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Phytosterols are among the most important plant sterol compounds. This study was conducted to identify and determine the amount of phytosterols in distributed yogurts in Tehran by gas chromatography method without derivatization. A total of 60 yogurt samples, including 20 pasteurized high -fat yogurt samples, 20 pasteurized cream yogurt samples, and 20 traditional high -fat yogurt samples, were collected randomly from dairy product supply centers in Tehran from January to March 2022. Then, the amount of cholesterol and four phytosterol compounds including brassicasterol, campesterol, stigmasterol, and beta -sitosterol in yogurt samples were determined using gas chromatography assay without derivatization. The results showed that the total sterols in high -fat, creamy, and traditional yogurt samples were 504.08±55.79, 816.21±51.87, and 332.8±41.22 mg/100mL, respectively. The highest and lowest percentage of cholesterol belongs to cream (%54.75±065) and traditional yogurt (%46.57±0.65), respectively(p<0.05). Also, the highest percentage of phytosterol belongs to traditional yogurt(%54.75±065) and there was a significant difference with other yogurts(p<0.05). The results also showed that the total phytosterols were more than the permissible limit of the national standard (3%) in all samples. According to the results, phytosterols are used in various yogurts distributed in Tehran, which is against the national standard of Iran. Therefore, periodic and regular evaluation of phytosterols in distributed yogurts should be done throughout the year by regulatory bodies and prevent the violation of consumers' rights. [ABSTRACT FROM AUTHOR]

Fibers obtained from the waste of fruits and grains are valuable sources in the preparation of various useful products such as yogurt. Considering the importance of consuming fibers in providing health, the purpose of this research was to investigate the physicochemical, textural and sensory properties of fat- free yogurt enriched with bamboo fiber. For this purpose, bamboo fiber was added to fat-free yogurt with percentages of 1, 2, and 3 %, and experiments including pH, acidity, total dry matter, syneresis, viscosity, colorimetry, and sensory evaluation were carried out during 3 weeks of storage in the refrigerator (441 °C). Produced samples were compared with fat-free yogurt and high-fat yogurt without fiber additives. Data showed that the addition of fiber to the yogurt samples significantly increased (P<0.05) the amount of acidity, total dry matter, viscosity, color index L◻, a◻ and becompared to non-fat and’ high-fat control samples. In addition, the results showed that the addition of fiber in yogurt samples significantly (P<0.05) reduces the syneresis, so that the non-fat control yogurt with 12.3% and the sample containing 3% fiber with 8.58 % showed the highest and lowest syneresis on the first day of production, respectively. In the sensory evaluation, the sample containing 2% bamboo fiber with the highest score was introduced as the best sample. Therefore, the application of bamboo fiber with a concentration of 2%, in addition to improving the textural, physical and chemical properties of yogurt, can also lead to consumer satisfaction. Hence, bamboo fiber can be used in the formulation of dairy products, including yogurt. [ABSTRACT FROM AUTHOR]

Fibers obtained from the waste of fruits and grains are valuable sources in the preparation of various useful products such as yogurt. Considering the importance of consuming fibers in providing health, the purpose of this research was to investigate the physicochemical, textural and sensory properties of fat- free yogurt enriched with bamboo fiber. For this purpose, bamboo fiber was added to fat-free yogurt with percentages of 1, 2, and 3 %, and experiments including pH, acidity, total dry matter, syneresis, viscosity, colorimetry, and sensory evaluation were carried out during 3 weeks of storage in the refrigerator (441 °C). Produced samples were compared with fat-free yogurt and high-fat yogurt without fiber additives. Data showed that the addition of fiber to the yogurt samples significantly increased (P<0.05) the amount of acidity, total dry matter, viscosity, color index L_, a!) and b- compared to non-fat/and high-fat control samples. In addition, the results showed that the addition of fiber in yogurt samples significantly (P<0.05) reduces the syneresis, so that the non-fat control yogurt with 12.3% and the sample containing 3% fiber with 8.58 % showed the highest and lowest syneresis on the first day of production, respectively. In the sensory evaluation, the sample containing 2% bamboo fiber | with the highest score was introduced as the best sample. Therefore, the application of bamboo fiber with a concentration of 2%, in addition to improving the textural, physical and chemical properties of yogurt, can also lead to consumer satisfaction. Hence, bamboo fiber can be used in the formulation of dairy products, including yogurt. [ABSTRACT FROM AUTHOR]

