Purpose: This study was performed to evaluate the microbial contamination levels of 100 commercial Kimchi samples and 200 ingredients samples such as dried red pepper powder, ginger, radish, garlic and onion. In addition, washing treatment was examined for its effectiveness in reducing microbial contamination levels in minor ingredients of Kimchi.
Methods: Populations of sanitary indication bacteria (total aerobic bacteria, coliforms, Escherichia coli) and pathogenic bacteria (Bacillus cereus, Enterohemorrhagic E. coli, Clostridium perfringens, Campylobacter jejuni/coli, Staphylococcus aureus, Salmonella spp., Vibrio parahaemolyticus, Listeria monocytogenes, and Yersinia enterocolitica) were investigated in all samples.
Results: In case of commercial Kimchi, total aerobic bacteria and coliforms were detected at the levels of 4.7~8.9 log CFU/g and 0~3.9 log CFU/g, respectively. Among minor ingredients, microbial contamination in ginger showed particularly higher than others. Levels of total aerobic bacteria and coliforms in ginger samples were 5.3~8.8 log CFU/g and 2.8~7.3 log CFU/g, respectively. For pathogenic bacteria, B. cereus ranged between 0~4.0 log CFU/g in all samples while others were not detected. The optimized washing treatment led to a decrease in the number of sanitary indication bacteria and pathogenic bacteria in all samples. For ginger samples, the reduction values of total aerobic bacteria and coliforms after washing treatment were 0.2∼3.2 log CFU/g and 0.3∼2.7 log CFU/g, respectively. Among the pathogenic bacteria, reduction values of B. cereus were 1.0∼3.9 log CFU/g.
Significance: According to these results, the reduction of microbial contamination in its ingredients is key-point to ensure the safety of Kimchi. Moreover, these results indicated that appropriate washing strategy could reduce microbial contamination level of commercial kimchi. Thus, there is an urgent need for a washing treatment system to control the microbiological risk factors.