Associations between wheat varieties and the functional microbial community of Nongxiangxing daqu from northern China

Abstract

Wheat and daqu, as raw materials, play important roles in spontaneous solid-state fermentation of Chinese Baijiu. Functional microorganisms contribute to the flavour of Chinese Baijiu. However, studies on the relationship between wheat and functional microorganisms of daqu are very limited. This study investigated the components of wheat and functional microorganisms in Nongxiangxing daqu (NXDQ) from northern China. Staphylococcus, Thermoactinomyces, unclassified_o_Enterobacterales, Kosakonia, Thermoascus, Thermomyces, Saccharomycopsis and Aspergillus were predominant biomarkers to daqu made of strong-gluten (SWDQ), medium-strong-gluten (MSWDQ) and medium-gluten wheat (MWDQ), which were positively related to the dominant volatile compounds tetramethylpyrazine in MWDQ and phenylethyl alcohol in MSWDQ. Based on the properties and volatile compounds in NXDQ, 37 functional microorganisms were obtained. Correlation analysis indicated that functional microorganisms were more influenced by the dominant components of wheat than by the trace ingredients. Furthermore, the starch of wheat was positively related to those biomarkers of MWDQ and MSWDQ, which mainly contributed to hydrolases and flavour. The crude protein (wet gluten) of wheat negatively influenced that of SWDQ, which was related to acidity. Our findings are helpful for comprehending the effect of wheat on microorganisms in daqu, and provide a theoretical basis for selecting wheat varieties to improve and stabilize the quality of daqu.