Yogurt Culture Research Articles

Rheological Properties and Sensory Profile of Yoghurt Produced with Novel Combination of Probiotic Cultures

Novel probiotic yoghurt was produced using the combination of bacterial cultures Lactobacillus plantarum HA119 and Bifidobacterium animalis subsp. lactis B94 and yoghurt bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. Its basic nutritional composition, colour, texture, rheological properties, and sensory profile were compared with yoghurt produced using the same technological process and standard yoghurt cultures (control sample), as well as other commercially available yoghurts with different milk fat contents. Despite the fat content of the yoghurt made with the new probiotic cultures being 1.44%, its apparent viscosity was similar to that of high-fat yoghurt (2.99%). Other results from rheological measurements indicate that the new yoghurt had a stronger protein network, presumably due to the higher number of exopolysaccharides compared to both control and commercial yoghurts. Sensory analysis revealed that there were no statistically significant differences between the novel probiotic yoghurt and high-fat yoghurt as perceived by panellists. In conclusion, this combination of probiotic cultures can be used to produce yoghurt with rheological and sensory properties similar to high-fat yoghurts, without the need for hydrocolloids or changes in the production process.

Enhancing probiotic survival and quality of fermented goat milk beverages with bael (Aegle marmelos) fruit pulp

This study aimed to assess the impact of bael fruit pulp on the viability of probiotic Lacticaseibacillus rhamnosus GG (LGG) and some physicochemical properties of bael-goat milk-based beverages during 21 days of refrigerated storage. Bael fruit pulp (BFP) was incorporated into goat milk (GM) at different levels (0 %, 5 %, 10 %, and 20 %), and fermented with LGG combined with conventional yoghurt culture. Products were analyzed at weekly intervals. Fermented GM without bael served as control. Redness (a*), yellowness (b*), chroma, and LGG viability were all significantly increased while pH, lightness (L*), and whiteness were dramatically decreased by the addition of BFP. After 14 days of storage, all fermented milk containing bael exhibited considerably (p < 0.05) greater LGG counts than the control. The product containing 20 % bael had the greatest viability counts (7.01 log CFU/mL) at the end of storage. Throughout the storage period, all of the products—including the control—maintained viable probiotic counts of greater than 6 log CFU/mL. The pH of the products decreased over time but was stabilized by bael. In conclusion, the findings demonstrate that goat milk is a perfect vehicle for LGG, and adding bael may boost the fermented goat milk's probiotic viability, physicochemical qualities, and nutritional value, thus improving its overall quality.

Microencapsulation of probiotic lactic acid bacteria using freeze-drying with isolated whey protein and trehalose as coating material [Mikroenkapsulasi bakteri asam laktat probiotik menggunakan pengeringan beku dengan protein whey isolat dan trehalosa sebagai material pelapis

Microencapsulation could be employed to coat bacteria with protective compounds to enhance their viability. The freeze-drying method uses low temperatures, thereby reducing heat damage. Bifidobacterium breve was used as a probiotic along with Streptococcus thermophilus and Lactobacillus bulgaricus, two common yogurt cultures. Yogurt, a nutrient-rich milk product, has the potential to be an effective probiotic carrier. This research aimed to examine how the freeze-drying process with varying ratios of coating materials affects the viability of the bacteria combination B. breve, S. thermophilus, and L. bulgaricus under acidic and bile salt conditions, as well as the microencapsulation efficiency and particle size. The treatments tested different ratios of whey protein isolate to trehalose as a coating (1:1, 1.5:1, 2:1, 2.5:1, 3:1). The 1:1 ratio yielded the best results, with lactic acid bacteria counts of 6.60 log colony/mL at pH 2.0, 6.84 log colony/mL at pH 3.0, 7.39 log colony/mL at pH 4.0, 7.47 log colony/mL at pH 5.0, 7.70 log colony/mL at pH 6.0, and 7.05 log colony/mL in a bile salt environment. This ratio demonstrated 107.96% microencapsulation efficiency and a particle size of 9.66 μm.

Quality Assessment of Greek-Style Set Yoghurt Fortified with Extracted and Dried Australian Native Fruit, Illawarra Plum.

