Survival of Escherichia coli O157:H7 and Listeria monocytogenes during kimchi fermentation supplemented with raw pork meat

Abstract

Kimchi, a traditional Korean food, is fermented by lactic acid producing bacteria. Among the many types of kimchi, soongchimchae is a typical type of kimchi that combines fermented vegetables and meat. We aimed to investigate the survival of Escherichia coli O157:H7 and Listeria monocytogenes during the fermentation of kimchi supplemented with pork meat. Regardless of whether it was assessed in cabbage kimchi or radish kimchi, in which pH levels differ, the population of E. coli O157:H7 gradually decreased during the fermentation at 4 °C and was no longer detected in cabbage samples after 14 post-fermentation days (PFDs). The pH of cabbage kimchi and radish kimchi were 5.8 and 6.0, respectively, at 0 PFDs, changing to 3.9 and 4.1 at 15 PFDs. Although the population of L. monocytogenes gradually decreased, L. monocytogenes did not survive in cabbage kimchi or radish kimchi after 15 PFDs. Compared with radish kimchi, the pH of cabbage kimchi dropped rapidly during the early fermentation period and reached a pH of 3.9 at 15 PFDs. We observed that pH changes during fermentation were associated with a reduction in foodborne bacterial pathogens. Antimicrobial factors and inhibitory mechanisms against foodborne bacteria need to be investigated in the different types of kimchi.