Metabolomic Profiling Reveals Dynamic Changes in Organic Acids During Zaolajiao Fermentation: Correlation with Physicochemical Properties and CAZymes

Zaolajiao (ZLJ) is a traditional national specialty fermented condiment in Guizhou, and organic acid is one of its main flavor substances. In the study, we used metabolomics and multivariate analysis to identify differential organic acids (DOAs) during ZLJ fermentation and explored their correlations with physicochemical indices and CAZymes. Eight DOAs were detected, with citric acid prominent early and lactic acid dominant late in fermentation. Citric acid exhibited a highly significant negative correlation (p < 0.01, |r| > 0.955) with AA3, GT4, and CE1, while showing significant positive correlation (p < 0.05) with GH1, soluble sugars, and total acids. Lactic acid exhibited a highly significant positive correlation with total acid, AA3, and GT4 (p < 0.05, |r| > 0.955). Conversely, it showed a significant negative correlation with soluble sugar (p < 0.05) and a highly significant negative correlation with GH1 (p < 0.05, |r| > 0.955). The most significant metabolic pathway for DOAs enrichment was the citrate cycle (TCA cycle).