experimental difficulties generated by the characterization of such mixtures and describe the precautions to take in order to carry out significant measurements. First, we explain the rheological behaviour by traditional granular interactions, such as wall and loosening effects. These interactions allow to predict dry compactness and the rheological behaviour of certain granular mixtures, whose diameters ratio of two successive classes n-1 and n satisfies D{sub n-1}/D{sub n}<0,2 with D{sub n}>D{sub n-1}. The introduction of another concept, named 'spacing', enabled us to evaluate the viscosity of suspension whose diameters ratio of two successive size ranges are large (D{sub n-1}/D{sub n}>0,2), and to predict the behaviour of hollow mixtures. We show moreover that it is possible to lower the viscosity and the yield stress of BUHP, by modifying the granulometric distribution of the components, while preserving the same quantity of water. Finally we highlight the particular action of the silica fume, consisted of welded spherical particles and forming not easily breakable clusters, onto the rheological behaviour of BUHP. (author)

Construction of a high-temperature viscosimeter and measurement of the viscosity of melts of the system aluminium-nickel; Aufbau eines Hochtemperaturviskosimeters und Messung der Viskositaet von Schmelzen des Systems Aluminium-Nickel

Energy Technology Data Exchange (ETDEWEB)

Kehr, Mirko

2009-10-29

The system aluminium-nickel is of importance as a model-system in materials science as well as a basic system for superalloys in technical applications. The knowledge of the thermophysical properties of the system aluminium-nickel has been limited to the areas close to the pure elements mainly related to the high melting temperatures of up to 1638 C. The viscosity, which is one of these thermophysical properties, depends on alloy composition as well as on temperature. The viscosity is of importance as an input parameter in computer simulations and for improving casting processes of metallic alloys. The viscosity of aluminium-nickel melts has been measured only once so far. However, not the whole concentration range of the aluminium-nickel system was covered by these data. In particular the viscosity values of the high melting alloys, which are of technological interest, were unknown. The measurement of the missing values was not possible due to the high melting temperatures using existing viscometers. A new oscillating cup viscometer has been constructed within this work. The viscometer has been tested measuring the viscosity values of pure metals, which are well known in literature. The test measurements have been done at temperatures up to 1800 C. A temperature of 2300 C is achievable with slight modifications. A new software for controlling the device and evaluation of the measured data has been developed. Several working equations for calculating the viscosity have been implemented. Furthermore a new approach has been used for detecting the damping of the oscillation of the pendulum containing the liquid sample. The viscosity of aluminium-nickel melts have been measured successfully. The measured values are in good agreement with the little number of known values. A good agreement with values calculated from diffusion experiments and computer simulations was observed as well. Several models for calculating the viscosity of liquid alloys have been tested and compared with the experimental values measured in this work. Not all the tested models can predict the viscosity values of aluminium-nickel melts plausibly. (orig.)

Acquisition of rheological and calorimetric properties of borosilicate glass to determine the free energy of formation

International Nuclear Information System (INIS)

Linard, Y.; Advocat, Th.

2000-01-01

No fundamental thermodynamic data, such as the entropy Δ f S T) and enthalpy Δ f H T) of formation are currently available for nuclear borosilicate glasses. They are necessary to assess the glass thermodynamic stability in water, one of the most important potential long-term glass alteration vectors. Three glass composition ranges were investigated: - 8 compositions ranging from a ternary B 2 O 3 -SiO 2 --Na 2 O (BSN) glass to the simulated SON 68 industrial glass for containment of high active nuclear wastes after reprocessing spent uranium oxide fuel from light water reactors. The basic BSN glass was gradually modified with the additives: Al 2 O 3 , CaO, ZrO 2 , Ce 2 O 3 , Li 2 O and Fe 2 O 3 , and non-radioactive surrogate fission product oxides. - A second using another BSN ternary glass to which Al 2 O 3 , MgO and a group of non-radioactive surrogate fission product oxides, representative of natural uranium GCR fuel, were added. - A third range consisting of various BSN ternary glass compositions. All the glass specimens were fabricated by melting the oxides, carbonates anal nitrates at 1273 to 1473 K in a platinum crucible. Experimental methods based on calorimetry and viscosimetry techniques were used to determine the heat capacity Cp of each glass composition, a necessary parameter in addition to the known heat capacities of the basic glass component oxides, for calculating Δ f S T) and Δ f S T). The heat capacity Cp was measured between 273 K and 1480 K through a combination of three experimental devices: a low-temperature adiabatic calorimeter, a differential scanning calorimeter, and an ice calorimeter. The glass configuration entropy S conf (T g ) necessary to obtain the glass entropy of formation (Eqn.(3)) was determined from tile glass rheological properties. A low-temperature viscosimeter was used to measure the strain ε of a glass specimen subjected to a given uniaxial stress σ to determine the viscosity η. A Couette viscosimeter was used to

