Spatial heterogeneity of microbiota and flavor across different rounds of sauce-flavor baijiu in Northern China

Sauce-flavor baijiu (SFB) is a traditional Chinese distilled liquor crafted through a distinctive brewing process, involving seven rounds of stack fermentation (SF) and pit fermentation (PF). To date, there remains a knowledge gap regarding the microbial succession and flavor throughout all rounds of SFB with distinctive northern characteristics. Through LEfSe analysis, Saccharopolyspora, Virgibacillus, Thermoascus and Thermomyces, and Lactobacillus and Issatchenkia were found to be the most differentially representative genera in SF and PF, respectively. A total of 93 volatile flavor compounds were found in base baijius through the gas-chromatography mass spectrometry. Moreover, 29 volatile flavor substances with significant difference in base baijius of different rounds were revealed using the OPLS-DA model and VIP values and Spearman correlation analysis shows that bacteria have a greater impact on differential flavor compounds than fungi. This study provides a new perspective and insight into the brewing of northern SFB.