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The aim of this research was to study the effects of whey protein concentrate (WPC) and casein hydrolysate (CH) on chemical (pH and titratable acidity), physical (consistency and syneresis) and sensory properties of yogurt containing probiotic bacteria. Reconstituted skim milk at 10% total solids was fortified with 1 and 2% of WPC, CH and blend of them (WPC to CH ratios of 1:1). Reconstituted skim milks were made with 11 and 12% total solids as control. Bioyogurts were prepared with commercial probiotic starter culture (Lactobacillus acidophilus, Bifidobacterium sp., Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). Fermentation was stopped at pH=4.6 and samples stored at 4°C for 21 days. Addition of WPC resulted in the highest pH value and the lowest titratable acidity. Acidity values of supplemented bioyogurt samples increased between 0.12 - 0.19% during 21 days of storage. Mَoreovere syneresis of these yogurts was lower and their consistency was higher than control. Bioyogurts containing WPC had the lowest syneresis and samples containing CH or WPC had the highest consistency. With regards to total acceptability, the best samples were bioyogurts supplemented with WPC and blend of WPC and CH.

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The aim of this research was to study the effects of whey protein concentrate (WPC) and casein hydrolysate (CH) on chemical (pH and titratable acidity), physical (consistency and syneresis) and sensory properties of yogurt. Reconstituted skim milk at 10% total solids was fortified with 1 and 2% of WPC, CH and blend of them (WPC to CH ratios of 1:1). For comparison, reconstituted skim milks were made with 11 and 12% total solids as control. Yogurts were prepared with commercial starter culture (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and their fermentation proccess were stopped at pH=4.6 and samples stored at 4°C up to 21 days. The lowest pH value was obtained when milk base was supplemented with WPC. pH values of all yogurt samples did not change significantly during 21 days of storage and ~0.18% increase in titratable acidity was observed during storage period. The lowest syneresis was observed in yogurts containing blend of WPC and CH. Moreover, the syneresis values of these yogurts increased slower than other samples during storage. Consistency of fortified yogurts was higher than control yogurt and the consistency values of these samples reduced slower than control sample during 21 days of storage. With regards to total acceptability, the best samples were yogurts supplemented with blend of WPC and CH.

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  Soy bean is a rich source of protein and has nutritional and health benefits due to the presence of phytostrogen and its role on prevention of disease, such as cancer- gained much popularity among its consumers. These days variety of soy bean products produced in food industry, eg. soy milk and fermented soy milk. Sensory evaluation of soy milk and soy yogurt have indicated that there is beany flavor which is objectionable to some consumers. In this study chemical, physiochemical and sensorial tests were done on samples of soy yogurt. Nine formulas of soy yogurt were prepared. The ratio of soy milk: cow milk were 70:30, 80:20 and 90:10 and gelatin added  as stabilizer by the percent of 0.2, 0.4 and 0.6 were used. To achieve a higher total solid and also to improve flavor and aroma of finished product, 2.5 percent non fat dry milk and 1.5 percent whey protein concentrate were added. Viscosity, synersis, acidity, pH and sensory test of formulas were done. Viscosity increased and synersis decreased significantly with the addition of cow milk to soy milk but overall acceptability did not show any significant difference. Sensory analysis of soy yogurt indicated that fortification with 30 percent cow milk and 0.4 percent gelatin gained higher score, when compared with other formulas. To the selected formula with highest score, 5, 10 and 15 percent strawberry flavor was added. Sensory analysis of flavored soy yogurt indicates that fortification with 15 percent strawberry has significantly higher acceptability compared with other formulas.  

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In present study, effects of different levels of inulin (0, 1 and 2%) on the physicochemical and sensory properties and probiotic survival in frozen yogurt was investigated. Results showed that inulin at concentration of 1% had no effect on pH but at level 2% had significant effect on pH. Addition of inulin increased overrun and viscosity.  The flow behavior of all samples showed their pseudoplastic nature; power law was the best model to predict their flow behavior. In comparison of control sample, frozen yogurts containing inulin had better melting properties and inulin at concentration of  2% increased the time of first dripping, significantly. Total acceptability of samples revealed that frozen yogurt with 2% inulin had the most appealing sensory characteristics.  In terms of probiotic survival, the sample with 2% inulin significantly improved the viability of Lactobacillus acidophilus and Bifidobacterium lactis.  

