ISOLATION AND IDENTIFICATION OF BACTERIA ASSOCIATED WITH SPOILAGE OF COMMERCIALLY PURCHASED YOGHURT AND HOMEMADE YOGHURT

Yoghurt, a widely consumed dairy product, is prone to microbial spoilage due to its nutrient-rich composition and storage conditions. The purpose of this study was to isolate and identify the microorganisms that cause homemade and store-bought yogurt to deteriorate. To mimic actual storage procedures, samples were gathered aseptically and kept at room temperature and in a refrigerator. Standard microbiological techniques, including serial dilution, growth on selective and differential medium, and biochemical assays, were used to isolate and describe the bacterial species discovered in damaged samples. The results demonstrated that the rate of bacterial contamination in handmade yoghurt was higher than that of commercial goods, most likely due to differences in pasteurization, preservation, and hygiene procedures. Escherichia coli, Lactobacillus species, Pseudomonas species, and Bacillus species were the most common spoilage microbes found. In order to reduce microbial deterioration and guarantee customer safety, the results highlight the significance of appropriate sanitary procedures, refrigeration, and quality control methods in the manufacturing and storage of yoghurt.