Microbiome-metabolome interplay in low-sodium Yunnan suancai: Unraveling quality enhancement through partial NaCl replacement with KCl

Suancai is a traditional fermented vegetable pickled in NaCl, but excess NaCl poses food safety risks. This study explored how replacing NaCl with 0 % and 20 % KCl affects microstructure, biogenic amines (BAs), volatiles, and bacterial communities during suancai fermentation, and revealed cross-correlations between microbes and metabolites. Low-sodium treatment promoted cell wall degradation, reduced nitrite and amino nitrogen levels, and significantly decreased total biogenic amines while enriching volatile variety and concentration. Variations in 33 volatiles led to differences in aroma quality between low-sodium and high-sodium suancai. Weissella and Lactiplantibacillus were the dominant genera, with Weissella cibaria, Lactiplantibacillus pentosus, and Lactiplantibacillus plantarum identified as core species under both conditions. Metabolome-microbiome analysis linked specific strains (e.g., Leuconostoc mesenteroides, Limosilactobacillus fermentum, W. cibaria, and L. plantarum) to spicy, fruity, and sour aromas and identified potential BAs degradation. Metacyc analysis identified key metabolic pathways associated with flavor in low-sodium suancai, such as amino acid biosynthesis and aromatic compound degradation. These findings highlight KCl as a partial NaCl replacement to improve suancai quality and safety.