Survival of Escherichia coli O157:H7 during processing and ripening period of KeÅŸ Cheese

Özen Kurşun Yurdakula, Seval Sevgi Kırdarb, Aylin Kasımoğlu Doğruc, Erhan Keyvana

Abstract

In this study the survival of Escherichia coli O157:H7 during the production process and ripening period of Keş cheese was investigated. Three vats containing equal amounts of raw milk were inoculated with 102, 104, 106 cfu mL-1 E. coli O157:H7, respectively andone vat remained uninoculated. Keş cheese was produced from both inoculated and uninoculated milks with the traditional method of the region. Cheese samples ripened at 6°C for 90 days and E. coli O157:H7 enumarations were done from uninoculated milk, inoculated milks, curds and different stages of ripening period. Most Probable Number technique was used for the analysis of E. coli O157:H7. Classical culture methods were used for the detection of aerobic mesophilic bacteria, lactococci and coliform bacteria. Also, control cheese was analysed for dry matter, salt content in dry matter and pH value. Elimination times were 45 days for 102 cfu mL-1, 75 days for 104 cfu mL-1, and 90 days for 106 cfu mL-1 of E. coli O157:H7. The final dry matter, salt content in dry matter and pH value were 82.52 %, 3.16 % and 4.58, respectively. Consequently, Keş cheese should be ripened at least 90 days in order to be considered as safe for public health.

Key words

Elimination times, Escherichia coli O157:H7, KeÅŸ cheese, traditional cheese, dairy producs