Revealing the correlation between microbial community and flavor compounds in traditional Chinese sourdough by integrating flavoromics and metagenomics.

Traditional Chinese sourdough (CTS) is mainly used for the fermentation of steamed pastries, providing a unique natural fluffiness and distinctive flavor, and thus holds important culinary value. However, the microbial mechanisms underlying the diversity of its regional characteristic flavors remain poorly understood. In this study, we integrated metagenomic sequencing with multi-platform flavor profiling-including high-performance liquid chromatography (HPLC), electronic nose, gas chromatography-mass spectrometry (GC-MS), and gas chromatography-ion mobility spectrometry (GC-IMS)-to characterize the physicochemical properties, microbial composition, and flavor compounds of 10 CTS samples collected from five provinces across China. A total of 1231 genera and 3358 species were identified, with Fructilactobacillus sanfranciscensis, Saccharomyces cerevisiae and Lactiplantibacillus plantarum being the dominant species. Flavor profiling analysis revealed 109 volatile organic compounds (VOCs), of which 11 key aroma-active compounds (e.g., 1-nonanol, phenethyl alcohol) were identified based on odor activity values (OAV ≥ 1). Using orthogonal partial least squares (O2PLS) modeling, we established associations between 25 potential flavor-producing microorganisms and specific metabolites. Notably, S. cerevisiae exhibited a significant positive correlation with acetic acid, 1-nonanol and glutamic acid, while L. plantarum showed a strong positive correlation with phenethyl alcohol. This study reveals the correlation patterns between microbial communities and flavor compounds in CTS, offering foundational insights for starter culture design, flavor standardization, and industrial application of traditional fermented doughs.