Growth inhibition of foodborne pathogens by kimchi prepared with bacteriocin-producing starter culture.

Kimchi (starter kimchi) was prepared with Leuconostoc citreum GJ7, a bacteriocin producer, with the objective of preventing growth and/or survival of foodborne pathogens such as Escherichia coli O157:H7, Salmonella Typhi, and Staphylococcus aureus. Numbers of the pathogens inoculated to 5.41 to 5.63 log CFU/mL into the filtrate of freshly made starter kimchi remained stable for the first 12 h of incubation at 10 °C. Reductions of 2.69, 2.88, and 3.42 log CFU/mL were observed 48 h after inoculation with E. coli O157:H7, S. Typhi, and S. aureus, respectively. Use of the bacteriocin-producing starter culture for kimchi fermentation significantly reduced the numbers of pathogens in the filtrate. Reductions of 3.85, 4.45, and 5.19 log CFU/mL were observed 48 h after inoculation for E. coli O157:H7, S. Typhi, and S. aureus, respectively. Presumably, the antimicrobial activity came from the ingredients of kimchi such as sulfur-containing compounds, low pH (approximately pH 4.5) produced by the conversion of sugars into organic acids and the bacteriocins potentially produced by lactic acid bacteria (LAB), such as kimchicin GJ7. Together, these data suggest that addition of a starter culture capable of producing bacteriocins could serve as a strategy to protect the fermented product from delivering pathogens upon consumption and that the kimchi filtrate itself may be used as a food preservative. Practical Application: The adaptation of the starter fermentation into kimchi induced a faster die off of the pathogens as compared to natural fermentation. The in situ bateriocin-production by Leuc. citreum GJ7 in kimchi would act with antimicrobial kimchi ingredients in a synergistic manner to protect the fermented product from delivering pathogens upon consumption.