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Probiotic yogurt is one of the most common and important probiotic products in the market. Researchers have revealed that the survival of probiotic organisms in yogurt during storage has often been low. An appropriate technique to preserve the survival rate of these organisms is to prepare yogurt powder using spray drying. The objective of this study was to investigation the effect of ingredient supplementation on survival of bacteria in probiotic yogurt during spray drying process. Effect of supplementing milk before preparing probiotic yogurt with various of ingredient (including whey protein concentrate, maltodextrin powder (DE=10-12), lactose, sodium caseinate and skim milk powder at a level of 1.5% (w/v) on survival of bacteria in probiotic yogurt powder after spray drying using inlet air temperature of 150 ˚C, air flow rate of 478 m³/h and feed flow rate of 2 L/h was investigated. The results indicate that supplementing milk with various ingredients prior to preparing probiotic yogurt not only enhances the growth of bacteria in fresh yogurt but also improve the survival rate these bacteria following spray drying and preparation of probiotic yogurt powder.    

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Probiotic products highly affect the health of consumers by reducing the risk of heart attacks and improving the desirable microflora in the intestinal tract. In this study the effect of yogurt (500g/d for 3 wk) enriched with either Bifidobacterium bifidum or Lactobacillus acidophilus on the level of cholesterol, Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL) of serum and as well on the intestinal microflora were investigated in 24 healthy volunteers. Statistical analysis indicated that lower levels of cholesterol and HDL were found after consumption of either one of bio-yogurts as compared to the control states (P<0.05), whereas changes of LDL were not significant. Also, in comparison with control periods the results of microbial counts indicated that the number of fecal coliforms excreted during the consumption of either one of the yogurt types were not noticeable, while the number of Bifidobacterium bifidum and Lactobacillus acidophilus increased significantly (P<0.05).

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In this research, the effect of kombucha on physicochemical (pH, acidity, syneresis, viscosity, vitamin C and ethanol) and overall acceptability of yogurt samples were measured during 21 days of storage at 8ºC. Thus the amounts of 5, 10 and 15 %(V/V) of concentrate of kombucha layer grown up on black tea, with yoghurt starter, were inoculated to the milk containing 2.2 % fat. Meanwhile, the yogurt starter was applied for producing control sample. Fermentation in all samples was stopped when the pH reached 4.6. The results showed that during the storage, decrease of pH and increase of acidity were minor (p<0.01), and with raising the kombucha concentration, these changes were significantly less than control sample (p<0.01); syneresis in all samples (the same as control) increased while viscosity decreased (p<0.01) and increasing of kombucha concentration was caused increase of syneresis and decrease of viscosity (p<0.01); vitamin C decreased and ethanol increased very little (p<0.01) and as the kombucha concentration increased, the quantities of vitamin C and ethanol increased (p<0.01). Raising the kombucha concentration caused reduction of overall acceptability score in samples (p<0.01); and during storage, this score decreased (p<0.01) a little in comparison with that in control sample. After production and during storage, the best physicochemical and sensory properties was observed in sample containing yogurt starter and 5% kombucha concentrate.  

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Interaction of menthol with polyethylene terephthalate bottles during storage time was tested at three different temperatures. Menthol is a mint flavor agent added to yogurt drinks in Iran and is considered as a factor affecting consumer acceptance. Absorption of menthol to packaging material could cause a loss of quality in the final product due to diminished flavor intensity. Tests were done on the effects of environmental conditions (storage for three months at temperatures of 4, 25, and 45°C) on flavor stability of yogurt drink samples. Absorbed flavor was extracted from PET bottles after the specified time periods and quantified using gas chromatography coupled with FID detector. Then, the diffusion coefficient of menthol into PET bottles (D_p) was determined using concentrations of absorbed menthol. Results showed different absorption levels under various conditions. After 90 days, the absorption quantities at 4, 25, and 45°C were 38.21, 186.66 and 700.50 ng g^-1 of PET bottle, respectively. It was concluded that amounts of menthol absorption into PET bottles increased with storage time and higher temperature. Elevation of storage temperature resulted in significant increase in diffusion coefficient of menthol in PET bottle.