Efecto de la concentración de sulfato de sodio en la viscosidad y difusividad térmica de barbotinas de arcillas rojas

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Victor Useche

2009-01-01

Full Text Available We reports the thermal diffusivity (αand kinematic viscosity (σ of red-clay suspensions used by Ceramica Italia SA. company in the productions of spraydried clay powders, in function of sodium sulphate concentration. The samples are formed in percentage in weight of a 64% of clay (solid and a 36% of water (liquid. It is made an addition curve of Na2SO4 from 0,018% to 0,153% in weight, in order to maintain similar density conditions (1.689 ± 0.007 g/cm3 and only change the viscosity of the sample. The dynamic viscosity (μ is measured using the viscosimeter BROOKFIELD-DV-II+Pro. Density (ρ is determined by a metallic pycnometer at 100 cm3. The thermal diffusivity is found by a SH-2 Sensor of the KD2-Pro System, which consists of 2 stainless steel needles 6mm separated, one is functioning as a source of heat and the other one is as a sensor of temperature. X-Rays fluorescence is used to found the chemical composition it reports the presence of SiO2 (64,4%, Al2O3 (21,8% y Fe2O3 (5,4% mainly. The rheological results indicate that the viscosity increases when the concentration of sodium sulfate increases in the sample, appearing a change in the state of dispersion of particles; since the suspensions demonstrate a behavior from fluid to reach a higher viscosity. The thermal diffusivity depends on the concentration of Na2SO4 that showed an average deviation of 3.5% and reported a minimum value of 0.00330 cm2/s and a maximum value of 0.00375 cm2/s. The Prandtl Numbers ( found for each concentration of Na2SO4 used, which were very much greater that one (Pr>> 1, which indicates the thermal boundary layer ismuch smaller than the hydrodynamic boundary layer.

Influence of contrast media viscosity and temperature on injection pressure in computed tomographic angiography: a phantom study.

Science.gov (United States)

Kok, Madeleine; Mihl, Casper; Mingels, Alma A; Kietselaer, Bas L; Mühlenbruch, Georg; Seehofnerova, Anna; Wildberger, Joachim E; Das, Marco

2014-04-01

Iodinated contrast media (CM) in computed tomographic angiography is characterized by its concentration and, consecutively, by its viscosity. Viscosity itself is directly influenced by temperature, which will furthermore affect injection pressure. Therefore, the purposes of this study were to systematically evaluate the viscosity of different CM at different temperatures and to assess their impact on injection pressure in a circulation phantom. Initially, viscosity of different contrast media concentrations (240, 300, 370, and 400 mgI/mL) was measured at different temperatures (20°C-40°C) with a commercially available viscosimeter. In the next step, a circulation phantom with physical conditions was used. Contrast media were prepared at different temperatures (20°C, 30°C, 37°C) and injected through a standard 18-gauge needle. All other relevant parameters were kept constant (iodine delivery rate, 1.9 g I/s; total amount of iodine, 15 g I). Peak flow rate (in milliliter per second) and injection pressure (psi) were monitored. Differences in significance were tested using the Kruskal-Wallis test (Statistical Package for the Social Sciences). Viscosities for iodinated CM of 240, 300, 370, and 400 mg I/mL at 20°C were 5.1, 9.1, 21.2, and 28.8 mPa.s, respectively, whereas, at 40°C, these were substantially lower (2.8, 4.4, 8.7, and 11.2 mPa.s). In the circulation phantom, mean (SD) peak pressures for CM of 240 mg I/mL at 20°C, 30°C, and 37°C were 107 (1.5), 95 (0.6), and 92 (2.1) psi; for CM of 300 mg I/mL, 119 (1.5), 104 (0.6), and 100 (3.6) psi; for CM of 370 mg I/mL, 150 (0.6), 133 (4.4), and 120 (3.5) psi; and for CM of 400 mg I/mL, 169 (1.0), 140 (2.1), and 135 (2.9) psi, respectively, with all P values less than 0.05. Low concentration, low viscosity, and high temperatures of CM are beneficial in terms of injection pressure. This should also be considered for individually tailored contrast protocols in daily routine scanning.

