Survival of Salmonella enteritidis during the manufacture of feta cheese made of pasteurized ewe's milk.

The behaviour of Salmonella enteritidis during the Feta cheese making process was investigated. Two lots of pasteurized whole ewe's milk were inoculated to contain 10(6) cfu/ml of S. enteritidis (strain AS1 and AS2) and were processed into Feta cheese following standard procedures. All samples were examined for S. enteritidis both quantitatively and qualitatively, while moisture, fat, water activity and pH were also measured. S. enteritidis was enumerated in duplicate samples by surface plating on SS agar. Selected salmonella-like colonies were identified biochemically and serologically. The enumerations have shown that S. enteritidis was initially entrapped in the curd. Then the growth of S. enteritidis gradually decreased and no Salmonellae were quantitatively enumerated after the 23rd day. However S. enteritidis was detected qualitatively in samples taken until the 38th day.