Turning over fermented grains elevating heap temperature and driving microbial community succession during the heap fermentation of sauce-flavor baijiu

Abstract

Turning over fermented grains is widely used during the heap fermentation of sauce-flavor baijiu to increase heap temperature, however, the effect of turning over fermented grains on heap fermentation is still unclear. The present study investigated the changes of microbial community structure and volatile compounds before and after turning over by using high-throughput sequencing combined with gas chromatography-mass spectrometry (GC-MS). Firstly, turning over fermented grains lead to a redistribution of acidity and moisture content in different layers of fermented grains and an increase in heap temperature. Secondly, a total of 41 volatile compounds were identified, among which the concentrations of ethanol, phenylethyl alcohol, acetic acid, and ethyl-9,12-octadecadienoate in fermented g