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This study was aimed at evaluating the flow behavior characteristics of yogurt enriched with fish oil (FO) microcapsules prepared by complex coacervation method. FO was microencapsulated in gelatin-acacia gum coacervates. Then, the microcapsules were dried, and yogurt was produced from the milk enriched with microcapsules powder. Rheological characteristics (as measured using a rotational viscometer) of yogurt were evaluated in the shear rate range of 0.262-7.86 s^-1 at 6˚C during 21 days of storage. Power Law model was used for calculation of consistency coefficient and flow behavior index of yogurt. As compared to the control, the enriched yogurt had higher apparent viscosity. Consistency coefficients of the enriched and the control yogurts were in the range of 24.42-28.82 and 15.31-17.76 Pa sⁿ, respectively. Yogurt samples showed a non-Newtonian shear-thinning flow behavior. Addition of FO microcapsules to yogurt may be useful for improving its health-promoting effect and consistency.

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In this research, the effect of whey protein concentrate (WPC) in the concentrations of 13, 16 and 19 percent with some of stabilizers including carboxymethyl cellulose (CMC), pectin and chitosan on the physicochemical properties such as acidity, pH, viscosity, overrun and melting resistance, as well as sensory properties such as taste, texture and overall acceptability in frozen yogurt were investigated. The results of statistical analysis showed that the effect of experimental treatments was significant (P<0.01) on all characteristics evaluated. By increasing the concentrations of WPC, increased the acidity and viscosity of the samples containing all three types of stabilizers, but decreased the pH, overrun and melting resistance percentage of frozen yogurt samples. The samples of frozen yogurt that enriched with carboxymethyl cellulose showed higher viscosity value than samples containing pectin and chitosan, but maximum percentage of overrun and melting resistance was observed in samples containing pectin. In evaluating the sensory characteristics, frozen yogurt containing 13% WPC and pectin had the highest score. According to the results of the physicochemical and sensory properties of frozen yogurt samples, the combination of whey protein concentrate with a concentration of 13% and pectin stabilizer was selected as the superior treatment.
 

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Yogurt whey powder, a byproduct of yogurt industry, is a natural source of protein that contains all the essential amino acids needed for a healthy diet.  In this study, functional orange fruit juice was prepared using Yogurt whey powder (1/5% -3% and 4/5%). The Antioxidant activity of Yogurt whey powder was measured using the ABTS method.The sensory evaluation of the beverage was done by 5 trained panelist using a five-point hedonic test The assessment of taste, texture, color, smell, mouth feel and, finally, the overall acceptance of the prepared drinks were carried out. Orange juicethat was prepared with 1/5% yogurt powder gained the highest score. The juices wereanalyzed on days 0, 20, 40 and 60 for Physicochemical and microbial tests. The results showed that the taste, smell, and overall acceptance declined with time, and acidity and pH did not change significantly. From the result of this study it can be concluded that using yogurt whey powder with high antioxidant activity and acceptable functional orange juice can be produced.

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 In this study the caseinat sodium film containing nanoclay and Echinophora Platyloba essential oil was used in order to possibility of using biodegradable packaging as well as  its effect on the viability of probiotic bacteria to cover the contents of yogurt. The samples were stored at 4 and 15 ° C for 21 days. The effect of packing material on the survival of Lactobacillus acidophilus was not significant, while on the growth of Bifidobacterium was significant. The highest number of bacteria was observed in the coating containing 1.5 grams of nanoclay and the lowest number of containers containing 0.75 grams of nanoclay. By increasing storage temperature and time, simultaneously, the process of decreasing the number of live bacteria was accelerated .the reduction of Lactobacillus acidophilus bacteria at 15 ° C after three weeks of storage / 0 was a logarithmic cycle, while in the same situation, the number of Bifidobacterium analisis bacteria decreased by 1.3 times, indicating a higher resistance of Lactobacillus acidophilus to acidic conditions of yogurt during the storage time. At 4 ° C, there was no difference in mean pH and acidity between different packaging samples, but there was a significant difference between all packaging samples at 15 ° C. The highest decrease in pH and maximum acidity was due to the packing of 1.5 g of nanoclay in the end of the storage time

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In this study, lutein Pigment (0.07, 0.13 and 0.2 %w/w ) and whey protein concentrate (0.2, 0.3 and 0.4 %w/w) were added to the milk.  Qualitative characteristics of yogurt samples were analysed regarding physico-chemical, microbiological, textural and sensory properties over 21 days. Adding whey protein concentrate and lutein, lowered the level of synersis and acidity but increased the amount of dry matter, fat, viscosity and pH of yogurt samples. According to the results of microbe analysis, there was not any evidence of the growth of mold, yeast and coliform bacteria in the samples. In the case of sensory properties, adding whey protein concentrate and lutein, raised the scores of texture, mouthfeel evaluation and lowered the scores of appearance evaluation. Among all treatments, yogurt containing 0.2 %, w/w whey protein concentrate and 0.07 %, pigment lutein earned the best score with respect to overall flavor and quality acceptability.   

