Temperature impact on microbial and metabolic profiles in kimchi fermentation.

Kimchi is a traditional Korean fermented food and harbors diverse bacteria. Therefore, proper temperature management contributes to the fermentation and preservation of kimchi. In this study, we explored fermentation temperature influences the bacterial composition and metabolite variations in kimchi, employing pyrosequencing for bacterial community analysis and mass spectrometry for metabolite profiling. Elevated temperatures within the range of 10-15 °C had a significant impact on the community of lactic acid bacteria (LAB) compared to 4 °C, leading to increased bacterial diversity and richness. We observed a significant increase in and , alongside a reduction in , during fermentation at 10-15 °C. These changes occurred within a similar pH range across different kimchi fermentation periods. We performed a liquid extraction via the acetonitrile method, which involved the collection of kimchi samples, and performed LC-MS analysis. Our analysis revealed approximately 5000 metabolites. Notably, we observed a significant increase in metabolite counts, with 3048 metabolites increasing at 10 °C and 2853 metabolites exhibiting a similar trend at 15 °C. Metabolite analysis showed an increase in lactic and succinic acid with increased glucose and sucrose consumption at 10 and 15 °C. These results indicated that elevated temperatures significantly influenced the glycolysis and tricarboxylic acid cycle, leading to increased acidity during the fermentation process. These findings show the crucial role played by temperature in controlling the fermentation process, thereby influencing the bacterial succession and the resulting flavor and taste of the product. Therefore, proper temperature management can effectively control kimchi fermentation and yield the desired sensory properties.