The Illawarra plum (IP) is native to Australia and has been used as a bush food for centuries. With rich phytochemicals and natural pigments, IP has the potential to be an added ingredient to improve the physicochemical properties of food, including yoghurt. This study prepared dried IP powders through vacuum drying (VD) and freeze drying (FD), produced extracts from these dried powders, and fortified them into Greek-style set yoghurt. The changes in colour, pH, titratable acidity (TA), syneresis, total soluble solids (TS), and phytochemicals were measured throughout a chilled storage period of 28 days. The results showed that FD and FD extract could provide a stable, distinct pink colour to yoghurt. IP powders and their extracts improved TS content and, thus, the consistency of yoghurt. Compared to the control, VD, FD, and FD extract of IP did not significantly affect the level of acidity or syneresis after 28 days of chilled storage. Yoghurt fortified with FD and FD extract had the greatest level of phenolics, anthocyanins, and radical scavenging antioxidant activities. This study revealed that IP powders and their extracts can positively improve the physicochemical properties of Greek-style set yoghurt. FD powder is recommended over its extract to fortify this yoghurt, as it can be cost-effectively prepared by freeze drying and then grinding the fresh fruit into powder. Future studies are needed to evaluate other variables in yoghurt preparation, including the concentration of IP and strains of yoghurt culture. Further, the consumer perception of sensory quality and acceptability of yoghurt fortified with FD IP powder should be investigated.

Investigation of the effects of yogurt cultures on Polycyclic Aromatic Hydrocarbons

The effect of cultures used in yogurt production on PAHs was investigated. PAH-free milk divided into 4 groups; (1) traditional village yogurt culture, (2) culture used with commercial yogurt, (3) combination culture of Lactobacillus delbrueckki ssp. bulgaricus, L. acidophilus, Streptococcus thermophilus, Bifidobacterium animalis ssp. lactis, B. infantis M-63, B. bifidum BGN4 and GOS, (4) combination of L. delbrueckki ssp. bulgaricus, L. acidophilus, B. lactis and S. thermophilus. Each group was divided into 4 subgroup and first group was kept as control while the other groups were treated with 50, 100, 200 µg kg-1 of a mixture 4 PAH [Benzo(a)pyrene, chrysene, benzo(b)fluoranthene, benzo(a)anthracene] respectively. Whereas the highest reduction was seen in 3rd group at 200 µg kg-1 with 21.7%, the lowest was seen in the 1st group at 200 µg kg-1 with 8.05%. It was concluded that yogurt cultures can inhibit PAHs in milk at a very low level and cannot completely degrade them.

QUALITATIVE STUDIES OF CREAM CHEESE MADE BY USING BIFIDOBACTERIUM BIFIDUM &amp; LACTOBACILLUS ACIDOPHILUS

World is facing a lot of health problems especially in under developed countries of Asia. This crucial situation demands beneficial foods. This study was planned to produce quality Cream cheese. Probiotic Cream cheese had been promoted for health benefits by using Bifidobacterium bifidum &amp; Lactobacillus acidophilus. Buffalo milk was used to produce Cream cheese. Five treatments were handled; T₀ was the regular treatment in which yoghurt culture was inoculated to make Cream cheese while a combination of yoghurt as well as Bifidobacterium bifidum &amp; Lactobacillus acidophilus was inoculated in T1, T2 and T3. Besides T4 was produced by using only Bifidobacterium bifidum &amp; Lactobacillus acidophilus. In the process milk was standardised up to 5% milk fat then it was pasteurized (63°C for 30 minutes). Cooled to 42°C and 2% starter culture was inoculated in that mixture. After incubation the pH reached up to 4.6. Salt (0.5-1%) was added and product packed into plastic cups and stored (4°C, 4 weeks). Qualitative study of the product showed that T4 treatment was better as compare to T₀, T1, T2 and T3. Conclusively, probiotic Cream cheese produced by using buffalo milk is beneficial for reducing health problems like gastric problems, colon cancer etc. This product can play a vital role in functional foods industry as well as cheese industry.

Development and Evaluation of Vegan Yogurts and Sour Milk Alternatives from White Lupin (Lupinus albus L.)

