Metabolic network of lactic acid bacteria driving the formation of characteristic flavor compounds in traditional Yunnan fermented soy whey (FSW) and their formation mechanisms
Lijing Liu, Tong Zhu, Jingan Yang, Jinyu Zhao, Jiashun Jiang, Wei Zhang, Menglong Liu, Yanan Shi, Hong Li, Yongjin Hu
Abstract
ABSTRACT Fermented soy whey (FSW) is a traditional coagulant for Yunnan fermented tofu, where its microbial communities and metabolites are decisive for the final product's flavor. This study aimed to systematically elucidate the dynamic interplay between microbial succession, metabolite profiles, and physicochemical parameters during FSW fermentation. Using an integrated multi-omics approach that combined non-targeted metabolomics (LC-MS), volatile compound analysis (GC-MS), and 16S rRNA sequencing (Illumina MiSeq platform), we revealed that the fermentation in all three sampled regions was driven by ecosystems dominated by Lactic Acid Bacteria (LAB). The process showed clear temporal dynamics: rapid LAB proliferation within the first 24 hours led to significant acidification and the formation of a foundational taste profile. LC-MS analysis identified a core organic acid network, driven by LAB, that produced key non-volatile compounds such as citric acid, cis-aconitic acid, and L-pyroglutamic acid. These synergistically created a complex “umami-sour-salty” taste foundation. Concurrently, GC-MS analysis revealed the formation of distinct volatile compounds in later stages (24-36h), which define the unique aromatic characteristics of each region. This work deciphers the microbial mechanisms behind flavor formation in FSW, providing a scientific basis for quality control and standardization.