Effects of Chinese Cabbage Juice Marination Pretreatment on the Quality and Microbial Succession of Fermented Tilapia Fillets

The quality improvement of aquatic raw materials through fermentation assisted by fruit- and vegetable-derived ingredients has attracted increasing attention in aquatic food processing. This study investigated the interactions between spontaneously fermented Chinese cabbage juice (SFCCJ) and tilapia fillets during marination pretreatment and characterized changes in physicochemical properties, flavor compounds, and microbial communities of the fillets during subsequent fermentation. SFCCJ pretreatment enriched fermentable substrates (reducing and total sugars) and functional components (phenolics, flavonoids, and nitrate) in tilapia fillets, reduced inter-sample variability in the initial microbial community, and increased the abundances of Pantoea, Weissella, and Lactobacillus. During subsequent fermentation, L* and a* values increased, while hardness, chewiness, and shear force decreased by up to 19.78%, 73.12%, and 44.02%, respectively, and springiness increased by 25.35%. Meanwhile, FAAs, IMP, AMP, lactic and acetic acids accumulated, accompanied by increases in characteristic volatiles such as linalool, 1-heptanol, benzaldehyde, E-2-hexenal, 3-octanone, and 2-hexanone. In contrast, fishy odor-related compounds, including 2-ethyl-1-hexanol, E-2-octenal, and diallyl disulfide, decreased. LAB, particularly Weissella, Lactobacillus, and Lactococcus, dominated the microbial community from 12 h onward. Microbial metabolic network analysis further showed that these genera were closely associated with physicochemical changes and flavor development, whereas Pantoea, Enterobacter, and Citrobacter were associated with biogenic amine accumulation. These findings provide new insights into the targeted quality improvement of tilapia.