Cow milk allergy (CMA) triggers a clinically abnormal immunological response to cow milk proteins. To address this issue, extensive studies have explored milk alternatives from various animal and plant sources. This study introduces a method for producing white lupin milk, resulting in fermented dairy-like products (vegan yogurt and sour milk alternatives). Four commercial yogurt cultures, including two mesophilic (CHN-11, CHN-22) and two thermophilic (YC-380, YC-X11) mixed bacterial cultures, were tested, with thermophilic ones yielding superior sensory outcomes for lupin-based yogurt alternatives. Incorporating inulin (2%) enhanced sensory appeal, particularly evident in strawberry and peach-flavoured variants, which achieved sensory scores comparable to cow milk yogurts. Furthermore, white lupin-based yogurts demonstrated superior water-holding capacity (up to 47.11 g/100 g in comparison with 42.35 g/100 g measured for cow milk yogurt), influencing texture and mouthfeel. They also exhibited favourable fatty acid profiles, notably rich in beneficial unsaturated fatty acids such as linoleic and linolenic acid (up to 10.15% and 8.43%, respectively), indicating potential health benefits. Sensory evaluation underscored the impact of starter cultures on product attributes, with certain cultures yielding more favourable results. In conclusion, white lupin emerges as a promising alternative protein source with the potential to produce high-quality dairylike products. While white lupin-based products hold promise as functional foods for individuals with specific dietary needs, further research is necessary to address potential allergenic concerns associated with white lupin proteins.

Development of a stable fermented creamy structure from hazelnut in the scope of plant-based food production

A hazelnut-based fermented creamy structure was developed from whole hazelnut kernels in the scope of plant-based food production. Firstly, heat-induced and acid-induced gelation of aqueous slurries of raw or roasted hazelnut kernels were investigated. The final structure was formed by heat treatment and fermentation by yoghurt culture along with supplementary sucrose. A stabilizer mixture of locust bean gum and xanthan gum was needed to prevent phase separation. Roasting treatment of hazelnuts reduced the temperature and increased the pH at which gelation started; however, a weak gel was obtained. On the other hand, fermentation of raw hazelnuts resulted in a gel structure with higher strength, yield stress, flow point and spreadability. Phase separation was not observed in the structures during storage. Viable lactic acid bacteria count was above 6 log cfu/g in the samples and a slight decrease was observed after storage at 4°C. Soluble protein content in the samples was reduced by roasting and fermentation but increased after storage. Roasting enhanced allergenicity of the water-soluble fraction while fermentation decreased it by about 70%. Raw hazelnuts are recommended for preparation of stable fermented gel structures with reduced allergenicity towards plant-based food production.

A Metabolomics Approach to Establish the Relationship between the Techno-Functional Properties and Metabolome of Indian Goat Yoghurt.

Goat milk has poorer fermentation characteristics due to the absence or only traces of αs1-casein, due to which goat yoghurt contains a less dense gel structure. Moreover, the fermentation characteristics of the milk vary between the breeds of the same species. Therefore, it becomes imperative to explore a few metabolites which could regulate the techno-functional properties of goat yoghurt. This study was aimed at relating the metabolite profile of yoghurt prepared from milk of Barbari, an indigenous goat breed of India, and its techno-functional properties (firmness, whey syneresis, and flow behaviour) using multivariate data analysis and regression models. Goat yoghurt was prepared with two different total solids (TS) levels (12 and 16%) and cultures, namely, commercial culture comprising a thermophilic yoghurt culture (A) and NCDC-263 comprising a mixed yoghurt culture (B). Results demonstrated a significant difference (p < 0.05) in whey syneresis with the increase in the TS level. Flow behaviour of all yoghurt samples showed a decrease in viscosity with an increase in shear rate, which confirmed its non-Newtonian behaviour and shear thinning nature, whereas frequency sweep confirmed its viscoelastic nature. Firmness was the most affected under the influence of different TS and culture levels. It was higher (p < 0.05) for 16-A, followed by 16-3B, and minimum for 12-2B. GC-MS-based metabolomics of the yoghurt revealed a total of 102 metabolites, out of which 15 metabolites were differentially expressed (p < 0.05), including 2-hydroxyethyl palmitate, alpha-mannobiose, and myo-inositol. Multivariate data analysis revealed clear separation among groups using principal component analysis and several correlations using a correlation heat map. Further, regression analysis exhibited methylamine (0.669) and myo-inositol (0.947) with higher regression coefficients (R2 values) exceeding 0.6, thus demonstrating their significant influence on the techno-functional properties, mainly firmness, of the yogurt. In conclusion, A gas chromatography-based metabolomics approach could successfully establish a relationship between the metabolome and the techno-functional properties of the yoghurt.

