Elucidating metabolic and flavor evolution in traditional Chinese soy sauce during industrial-scale fermentation: A multi-omics approach

The dynamic changes in metabolomics and flavoromics during the industrial-scale fermentation of Chinese traditional soy sauce were evaluated. The results revealed that the amino acid nitrogen content gradually increased to 1.03 g/100 mL after 60 days of fermentation. The reducing sugar content peaked at 86.57 mg/mL on the 7th day fermentation. A total of 573 nonvolatile metabolites were detected, among which amino acids, peptides, and analogues accounted for the largest proportion (21 %). The key stage of metabolite transformation was the early fermentation stage (1-10 d), and amino acid metabolism dominated the entire fermentation process. A total of 119 VFCs were detected. The contents of esters, alcohols, aldehydes, ketones and phenols increased, whereas the contents of acids fluctuated. A significant correlation was noted between the changes in characteristic VFCs and metabolites; thus, the content of the characteristic VFCs is potentially increased by supplementing the related metabolites in positive metabolic pathways.