Analysis of Physicochemical Characteristics, Flavor, and Microbial Community of Sichuan Industrial Paocai Fermented by Traditional Technology

Sichuan Paocai is a representative traditional fermented vegetable in China, which is deeply embedded in local geographical and cultural heritage. However, regional differences in product characteristics remain poorly understood. In this study, the physicochemical properties, volatile compounds, and microbial communities of Paocai from seven production regions in Sichuan (named FB, AB, BZ, CD, DZ, MY, and YS) were systematically investigated. Parameters including pH, salinity, nitrite, organic acids, and color were determined, while volatile profiles were analyzed using an electronic nose and comprehensive two-dimensional gas chromatography–mass spectrometry. A total of 294 volatile compounds were identified, with alcohols, esters, and isothiocyanates emerging as the major contributors to flavor differentiation. UMAP and OPLS-DA analyses revealed distinct regional clustering, which was consistent with electronic nose profiling, and 111 volatile compounds were identified as key aroma markers. Microbial diversity was assessed using 16S rRNA gene sequencing, demonstrating that Lactobacillus, Lentilactobacillus, Pediococcus, and Weissella were the dominant taxa, although the richness varied significantly across regions. An LEfSe analysis further identified region-specific biomarkers, including Pediococcus, Lactococcus, and Leuconostoc in FB; Lactobacillus in AB; Pediococcus ethanolidurans in BZ; Levilactobacillus in DZ; Lentilactobacillus in MY; and a more diverse microbiota in MS. A correlation analysis highlighted the pivotal roles of distinct microbial groups in shaping and transforming flavor compounds across different regions. Overall, these findings provide scientific guidance for the development of high-quality, region-specific products and contribute to the protection, branding, and market competitiveness of geographically indicated foods.