Microbial succession-potential influence mechanism on flavor modulation in spontaneously fermented Moringa oleifera leaves: An integrative multi-omics approach.

In this study, the relationship between flavor composition and microbial succession in Moringa oleifera pickles (MOPs) at different stages of spontaneous fermentation was systematically investigated. The results demonstrated a significant increase in the content of organic acids and amino acids during fermentation including malonic acid, citric acid, valine (Val), and asparagine (Asn). These compounds not only enhanced the overall flavor profile but also provided favorable nutritional conditions that supported microbial succession. Furthermore, an integrated aroma network was established through the combined application of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS). GC-MS identified key aroma-active compounds such as ethyl caproate (fruity note), 3-hexenal (green, grassy note), and 2-phenylethanol (floral, rosy note). Complementarily, GC-IMS confirmed that esters, alcohols, and terpenes were the major contributors to fruit-like, mushroom-like, and fresh herbal aromas, indicating their critical role as flavor-modulating compounds throughout fermentation. Metagenomic analysis revealed Corynebacterium, Escherichia, Pseudomonas, Xanthomonas, and Pantoea as the dominant microbial genera involved in fermentation. These microbes primarily participated in amino acid, carbohydrate, and nucleotide metabolism and exhibited a close association with the formation of key flavor compounds. The strong influence of microbial succession on flavor evolution is likely driven by the observed correlations between microbial taxa and volatile organic compounds (VOCs). These correlations may stem from a series of complex ecological and metabolic interactions, including substrate competition, niche adaptation, and upstream-downstream dependencies within microbial metabolic networks. This study provides a theoretical foundation for the quality control of MOPs and the mitigation of potential pathogenic microorganisms, thereby supporting its application in enhancing product quality and consumer sensory satisfaction in the pickle industry.