To investigate the dynamic changes in fermented grains during the second round of stacking fermentation of cave-brewed Jiangxiangxing Baijiu, gas chromatography-mass spectrometry (GC-MS) and high-throughput sequencing were employed to systematically analyze the composition of volatile flavor compounds and the structure of the microbial community. The results demonstrated that as fermentation progressed, the temperature and moisture content of fermented grains significantly increased from 29.67 ℃ and 45.12% to 44.33 ℃ and 54.94%, respectively. Additionally, the starch content decreased from 32.24% to 25.82%. A total of 364 bacterial genera and 97 fungal genera were detected, with the dominant bacterial genera being Virgibacillus, Oceanobacillus, and Kroppenstedtia. The dominant fungal genera were Thermomyces, Thermoascus, and Saccharomycopsis. During fermentation, the abundance of dominant bacteria such as Virgibacillus initially increased and then decreased; regarding the fungal community, the abundance of Thermomyces gradually decreased and Monascus became enriched. A total of 44 volatile flavor compounds were detected during the fermentation process, predominantly esters, aldehydes, and alcohols. Correlation analysis demonstrated that Lactobacillus and Monascus exhibited significant positive correlations (|r| > 0.7, P < 0.05) with the contents of various esters, suggesting their important roles in the flavor formation of cave-brewed Jiangxiangxing Baijiu. This study systematically elucidated the dynamic correlations among the physicochemical properties, microbial community succession, and flavor metabolite formation of fermented grains during the second round of stacking fermentation of cave-brewed Jiangxiangxing Baijiu, providing a theoretical basis for in-depth research on its fermentation mechanism and process optimization.

The microbial community structure and volatile flavor compounds in chopped pepper with ginger shreds at the post-ripening stage were analyzed by high-throughput sequencing and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively, and the relationship between them was analyzed multivariate statistical analysis. The results showed that Proteobacteria, Firmicutes and Bacteroidetes were identified as the dominant bacterial phyla, and Ascomycetes and Basidiomycetes as the dominant fungal phyla. At the genus level, nine core bacterial genera and 11 core fungal genera were identified. The major bacterial genera identified were Ralstonia, Acinetobacter and Enterobacter, and the major fungal genera identified were Colletotrichum, Penicillium and Fusarium. A total of 87 volatile compounds were identified, including 15 hydrocarbons, 10 acids, 28 alcohols, 3 aldehydes, 11 esters, 5 ketones, 5 phenols, 3 ethers, 2 terpenes and 5 other compounds. Based on Pearson’s correlation coefficient, the correlation between 36 differential volatile flavor substances (P < 0.05, variable importance in the projection (VIP) value greater than 1) and dominant microorganisms was analyzed. It was found that the changes of many flavor substances were significantly correlated with the genera Debaryomyces, Enterobacter and Erwinia. This study will provide data support for improving the quality of chopped pepper with shredded ginger.