Bidirectional modulation of microbial communities by tea polyphenols and gallic acid enhances quality in dry...

Tea polyphenols (TP) and its primary component gallic acid (GA) possess antibacterial and antioxidant properties, serving as natural additives to enhance the safety and quality of fermented meat products. This study investigated the bidirectional regulatory effects of TP and GA on microbial dynamics and quality attributes in dry fermented sausages. TP (1-4 mg/mL) enhanced the growth of Lactiplantibacillus plantarum while inhibiting Staphylococcus aureus and Escherichia coli, promoting lactic acid bacteria (LAB) dominance and reducing spoilage and pathogenic bacteria. Sausages treated with TP showed reduced levels of biogenic amines (291.06 vs. 376.22 mg/kg) and NDMA (0.86 vs. 1.32 μg/kg), improved texture (hardness and springiness), and better color stability, all without affecting sensory acceptability. Metabolomic and metagenomic analyses suggested that GA enriched beneficial Lactococcus garvieae and suppressed spoilage-associated Enterococcus faecalis and Citrobacter freundii. Besides, it promoted the microbial-mediated production of key antioxidant metabolites and flavor enhancers (e.g., purpurogallin, sesamol). These results indicated that TP and GA could serve as multifunctional additives that enhance fermentation efficiency, microbial safety, and sensory quality by precisely regulating microbial communities and their metabolic functions.