Survival and Acid Tolerance of Shigatoxigenic Escherichia coli (STEC) During Frankfurter Sausage Storage

This study was carried out to understand how sausage matrices affect the survival and acid tolerance of STEC O157 and O26. STEC O157 and O26 were inoculated on sausage surface approximately 5 log. After inoculation sausages were vacuum packed and stored at 4°C. Pathogen counts and synthetic gastric fluid (pH 1,5) experiments were conducted on day 0, 15 and 30 of the storage. Three trials were conducted for each pathogen separately. Both serogroups had viable counts on sausage during storage, STEC O26 count decreased about 1log and O157 about 3log during storage. At the end of the storage both O26 and O157 were viable on the sausage surface 4.59 log and 2.54 log respectively. For acid survival experiments pathogen counts were obtained on 30th, 60th and 90th minute of synthetic gastric fluid (SGF) exposure. Our results show that O26 endured acid stress longer than O157 during SGF experiments throughout storage of frankfurters. The results of this study may support the idea that some non-O157 STEC strains might be more resistant to acid stress than O157 STEC but further studies should be conducted before drawing a conclusion.

Anahtar Kelimeler:

Frankfurter, STEC, survival, acid tolerance, synthetic gastric fluid.

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