Performance Analysis of Industrially and Traditionally Used Cultures in Yogurt Production Considering Microbial Risk

Yogurt is a fermented milk product produced by two ways; traditional method where local cultures is used and industrial method where industrial starter culture is used for yogurt production in dairy industries. In this study, yogurt cultures were collected from the local markets and from modern dairy plants. This study was undertaken to analyze the performance of industrially used thermophillic, mesophillic homofermentative culture and traditionally used cultures in yogurt production. Thermophillic, mesophillic homofermentative and BAU dairy farm used yogurt culture needed 4, 5 and 3 hours to complete yogurt production and percentages of acidity were 0.76, 0.73, and 0.74 respectively. Local market culture needed highest time (6 hours) for yogurt production and percentage of acidity was 0.96. Maximum (10 coliform cfu) was found in sample-4, but coliform was absent in sample-1 and sample-2. Total yeast count was nill for all samples. Salmonella and shigellae was found in sample-3 and sample-4 yogurt sample. Syneresis and total fungal count was done to find out the shelf life quality of yogurt samples. After 12 days syneresis observed in sample-2 but for sample-1 it was found after 11 days. Syneresis observed in Sample-3 and Sample-4 after 10 days. This study stated that, the yogurt made by mesophillic homofermentative culture has long shelf life than other yogurt culture, so mesophillic homofermentative culture is more suitable for industrial yogurt production.