Mechanistic insights into microbial contribution and key flavor formation of cereal vinegar fermentation in the industrial closed solid-state fermenter.

The closed solid-state fermenter was applied in vinegar factory production to improve controllability and reduce labor. However, microbial roles and key flavor formation mechanisms remain unclear in this controlled fermentation system. In the present study, the microbial metabolic network related to substrate degradation and key flavor formation was reconstructed in the industrial solid-state fermenter. Acetobacter, Lactobacillus, Limosilactobacillus, and Acetilactobacillus were proven key functional microorganisms. Limosilactobacillus and Acetilactobacillus were key microorganisms for substrate degradation in the early stages, while Lactobacillus predominantly facilitates substrate degradation in the late stages. Acetobacter, Lactobacillus, and Limosilactobacillus play a vital role in flavor formation in the whole stages. Furthermore, the metabolic activity of key microorganisms could be regulated by temperature and aeration rate, further affecting substrate degradation and flavor formation. This study contributed to understanding the relationship between active microorganisms and flavor formation, and these results provide a basis for the targeted regulation of flavor profiles through the regulation of temperature and aeration rate of the industrial closed solid-state fermenter in the future.