Microbial community structure analysis and screening of dominant strains in Guizhou white sour soup: enhancing safety, improving flavor, and shortening fermentation cycle.

White sour soup (WSS) is a traditional fermented food from Guizhou, China. To address the issues of long fermentation cycles, inconsistent quality, and safety risks, this study screened core strains based on microbial diversity. Analysis of 20 WSS samples revealed Lactobacillus, Geotrichum, and Pichia as dominant genera, with eight harmful microorganisms detected in naturally fermented samples. Lacticaseibacillus paracasei MY6 and Pichia pseudolambica PY4 were selected as starter cultures. In the inoculated fermentation group (H), no harmful microorganisms were found, and pH, titratable acidity, and nitrite levels reached 2.95 ± 0.01, 8.78 ± 0.19 mg/g, and 9.01 ± 0.18 mg/kg. The H group presented superior overall sensory quality. GC-IMS identified 36 volatile organic compounds (VOCs), with 16 biomarkers distinguishing different WSS samples. Among them, 2-pentylfuran, methanol, and 2-propanone may serve as characteristic VOCs of the H group. This study offers theoretical support for the standardized and safe production of WSS.