Propriedades termofísicas de soluções-modelo similares a sucos: parte II Thermophysical properties of model solutions similar to juice: part II

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Sílvia Cristina Sobottka Rolim de Moura

2005-09-01

Full Text Available Propriedades termofísicas, densidade e viscosidade de soluções-modelo similares a sucos foram determinadas experimentalmente. Os resultados foram comparados aos preditos por modelos matemáticos (STATISTICA 6.0 e obtidos da literatura em função da sua composição química. Para definição das soluções-modelo, foi realizado um planejamento estrela, mantendo-se fixa a quanti-dade de ácido (1,5% e variando-se a água (82-98,5%, o carboidrato (0-15% e a gordura (0-1,5%. A densidade foi determinada em picnômetro. A viscosidade foi determinada em viscosímetro Brookfield modelo LVF. A condutividade térmica foi calculada com o conhecimento das propriedades difusividade térmica e calor específico (apresentados na Parte I deste trabalho MOURA [7] e da densidade. Os resultados de cada propriedade foram analisados através de superfícies de respostas. Foram encontrados resultados significativos para as propriedades, mostrando que os modelos encontrados representam as mudanças das propriedades térmicas e físicas dos sucos, com alterações na composição e na temperatura.Thermophysical properties, density and viscosity of model solutions similar to juices were experimentally determined. The results were compared to those predicted by mathematical models (STATISTIC 6.0 and to values mentioned in the literature, according to the chemical composition. A star planning was adopted to define model solutions composition; fixing the acid amount in 1.5% and varying water (82-98.5%, carbohydrate (0-15% and fat (0-1.5%. The density was determined by picnometer. The viscosity was determined by Brookfield LVF model viscosimeter. The thermal conductivity was calculated based on thermal diffusivity and specific heat values (presented at the 1st . Part of this paper - MOURA [7] and density. The results of each property were analyzed by the response surface method. The found results were significant, indicating that the models represent the changes of

Caracterização reológica de sorvetes Rheological characterization of ice cream

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Katherine Helena Oliveira

2008-09-01

Full Text Available O conhecimento do comportamento reológico é de grande importância no processamento, manuseio, controle de qualidade e desenvolvimento de produtos alimentícios. A literatura relata que a maioria dos alimentos apresenta comportamento não newtoniano, em que a sua viscosidade pode variar com o tempo e com as condições de escoamento. Neste trabalho foi realizada a caracterização reológica de cinco diferentes tipos de sorvetes. As amostras nos sabores creme, creme light, limão, iogurte e soja banana foram fornecidas pela empresa Amoratto Sorvetes Artesanais, localizada na cidade de Florianópolis/SC. Os dados reológicos foram obtidos através de um reômetro com geometria de cilindros concêntricos. Os ensaios foram realizados em três diferentes temperaturas (-2, 0 e 2 °C e os resultados experimentais foram ajustados pelos modelos de Bingham, Casson, Herschel-Bulkley e Lei da Potência. As diferentes amostras apresentaram comportamento não newtoniano nas três temperaturas. Os parâmetros reológicos (K e n foram obtidos através do ajuste dos modelos e o da Lei da Potência mostrou o melhor ajuste aos resultados, com coeficientes de correlação (r iguais a 0,99 para quatro das cinco amostras, nas três diferentes temperaturas.The knowledge of rheological behavior is an important part of processing, handling, quality control and development of food products. Literature shows that most foodstuffs present non-Newtonian behavior, where their viscosity may vary with time, as well as with flow conditions. The rheological characterization of five different kinds of ice cream was carried out in this work. The samples studied were vanilla flavor, light vanilla flavor, lemon, yoghurt and banana soy, supplied by Amoratto Sorvetes Artesanais, located in Florianópolis/SC, Brazil. The rheological data were obtained using a rotational viscosimeter with concentric cylinder geometry. The trials were carried out at three different temperatures (-2, 0

