TECHNOLOGICAL PROPERTIES OF A NEW STRAIN OF BACTERIA LACTOBACILLUS DELBRUECKII SUBSP. BULGARICUS K 1903, ISOLATED FROM YAKUT KUMISS

The aim of research is to study the technological properties of the isolated strain of lactic acid microorganisms Lactobacillus delbrueckii subsp. bulgaricus K 1903 and its practical application. Objectives: to study the technological properties of L. delbrueckii subsp. bulgaricus K 1903; to conduct an experimental production of a fermented milk product using L. delbrueckii subsp. bulgaricus K 1903. The object of research was the strain L. delbrueckii subsp. bulgaricus K 1903, isolated from Yakut kumiss. The study of the technological properties of the strain was carried out at a maximum temperature of 50 °C. The optimum development temperature for the strain was 37–40 °C, the minimum temperature was 25 °C, and the maximum temperature was 45–50 °C. By 16 hours, the strain ferments milk with the formation of a creamy clot that has a pleasant taste without. The fermentation activity of the new strain was compared with the prototype strain L. delbrueckii subsp. bulgaricus VKPM V 3141. According to the research results, it was noted that the lag-phase period of the new strain was shorter (2.5 hours) than that of the test culture (4.5–5 hours), this property is an important condition for the industrial production of fermented milk products. The rate of biomass accumulation in the new strain was twice as high as in the test culture, i.e., the optical growth density of the culture of the new strain after 12 hours of incubation in a nutrient medium based on skimmed milk hydrolyzate (SOM) reached 18 OD, while in the test culture, it was 9 OD. Thus, the properties of the new L. delbrueckii subsp. bulgaricus K 1903 prove the expediency of its use in the composition of direct ferments.