MICROBIAL ANALYSIS OF RAW AND DIFFERENT BRANDS OF PASTEURIZED MILK

Abstract

A total of 32 milk samples were collected from 8 sources. Among them three were raw (designated as R1 to R3) and five were pasteurized milk (designated as P1 to P5). Each of the collected samples was investigated during the period from May to December, 2012. Microbiological tests such as viable plate count, coliform plate count, Staphylococcus plate count and Gram’s staining were performed to determine the loads of microbes in raw and different brands of pasteurized milk. Total viable counts (TVC) of three raw milk samples, R1, R2 and R3, were 745000 cfu/ml (log 5.87), 1357500 cfu/ml (log 6.13) and 1972500 cfu/ml (log 6.29), respectively. The presence of Escherichia coli in the samples of R1, R2, and R3 were 236 cfu/ml (log 2.37), 268 cfu/ml (log 2.42), 940 cfu/ml (log 2.97), respectively, but the presence of Staphylococcus were 798 cfu/ml (log 2.90), 590 cfu/ml (log 2.77), 615 cfu/ml (log 2.78), respectively. The average values of TVC (cfu/ml) were 98500 cfu/ml (log 4.99), 68450 cfu/ml (log 4.83), 195000 cfu/ml (log 5.29), 18950 cfu/ml (log 4.27) and 53375 cfu/ml (log 4.72), respectively for the samples of P1, P2, P3, P4, and P5 brands of pasteurized milk, where as Staphylococcal count were 869 cfu/ml (log 2.93), 647 cfu/ml (log 2.81), 443 cfu/ml (log 2.64), 858 cfu/ml (log2.93) and 28 cfu/ml (log1.45), respectively. The coliform counts were 166 cfu/ml (log 2.21), 91 cfu/ml (log1.95), 348 cfu/ml (log 2.54) and 101 cfu/ml (log 2.00) for the samples of P1, P2, P3, and P5, respectively. Coliform were not detected in P4 pasteurized milk sample. Therefore, it was concluded that high counts of bacteria were found in most of the samples. The detection of high counts of Staphylococcus coupled with the presence of E. coli are of public health significance to consumers.