Insights into the salt-dependent mechanisms of physicochemical changes, microbial succession, and biogenic amine...

Excessive biogenic amine formation is a major safety concern in salt-reduced Doubanjiang fermentation. This study compared high- (12%), medium- (9%), and low-salt (6%) systems to elucidate physicochemical dynamics, microbial succession, and mechanisms promoting biogenic amine accumulation. Salt reduction accelerated acidification and proteolysis, with the low-salt system showing the highest total acidity (0.73 g/100 g) and free amino acids (2684.86 mg/100 g), accompanied by excessive biogenic amine accumulation (1456.95 mg/kg). Microbial communities responded strongly to salinity, with Weissella and Bacillus dominating under low-salt conditions, whereas Tetragenococcus and Millerozyma prevailed at higher salinities. Metagenomic and culturomic analyses further identified key functional strains associated with biogenic amine metabolism. Microbially driven acid accumulation and increased amino acid availability, together with activation of decarboxylases induced by acid stress, jointly promoted biogenic amine formation in the low-salt system. These findings clarify salt-dependent mechanisms of biogenic amine formation and provide guidance for designing safe reduced-salt fermentation strategies.