Lactiplantibacillus plantarum-mediated modulation of volatile flavor and quality in low-salt spontaneously fermented yellow capsicum sauce

Yellow capsicum sauce (YCS) is a special fermented condiment in Hainan province, China, and its fermentation typically occurs in a high-salt environment. In this study, the effects of different salt contents (5, 10, 15, and 20%, w/w) on microbial communities and volatile flavor profiles in YCS were systematically investigated by metagenomic approach and HS-SPME-GC-MS. The results revealed that Lactiplantibacillus (54.66%) was the dominant genus in low-salt samples (SF5), while its abundance was less than 6% in higher salinity levels (SF15 and SF20). A total of 48 volatile flavor compounds (VFCs) were detected in the naturally fermented YCS, with alcohols and esters being the primary VFCs. Low-salt fermentation facilitated the accumulation of VFCs, and the total VFCs content in SF5 was the highest. Aroma compounds showed a strong correlation with Lactiplantibacillus plantarum. To further validate the findings, L. plantarum MA1 isolated from SF5 was inoculated into the low-salt YCS substrate for bioaugmented fermentation. This strain significantly increased key aroma components, such as cis-3-hexenyl isovalerate, hexyl 3-methylbutanoate, and ethyl acetate. Moreover, it significantly increased the lactic acid content while reducing the nitrite content, thereby more effectively preserving the fresh yellow color of capsicum sauce and the stability of its spiciness.