[Nutrional value of the national dairy product kurut and its place in the nutrition of adolescents of the Kyrgyz Republic].

Kurut is a universal fermented milk product that is added as a seasoning to various dishes and is consumed as a separate meal. It is a good source of macro- and micronutrients in an easily assimilated form, contributing to the maintenance of beneficial intestinal microflora. The product is popular among children and adults in Kyrgyz Republic, and is in great demand as a healthy food. In this regard, the study of the nutritional value and quality of kurut is an urgent task. The purpose of the work was to study the nutritional value of the national fermented milk product kurut, and to assess its place in the daily diet of adolescents. Material and methods. The content of protein, fats, mineral substances and table salt in 8 types of most common kurut has been determined. The determination of protein was carried out by the Kjeldahl method, fat - by the Soxhlet method, mineral substances - by the atomic emission spectrometry method, and sodium chloride - by the titrimetric method. To study the eating behavior and frequency of kurut consumption, a questionnaire survey of 7251 schoolchildren aged 14 to 18 from different regions of the Kyrgyz Republic (41.8% of boys and 58.2% of girls) has been conducted. Results and discussion. According to the results of the survey, all teenagers noted that they had tasted kurut at least once and they liked its salty and sour taste. The total number of schoolchildren consuming kurut averaged 80.1% (87.3% in the southern regions, 80.6% in highlands and 72.5% in the northern regions). The proportion of children who consume kurut daily and do not consume kurut was the same and equals 20.9 and 19.9%, respectively. Regular kurut consumption (1-2 times a week and 1-2 times a month) was noted with the same frequency in adolescents (on average, 29.4 and 29.8%, respectively). The adolescents indicated that they buy kurut in a retail network and from private traders in markets and other accessible outlets. According to the results of our work, the mass fraction of protein in the studied kurut samples averaged 14.6±0.1% (the standard indicator is not less than 16.0%), which covers the daily requirement in protein by an average of 16.9%. Fat mass fraction was 1.8±0.1% (standard value 1.0-26.0%) and covered the daily requirement in fats by an average of 2.05%. Mineral composition of kurut practically corresponded to the composition of dairy products, however, the content of table salt was increased, especially in the home kurut (3.5 times) from the established standards (2-3%). In industrial kuruts "Kinder" and "Baatyr", the content of table salt was almost 2 fold lower than in home kurut, amounting to 5.8-5.9%. Conclusion. Kurut is a national fermented milk product popular among teenagers, which is a good source of minerals and trace elements. The increased content of table salt, especially in home-made kurut, indicates the need for explanatory communication work among children and adolescents, since frequent consumption of kurut can cause the development of alimentary diseases in childhood and in the subsequent years of a person's life. It is also necessary to carry out sanitary and educational work among the population to comply with the technology for preparing the product, especially by reducing the amount of added table salt.

[Development of fermented milk product based on mare milk and lactic microorganisms association].

Since ancient times, mare's milk has been widely used by many peoples. Thanks to its unique composition, it is now used in the nutrition of people with allergies to cow's milk, in the technologies of foods for special dietary uses, etc. To expand the range of products with useful properties, it is advisable to develop fermented milk products based on mare's milk. Numerous studies indicate that the use of fermented milk products provides various health benefits. And the use of probiotic cultures in the composition of starter cultures for fermented milk products allows you to add a number of functional properties to the product. However, the only fermented milk product available on the market from mare's milk is koumiss. Therefore, the development of new fermented milk products based on mare's milk is relevant and in demand. The aim of the study was to develop a fermented milk product based on mare's milk using an association consisting of yogurt starter culture and a probiotic strain of L. rhamnosus F. Material and methods. For the development of a fermented milk product based on mare's milk, the yogurt starter STBp (S. thermophilus and L. delbrueckii subsp bulgaricus) and the probiotic culture L. rhamnosus F (GenBank MN994629) from the collection of lactic acid and probiotic microorganisms of VNIMI were chosen. As a basis for the fermented milk product, mare's milk was used with the addition of dry mare's or dry cow's milk, pre-pasteurized at a temperature of 65±1 °C with a holding time of 30 min and cooled to a fermentation temperature of 37±1 °C. In the course of the work, the activity of acid formation during product fermentation, the duration of fermentation and the dynamics of the number of lactic acid bacteria and L. rhamnosus F probiotic strain during fermentation were studied, depending on the ratio of cultures in the ferment, the dose of the ferment introduced and the base for fermentation. The antimicrobial activity of the product was determined by agar well diffusion assay. Results. It was found that L. rhamnosus F has a low acid-forming activity, so the use of a combined starter culture (association) was proposed. It was determined that the addition of cow's milk powder to mare's milk positively affects the activity of acid formation; after 6 hours of fermentation, the pH value varied in the range of 4.6-4.83, and after 8 hours pH was 4.44-4.65. When dry mare's milk was added, the pH value after 8 hours of fermentation was in the range of 4.71-4.98 pH units. The influence of the amount of combined starter culture (association) and its cultures ratio, the duration of fermentation on the content of lactic acid bacteria, including the probiotic strain L. rhamnosus F in the fermented milk product based on mare's milk, was established. The largest amount of L. rhamnosus F was contained in the product fermented by 7% association with the ratio of cultures 1/4 and 1/6 and after 8 h it amounted to 7-9.5×108 CFU/cm3. Conclusion. Summarizing the results of the research, the technology of a fermented milk product based on mare's milk was developed: the amount of starter culture (associations) - 7%, the ratio of cultures - 1 part of the starter culture for yogurt and 6 parts of L. rhamnosus F (1/6), the fermentation temperature - 37±1 °C, the duration of fermentation - 6 hours with the addition of cow's milk powder and 8 hours with the addition of mare's milk powder. The developed fermented milk product has antimicrobial activity against opportunistic and pathogenic microorganisms E. coli ATCC 25922, S. aureus ATCC 6538, S. typhimurium ATCC 14028.

