Combination approach of paired starter culture and lactic acid on inhibiting autochthonous lactic acid bacteria for extending kimchi shelf life

Excessive kimchi fermentation by lactic acid bacteria (LAB) during distribution and storage may negatively influence the organoleptic properties of kimchi. Thus, this study aimed to extend kimchi shelf life by inhibiting the growth of autochthonous lactic acid bacteria by applying paired starter culture, consisting of nisin-producing Lactococcus lactis WiKim0098 and nisin-resistant Leuconostoc citreum WiKim0096, and lactic acid. To maximize nisin production in the L. lactis WiKim0098 culture medium, the food grade medium composition and culture conditions were optimized using response surface methodology. Leu. citreum WiKim0096 exhibited resistance to nisin owing to high positive surface charge and was successfully used as a paired starter. In the kimchi application experiments, paired starter culture addition delayed the over-acidification (more than 1% as acidity) of kimchi for approximately 5-6 days, and when combined with lactic acid, delayed the ripening for more than 8 days compared to control kimchi fermented at 10 degrees C. The results of bacterial community and metabolite analysis via principal component analysis showed that paired starter culture and lactic acid inhibited the LAB growth at the early stage of kimchi fermentation. Our results suggest that combining paired starter culture with lactic acid can effectively extend the kimchi shelf life. Specifically, it is expected to be effectively applicable to kimchi products intended for export, which demand extended shelf life.