Influence of Hesperidin on the Physico-Chemical, Microbiological and Sensory Characteristics of Frozen Yogurt.

Frozen yogurts contain yogurt culture bacteria, which might impart health benefits to their consumers. Global frozen yogurt market sales are expected to grow by 4.8% by 2028, which represents an important opportunity for the industry, consumers and researchers. Polyphenols are metabolites found in plants which have antioxidant and anti-inflammatory properties and might prevent chronic diseases such as cancer, diabetes and cardiovascular diseases. The objective of this study was to elucidate the effect of the polyphenol hesperidin on the physico-chemical, microbiological and sensory characteristics of frozen yogurts. Hesperidin was incorporated into frozen yogurt at three concentrations (125, 250 and 500 mg/90 g of product), while yogurt with no hesperidin was used as a control. The viscosity and overrun of the frozen yogurt were analyzed on day 0. The hardness, pH, color and Lactobacillus bulgaricus and Streptococcus thermophilus counts were determined after 0, 30 and 60 d. The melting rate was determined at 60 and 90 min after 0, 30 and 60 d. The bile and acid tolerances of both S. thermophilus and L. bulgaricus were measured after 7 and 60 d. A hedonic scale of nine points was used to measure sensory attributes. Data were analyzed at α = 0.05 with an ANOVA with Tukey's adjustment, and McNemar's test was used to analyze purchase intent. Hesperidin did not influence the pH, overrun or microbial characteristics. Polyphenol addition compared to the control decreased the melting rate but increased the hardness and bile tolerance of L. bulgaricus, as well as the L* and b* values. The sensory characteristics were not influenced by the lowest concentration of hesperidin, as it was not statistically different from the control. Moreover, consumers were interested in purchasing frozen yogurt with added hesperidin after learning about the health claim. This study can assist in the development of a healthier frozen yogurt in an increasingly competitive market.

Utilisation of Lacticaseibacillus casei ATCC 393‐derived exopolysaccharide for camel milk yoghurt production and its potential anticancer and hepatoprotective properties

Camel milk yoghurts were created using probiotic lactic acid bacteria (LAB) with exopolysaccharide (EPS) production capabilities. Lacticaseibacillus casei ATCC 393, identified as the most efficient EPS producer, was incorporated into conventional yoghurt culture. We compared the effects of adding L. casei ATCC 393 with EPS powder (SLLP) against lactulose. Evaluations included LAB, yeast, mould, cytotoxicity and IC50 values in the samples. The results demonstrated increased bacterial counts, LAB viability, viscosity, antiproliferative effects and a lower IC50 in SLLP, indicating the potential application of EPS‐producing L. casei ATCC 393 and its derived EPS in the development of functional foods.

Utilization of pomegranate and black grape seed by-products in yogurt production: Effects on phenolic compounds and antioxidant activity.