Viscosidade do Sangue como Parâmetro de Diagnóstico da Síndrome Ascítica em Linhagens de Frangos de Corte com Diferentes Suscetibilidade Blood Viscosity as Diagnostic Parameter for Ascites in Broiler Chickens Strains of Different Susceptibility

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SF Fontes

2000-04-01

Full Text Available O objetivo deste trabalho foi investigar o desenvolvimento de ascites em duas linhagens diferentes de frangos de corte, Hubbard e Pescoço-pelado, através da variação da viscosidade do sangue. As aves foram criadas até 45 dias de idade em duas temperaturas ambiente diferentes (termoneutra e fria e com dieta de ração à base de milho e farelo de soja, peletizada e de alta energia. Aos 28 e 45 dias de idade, amostras de 8 mL de sangue foram obtidas para determinação da viscosidade aparente em um viscosímetro de cilindros concêntricos da marca Brookfield, modelo LVDII+ e para determinação do hematócrito. Aos 28 dias de idade foram verificadas algumas ocorrências de ascite nas aves da linhagem Hubbard criadas à temperatura ambiente fria, e aos 45 dias de idade, todos os frangos de corte dessa linhagem criados no ambiente frio apresentaram ascite. A linhagem Pescoço-pelado foi resistente ao desenvolvimento de ascite em todas as idades e temperaturas ambiente. A análise dos resultados da viscosidade aparente do sangue indicaram que aves com valores similares ou maiores que 4 cP (centipoise apresentaram ascite. Podemos concluir que na linhagem comercial o valor de 4 cP para a viscosidade aparente parece identificar o desenvolvimento de ascite.The objective of this work was to investigate the development of ascites in broilers from Hubbard and Naked-neck strains based on the change in blood viscosity. The broilers were reared up to 45 days of age at different environmental temperatures (thermoneutral or cold and fed pelleted diets with high energy content. At 28 and 45 days, blood samples were obtained to measure the apparent blood viscosity, using a viscosimeter of concentric cylinders, and hematocrit. The results showed that at 28 days of age, some occurrence of ascites was verified in Hubbard birds living in the cold environment, but at 45 days of age all the birds reared at cold temperature had developed ascites. The Naked

Comportamento de propriedades físicas, químicas e reológicas do suco de acerola armazenado a baixa temperatura Physical, chemical and rheological behavior of West Indian cherry juice stored at low temperature

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José E. Gomes

2001-05-01

Full Text Available Estudou-se o comportamento físico, químico e reológico do suco de cinco genótipos de acerola (CL2, CL5, CL11, R1 e R2 depois de lavadas, as frutas (2 kg foram esmagadas em um processador manual. Do extrato obtido, em peneira de 1,6 mm, para separar o suco dos resíduos e sementes, foi acondicionado 20 mL de suco de cada amostra em tubos plásticos com dimensões 5 x 3 cm, que foram armazenados em freezer a uma temperatura de -10 °C, durante 10 meses. As leituras de sólidos solúveis totais foram refratométricas, o pH foi aferido através de um potenciômetro, o teor de vitamina C pela técnica da redução do iodo e a viscosidade aparente com viscosímetro de cilindros concêntricos. As determinações foram realizadas inicialmente (mês 0 e bimestralmente (2°, 4°, 6°, 8° e 10° mês. Os parâmetros de viscosidade e vitamina C foram os que mais variaram. O genótipo CL-2 se destacou no teor de sólidos solúveis totais e os R1 e R2 em teores de vitamina C. Os sucos analisados mostraram comportamento reológico não-newtoniano e pseudoplástico.With the objective to study physical, chemical and rheological behavior of West Indian cherry juice of five genotypes (CL2, CL5, CL11, R1 and R2 an experiment was conducted with the juice extracted from 2 kg of mature fruits after washing, dried and squashed in a manual processor. The juice was sieved in a 1.6 mm sieve; 20 mL samples were packed in plastic tubes (5 x 3 cm and stored in a freezer at -10 °C for a 10 month period. The evaluations of total soluble solids were refractometric, the pH was determined by potentiometer, vitamin C was measured by iodine reduction technique and apparent viscosity determined in concentric cylinders viscosimeter. The determinations were done initially and at intervals of two months (0, 2nd, 4th, 6th, 8th and 10th. Viscosity and vitamin C were the characteristics which varied highly. The genotype CL-2 surpassed other genotypes in total soluble solids and the