Vibration-induced particle formation during yogurt fermentation-Effect of frequency and amplitude.

Machinery such as pumps used for the commercial production of fermented milk products cause vibrations that can spread to the fermentation tanks. During fermentation, such vibrations can disturb the gelation of milk proteins by causing texture defects including lumpiness and syneresis. To study the effect of vibrations on yogurt structure systematically, an experimental setup was developed consisting of a vibration exciter to generate defined vibrational states and accelerometers for monitoring. During the fermentation of skim milk, vibrations (frequency sweep: 25 to 1,005 Hz) were introduced at different pH (5.7 to 5.1, step width 0.1 units) for 200 s. Physical properties of set gels (syneresis, firmness) and resultant stirred yogurts (visible particles, rheology, laser diffraction) were analyzed. Vibrational treatments at pH 5.5 to 5.2 increased syneresis, gel firmness, and the number of large particles (d > 0.9 mm); hence, this period was considered critical. The particle number increased from 34 ± 5 to 242 ± 16 particles per 100 g of yogurt due to vibrations at pH 5.4. In further experiments, yogurts were excited with fixed frequencies (30, 300, and 1,000 Hz). All treatments increased syneresis, firmness, and particle formation. As the strongest effect was observed by applying 30 Hz, the amplitude was set to vibration accelerations of a = 5, 10, 15, 20, and 25 m/s2 in the final experiments. The number of large particles was increased due to each treatment and a positive correlation with the amplitude was found. We concluded that vibrations during gelation increase the collision probability of aggregating milk proteins, resulting in a compressed set gel with syneresis. Resultant stirred yogurts exhibit large particles with a compact structure leading to a reduced water-holding capacity and product viscosity.

Production of reuterin in a fermented milk product by Lactobacillus reuteri: Inhibition of pathogens, spoilage microorganisms, and lactic acid bacteria.

We assessed the antimicrobial activity of reuterin produced in vitro in glycerol aqueous solutions in situ by Lactobacillus reuteri ATCC 53608 as part of a fermented milk product against starter (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus), spoilage (Penicillium expansum), pathogenic (Staphylococcus aureus Salmonella enterica ssp. enterica, and Listeria monocytogenes), and pathogen surrogate (Escherichia coli DH5α) microorganisms. We also assayed the influence of cold storage (28 d at 4°C) and reuterin on the color and rheology of the fermented milk product. We obtained maximum reuterin concentrations of 107.5 and 33.97 mM in glycerol aqueous solution and fermented milk product, respectively. Reuterin was stable throughout its refrigerated shelf life. Gram-positive microorganisms were more resistant to reuterin than gram-negative microorganisms. Penicillium expansum and Lactobacillus reuteri ATCC 53608 survived at concentrations up to 10 and 8.5 mM, respectively. Escherichia coli DH5α was the most sensitive to reuterin (0.9 mM). The presence of reuterin did not cause relevant changes in the quality parameters of the fermented milk product, including pH, acidity, soluble solids, color, and rheological aspects (storage and loss moduli and viscosity). This study demonstrated the viability of using Lactobacillus reuteri ATCC 53608 as a biopreservative in a fermented milk product through reuterin synthesis, without drastically modifying its quality parameters.

Metagenome-assembled genomes for biomarkers of bio-functionalities in Laal dahi, an Indian ethnic fermented milk product.

