Stability of Lactic Acid Bacteria in Pasteurized Cow’s and Goat’s Milk

Abstract

This study was done to determine the effect of pasteurization on the stability of lactic acid bacteria (LAB) and its enzyme in raw and pasteurized cow’s and goat’s milk. The total viable count for plate count of the bacterial growth concentration was higher in both pasteurized cow’s and goat’s milk at 2.48 log CFU/ml. This is followed by raw cow’s milk (1.59 log CFU/ml) and raw goat’s milk (0.65 log CFU/ml). Lactic acid bacteria (LAB) was found to be similar in both raw cow’s and goat’s milk (p>0.05), and pasteurized milk of both animals also contained the same amount of LAB (p>0.05). LAB was still detected in pasteurized milk (p<0.05), indicating the stability of LAB against the pasteurization temperature. Interestingly, based on API ZYM assay kit results, there were nine different enzymes detected in all samples, which were leucinearylamidase, valinearylamidase,cystinearylamidase, trypsin, α-chymotrypsin, naphthol-AS-BI-phosphohydrolase, α-glucosidase, β-glucosidaseand acid phosphatise. The results revealed that different types of lactic acid bacteria were detected in treated and non-treated milk samples produced by different animals, indicating the different stability levels of LAB against pasteurization.