Comparison of chemical composition and microbial profile of raw and pasteurized milk of the Western Cape, South Africa

Abstract

During the present study raw andpastuerized milk samples were collected from the three major dairy factories during March- August 2001. The raw milk supplied by farmers to the selected factory was collected fiom bulk tank. Similarly pasteuized milk samples, processed and distributed by those factories, were randomly collected fiom three different food stores and retailers of the Western Cape of South Africa. The frequency of the isolation of the microorganisms, from both raw and pasteuized milk, revealed a hgher prevalence of S. aureus in the raw milk (15.38%) followed by those of E. coli (14.3%) that was also isolated at a rate of 3.6% form pasteuized milk. Also, other mastitis-isolated pathogens found were Sheptococcus agalacfiae (8.79%), Sheptococcus dysglactiae (12.09%), Sheptococcus uberis (6.72%), Enterococcus faecalis (8.35%) which was also found in 2.2% of the pasteuized milk samples and Staphylococcus epidennidis (8.79%) that were also found in pasteuized milk (2.2%). Other identified isolates, were also represented. However, all samples revealed negative results for the growth of Salmonella and Listeria monocytogenes. Descriptive and fiequency analysis showed higher means, standard error of means and standard deviation for the somatic cell counts, total bacterial counts, coliform counts and E. coli counts, although their minimum values revealed a negative or a very low levels. A lower level was also obtained for the chemical content (fat, protein, lactose, SNF and total solids) of the pasteuized milk compared to the raw milk samples for all studied companies. Also the percentage of the added water was very high in the processed milk compared to the samples fiom herd raw bulk milk. Moreover the significant variation between the measurements were estimated. © 2008 Academic Journals Inc.