Pathogenic Escherichia coli and Salmonella Can Survive in Kimchi during Fermentation

Abstract

The survival of Escherichia coli and Salmonella strains during diced white radish kimchi fermentation was studied. Kimchi batches inoculated with the pathogens were fermented at 4, 15, and 25 degrees C for 42 to 384 h. Cell counts of E. coli and Salmonella were enumerated on E. coli-coliform count plates and xylose lysine deoxycholate agar, respectively. Baranyi (primary model) and polynomial (secondary model) models, validated by root mean square error, were used to describe the kinetic behavior of the pathogens. In the primary model, both the death phase shoulder (E. coli: 208.18 to 8.25 h, 4 to 25 degrees C; Salmonella: 79.91 to 0.97 h, 4 to 25 degrees C) and bacterial cell counts (log CFU per gram per hour) decreased with increasing temperature (P < 0.05) (death rate: E. coli: -0.02 to -0.09, 4 to 25 degrees C; Salmonella: -0.01 to -0.10, 4 to 25 degrees C), the results being equally significant in the secondary model. The root mean square error (0.480 to 0.485) showed that the model performance was good. The fermentation temperature and time are the critical factors that control pathogenic E. coli and Salmonella in kimchi.