The present study investigated the potential utilization of pomegranate and black grape seed by-products of the food industry in yogurt production. Specifically, we examined the effect of polyphenols on antioxidants in yogurts produced using two different starter cultures: classical yogurt culture (Lactobacillus delbrueckii subsp. bulgaricus + Streptococcus thermophilus) and yogurt culture supplemented with L. casei. Various parameters, including pH, acidity, viscosity, fat content, protein content, dry matter content, color, microbiological properties, and sensory attributes, were analyzed in the yogurt products. The present findings indicate that incorporating pomegranate and grape seed powder and using different starter cultures significantly affected the yogurt's phenolic content and antioxidant activity. Furthermore, we observed decreased phenolic content and antioxidant activity during the 21-day storage period. Interestingly, yogurts produced with pomegranate seed powder and L. casei culture exhibited higher antioxidant activity than the other samples. Importantly, none of the yogurts containing pomegranate and grape seed powders had microbial counts below 107 cfu/g for L. delbrueckii subsp. bulgaricus, S. thermophilus, and L. casei, indicating no adverse effects on probiotic properties. Sensory evaluation revealed that the yogurt product prepared with grape seed powder and a combination of yogurt culture (L. delbrueckii subsp. bulgaricus + Streptococcus thermophilus) and L. casei was particularly well-received. In conclusion, the functional properties of grape seed powder and pomegranate seed powder make them suitable natural ingredients for enhancing the antioxidant activity of yogurt. The study highlights the potential of utilizing these by-products to develop yogurt products with added health benefits.

Effect of using dried white sapote fruit (Casimiroa edulis) on the quality characteristics of bio-low-fat goat milk yoghurt drink

The white sapote tree is cultivated in Egypt on a limited scale owing to its dietary fruits. For its medical and functional characteristics, different levels of dried white sapote fruit (DWSF) were utilized in the manufacturing of probiotic goat yoghurt drinks as a milk fat replacer, as well as yoghurt cultures of Lactobacillus acidophilus La-5 and Bifidobacterium bifidum Bb-11. The implications of DWSF on the rheological properties (apparent viscosity, flow behavior index, plastic viscosity, consistency coefficient, and yield stress), gross composition, color, sensory, bioactive, and microbiological properties of yoghurt drinks were studied throughout 15 days of storage at 4 °C. The addition of DWSF enhanced the bioactive compounds, water-holding capacity, sensory properties, rheological parameters, color, and bacterial growth. Furthermore, mold, yeast, and coliform were not found in any of the samples untilthestoragetimewas over. The total number of viable cells in probiotic treatments was kept at a functional level (>106 CFU/mL) for 15 days. The aggregate results showed that it is possible to generate high-quality bio-yoghurt drinks from goat milk with a delightful flavor, appearance, body & texture, and color by substituting goat milk fat with up to 75 % dried white sapote fruit. The successful creation of high-quality bio-yoghurt drinks from goat milk, enriched with DWSF, not only presents a delightful flavor, and pleasing texture but also signifies a health-conscious innovation. This research paves the way for further investigations into the integration of novel fruit-based ingredients in dairy products, offering new dimensions in the functional foods field.

Consumer perception of a new non-dairy functional beverage optimized made from lactic acid bacteria fermented date fruit extract

The date extract (DE) was used as a medium for yogurt culture to produce a new non-dairy functional food for vegetarian consumers and people who are intolerant/allergic to dairy products, employing response surface methodology to optimize three parameters (date extract/water ratio (mL), sucrose concentration (g/L), and starch concentration (g/L)), to improve titrable acidity (TA), and overall acceptance, and to monitor with an unstructured mathematical model, cell growth, lactic acid production, nutriment consumption, and viscosity development, as well as the evaluation of sensory analysis of the beverage obtained. The optimal conditions for titrable acidity and overall acceptance of the final beverage are achieved by mixing (555.1/444.9 mL date extract/water ratio, 21.13 g/L sucrose concentration, and 57 g/L starch concentration). The models built demonstrated that R2 values were high, confirming the models' efficiency. After 6 h of fermentation, the maximum cell mass in the culture reached 14.21 log10 CFU/mL. In terms of lactic acid, the maximum value of TA was 36 °D. LAB growth considerably reduced sugar content (92.48 g/L) while increasing protein content (25.48 g/L) during varied fermentation via bioactive peptide synthesis. A panel of 60 people participated in the study; sensory analysis results indicate that fermented beverages may be an appealing product to consumers. Therefore, DE-based fermented beverage can be a sustainable and value-added product that meets the criteria of acceptance by consumers, including those that are intolerant to lactose.

