Comparison of inactivation kinetics of Yersinia enterocolitica in vegan and non-vegan kimchi during fermentation

Abstract

Yersinia enterocolitica is occasionally detected in kimchi, a traditional food prepared from fermented vegetables. Changes in growth properties of Y. enterocolitica during kimchi fermentation are largely unknown. We investigated the viability of Y. enterocolitica during the fermentation of vegan and non-vegan kimchi at different temperatures. Changes in Y. enterocolitica population, pH, and titratable acidity were measured for 24 days. In a suspension test with kimchi juice, populations of three Y. enterocolitica strains were above 3.30 log₁₀ CFU/mL at pH > 5 for 7 days. Yersinia enterocolitica counts in vegan kimchi were considerably reduced at 0 °C and 6 °C. During fermentation at 6 °C, Y. enterocolitica populations in non-vegan kimchi and vegan kimchi were not detected starting from days 14 and 10, respectively. In kimchi samples stored at 0 °C and 6 °C, Y. enterocolitica survival correlated with pH changes during fermentation; in samples stored for up to 24 days, Y. enterocolitica was not detected. According to the k _max values from the "log-linear with shoulder and tail" model, Y. enterocolitica was more sensitive to vegan kimchi fermentation than to non-vegan kimchi fermentation. Our findings provide an important basis for ensuring the safe production of kimchi without Y. enterocolitica contamination. Further research is necessary to elucidate the mechanism of Y. enterocolitica inactivation and the major bacterial and physicochemical factors involved in kimchi fermentation.

Keywords: Antimicrobial effect; Fermented kimchi; Foodborne pathogen; Survival kinetics.

Fig. 1

Survival properties of Yersinia enterocolitica in kimchi juice at different pH levels. AY. enterocolitica ATCC 9610; BY. enterocolitica ATCC 23715; CY. enterocolitica ATCC 27729. Not Detected (ND) indicates that the concentration of the analyte may have been below the detection limit.

Fig. 2

Survival curve of Yersinia enterocolitica strain ATCC 27729 during fermentation in non-vegan and vegan kimchi at 0 °C and 6 °C. A Kimchi group stored at 0 °C; B Kimchi group stored at 6 °C.