Laal dahi is a sweetened and soft pudding-like fermented milk product of the Eastern regions of India, which has not been studied for its microbial community structures and health promoting functionality in terms of 'omics' approaches. We applied metagenomic and metagenomes-assembled genomes (MAGs) tools to decipher the biomarkers for genes encoding for different health promoting functionalities in laal dahi. Abundance of bacterial domains was observed with negligible presence of eukaryotes and viruses. Bacillota was the most abundant phylum with different bacterial species viz., Enterococcus italicus, Lactococcus raffinolactis, Lactobacillus helveticus, Bifidobacterium mongoliense, Hafnia alvei, Lactococcus lactis, Acetobacter okinawensis, Streptococcus thermophilus, Thermus thermophilus, Leuconostoc citreum, Leuconostoc pseudomesenteroides, Acetobacter orientalis, Lactobacillus gallinarum, Lactococcus chungangensis and Lactobacillus delbrueckii. Comparison of laal dahi microbiome with that of similar fermented milk products was also carried out after retrieving the metagenomic datasets from public databases. Significant abundance of Lb. helveticus, E. italicus, Lc. raffinolactis and Lc. lactis in laal dahi. Interestingly, Bifidobacterium mongoliense, Lb. gallinarum, Lc. chungangensis and Acetobacter okinawensis were only detected in laal dahi but Streptococcus infantarius, Lacticaseibacillus rhamnosus and Lb. johnsonii were absent. Reconstruction of putative single environment-specific genomes from metagenomes in addition to subsampling of the abundant species resulted in five high-quality MAGs identified as Lactobacillus delbrueckii, Lactobacillus helveticus, Lactococcus chungangensis, Lactococcus lactis and Streptococcus thermophilus. All MAGs showed the presence of various genes with several putative functions corresponding to different probiotic and prebiotic functions, short-chain fatty acids production, immunomodulation, antitumor genes, essential amino acid and vitamin biosynthesis. Genes for γ-Aminobutyric acid (GABA) production were only detected in MAG of Lactococcus lactis. Gene clusters for secondary metabolites (antimicrobial peptides) were detected in all MAGs except Lc. chungangensis. Additionally, detection of clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) elements was observed only in Lactobacillus delbrueckii and Streptococcus thermophilus. Annotation of several genes with potential health beneficial properties in all five MAGs may support the need to explore the culturability of these MAGs for future use in controlled fermentation of functional dairy products.

Improved gut microbiome recovery following drug therapy is linked to abundance and replication of probiotic strains.

Probiotics have been used for decades to alleviate the negative side-effects of oral antibiotics, but our mechanistic understanding on how they work is so far incomplete. Here, we performed a metagenomic analysis of the fecal microbiota in participants who underwent a 14-d Helicobacter pylori eradication therapy with or without consumption of a multi-strain probiotic intervention (L. paracasei CNCM I-1518, L. paracasei CNCM I-3689, L. rhamnosus CNCM I-3690, and four yogurt strains) in a randomized, double-blinded, controlled clinical trial. Using a strain-level analysis for detection and metagenomic determination of replication rate, ingested strains were detected and replicated transiently in fecal samples and in the gut during and following antibiotic administration. Consumption of the fermented milk product led to a significant, although modest, improvement in the recovery of microbiota composition. Stratification of participants into two groups based on the degree to which their microbiome recovered showed i) a higher fecal abundance of the probiotic L. paracasei and L. rhamnosus strains and ii) an elevated replication rate of one strain (L. paracasei CNCMI-1518) in the recovery group. Collectively, our findings show a small but measurable benefit of a fermented milk product on microbiome recovery after antibiotics, which was linked to the detection and replication of specific probiotic strains. Such functional insight can form the basis for the development of probiotic-based intervention aimed to protect gut microbiome from drug treatments.

Human gut metatranscriptome changes induced by a fermented milk product are associated with improved tolerance to a flatulogenic diet.

Healthy plant-based diets rich in fermentable residues may induce gas-related symptoms, possibly mediated by the gut microbiota. We previously showed that consumption of a fermented milk product (FMP) containing Bifidobacterium animalis subsp. lactis CNCM I-2494 and lactic acid bacteria improved gastrointestinal (GI) comfort in response to a flatulogenic dietary challenge in healthy individuals. To study the effects of the FMP on gut microbiota activity from those participants, we conducted a metatranscriptomic analysis of fecal samples (n = 262), which were collected during the ingestion of a habitual diet and two series of a 3-day high-residue challenge diet, before and following 28-days of FMP consumption. Most of the FMP species were detected or found enriched upon consumption of the product. FMP mitigated the effect of a flatulogenic diet on gas-related symptoms in several ways. First, FMP consumption was associated with the depletion of gas-producing bacteria and increased hydrogen to methane conversion. It also led to the upregulation of activities such as replication and downregulation of functions related to motility and chemotaxis. Furthermore, upon FMP intake, metabolic activities such as carbohydrate metabolism, attributed to B. animalis and S. thermophilus, were enriched; these activities were coincidentally found to be negatively associated with several GI symptoms. Finally, a more connected microbial ecosystem or mutualistic relationship among microbes was found in responders to the FMP intervention. Taken together, these findings suggest that consumption of the FMP improved the tolerance of a flatulogenic diet through active interactions with the resident gut microbiota.