ISOLATION AND IDENTIFICATION OF Escherichia coli FROM PASTEURIZED MILKS AVAILABLE IN BANGLADESH

Abstract

Milk is considered as an ideal food, containing all essential nutrients and minerals. However, milk contaminated with pathogenic bacteria could be threat to life. The major source of such contamination is from poor hygienic or sanitary condition of the person associated with collection and handling of milk, before, during or after pasteurization. Now-a-days, milk is marketed mostly as pasteurized milk. Thereby, investigation was conducted on the assessment of sanitary quality of pasteurized milk sample belonging to three different brands of Bangladesh namely Aftab milk, Pran milk and Milk vita, sold in local retail stores. The mean total viable counts as determined were 104166.7 ± 22238.47 cfu/ml (log 5.005 ± 0.001) in Aftab milk, 53633.33 ± 7780.08 cfu/ml (log 4.725 ± 0.002) in Pran milk and 1653.33 ± 266.29 cfu/ml or (log 3.213 ± 0.009) in Milk vita samples. The result revealed the highest extent of microbial contamination that occurs on their proliferation in different brands of pasteurized milk. The presence of numbers of coliforms exceeding the microbiological limit in pasteurized milk samples may be indicated poor processing control, post-process contamination or packaging. The mean coliform counts as encountered 105.3 ± 8.69 cfu/ml (log 2.018 ± 0.019) in Aftab Milk, 46.6 ± 5.27 cfu/ml (log 1.66 ± 0.05) in Pran milk and 0.2 ± 0.281 cfu/ml in milk vita. Statistically the coliforms were found more closely related to total viable count. These appear to be alarming possibility because of being associated with potential food hazards. The distribution of microbiological count for selected microbial groups in pasteurized milk sample of three brands, such as total viable counts and coliform counts demonstrated the fact that the sanitary conditions under which the product was handled, processed and stored need to be improved.