Difference between traditional brewing technology and mechanized production technology of jiangxiangxing baijiu: Micro ecology of zaopei, physicochemical factors and volatile composition

Mechanized production of Jiangxiangxing Baijiu (JB) stands as a pivotal trend in today's Baijiu industry. This study, employing high-throughput sequencing and headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) technology, comprehensively analyzed the micro ecology, physicochemical factors, and volatile components during pit fermentation, comparing traditional fermentation Zaopei (TZP) and mechanized fermentation Zaopei (MZP). According to the research findings, the dominant microorganisms in the fermentation process of ZP comprise Lactobacillus, Monascus, Issatchenkia, and Zygosaccharomyces. In addition, functional microorganisms like Zygosaccharomyces, Monascus, Issatchenkia, Leiothecium, Candida, Pichia, and others exhibited differences on day 0 and throughout the fermentation process. These differences are attributed to the effects of distinct fermentation environment and physicochemical factors. Furthermore, comprehensive analysis detected 87 volatile compounds in TZP and MZP, with 56 showing significant differences, primarily including alcohols, aldehydes, ketones, acids, esters, and aromatics. Additionally, fermentation can be classified into two phases based on ethanol and volatile compounds production: the initial phase (0-12 days, P1) primarily focuses on alcohols production, while the subsequent phase (12-30 days, P2) concentrates on volatile compounds generation. The subsequent correlation analysis indicates that variations in volatile compounds primarily arise from shifts in microbial composition, with notable differences observed in fungi, specifically Monascus, Zygosaccharomyces, and Issatchenkia, which drive the disparities in volatile compounds. This study provides an important theoretical basis and practical guidance for the realization of mechanized high-quality production of JB.