A metagenomic survey of bacterial communities from kurut: The fermented cow milk in Kyrgyzstan.

Kurut is a traditional dry dairy product mostly consumed in Central Asia. In this study, the distribution of the dominant bacteria present in kurut samples (n=84) originated from seven (Chuy, Issyk-Kul, Talas, Naryn, Jalal-Abad, Osh, and Batken) regions in Kyrgyzstan were analyzed with Illumina iSeq100 platform. The dominant phylum detected was Firmicutes followed by Proteobacteria, Actinobacteria, Cyanobacteria/Chloroplast, and Tenericutes. The most abundant family detected was Lactobacillaceae followed by Streptococcaceae, Enterococcaceae, Chloroplast, and Leuconostocaceae. At the genus level, Lactobacillus was the predominant one in samples and Streptococcus, Enterococcus, Lactococcus, and Streptophyta followed this. Further comprehensive characterization analyses in kurut samples may have potential applications both in industrial starter culture developments and also future therapeutic approaches based on potential strains with probiotic properties.

[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.

Characterization of the key odorants in kurut with aroma recombination and omission studies.

Kurut is a traditional acid-coagulated cheese from the northwest region of China. Using gas chromatography olfactometry and aroma extract dilution analysis, we identified 21 potent odorants from kurut within the flavor dilution factor range of 8 to 256. We developed a kurut matrix to determine the odor thresholds of key aroma compounds in kurut. The odor activity values of these 21 potent volatile compounds revealed that 18 were present at concentrations above their odor threshold values and therefore contributed to the overall aroma of kurut. The result of aroma recombinant experiments prepared by mixing the 18 most important odorants at the concentrations in which they occurred in kurut showed that the overall aroma profile of the recombinant sample was very similar to that of kurut. Omission experiments indicated that acids, furans, esters, and ketones were the most important volatile compounds in kurut. Some aroma compounds-such as butanoic acid, homofuraneol, ethyl hexanoate, and ethyl butanoate-play the most important roles in the overall flavor profile of kurut. Some odorants with a high flavor dilution factor, such as sulfur compounds, may have little effect. The study of key aroma compounds in kurut could provide important information for researching and developing traditional Chinese cheese products.