According to the increasing demand of advanced societies for the consumption of functional foods, especially in dairy products, the use of natural -based materials such as plant essences in the field of enriching food products with their antimicrobial and antioxidant compounds, as well as the use of wheat germ powder as a rich source of dietary fibers and vitamins and minerals and their effects on the viability of starter bacteria (due to their prominent role in improving human health) are seem to be necessary. Investigating the effects of using processed essential oils and wheat germ powder simultaneously in yogurt is considered in this research. Sensory, physicochemical characteristics and bacterial conting of set yogurt including Streptococcus thermophilus and Lactobacillus bulgaricus, were tested during the storage period to study the simultaneous effect of plant essential oils and sprouted wheat powder. The essential oils used included tarragon and thyme with different proportions and at three levels (400, 1200, 2000 microliters per liter of yogurt). Yogurt physicochemical tests such as acidity and water holding capacity, hedonic sensory test, rheology test (apparent viscosity) and microbial count tests were conducted to check the viability of starter bacteria in yogurt during the 14 -day storage period. Based on the results obtained from the analysis of variance of the tested samples, the concentration of essential oil significantly (p<0.05) reduced the acidity and viability of starter bacteria of the product, but it had not a significant effect on the viscosity the sensory characteristics. In this regard, thyme and wheat germ powder showed a negative and unfavorable effect, especially in high concentrations. Thyme had a higher antimicrobial effect on yogurt starter bacteria, while tarragon showed less antimicrobial activity. The sensory score of samples containing tarragon has increased slightly during storage, so in general tarragon is prone to be used in yogurt production. Wheat germ powder first had an increasing and then decreasing effect on the acidity of the product during the storage time of yogurt. Also, the addition of wheat germ powder increases the viscosity and water holding capacity of the product, but in high amounts it reduces the sensory score, and therefore its use in yogurt should be controlled. In general, wheat germ powder has a positive effect on the viability of both starter bacteria counted in this research, which can be due to the supply of nutrients for their further growth. [ABSTRACT FROM AUTHOR]

During the current research, a traditional nomadic Iranian dairy product named Masineh was produced, which is prepared from heated yogurt drink and herbal additives including turmeric, dill seed powder and cumin. Some physicochemical and microbial characteristics of Masineh samples were investigated during 21 days of storage at 4°C. In addition, the antioxidant properties, antimicrobial effects and organoleptic properties of the product were investigated and compared with the control sample (heated yogurt drink without additives). The results showed that herbal additives significantly reduced the counts of bacteria, mold and yeast in Masineh compared to the control sample (P<0.05). In Masineh, the highest inhibitory effect was observed against Staphylococcus aureus with 30.91 mm, and the lowest inhibitory effect was observed against Escherichia coli with an average of 15.50 mm, followed by Aspergillus niger with an average of 18.12 mm. In addition, the phenolic compounds and DPPH and ABTS inhibition percentages were higher in Masineh than control sample. The pH and viscosity of Masineh were higher than that of drinks without additives, and during storage, these values decreased significantly (P<0.05). Also, the results of the sensory evaluation showed that the sensory evaluators considered the taste of the masineh to be favorable and did not report a significant difference with the control sample in terms of overall acceptance, although the color of the masineh had a lower score. Therefore, according to the obtained results, Masineh is introduced as a beneficial dairy drink, in which by the use of herbal additives, its antioxidant properties and microbiological properties are strengthed. [ABSTRACT FROM AUTHOR]

