Physicochemical properties, microbial community evolution, and flavor compounds during the mechanized production of Jiangxiangxing high-temperature daqu

Abstract

: Mechanized production of high-temperature Daqu is on the rise and has become a pivotal trend in Baijiu industry. This study comprehensively examined the physicochemical properties, microorganisms and flavor compounds during the processes of mechanized production of high-temperature Daqu using high-throughput sequencing and headspace solid-phase microextraction combined with full two-dimensional gas chromatography-mass spectrometry (HS-SPME-GC×GC-MS) technology, and it further clarified the relationship between the microbiota and flavor. The results showed that 309 volatile compounds during Daqu fermentation were found, with the high-temperature stage crucial for flavor development. Partial Least Squares Discriminant Analysis (PLS-DA) further identified 26 key compounds, mainly pyrazines with a baking aroma. During the fermentation process, fungal activity predominates in the initial stages, whereas bacterial activity becomes more pronounced in the middle to late stages. During the initial fermentation stage, microbes mainly come from raw materials and Muqu, with Pantoea , Kroppenstedtia , and Virgibacillus being dominant. As fermentation continues, Kroppenstedtia , Virgibacillus , Saccharopolyspora , Bacillus , Thermoascus , and Thermoyces become prevalent. Bacteria played a more crucial role than fungi in forming key flavor compounds, with Virgibacillus , Scopulibacillus , and Thermomyces showing strong positive correlations with most pyrazine compounds. These results contribute significantly to the comprehensive understanding and enhancement of the mechanized fermentation process of High-temperature Daqu.

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