Improving quality, flavor profiles, and safety of low-salt pickled potherb mustard using Lactiplantibacillus plantarum WZW-1 as microbial starter on an industrial-scale fermentation.

Low-salt fermentation has attracted considerable attention in the fermented vegetable industry; however, its application is limited by poor flavor, quality, and toxic metabolite accumulation. In this study, the direct vat set (DVS) strain Lactiplantibacillus plantarum WZW-1 was used as the starter culture for the industrial-scale fermentation of low-salt pickled potherb mustard (PPM). Notably, physicochemical properties, flavor profiles, biogenic amine (BA), microbial succession, and metabolic functions of the products produced through natural fermentation and DVS-inoculated fermentation (DLF) were compared. The results showed that DLF-prepared products exhibited superior color, texture, sensory, and quality. Compared with low-salt without starter (LSF), the total BA content in the DLF group decreased by 61.66% and 51.92% on day 7 and 14, respectively (p < 0.05). Moreover, strain WZW-1 promoted flavor development, restrained excess acetic acid production, improved volatile metabolite diversity, and enriched characteristic aromas (e.g., isothiocyanates, alcohols, and esters), thereby improving the overall flavor quality and safety of low-salt PPM. The relative abundance of Lactiplantibacillus increased from 0.05 to 13.02% in LSF to 27.86-68.43% in DLF group during 0-21 days of fermentation. Notably, Lactiplantibacillus plantarum and Levilactobacillus brevis were identified as the key functional strains in the DLF group, predominantly contributing to carbohydrate, lipid, amino acid, and nucleotide metabolic pathways. Metagenomic annotation analysis further revealed that the DLF group exhibited higher relative gene abundance of alcohol dehydrogenase and aryl-alcohol dehydrogenase and lower abundance of BA-producing enzymes. These effects consequently promoted volatile alcohol production and reduced BA accumulation in low-salt PPM. Therefore, the application of Lactiplantibacillus plantarum WZW-1 as a DVS starter shows great potential for industrial production of low-salt PPM.