An article in Epidemiology and Infection, a 2021/2022 outbreak of E. coli in kimchi is discussed. While we would think that the fermented kimchi product would not have issues with enteric pathogens, this case proves otherwise. The E.coli (STEC) was thought to come in on the Napa cabbage which was grown in Washington state. The second issue was that E.coli was acid tolerant, allowing it to survive in product down to pH of 4.1. Generally, low pH and contribution of lactic acid bacterial growth (Lee, 2021) would eventually eliminate pathogens, but in this case, the product was consumed closer to the manufacturing date.
From the article, "Given that kimchi is acidic in nature, typically with a pH less than 4.5 [Reference Kim, Jang, Kim, Lee, Kim, Ryu and Rhee14], it is often assumed to be an unlikely source for foodborne outbreaks. However, the present outbreak, and those noted above from East Asia, have called this assumption into question. Interestingly, pH testing in this outbreak revealed that pH decreased over time throughout the product’s shelf life. With decreased pH thought to reduce pathogenic load, it is notable that cases in this outbreak had consumption dates closer to the beginning of the product’s shelf life, when pH was likely higher, and the product was less acidic. It is also notable that a positive result for STEC O157 in this outbreak was found in a product with a pH result of 4.1, indicating that this strain of STEC O157 may have also been acid-tolerant, surviving exposure to this pH. Research is ongoing to determine if this may have been the case. This outbreak serves as a reminder that kimchi is a potential source of foodborne outbreaks, and that mitigating measures to prevent pathogen introduction and growth should be considered in the manufacturing process."
Epidemiology and Infectionhttps://www.cambridge.org/core/journals/epidemiology-and-infection/article/fermenting-a-place-in-history-the-first-outbreak-of-escherichia-coli-o157-associated-with-kimchi-in-canada/B8EC9B59037C9506D1EAE19DDD4E9AAC
Fermenting a place in history: The first outbreak of Escherichia coli O157 associated with kimchi in Canada