DETERMINATION OF SOME PHYSICAL AND CHEMICAL PROPERTIES OF PECTIN SUBSTANCES FROM THE SOLVENT CAKE OF TAGETES PATULA L. INFLORESCENCES

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N. M. Chervonnaya

2017-01-01

Full Text Available Big molecular weight conditions are responsible for some properties, which are absent in low molecular compounds. Therefore, its determination allows revealing of some physical and technological properties of biopolymers and prediction of the possibility of their practical application. The aim of this work was to determine an average molarweight, to study the superficial properties at the border of “solution-air” phases, and to establish an isoelectric spot of water solutions of pectin substances (PS, isolated from a solvent cake of Tagetes patula inflorescences. Materials and methods. Polysaccharide complexes were isolated from the solvent cake of Tagetes patula inflorescences of Carmen species which was left after a raw material extraction with ethanol 40% with the method of Kochetkov and M. Sinnera. The time of water and PS solutions flow out was measured by the use of a capillary Ostwald viscosimeter; different types of viscosity were calculated. The density of solutions was determined by using a picnometric method, however due to the closeness of density of the analyzed solutions and water, they were not considered in the calculation of the relative viscosity. Series of solutions with 0.01 to 0.5% concentrations were prepared from 1% PS water solutions to determine a surface activity. Monometric liquid tension variations were set in Rehbinder’s apparatus in the moment of an air bubble appearance on the surface of PS solution. Isoelectric spot (IES of PS was determined in acetate buffer solution with pH within 3.2 to 6.2 by using the viscometer method. Results and discussion. Fractioning of the obtained polysaccharide complexes showed that efficiency of the pectin substances amounted to 2.2%. Calculation shows that an average molar weight of PS amounted to 45272 g/mol. About the degree of interaction between macromolecules of polymer and solvent, structural properties of macromolecule, the degree of its branching can be judged by the

Etude des propriétés rhéologiques des coupes lourdes à haute température et pression Study of the Rheological Properties of Heavy Cuts At High Temperature and Pressure

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Cohen A.

2006-11-01

Full Text Available Les procédés rencontrés dans la valorisation des résidus et des huiles lourdes font appel à des équipements dont le dimensionnement optimal exige la connaissance précise des propriétés rhéologiques de la phase hydrocarbonée impliquée et ce, dans un large domaine de température et de pression. En conséquence, le Laboratoire de Thermodynamique du Centre Réacteurs et Processus de l'École Nationale Supérieure des Mines (ENSM de Paris s'est attaché au développement d'un viscosimètre approprié à ces mesures. Il est basé sur la détermination du couple résistant provoqué par le fluide à étudier, cisaillé entre deux cylindres coaxiaux en rotation relative. Le domaine de viscosité balayé s'étend de 10 à 40 000 cP, les température et pression maximales d'utilisation étant respectivement de 500°C et 30 MPa. La qualité des résultats fournis par cet appareillage a été testée, à des températures et dilution variables, sur quelques coupes lourdes issues des bruts Safaniya et Boscan après désasphaltage ou hydroviscoréduction. On obtient ainsi des valeurs fiables, reproductibles et précises de la viscosité des coupes lourdes hydrocarbonées sur un large domaine de température. Au-delà de 430-440°C toutefois, la pression opératoire de la cellule, fixée par la quantité du gaz admis, augmente brusquement, révélant un craquage thermique important des échantillons et offrant ainsi un moyen d'étude et de simulation des procédés industriels de viscoréduction. Processes used for the upgrading of residues and heavy oils makes use of equipment for which the optimal sizing requires the exact understanding of the rheological properties of the hydrocarbon phase involved over a wide temperature and pressure range. Therefore, the thermodynamics laboratory of the ENSM Center for Reactors and Processes has carried out the development of a viscosimeter suited for such measurements. It is based on determining the

