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

The behaviour of Escherichia coli O157:H7 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 O157:H7 with inoculum level of 103 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 O157:H7 during manufacture and storage period. During cheese manufacture the number of E. coli O157:H7 increased by 106 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 O157:H7, 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.