Probiotic yoghurt fortified with rosehip seed powder: Viability, physicochemical, and sensorial properties

The impact of rosehip seed powder (RSP) fortification (1, 2, and 3%) on some physicochemical characteristics and bacterial survival of set type probiotic yoghurt was evaluated during 21-d storage at 4°C. Textural, microstructural, total phenolic content, antioxidant activity, and sensorial attributes were also assessed in the samples, with and without RSP fortification. Milk was fermented by yoghurt cultures with the inclusion of the probiotic cultures comprising Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis. The total solid, protein, and total phenolic contents in yoghurts fortified with RSP were significantly higher than control, and an enhancement in the yoghurt's antioxidant capacity and firmness, while a reduction in yoghurt's adhesiveness and syneresis occurred (p &lt; 0.05). However, sensory scores were lower in RSP-fortified yoghurts than in control. Throughout 21-d storage, the yoghurt's titratable acidity increased while its syneresis and pH decreased. The present work also determined that RSP fortification of probiotic yoghurt increased (p &lt; 0.05) in L. acidophilus and B. animalis subsp. lactis growth (up to 8.24 and 8.10 log CFU/g, respectively) as compared to their respective controls (7.84 and 7.83 log CFU/g, respectively), and probiotic counts in yoghurts fortified with RSP remained over 6 log CFU/g at the end of storage. The documented knowledge of fortifying probiotic yoghurts with RSP could inspire the dairy industry to generate a novel synbiotic product while utilising wasted rosehip seeds as processing waste.

An innovative approach: Formulation and evaluation of fermented oat milk using native yoghurt cultures

This study aimed to develop a fermented oat milk product using native yoghurt cultures as a potential alternative to dairy-based yoghurt products. Three samples were prepared; the first sample is the control (FCM: based on cow's milk), the second based on oat milk (FOM) and the third (FOM+MJ) based on oat milk with a portion of melon juice. The physicochemical, microbiological, sensory characteristics, and the nutritive value of the resulting products were evaluated. Results showed the longer microbiological stability of oat-based yogurt. The sensory evaluation indicated that the FOM was the more appreciated by the panelists. Overall, the study demonstrated the feasibility of using native yoghurt cultures to ferment oat milk and produce a product with desirable characteristics. This approach could offer a potential solution for consumers who are lactose intolerant or prefer plant-based products, while still providing the health benefits of traditional yoghurt products.

Development and properties of functional yoghurt enriched with postbiotic produced by yoghurt cultures using cheese whey and skim milk.

This study aimed to examine the effects of supplementation of postbiotics derived from Streptococcus thermophilus (ST) and Lactobacillus delbrueckii subsp. bulgaricus (LB) in cheese whey (CW) and skim milk (SM) on antioxidant activity, viability of yoghurt starters, and quality parameters of low-fat yoghurt during 22 days of storage. The LB-CW (L delbrueckii ssp. bulgaricus postbiotic-containing cheese whey) sample exhibited the highest antioxidant activity, with 18.71% inhibition (p > 0.05). This sample also showed the highest water holding capacity (77.93%; p < 0.05) and a trend toward receiving the most favorable sensory attributes (p > 0.05) compared to the other samples. The LB-CW and LB-SM yoghurt samples exhibited significantly higher body and texture scores compared to the ST-SM-fortified yoghurt (p < 0.05). However, there was no significant difference in the overall acceptability of the LB-SM and ST-SM yoghurt samples across both starters (p > 0.05). Such findings highlight the potential of postbiotics as functional ingredients to enhance the nutritional and sensory aspects of yoghurt, further contributing to its appeal as a health-promoting product.

Buffalo yogurt fermented with commercial starter and Lactobacillus plantarum originating from breast milk lowered blood pressure in pregnant hypertensive rats

