Behavior of Escherichia coli O157:H7 during the Manufacture and Ripening of Feta and Telemes Cheeses
Abstract:Pasteurized whole ewe's and cow's milk was used in the manufacture of Feta end Telemes cheeses, respectively, according to standard procedures. In both cases, the milk had been inoculated with Escherichia coli O157:H7 at a concentration of ca. 5.1 log CFU/ml and with thermophilic or mesophilic starter cultures at a concentration of ca. 5.3 to 5.6 log CFU/ml. In the first 10 h of cheesemaking, the pathogen increased by 1.18 and 0.82 log CFU/g in Feta cheese and by 1.56 and 1.35 log CFU/g in Telemes cheese for the trials with thermophilic and mesophilic starters, respectively. After 24 h of fermentation, a decrease in E. coli O157:H7 was observed for all trials. At that time, the pH was reduced to 4.81 to 5.10 for all trials. Fresh cheeses were salted and held at 16°C for ripening until the pH was reduced to 4.60. Cheeses were then moved into storage at 4°C to complete ripening. During ripening, the E. coli O157:H7 population decreased significantly (P ≤ 0.001) and finally was not detectable in Feta cheese after 44 and 36 days and in Telemes cheese after 40 and 30 days for the trials with thermophilic and mesophilic starters, respectively. The estimated times required for one decimal reduction of the population of E. coli O157:H7 after the first day of processing were 9.71 and 9.26 days for Feta cheese and 9.09 and 7.69 days for Telemes cheese for the trials with thermophilic and mesophilic starters, respectively.
Document Type: Research Article
Affiliations: 1: Laboratory of Hygiene of Foods of Animal Origin, Veterinary Faculty, University of Thessaly, Karditsa, Greece 2: Department of Food Hygiene and Technology, Laboratory of Milk Hygiene and Technology, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki 54006, Greece 3: Agricultural Union of Larisa, "Olympus" Dairy, 41334 Larisa, Greece
Publication date: April 1, 2002
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