The consumption of fermented milk products, including yogurt, has been increased dramatically as people become aware of the functional and health resources. Quinoa seeds have recently received more attention due to their favorite nutritional properties and high content of protein, amino acids, fatty acids, minerals, and essential vitamins. Therefore, in this study, the fortification of beneficial yogurt with quinoa and its effect on physicochemical and microbial and organoleptic properties of product were investigated. Flour of quinoa seeds were added to yogurt milk at three levels (2, 4, and 6%). A sample of each treatment is selected every week and were analysed with respect to physicochemical (texture, pH, acidity, dry matter, hydration, etc.), microbial (starter count and yeast mold), and sensory properties compering to control samples. Based on the results of physicochemical tests, addition of quinoa flour significantly reduced syneresis, pH, and increased acidity, dry matter, viscosity, fiber, fat, and ash contents. The evaluation of color of samples showed that L index decreased while a and b indexes increased significantly with increasing the percentage of quinoa flour. On the other hand, the starters counts increased in fortified samples due to the nutrients of quinoa. Sensory properties were not significantly different between fortified and control sample except of texture that was improved with quinoa addition. The results of this study showed that the use of quinoa flour in stirred yogurt can led to producing a product with desirable and functional characteristics [ABSTRACT FROM AUTHOR]

Yogurt is a fermented dairy product that is popular all over the world. Using probiotic bacteria, a product called probiotic yogurt has been produced, which is known as a healthy and special (beneficial) food. For better survival and growth and activity of probiotic bacteria on the one hand and to improve the technological properties of probiotic yogurt on the other hand, prebiotic compounds are added to its formulation. Lactobacillus bifidobacterium bifidium was used to prepare probiotic yogurt as well as inulin 0.5 and 1% as a prebiotic. The produced samples were evaluated from the point of view of the mentioned tests and compared with the control sample (probiotic yogurt without prebiotic compounds). In inulin treatments of 0.5 and 1%, the results of pH, acidity, synersis, acetaldehyde and probiotic bacterial count were significantly different. Taste, texture, color, odor, organoleptic and general acceptance were evaluated by 10 trained refree. The results showed that yogurt samples containing inulin had the best sensory properties. According to the results of this study, the yogurt sample contained inulin, the lowest percentage of synersis and the highest number of live probiotic bacteria at the end of storage. In terms of probiotic bacterial count, the inulin content sample was better than the control sample. Also, the sample containing inulin had the lowest pH and the control sample had the highest acidity at the end of storage. The results indicate the effective and positive role of prebiotic compounds in the formulation of probiotic yogurt. The present study showed that prebiotic materials can be used to improve the quality properties and increase the survival of probiotic bacteria in yogurt. [ABSTRACT FROM AUTHOR]

Low-fat dairy products don't have desirable texture and sensory properties because of having low levels of fat. Pear powder can be used as a carbohydrate-based fat replacer for fortification and improving the texture of low-fat dairy products due to having a positive effect on texture improvement and desirable nutritional compounds such as pectin, lignans, phenolic compounds and dietary fiber. In this context, pear powder was added to milk (1.5% fat) at levels 1, 2 and 3%. The experimental yogurts were compared with control yogurts produced from whole milk (3% of fat) and low-fat milk (1.5% of fat). The samples were stored for 15 days at 4 ± 1 °C and their physicochemical, texture and sensory properties were evaluated during storage. According to results, increasing the rate of pear powder in yogurt samples caused to a significant increase in acidity, viscosity, water- holding capacity and firmness and decrease in pH and syneresis (p<0.05). In all samples, while acidity, viscosity, firmness and water-holding capacity increased significantly during storage, pH and syneresis decreased (p<0.05). The sample containing 3% pear powder and low fat control sample had highest (0.215 N) and lowest (0/09 N) firmness, respectively. Sensory evaluation performed by the panelists also showed that the overall acceptability was higher at full fat control yogurt (19.70 score) and samples treated with 1% (19.64 score) of pear powder than other samples. According to the results, it was found that the pear powder at 1% level could improve the sensory and qualitative properties of yogurt samples. [ABSTRACT FROM AUTHOR]