Viscosities reproductive patterns for use in videofluoroscopy and rehabilitation therapy of dysphagic patients Padrões reprodutíveis de viscosidade para uso em videofluoroscopia e na terapia de reabilitação de pacientes disfágicos

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Milton M. B. Costa

2007-12-01

Full Text Available BACKGROUND: Usually the suitable consistence identified and indicated as safe by videofluoroscopic method has been empirically obtained by association of barium sulfate solution with meals. However, it has been evidenced to be very difficult to reproduce this consistence in nutritional rehabilitation therapy from subjective information. AIM: To build two reproductive similar crescent viscosities series of solutions, with and without barium sulfate, to be used, the first, as radiological contrasted mean and the second, as base to reproduce the defined safer consistence, in the oral diet rehabilitation of dysphagic patients. METHODS: Two viscosity solutions series were obtained from starch and distilled water with and without 100% barium sulfate solution. The viscosity levels were defined step by step with digital viscosimeter (Brookfield, model LVTD-II and with infrared thermometer Icel TD - 960. The fluids viscosity was register in centipoises, with their inferior and superior values followed by complimentary information about spindle kind, rotation speed and temperature. RESULTS: The two series of solutions, with and without barium sulfate, could be defined as aqueous (>1-143,5 cP, fine liquid (428 - 551 cP, thick liquid (4.284 -7.346,5 cP, pasty (7.346,4 - 13.035 cP, pasty thick (19.260 - 34.320 cP and creamy (163.500 - 255.300 cP. CONCLUSION: The study could offer reproductive formulas, with and without contrast mean, to be follow for obtaining the desirable viscosity to be used, each of them, in radiological evaluation and in nutritional diet minimizing the gaps fails between evaluation and therapy.RACIONAL: Com freqüência, a consistência identificada e indicada pelo exame videofluoroscópico como segura, para uso nos pacientes disfágicos, tem sido empiricamente produzida pela mistura de alimentos com a solução de sulfato de bário. É expressiva a dificuldade observada quando se busca reproduzir esta consistência, subjetivamente

Caracterização do grânulo de amido de bananas (Musa AAA-Nanicão e Musa AAB-Terra Characterization of starch granules from bananas Musa AAA-Nanicão and Musa AAB-Terra

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M.C.J. Freitas

2005-06-01

moderadas entre si e bastante distintas em relação ao amido de milho, não explicaram a alta resistência dos amidos das bananas à digestão enzimática. Os parâmetros obtidos nas análises permitiram, pela primeira vez avaliar as características e diferenças entre grânulos de amido de espécies distintas de banana e suas relações ao amido de milho.Banana starch has been studied in the area of Nutrition ever since the concept of RS was introduced. The starches of Musa Type AAA-Nanicão and Musa Type AAB-Terra were characterized according to their physiological responses [12]. As a continuation, this study presents other physical and morphological features of starch granules from both species of banana, comparing them with native starch from commercial corn. The banana starches were extracted according to CHIANG, CHU & CHU [3]. The morphology of the granules was examined after hydrolysis in vitro pancreatic alpha-amylase. The respective X-ray amylogram and diffractogram were prepared. The length of the starch granules from Musa Type AAA-Nanicão was 30-40µm. The starch granules from Musa Type AAB-Terra also presenting an oval, elongated shape, were slightly shorter between 20-30µm. The enzymatic attack in vitro initiated on the once smooth surface and the corrosion caused superficial and apical grooves. A scanning electron microscopy showed that the 24 hour hydrolysis in vitro was limited, and occurred mostly in the amorphous layers of both species. The pattern of corrosion was distinctly different in the corn starch. In the viscosimeter the banana starch suspensions demonstrated a great capacity for hydration and a smaller capacity for retrogradation as compared to corn starch, especially the starch from Musa Type AAA-Nanicão; the starch from Musa Type AAB-Terra presented a greater paste stability. In the X-ray diffraction analysis, the banana starch granules were shown to be the standard type B and C for Musa Type AAA-Nanicão and Musa Type AAB