Correlational Analysis of the Physicochemical Indexes, Volatile Flavor Components, and Microbial Communities of High-Temperature Daqu in the Northern Region of China

Abstract

<i>Daqu</i> is a microbial-rich baijiu fermentation starter. The high-temperature <i>Daqu</i> plays an essential role in the manufacturing of sauce-flavored baijiu. However, few studies have focused on three kinds of high-temperature <i>Daqu</i> (white, yellow, and black <i>Daqu</i>) in northern China. In this study, the physicochemical indexes, volatile flavor compounds, and microbial characteristics of the three different colors of high-temperature <i>Daqu</i> in northern China were comparatively analyzed to reveal their potential functions. White <i>Daqu</i> (WQ) exhibited the highest liquefying power and starch, and black <i>Daqu</i> (BQ) showed the highest saccharifying and esterifying powers. A total of 96 volatile components were identified in the three types of <i>Daqu</i>, and the contents of the volatile components of yellow <i>Daqu</i> (YQ) were the highest. The microbial community structure analysis showed that <i>Bacillus</i> and <i>Byssochlamys</i> were dominant in BQ, <i>Kroppenstedtia</i> and <i>Thermoascus</i> were dominant in WQ, and <i>Virgibacillus</i> and <i>Thermomyces</i> dominated the YQ. The RDA analysis revealed the correlation between the dominant microorganisms and different physicochemical indexes. The Spearman correlation analysis indicated that <i>Oceanobacillus</i>, <i>Saccharopolyspora</i>, <i>Staphylococcus</i>, <i>Pseudogracilibacillus</i>, <i>Byssochlamys,</i> and <i>Thermomyces</i> showed positive correlations with part of the majority of the key volatile flavor compounds. This work provides a scientific basis for the actual production of different colors of high-temperature <i>Daqu</i> in the northern region of China for sauce-flavored baijiu.