Eve’ yogurt is one of the nutritive dairy products in Iran. The aim of this study was molecular identification of lactic acid bacteria isolated of ewe yogurts from 3 different regions of Iran (Mashhad, Dezful, and Hamedan)and assessment of their technological properties. A total of 47 isolates were molecularly identified by PCR of 16S rDNA gene and sequencing. Isolates were evaluated for technological properties including Lactic acid and diacetyl production, lipolytic, urease, and proteolytic activities.The statistical analysis of data using SPSS software indicated that diacetyl production and pH changes by bacterial isolates for 24 hours were significantly (P<0.05) different among yogurts from Dezful, Hamedan and Mashhad. The technological properties of isolates demonstrated thatStreptococcussalivariussubsp. thermophilus (H1, H2) and Lactobacillus delbrueckiisubsp. bulgaricus (H1, H2, H3, H7, H9, H10) of ewe’s yogurt from Hamedan have high technological properties. Also, based on the analysisresults of the organoleptic properties and texture stiffness of yogurts produced by selected isolates,S.salivarius(H2)andL. delbrueckii(H3) suggested as a suitable starter culture. [ABSTRACT FROM AUTHOR]

Yogurt is one of the most popular dairy products that is widely consumed around the world, which has received much attention due to its high nutritional value and economic importance. Therefore, in this study, by considering different indicators, in order to improve the nutritional properties of yogurt and produce products with desirable and uniform quality, by adding essential oils to control acidity, prevent and cover the acidity over time and also achieving antioxidant properties. In this study, after preparing probiotic yogurts containing saffron, thyme and black cumin essential oils at four levels (0, 0/5, 1 and 2), physicochemical properties (PH, acidity, color, hydration and viscosity) and sensory properties were studied in a completely randomized manner in three replications over 21 days. The results of the evaluations of this study showed a significant effect of independent variables and also their synergistic effect at the level of 0.5% on the properties of yogurt. Under optimal operating conditions based on the results of antioxidant activity, it was observed that increasing the concentration of essential oil increases the antioxidant properties and during storage, the antioxidant properties gradually decreased significantly. In the study of color parameters, it was observed that the brightness decreased with increasing the concentration of essential oil so that the control sample had a higher L* index, also a* and *b index increased with increasing essential oil concentration. The increase in b* index was more due to the presence of carotenoid pigments in saffron essential oil. The pH changes of yogurt treatments were completely affected by microbial growth in the treatments, which significantly reduced and increased the acidity over a period of 21 days (P ≤ 0.05). Enrichment of probiotic yogurt formulated with essential oil can be a good option in improving the functional properties of the final product and enhancing its antioxidant properties. [ABSTRACT FROM AUTHOR]

There are limited studies on dairy products containing millet seeds or millet milk. Considering nutritional value of millet, the aim of this study was to evaluate the production of yogurt containing millet milk and to investigate its physicochemical and sensory properties. The replacement of 0, 10, 15 and 20% (V/V) of millet milk (2.5%) with low-fat milk was performed and its effect on physicochemical (pH, synersis and contents of dry matter, fat, protein, total phenol, minerals and fiber) and sensory characteristics of yogurt during 21 days of storage (days 1, 7, 14 and 21), were evaluated. Results showed that replacement of 10% millet milk with low-fat milk, increased pH and decreased syneresis and protein content. With increasing millet milk to 15 and 20%, pH, dry matter and fat content were decreased and syneresis, protein and phenolic compounds content were increased significantly (P<0.05). With adding 20% millet milk, fiber content was increased to 0.09% and calcium content was decreased to 40.5 mg/kg in yogurt. Sensory evaluation results showed that yogurt containing 10% and 20% millet milk had the highest and lowest acceptability, respectively. According to the results of sensory evaluation and due to the results of pH, acidity, dry matter, fat content and syneresis during the storage period, yogurt sample containing 10% millet milk is introduced as the best formulation. [ABSTRACT FROM AUTHOR]

This research aimed to analyze the influence of probiotic bacteria on the microbiological, physico-chemical, technological, and sensory characteristics of goat yogurt during 28 days of refrigerated storage. Results revealed that the incorporation of two probiotic bacteria did not significantly influence (P> 0.05) the physico-chemical characteristics such as pH, lactic acidity, total solids, syneresis, water holding capacity and protein, color, viscosity and texture parameters and sensory properties of the inoculated samples, compared to the control. Similarly, the probiotic viability was maintained at all stages of storage at the rate of 108 CFU g-1. Therefore, this research shows that yogurt is an appropriate vehicle for probiotic bacteria and provides new insights regarding their impact on the metabolism of this functional food while preserving its quality. [ABSTRACT FROM AUTHOR]