Nutritional therapy, which may have advantages over medication, is being investigated as a novel treatment for pregnancy-induced hypertension. Several studies have shown that probiotic yogurt supplementation during pregnancy has beneficial effects on maternal and fetal health. In this study, fermented buffalo milk was produced with yogurt culture and Lactobacillus plantarum B, a probiotic isolated from healthy breast milk with high angiotensin-converting enzyme inhibitory activity. The fermentation conditions under which the angiotensin-converting enzyme (ACE) inhibitory activity reached 84.51% were optimized by the response surface method as follows: 2 × 106 cfu/mL of L. plantarum B, yogurt culture 2.5 × 105 cfu/mL, and 8 h at 37°C. The distribution of ACE inhibitory peptides from fermented buffalo milk and fermented cow milk were further analyzed by liquid chromatography-mass spectrometry. By searching according to the structural features of ACE inhibitory peptides, 29 and 11 peptides containing ACE inhibitory peptide features were found in fermented buffalo milk and fermented cow milk, respectively. To investigate the in vivo antihypertensive activity of fermented buffalo milk, 18 pregnant rats were divided into 3 groups (n = 6 in each group) and administered 10 mL of normal saline, yogurt (20 mg/kg), or labetalol hydrochloride (4 mg/kg) daily from the beginning of pregnancy to parturition. To induce hypertension, methyl nitrosoarginine (125 mg/kg) was injected subcutaneously every day from d 15 of pregnancy to the day of delivery. Blood pressure was not significantly changed in the yogurt and labetalol groups after induction of hypertension and was lower compared with the normal saline group, but there was no difference between the yogurt and labetalol groups. This implied that the buffalo yogurt had a preventive and antihypertensive effect in the pregnancy-induced hypertensive rat model. Further studies to determine the mechanism of action, as well as a randomized control trial, are warranted.

Assessment of stability and bioactive compounds in yogurt containing novel natural starter cultures with the ability to promote longevity in Caenorhabditis elegans

Yogurt represent one of the oldest fermented foods containing viable lactic acid bacteria and many bioactive compounds that could exhibit beneficial effects on human health and train our immune system to better respond to invading pathogens. Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus are commonly used for yogurt preparation under controlled temperature and environmental conditions. In this study, we investigated probiotic features of S. thermophilus BGKMJ1-36 and L. bulgaricus BGVLJ1-21 strains isolated from artisanal sour milk and yogurt by using Caenorhabditis elegans as an in vivo model system. Further, we evaluated content of total fat, saturated fatty acids, proteins, and lactose, as well as vitamins and AA of yogurt prepared from above-mentioned starter cultures during 21 d of storage at 4°C to get insights of final product stability. We showed that S. thermophilus BGKMJ1-36 and L. bulgaricus BGVLJ1-21 strains applied in combination upregulated the expression of autophagy-related genes in C. elegans. Beside autophagy, we observed activation of TIR-1-dependent transcription of lysozyme-like antimicrobial genes involved in the immune defense of C. elegans. Upregulation of these genes strongly correlates with an increase in the longevity of the worms fed with yogurt culture bacteria. Further, we showed that yogurt prepared with S. thermophilus BGKMJ1-36 and L. bulgaricus BGVLJ1-21, as a final product, is rich with vitamin B2 and dominant AA known by their prolongevity properties. Taken together, our study pointed to the beneficial features of the tested starter cultures and yogurt and highlighted their potential to be used as a fermented food with added-value properties.

Comparison of Amino Acid Profile, ACE Inhibitory Activity, and Organic Acid Profile of Cow and Goat Yogurts Produced with Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12, and Classical Yogurt Culture.

In this study, we aimed to produce a standard, more functional, and nutritious yogurt by using 5 different combinations of cow milk and goat milk and 2 types of starter cultures (classical yogurt culture and commercial probiotic culture). It was determined that the use of different milk types and different starter cultures in yogurt production had a statistically very significant effect (P < 0.01) on all physicochemical, microbiological, and biochemical properties. In addition, the storage period was effective on all parameters examined at varying rates. In the context, the use of goat milk in the experimental yogurt samples caused an increase in the ACE inhibitory activity values and the count of S. thermophilus, while the use of cow milk caused an increase in serum separation and pH values. On the other hand, serum separation, pH values, and ACE inhibitory activity and phenylalanine and leucine levels were found to be higher in the yogurts produced by using ABT-2 probiotic culture. It was observed that an increase in the levels of asparagine, aspartic acid, proline, and serine, as well as lactic acid, orotic acid, and citric acid, is higher in the yogurts produced by using classical yogurt culture. It has been concluded that the combination of goat milk and cow milk at different proportions and the use of probiotic culture together in yogurt production can produce yogurt that is more functional and richer in terms of organic compounds and essential amino acids.