Effect of Different Types of Milk on Shelf Life and Microbial Quality of Rabri

Study was conducted to evaluate the effect of various four storage periods (0 day, 5 days, 10 days and 15 days) and four different types of milk (cow milk, buffalo milk, combined milk and skim milk) used for the preparation of Rabri. These samples were stored at 5˚C, and evaluated the three species of microorganisms (standard plate count X 105 Cfu/g, coliform count X 102 Cfu/g and yeast&mould count X 102 Cfu/g) which were noticed during storage. This evaluation process replicated thrice. The various storage periods and four different types of milk used for the preparation of Rabri, affected significantly at 0.1 % level of significance but the microbial populations were not affected significantly at 5% level of significance. The interaction between storage periods and milk, storage periods and microbes and milk and microbes significantly affected at the level of 0.1%. The overall interaction among storage period, milk and microbes found to be non-significant effect at 5% level of significance. The intensity of contamination was depending on types of milk and days of storage periods. The presence of total solids plays role in growth of microbes such as least number of cfu/g present in sample prepared by buffalo milk, whereas highest noticed in skim milk. The role of storage periods, as Rabri samples got old the intensity of contamination and growth of microbes increased. Least number of cfu /g noticed at 0 day and highest at 15 days of storage. The significant increase in SPC was observed after 10 to 15 days, but non-significant growth of coliform count and yeast mould count was noticed between 0 to 10 days of storage but growth was observed after 10 days of storage. It was recommended that the best quality of Rabri can be obtained by using buffalo milk at current day of preparation, the least microbial load was found at 0 to 10 days of storage but it would be remain consumable up to 15 days when it stored at 5˚C.