Abstract: This study aimed to systematically elucidate the dynamic succession of the microbial community and its relationship with quality formation during the fermentation of lacto-fermented Chinese cabbage. Quality parameters such as texture, color, taste characteristics (using an electronic tongue), and total acid, soluble solids and nitrite contents were evaluated at different fermentation stages, and volatile flavor substances were analyzed by gas chromatography-ion mobility spectrometry (GC-IMS). 16S rDNA high-throughput sequencing was used to analyze the changes in microbial community structure, and non-targeted metabolomic analysis was also performed. The results showed that the springiness and hardness of fermented Chinese cabbage gradually decreased as fermentation progressed, while the stickiness and chewiness increased significantly in the late stage of fermentation. The contents of total acid and soluble solids continued to rise, while the nitrite content showed a typical trend of first increasing and then decreasing and was significantly lower than the limit stipulated by the Chinese National Standard in the late fermentation stage. A total of 89 volatile flavor compounds were identified, mainly including esters, alcohols, aldehydes, ketones, and acids. Benzaldehyde, 1-propanol, 1-hexanol, 2-heptanol, and other volatile flavor compounds contributed significantly to the overall aroma of fermented Chinese cabbage, and the late fermentation stage was the key period for flavor compound enrichment. Microbial community analysis showed that the community structure gradually changed from a diverse environmental microbiota to a lactic acid bacteria-dominated community, and the α-diversity decreased significantly. Metabolomic analysis revealed that lactic acid, malic acid, fumaric acid, and other organic acids, as well as a variety of free amino acids and nucleosides, accumulated significantly in the late stage of fermentation, which was highly consistent with the establishment of lactic acid bacteria dominance. Correlation analysis between microbial genera and key flavor metabolites indicated that the succession of the microbial community during the fermentation process drove the production of key metabolites, which in turn affected physicochemical properties and sensory characteristics of fermented Chinese cabbage. This indicates a close association among microorganisms, metabolites and flavor.

Key words: fermented Chinese cabbage; lactic acid bacteria fermentation; microbial community; quality development; flavor substances