BIOTECHNOLOGICAL INTERVENTION USING PROBIOTIC MICROBES TO SUSTAIN THE SHELF LIFE QUALITY OF MILK PRODUCTS

Dhasarathan P. C. Padmalatha and A. J. A. Ranjitsingh*

ABSTRACT

Dairy products are highly perishable at room temperature. To enhance their storage at ambient temperatures, biotechnological intervention is warranted. For this operation microbes can be used as tools. Probiotic microbes isolated from fermented milk product like curd can be used to extend the shelf life of milk products by combining it with other commercial strains. Prolonged storage of milk products like curd in ambient temperature promotes spoilage by enhancing the growth of microbes and converts it in to a highly acidic product with unpleasant odour and rejection. To overcome these issues and to enhance the shelf life period at ambient temperature starter microbial inoculums can be applied. In the present study. Bacillus brevis (MMI strain) a bacterial isolate from curd and yoghurt was combined with a commercial probiotic starter strain Lactobacillus acidophilus in different ratios and this bacterial combination was used as starter culture to ferment raw and pasteurized milk in the curd formation. L. acidophilus and B. brevis mixture in the ratio 1:1(v/v) was found to yield a good quality curd with a short curdling period without any whey formation. The acidity of the curd was 0.45% to 0.64% and PH ranged between 6.95 - 6.61 during the storage time of 0 – 144 hours. The microbial count ranged between 10 - 342 108CFU/ml, during 0 - 144 hours. The shelf life, taste and sensory qualities of curd developed from raw and pasteurized milk remained in good quality for five days while applying L. acidophilus and B. brevis combinations as starter cultures. The present report will ensure the commercial availability of the curd for an enhanced shelf life period.

Keywords: B .brevis, L. acidophilus, pasteurized milk, curd, dairy products.