Goat's milk yogurt has a high nutritional value and digestibility and less allergenicity than cow's milk products. The problem with goat's milk yogurt is the specific taste that results from the high concentrations of volatile fatty acids that cause goat's taste and limit consumers' acceptance of this product. In this research, the effects of adding 20% pineapple and peach nectar on physicochemical (dry matter, fat, protein, acidity, synersis, water holding capacity and viscosity) and sensory properties of goat's milk yogurt during 28 days of refrigerated storage were evaluated. The results showed that adding nectar significantly reduced the amount of dry matter (p <0.05). In nectar-containing samples, dry matter content had increasing trend during storage. Fat and protein levels were significantly lower than thoese of control samples (p <0.05). The pH of nectar containing yogurts during storage was significantly lower and its acidity was significantly higher than that of control yogurt (p <0.05). The trend of synersis changes in nectar-containing yogurt samples was increasing in the first week and then decreased until the end of the storage period and the process of changes in water storage capacity was initially decreasing and then increasing. The viscosity increased during the first week and then decreased significantly until the end of the storage period (p <0.05). The viscosity of nectarcontaining yogurt samples was significantly lower than that of control sample (p <0.05). Sensory evaluation results showed that the highest overall acceptance score was given to the sample containing pineapple nectar (4.66, 4.46) and the lowest overall acceptance score to the sample containing peach nectar (3.36, 3.33) due to its dark color and sour taste on the 1st and 14th days respectively. Based on the experiments, the use of pineapple nectar is a good method in order to cover goat taste in goat's milk yogurt with preserved its qualitative characteristics. [ABSTRACT FROM AUTHOR]

The use of milk fat substitutes in the manufacturing of dairy products is highly considerable in order to decrease in suffering chronic diseases and amount of calorie intake. However, semi-fat or non-fat dairy products have defects in their texture and sensory properties. The aim of this study was to investigate the effect of using whey protein isolate and locust bean gum as fat replacers on quality properties of non-fat yogurt. For this purpose, set-type yogurt samples were manufactured using non-fat milk (lees than0/1%) and different concentrations of locust bean gum (0.25 and 0.50 gL-1), whey protein isolate (5 and 10 gL-1) and combination of locust bean gum and whey protein isolate (0.25 + 10 gL-1 and 0.50 + 5 gL-1, respectively). Control samples were also manufactured using whole milk (3% fat) and non-fat milk (less than 0/1%) without locust bean gum or whey protein isolate. The manufactured samples were stored in (4±1°C) for 15 days and their physicochemical, texture and sensory properties were analyzed during storage. The results showed that the use of different concentrations of locust bean gum and whey protein isolate significantly influenced the pH, acidity, water holding capacity, synersis, viscosity, hardness, springiness, cohesiveness, adhesiveness, appearance and color, texture and consistency, odor and flavor and total sensory scores (p<0.05). While water holding capacity, acidity, hardness and viscosity were increased significantly during storage in all samples, syneresis, pH and odor and flavor decreased significantly (p<0.05). In conclusion, the results of different analysis showed that use of 5 gr.L-1 whey protein isolate, 10 gr.L-1 whey protein isolate and 0.25 gr.L-1 locust bean gum + 10 gr.L-1 whey protein isolate instead of milk fat in formulation of non-fat set type yogurt led to manufacturing of final product with the most acceptable physicochemical, texture and sensory properties. [ABSTRACT FROM AUTHOR]

