Study on the growth and survival of Escherichia coli O157:H7 during the manufacture and storage of Iranian white cheese in brine

ABSTRACT

The behaviour of Escherichia coli O157H7 was studied during the manufacture and storage of Iranian white cheese in brine. Cheese was manufactured using pasteurized cow milk and inoculated with E. coli O157H7 with inoculum level of 10[3] cfu/ml. Four treatments were designed. Cheeses were made with or without starter culture and kept immersed in 6 or 8% salt brine during ripening and storage. Cheese samples were analysed for E. coli O157H7 during manufacture and storage period. During cheese manufacture the number of E. coli O157H7 increased by 10[6] cfu/g, but during ripening and cheese storage the number of organism decreased significantly in the cheese samples made with starter culture [P<0.05]. The results showed an inhibitory effect of starter culture on E. coli O157H7, but the organism can survive in this kind of cheese for up to 60 days of storage, respecting using starter culture, salt brine concentration and cheese storage time