The ones marked may be different from the article in the profile. The yoghurt samples were cooled to 25 c by resting in a temperature controlled room 15 c and then stored at 35 c for a period of 12 hours. Read rheological characterization of stirred yoghurt. Chemical, nutritional, rheological, and organoleptical. Rheology and sensory profiling of settype fermented milks made with different commercial probiotic and yoghurt starter cultures.
The aim of this study was the rheological monitoring of structure evolution and development during the production stages and storage of stirred yoghurt, which was performed by means of steady and oscillatory shear experiments. C and the three replicates of the stirred yoghurt were analyzed after 1, 7 and 14 d of manufacturing. The rheological tests revealed that increasing the casein and fat content led to increase the apparent viscosity of the stirred yoghurt and its dependence on. The missing link sensory and rheology study of low fat stirred yoghurt heidi l. Bingham, a professor at lafayette college, in 1920, from a. A rheological study was carried out in order to characterise the stirred yoghurt flow behaviour, evaluating its dependency both on shear rate and temperature. Fortification of banana stirred yogurt with calcium. In the present work an experimental investigation was conducted to obtain a correlation for the determination of convective heat transfer coefficients of stirred yoghurt in a plate heat exchanger. Stirred yogurt is obtained by breaking the gel after fermentation in tanks.
Request pdf rheological characterization of stirred yoghurt. Spectroscopic prediction of rheological properties of. Effects of starter cultures on small deformation rheology. Development and breakdown of structure in yoghurt studied by oscillatory rheological measurements. Effects of starter cultures on small deformation rheology of. Syneresis and rheological behaviors of set yogurt containing green. Milk was fermented at three different temperatures 37. The aim of this study is to find correlations between rheological parameters and sensory attributes. A maximum in loss angle was observed during the gel development.
The influence of storage on the aroma release in headspace and rheological properties in strawberryflavored fatfree stirred yogurts was determined. Yoghurt rebodying could not be explained by fulfilling ionic equilibrium. Nrs the missing link sensory and rheology study of low. Simulation of stirred yoghurt processing in plate heat exchangers. Rheological behavior of two commercial brands of stirred yogurt were investigated using a haake rv 20 rotational viscometer. Yoghurt properties were followed by dynamic rheometry bohlin universal.
Flavor release and rheology behavior of strawberry fatfree. Ramaswamy, simultaneous evaluation of shear rate and time dependency of stirred yogurt rheology as influenced by added pectin and strawberry concentrate, journal of food engineering, 21, 3, 385, 1994. Rheology of stirred yogurts, journal of texture studies. Steadyshear viscosity of stirred yogurts with varying. Attractive electrostatic and disulphide interactions were not involved in the gel rebodying and increasing calcium concentration in the set gel limited rebodying.
Simultaneous evaluation of shear rate and time dependency of stirred yogurt rheology as influenced by added pectin and strawberry concentrate. Food rheology is the study of the deformation and flow of food materials rao, 1999. Three periods of storage at 10 c were chosen for analysis. The factors responsible for the increase in viscosity of stirred yoghurts are therefore in the manufacture of stirred yoghurts, a setstyle yoghurt gel is essentially. In a typical yoghurt production process, additives and flavours are added after the fermentation process bylund, 1995. Structure breakdown of stirred yoghurt in a circular pipe. A shift in the temperature dependency was evidenced at 25 c. Viscometry, journal of texture studies on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Creamy stirred yogurt an indulgent treat for all the senses. However, dynamic rheology has been applied to stirred yoghurt only in commercial samples 16,17.
Heat transfer and rheology of stirred yoghurt during cooling in plate heat exchangers. Solid rheology and texture they describe the flow characteristics of materials but also they can be used to monitor certain processes, e. The present study was performed to evaluate effects of starter properties on the linear viscoelastic behaviour of stirred yoghurt and to compare data with dynamic properties of yoghurt gels produced simultaneously. Food rheology is the study of the deformation and flow of food materials 1. Pdf rheological properties of stirred yoghurt as affected by gel ph. Rheological monitoring of structure evolution and development. Effects of starter cultures on small deformation rheology of stirred yoghurt. The rheological properties of a lowfat and a fullfat yoghurt were investigated under continuous and oscillatory flow conditions with a rotational coaxialcylinder. Chemical, nutritional, rheological, and organoleptical characterizations of stirred pumpkin yoghurt. Plasma ldl cholesterol lowering by plant phytosterols in a hamster model. Rheology of stirred yogurts ramaswamy 1991 journal. A rheological study was carried out in order to characterise the stirred yoghurt flow, behaviour, evaluating its dependency both on shear rate and.