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Ice cream yogurt is one of the dairy frozen products, which is in terms of physical characteristics and the appearance of ice cream. Due to the presence of lactic acid bacteria and the fermentation process, it has a high nutritional value; also it has a lower amount of sugar and fat than ice cream. In the present study, the effect of adding White mulberry juice and Teranjabine (at 0, 20, 40, 60, 80 and 100% levels) on some physicochemical properties (percentage of Over-run, pH, acidity, melting resistance, apparent viscosity and total sugar content) and the sensory evaluation of ice cream yogurt were evaluated. The statistical method was factorial experiment in a completely randomized design with three replications. According to this study, With Increasing the percentage of white mulberry juice and Teranjabine in ice cream yogurt samples: acidity and viscosity increased (p <0.05), Over-run and melting resistance decreased and increased respectively (p <0.05), and pH and total sugar content increased and decreased respectively (p <0.05). According to the results of the sensory evaluation, the best sample from the taste, color, texture, sweetness and overall acceptance of the sample with the replacement level of 40% white mulberry juice and 60% Teranjabine were taken. Totally, the sample of containing 40% White mulberry juice and 60% Teranjabine was selected as the best sample, which can be produced as a dietary product in dairy industry.

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The purpose of this study was to investigate physicochemical, rheological and sensory properties of stirred yoghurt fortified with fermented rice bran and lettuce extract. For lettuce extraction was performed by ultrasound method. Fermented rice bran (2,4,6 and 8%) and lettuce extract (0.5,1,2 and 3%) were added to sterile milk. Starter culture (Lactobacillus bulgaricus and Streptococcus thermophilus) were inoculated at 42 °C. After incubation, sensory evaluation was performed and then physicochemical tests including pH, acidity, synersis, and viscosity were performed on the specimens.The samples were stored (in the refrigerator) for 21 days and they were analyzed every 7 days. The results showed that samples containing fermented rice bran and lettuce extract had a lower pH (4.36 against 4.28) and acidity (92.8 against 96.4) than control samples. Also, by decreasing pH and increasing acidity, which weakened the gel structure of casein micelles, it increased synersis (2.64 against 20.26) and reduced viscosity (5510.52 against 3956.65 mPa.s) in the samples. Also, adding fermentation rice bran and lettuce extract caused changes in the chemical composition of the samples which increased the amount of dry matter and increased the amount of phenolic compounds. The results of sensory evaluation showed that adding lettuce extract to the samples resulted in a significant reduction in sensory evaluation. Yoghurt containing 6% fermented rice bran, and the sample containing 6% fermented rice bran and 2% lettuce extract had the highest sensory rating. The results revealed that yoghurt containing fermented rice bran can be considered as a functional product with good health properties.

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Bumblebee is a useful insect that plays an important role in pollinating by nature. Gastrointestinal digestive tract has symbiotic microorganisms. The use of probiotic supplements in the beekeeping industry increases the rate of growth and improves feed conversion and improves resistance to disease and increases the production of honey. The purpose of current study was to investigate the effect of adding two bacteria of Lactobacillus plantarum and Lactobacillus pentosus isolated from honey in the bee stomach to stirred yoghurt and its viability and its effect on physico-chemical and sensory properties of stirred yogurt. In this study, probiotic properties of Lactobacillus Pentosus and Lactobacillus plantarum isolated from honey in the bee stomach, including resistance to acid, resistance to bile salts (bile), resistance to gastric juice (pepsin, trypsin), lack of hemolytic activity, hydrolyzed alanine was studied.  Four treatments were designed according to a completely randomized design and the results of the tests were analyzed by Duncan's mean comparison test at %95 confidence level by Minitab 16 software. The results showed that both probiotic bacteria showed probiotic properties and with increase in storage time, the sensory properties significantly (p≤0.05) decreased. The highest score of texture and color were belonged to the treatments containing Lactobacillus plantarum and Lactobacillus pentosus. The survival rate of probiotic bacteria in all treatments decreased during storage, and the highest survival rate after 28 days of storage belonged to the inoculated sample with Lactobacillus plantarum which had also the lowest acidity. Also, in terms of sensory properties, this treatment had the highest taste and flavor. According to the results stirred yogurt inoculated with Lactobacillus plantarum was selected as optimum treatment for the highest survival and sensory properties.