Dynamics of biogenic amine formation in fermented mandarin fish: Insights from precursor utilization and microbial succession

The high protein content of mandarin fish (Siniperca chuatsi) provides abundant substrates for biogenic amines (BAs) formation during fermentation, but the temporal dynamics and microbial drivers of BAs accumulation remain unclear. This study systematically investigated the succession of free amino acids (FAAs), BAs, and bacterial communities during fermentation. Results showed that the total FAAs peaked on day 5, whereas total BAs reached a maximum on day 10 (767.58 mg/kg). The BAs surge initiated at day 7.5, approximately 2.5 days after the FAAs peak. Putrescine, cadaverine, histamine, and tyramine were the predominant BAs, accounting for >98% of total BAs. Correlation analysis revealed strong negative correlations between BAs and their precursor FAAs (|R| = 0.588-0.842), suggesting the decarboxylation-driven conversion. Microbial succession identified candidate genera positively associated with BAs accumulation, including Vibrio and Morganella, while the late-stage decline of Vibrio and the increase of Vagococcus coincided with BAs reduction. Metagenomic analysis revealed that amino acid decarboxylase gene abundance peaked at day 10, while BA-degrading gene abundance peaked at day 15, consistent with the BAs dynamics. Days 5 to 10 are identified as a period that may warrant enhanced monitoring in industrial practice. A sequential temporal pattern linking substrate availability, microbial shifts, and BAs dynamics is described. These findings provide insights into the sequential dynamics of BAs formation in fermented mandarin fish and provide a scientific foundation for quality management in traditional fermented fish products.