SURVIVAL OF LACTOBACILLUS-ACIDOPHILUS AND BIFIDOBACTERIUM-BIFIDUM IN COMMERCIAL YOGURT DURING REFRIGERATED STORAGE

Samples of five brands of commercial yoghurt were obtained directly from the processors and enumeration of viable Lactobacillus acidophilus and Bifidobacterium bifidum and determination of pH was carried out at three-day intervals over a five-week period. Three of the five products contained 10(7)-10(8) g(-1) viable cells of L. acidophilus, whereas the other two products contained less than or equal to 10(5) of this organism initially. Similarly , the initial count of B. bifidum was 10(6)-10(7) g(-1) in two of five products, while the viable numbers of this organism were less than or equal to 10(3) in the other three products. All the products showed a constant decline in the viable count of L. acidophilus and B. bifidum during storage. Initial pH values ranged from 4.07 to 4.36 and these declined after five weeks of storage to pH 3.8-4.26.