Comparison of bacterial contamination of raw and pasteurized milk used in Shahrekord in 2006

Milk is very important for the human nutrition. Control and monitoring of its preparation, transport, storage and presentation, based on healthy principals is essential. Therefore, this study was aimed to compare bacterial contamination of raw and pasteurized milk used in Shahrekord, Iran in 2006. This descriptive-analytical study is a descriptive analytical which has been done in 2006 in milk production factories in Shahrekord Township. In this order, 300 samples of raw milk using sterile containers of 200 cc volume, from five points and also randomly 120 samples of pasteurized milk from milk production factories have been gathered, on winter and summer seasons. Coli forms measured using MPN method in lactose broths medium and total count method used for the total bacteria in violate red bile Agar medium. E. coli determined in eosin methylene blue medium and IMVIC tests were used for coli form differentiation. Data were analyzed using descriptive statistics and Chi-square, Mann-Whitney, and Kruskal-Wallis tests. The results showed that 208 of 300 (70%) and 242 of 300 (80.5%) of the raw milk samples were contaminated with E. coli and coli forms, respectively. The most (88%) and the least (%58.3) rate of contamination were in the samples from southwest and northeast area, respectively (P<0.05). The rate of contamination of raw milk prepared during summer with E. coli and coli forms were more than those prepared in winter (P<0.05). Regarding the contamination of raw milk with E. coli and the other coli forms, particularly in summer, following of healthy principles and supervision in preparation, transport, storage, and selling of milk especially during the hot seasons are necessary.