Effect of electron beam irradiation on sliced Korean cabbage (Brassica rapa L. ssp. pekinensis) kimchi: Kinetics of microbial inactivation and changes in physiochemical and microbial quality

Abstract

Ensuring microbial safety and controlled kimchi fermentation without thermal sterilization is challenging owing to the background microbiota present in raw materials of kimchi. In this study, we investigated the effect of electron beam (EB) irradiation on naturally occurring microbiota and physicochemical characteristics of sliced Korean cabbage kimchi (KCK). In addition, the inactivation kinetics of natural microbes during EB irradiation were evaluated. The total aerobic bacteria (TAB) and total lactic acid bacteria (TLAB) counts in sliced KCK significantly decreased (p < 0.05) with an increase in EB irradiation. In particular, the total coliform (TC) count in unripened and optimally ripened kimchi was reduced to below the detection limit (1 log CFU/g) following 4 kGy EB irradiation. In contrast, no significant difference was observed in the physicochemical characteristics, viz., pH, titratable acidity, salinity, electrical conductivity, and reducing sugar content between the non-irradiated and irradiated slices of KCK. These results imply that EB irradiation effectively controlled microorganisms i.e., TC without adversely affecting the quality of kimchi. Furthermore, we determined that the Gompertz model was relatively more suitable for predicting the inactivation of TAB, TLAB, TC, or yeast and molds in sliced KCK than the linear model.