Yogurt is a fermented dairy product, which is a popular product throughout the world and has positive effects on public health, due to its nutritional properties.Aloe veraextract isa kind of vegetable derivative, which has high nutritional value and antibacterial properties. In this research the effects of Aloe veraextract (0.5, 1, 1.5, 2% w/w) addition on the textural (syneresis), chemical (pH, acidity), viability of yoghurt probiotic microorganisms, yeast and mold, antioxidant properties and sensorial attributes of stirred probiotic yogurts were investigated during the shelf life (1st, 7th, 14th and 21th day of production). The results showed addition of Aloe vera extract decreased the pH value and increased acidity but decreased syneresis. Bifidobacterium and Lactobacillus viability increased with Aloe Vera extract addition but yeast and mold counts decreased. The addition of Aloe veraextract increased antioxidant properties of yoghurt. Sensorial analysis indicated that panelists preferred yogurt samples with low Aloe vera extract rates. However, higher rates of Aloe vera extract affected the flavor and overall acceptability and lowered their panelist scores. During time, pH decreased and acidity and syneresis increased. Overall, it was concluded that the best treatment from all aspects, was 0.5% Aloe veraextract. [ABSTRACT FROM AUTHOR]

Yoghurt, with viscous texture and containing volatile compounds, has special appeal for the consumer. In this study, to produce such a yoghurt without any additives, two types of yoghurt from ewe and cow milk were prepared. The samples were evaluated for physicochemical and volatile compounds and viscosity on the first, 7th, and 14th days of shelf life. In addition, the enumeration and viability of Lb. bulgaricus and Str. thermophilus were studied. Ewe yoghurt had more dry matter, protein, and acid production ability compared to cow yoghurt, with lower pH. The number of lactobacilli was greater in ewe yoghurt which caused increase in acidity and decrease in pH value in ewe yoghurt. The number of lactobacilli and streptococcus decreased during shelf life of both yoghurts. The viscosity of ewe yoghurt was greater than cow yoghurt and it increased during 14 days of storage. Regarding volatile compounds, acetaldehyde and diacetyl decreased during shelf life while ethanol increased in both cow and ewe milk yoghurt. [ABSTRACT FROM AUTHOR]

Microbial detoxification is considered as one of the most common methods used for the elimination of aflatoxins. Reports indicate that S. cerevisiae can be effective in removing aflatoxins through the adsorption of aflatoxins to their cell wall. In the current research, the ability of S. cerevisiae (viable, acid-, heat- and ultrasound-treated yeasts) to bind aflatoxin M1 was assessed in yoghurt. To this end, firstly, recombinant milk containing 12% solids, non-fat skimmed milk powder was prepared. Next, the samples were spiked by aflatoxin M1 using different concentrations (100, 500 and 750 pg mL-1). When the starter bacteria were added to the milk, the treated yeasts were added as well. The concentration of aflatoxin M1 residue in the supernatant of the yoghurt samples after different storage times (1, 7, 14 and 21 days) was measured using the ELISA method. The results showed that all treatments containing viable, acid-, heat-, ultrasound-treated yeast and starter bacteria were able to adsorb aflatoxin M1, and the ability of the treated yeast was significant as compared with the control (P< 0.05). Among the treated yeasts, the ability of the acid-treated yeasts was higher in toxin binding. Overall, it can be concluded that using S. cerevisiae for the biological adsorption of aflatoxin M1 is effective in fermented dairy products. [ABSTRACT FROM AUTHOR]

Probiotics are live microorganisms which when consumed in adequate amounts, can have a beneficial effect on the host. Lactic acid bacteria are the most common type that have been introduced as probiotics and are present in dairy products. The aim of this study was to isolate and identify the probiotics from microbial flora of cow milk and its traditional yogurt in Khoi area. To achieve this goal, the lactic acid bacteria were isolated by phenotypic methods (cellular morphology, colony pigmentation, Gram staining, catalase test, biochemical tests including growth in different temperatures 10°C, 15 °C and 45 °C, various concentrations 4 % and 6.5 % of salts and fermentation of 17 types of sugar) and their probiotic potential (resistant to stomach acid and bile salts) were evaluated. Then, to identify more accurately, the 16S rRNA gene of Lactobacilli were replicated with pairs of specific primers and then the purified PCR product was sent for gene sequencing. At the end, 14 strains of Lactobacilli were reported as the natural microbial flora with probiotic potential in Khoi area. These bacteria provide the good quality of the dairy products in those areas and can be used as the starter culture in industrial manufacture of dairy products. [ABSTRACT FROM AUTHOR]