A multi-dimensional exploration of taste formation in suansun: from amino acids, organic acids, to microbial...

Three Lactobacillus plantarum strains (LPS1, LPS2, LPS3) were inoculated into suansun; integrated non-targeted metabolomics and metatranscriptomics were then applied to investigate their roles in taste development and metabolic regulation. LPS3, with high initial amino acid levels and a 52 % reduction in total free amino acids (FAAs) during fermentation, was best suited for short-cycle fermentation. LPS2 produced a strong but short-lived umami taste, while LPS1, characterized by stable metabolic activity, was more appropriate for standardized production with balanced flavor. Acid profile analysis showed that LPS2 generated the highest levels of acetic acid, resulting in sharp but transient sourness. LPS3 maintained higher lactic acid levels at late fermentation and showed a 77.16 % reduction in citric acid (vs. lower reductions in LPS1 and LPS2), yielding a more moderate and stable acidity. In contrast, LPS1 showed a simpler and less intense acidic profile. Microbial community profiling revealed sustained dominance of Lactobacillus plantarum in LPS2 and LPS3, whereas LPS1 was notably enriched with Weissella cibaria. Transcriptomic analysis showed that genes encoding acetaldehyde oxidase and phosphatidylethanolamine methyltransferase-key enzymes in pyruvate-to-acetyl-CoA conversion-were upregulated in LPS1 and LPS2. Additionally, LPS1 showed elevated expression of the HpaH gene, involved in aromatic amino acid metabolism, contributing to enhanced organic acid production. This study is the first to delineate how distinct Lactobacillus plantarum strains differentially regulate flavor formation in suansun, providing valuable insights for precision fermentation and product quality improvement.