Determination of the survival levels of acid-adapted Escherichia coli O157:H7in sucuk (Turkish-type fermented sausage)

Abstract

This study aimed to determine the time taken for Escherichia coli O157:H7 to adapt to different types of acids and the effect of acid adaptation on the survival level of E. coli O157:H7 in sucuk (Turkish-type fermented sausage). E. coli O157:H7 cells were adapted to acids in a tryptic soy broth (TSB) set to pH 5.5 for 1-, 2-, 3-, and 4-h periods using hydrochloric, acetic, lactic, and citric acid. The acid tolerance of acid-adapted and nontreated cells was determined in TSB of pH 3.5 and then acid-adapted and nontreated E. coli O157:H7 (105 CFU/g) was added to sucuk. In the adaptation trial in which acetic acid was used, the highest acid resistance was seen in the 3-h adaptation samples, and in the lactic acid trials, the highest acid resistance was seen in the 3- and 4-h adaptation samples. In the adaptation trials with hydrochloric acid, it was observed that the duration of the adaptation period did not increase the resistance. It was determined that the survival rate of E. coli O157:H7 in sucuk was significantly increased through acid adaptation. As a result, it was understood that acid-adapted E. coli O157:H7 can maintain its viability in sucuk for at least 15 days.