Impact of NaCl on physicochemical properties, microbial community, and pathogen surveillance in the Chinese traditional fermented broad bean (Vicia faba L.) paste

Doubanjiang (DBJ), a mixed fermented broad bean (Vicia faba L.) and red pepper (Capsicum annuum L.) condiment used worldwide, is known for its high-salt content (∼20g/100g). Industry demands sodium reduction in DBJs. In this study, we investigated the physicochemical properties, microbial community changes, and pathogen surveillance in DBJ samples with varying salt contents (10g/100g, 15g/100g, 20g/100g and 25g/100g). Our findings revealed that these samples could be categorized into two groups: low-salt (10g/100g) and high-salt samples (15-25g/100g). In low-salt samples, Lactobacillus emerged as the predominant bacteria, exhibiting higher antioxidant activity. The most concentrated organic acids were γ-aminobutyric acid and lactic acid. Conversely, Staphylococcus dominated the bacteria composition in high-salt samples. Human pathogenicity such as Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae were discovered in both low- and high-salt samples. Higher abundance of antimicrobial resistances was observed in high-salt samples while slightly increased biogenic amine content in low-salt samples. This knowledge provides insights into impact of NaCl on fermented broad bean (Vicia faba L.) paste.