It covers both rheological and sensory evaluation of low fat stirred yoghurt prepared with different combinations of texturizers, like pectin, starches and gelatine. A shift in the temperature dependency was evidenced at 25 a. Pdf heat transfer and rheology of stirred yoghurt during. Steady and dynamic rheological behaviour of frozen soy. This study aimed to apply cryoscanning electron microscopy and confocal laser scanning microscopy to determine the optimal temperature for processing buffalo yoghurt. Rheological characteristics of 2 commercial brands of stirred yogurt were evaluated using a haake rotovisco model rv 20 with an m.
Whether topped with chocolate, mixed with fruits or on its own, premium, indulgent yogurts have become the preferred choice of dessert for the health conscious consumer. This cited by count includes citations to the following articles in scholar. Stirred yogurt is made by fermenting milk and stirring the set curd to break the rigid gel structure to obtain a viscous liquid 33. Effect of fermentation temperature on the rheology of set. For thicker, greekstyle yogurt, after incubation, spoon the yogurt into a cheeseclothlined colander set over a. Evaluation of rheological, physicochemical, and sensory.
Effects of polymerized whey proteins isolates on the quality of stirred yoghurt made from camel milk. Further information has been provided by muller 1973 and sherman 1979. Rheology of stirred yogurts, journal of texture studies 10. Heat transfer and rheology of stirred yoghurt during cooling. To describe the rheological behaviour of stirred yo. A methodology was developed to evaluate simultaneously the shear rate and time dependency of stirred yogurt rheology. Stability and rheological properties of stirred yogurts.
Differences between the transmission and backscattering dws correlations suggest the formation of a high shear rate band near. Heat transfer and rheology of stirred yoghurt during cooling in plate heat exchangers article pdf available in journal of food engineering 572. It was shown in this work that the simple rheological tests can be used to estimate the structure breakdown rate of stirred yoghurt in pipe flow. Development and breakdown of structure in yoghurt studied. Yoghurt is a fermented dairy product, having several health benefits. Viscometry rheological characteristics of stirred yoghurt, varying in dry matter content.
Simulation of stirred yoghurt processing in plate heat. Results indicate that count of lab for banana stirred yogurt fortified with cag was increased in compared with the control. Wyss weitzlab group meeng tutorial 10x1035 0 5 10 strain 0 2 4 6 8 10 12 time s. Most of the basic plain yogurts are set yogurts, which are fermented in the container that they are eventually sold in, while most fruitflavored yogurts are stirred yogurts. Apr 06, 2004 the influence of storage on the aroma release in headspace and rheological properties in strawberryflavored fatfree stirred yogurts was determined. Impact of gelation conditions and structural breakdown on the. Rheology for the food industry gipsy tabilomunizaga a, gustavo v. Time dependent stress decay rheology of stirred yogurt. Set yoghurt storage modulus depended on ph but not on fermentation time. Moreover, nethyl maleimide addition had no effect on the stirred yoghurt.
Nrs the missing link sensory and rheology study of low fat. Ambient yoghurt production is the same as stirred type whit the difference of the ambient yoghurt is heattreated after fermentation in order to inactivate the lab and so therefore. Rheological behaviour of lowfat and fullfat stirred yoghurt. Heat transfer and rheology of stirred yoghurt during cooling in plate heat exchangers by i. Yoghurt properties were followed by dynamic rheometry bohlin universal rheometer and by penetrometry stevens lfra texture analyzer and the measuring methods were compared.
