Assessment of the Growth and Survival of Escherichia coli O157:H7 During the Manufacture and Storage of Iranian White Cheese and Probiotic Cheese

摘要

During the past two decades probiotic (health promoting) micro-organisms have been increasinglyincluded in various types of food products, especially in fermented milks. E. coli O157:H7 outbreaks associatedwith consumption of ovine or cow cheese products have been reported in several countries. The aim of thepresent study was to determine the effect of pH and different probiotic bacteria on survival of E. coli O157:H7during manufacture and storage of feta cheese and probiotic cheese. Cheese was manufactured usingpasteurized cow milk and inoculated with E. coli O157:H7 with inoculums level of 104 cfu/ml. Two batches ofcheese were prepared, one of them was treated with starter while the other sample use mix starter and probioticbacteria (Lactobacillus acidophilus 4962, Lactobacillus acidophilus La5). Cheese samples were analyzed forE. coli O157:H7 during manufacture and storage period. During cheese manufacture the umber of E. coliO157:H7 increased by 107cfu/g, but during ripening and cheese storage the number of organism decreasedsignificantly in the cheese samples made with probiotic bacteria than feta cheese (P<0.05).results presented inthis study showed that the manufacturing procedure of feta cheese in brine and probiotic cheese do noteliminate E. coli O157:H7, although the population of the organism decrees in probiotic cheese than Iranianwhite cheese cheese.