Effects of a novel salt-tolerance Lactiplantibacillus plantarum on the physicochemical properties and volatile profiles of broad-bean paste

Broad bean paste (BBP) is a traditional Chinese condiment whose spontaneous fermentation often leads to unstable quality and safety concerns. This study isolated a novel halotolerant <i>Lactiplantibacillus plantarum</i> YQ1 from BBP as a starter culture. The strain exhibited exceptional salt tolerance (18% NaCl), acid and bile resistance, and a favorable biosafety profile. In BBP fermentation, it significantly reshaped metabolites, increasing tartaric and lactic acids, and promoting threonine accumulation. Volatile analysis demonstrated substantial improvements in desirable aroma compounds, with phenethyl alcohol increased by 436.37% and benzyl alcohol increased by 553%. Meanwhile, undesirable benzaldehyde, 3-methylbutanoic acids and 2-methylbutanoic acid decreased by 87%, 81%, and 62%. Genomic analysis further identified key genes underpinning these traits, as well as phenylalanine metabolism and alcohol-derived aroma biosynthesis. These findings highlight the potential of <i>L. plantarum</i> YQ1 as a starter culture to enhance the flavor, minimize off-flavors, and stabilize fermentation for high-salt BBP production.