BACTERIAL OBSERVATION OF KEFIR IN THE PROCESS OF ITS STORAGE

Abstract

Kefir as a traditional fermented food has numerous health benefits due to its unique chemistry reflected in its superior nutritional value. The physicochemical and microbial composition of kefir depends on the type of milk, time and temperature of fermentation, and storage conditions. Lactic acid bacteria are primarily responsible for the microbial composition of kefir. They help convert the lactose in milk into lactic acid, which lowers the pH. Other kefir microbial components include lactose fermentation yeast, which produces ethanol and carbon dioxide. Non-lactose yeast and acetic acid bacteria also take part in the fermentation process. After fermentation, the grains are increased by about 5-7% of the original biomass. When they increase in milk, the proportions of microorganisms in the grain differ from those present in the final product. It is important that the characteristics of the kefir are not lost during storage, as a permanent metabolic activity of the residual kefir microbiota may occur. According to the nature and degree of danger to human health, food contamination caused by microflora occupies the first place. According to the list of food products by the degree of contamination by microorganisms and the frequency of food poisoning cases developed by the World Health Organization, milk and lactic acid products belong to the first category as the most often serving as a direct source of food poisoning. Bacteriological analysis revealed that the number of lactic acid microorganisms, yeast and mold increased gradually taking into account different storage temperatures for five days: room temperature (20°C) and t = 5 ± 1°C. Kefir can be stored for up to one day without a significant increase in the number of microbial cells in a refrigerator (4°C). The highest indicators of microflora, yeast and kefir fungi has been obtained on the 5th day at a temperature of + 20°C. Storage of lactic acid products at elevated temperatures leads to an increase in the microflora of yeasts and molds, which leads to spoilage of the product and a change in its organoleptic properties.