The yoghurt was stirred to smoothen and to obtain semisolid consistency. Most of the basic plain yogurts are set yogurts, which are fermented in the container that they are eventually sold in, while most fruitflavored yogurts are stirred yogurts, because flavors and fruit. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Stress decay behavior of two stirred yogurt samples was evaluated at various shear rates 100500 s. A shift in the temperature dependency was evidenced at 25 degreesc. Abstract rheological characteristics of 2 commercial brands of stirred yogurt were evaluated using a haake rotovisco model rv 20 with an m. Yogurt can be classified as pseudoplastic material contains a yield stress that has to be exceeded for flow to be initiated that can be either a viscoelastic fluid if we are dealing with stirred or drinking. Rheology of stirred yogurt request pdf researchgate. Yoghurt starter culture consists of a blend of streptococcus thermophilus and lactobacillus delbrueckii subsp bulgaricus. The spme fiber was carefully chosen, and results are presented in detail choice and degradation. Rheology of stirred yogurt as affected by added milk fat. Stirred yoghurt is a nonnewtonian fluid, obtained by promoting the growth of lactobacillus delbrueckii subsp.
The headspace composition was assessed in a flask in static mode. Furthermore, a correlation appeared to exist between t 2, water binding, and the rheological properties of the stirred. Effects of starter cultures on small deformation rheology of stirred yoghurt effects of starter cultures on small deformation rheology of stirred yoghurt rohm, h kovac a. Stirred yoghurt produced from uht milk enriched with skim milk powder and by using 11 commercial starter cultures was subjected to dynamic rheological measurements with a cone and plate device. Rheological and physical properties of yogurt enriched with. Rheology of stirred yogurts ramaswamy 1991 journal of.
During the conditioning process stirring, pipe flowing and pumpage, the product is subject to shearing constraints which result in the destructuring of the protein matrix affecting the rheological properties. Simultaneous evaluation of shear rate and time dependency. Most fluid foods including dairy fluids like cream, ice cream mix, stirred yoghurt and liquid infant foods shows complex flow behaviour at different stages of processing and it requires study of its flow behaviour for better control over the processing parameters. The physical attributes of yogurts, including the lack of visual whey separation and. Steadyshear viscosity of stirred yogurts with varying ropiness journal of rheology 43, 1643 1999.
Box 447, chillan, chile b department of biological systems engineering, washington state university, pullman, wa 991646120, usa received 10 october 2003. Determination of yogurt quality by using rheological and. Rheology is the science of deformation and flow within a material. The spme fiber was carefully chosen, and results are presented in detail choice and. Relation between sensory texture analysis and rheological properties of stirred yogurt volume 66 issue 4 anne skriver, jens holstborg, karsten b. Whether topped with chocolate, mixed with fruits or on its own, premium. Simulation of stirred yoghurt processing in plate heat exchangers carla s. Qvist skip to main content accessibility help we use cookies to distinguish you from other users and to provide you with a better experience on our websites. Structure breakdown of stirred yoghurt in a circular pipe as. Creamy stirred yogurt an indulgent treat for all the senses almost everyone enjoys a special treat after dinner. Rheological characteristics of 2 commercial brands of stirred yogurt were evaluated using a haake rotovisco model rv 20 with an m5osc measuring head and mv1 rotor assembly from measured shear stress values under a programmed 3cycle up and downshear rate at 100 s.
Heat transfer and rheology of stirred yoghurt during. The shear flow behaviour of stirred yoghurt in the coneandplate and cylindrical couette geometries was studied using diffusing wave spectroscopy dws and nuclear magnetic resonance nmr velocimetry. The rheological characterization of stirred yogurt with added milk fat, na caseinate or micellar casein and gelatin 4 bloom strengths, starch or a xanthan gumlbg 50. It is a branch of physics which deals with the deformation and flow of materials, both solids and liquids.
Heat transfer and rheology of stirred yoghurt during cooling in plate heat. Dynamic and shear values were measured at 8c and syneresis at 4c. Yoghurt properties can be enhanced by the addition or treatment with various additives. Spectroscopic prediction of rheological properties of stirred. A rheological study was carried out in order to characterise the stirred yoghurt flow behaviour, evaluating its dependency both on shear rate and. If more whey separates out of the yogurt, just stir before serving. Differences between the transmission and backscattering dws correlations suggest the formation of a high shear rate band near the surface of a moving cone of a coneandplate geometry at low.
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