Correlation Analysis of Physicochemical Indexes, Volatile Fla-vor Components and Microbial Communities of High-Temperature Daqu in North Region of China

Daqu is a microbial rich Baijiu fermentation starter. The high-temperature Daqu plays an essential role in the manufacturing of Sauce-flavor Baijiu. However, few studies focus on three kinds of high-temperature Daqu (white, yellow and black Daqu) in northern China. In this study, the physicochemical indexes, volatile flavor compounds, and microbial characteristics of the three different colors of high-temperature Daqu in northern were comparatively analyzed to reveal the potential functions. White Daqu (WQ) exhibited the highest liquefying power and starch, and Black Daqu (BQ) showed the highest saccharifying power and esterifying power. A total of 96 volatile components were identified in the three Daqus, the contents of volatile components of Yellow Daqu (YQ) were the highest. Microbial community structures analysis showed that Bacillus and Byssochlamys were dominant in BQ, Kroppenstedtia and Thermoascus were dominant in WQ, Virgibacillus and Thermomyces dominated the YQ. The RDA analysis revelaed that correlation between the dominant microorganisms and different physicochemical indexes. The Spearman correlation analysis indicated that Oceanobacillus, Saccharopolyspora, Staphylococcus, Byssochlamys and Thermomyces showed positive correlations with majority key volatile flavor compounds. This work will provide a scientific basis for the actual production of different colors of high-temperature Daqu in the northern region of Sauce-flavor Bajiu.