Combing the Entropy Weight Method with Fuzzy Mathematics for Assessing the Quality and Post-Ripening Mechanism of High-Temperature Daqu during Storage

This study investigated the physicochemical properties, enzyme activities, volatile flavor components, microbial communities, and sensory evaluation of high-temperature Daqu (HTD) during the maturation process, and a standard system was established for comprehensive quality evaluation of HTD. There were obvious changes in the physicochemical properties, enzyme activities, and volatile flavor components at different storage periods, which affected the sensory evaluation of HTD to a certain extent. The results of high-throughput sequencing revealed significant microbial diversity, and showed that the bacterial community changed significantly more than did the fungal community. During the storage process, the dominant bacterial genera were Kroppenstedtia and Thermoascus. The correlation between dominant microorganisms and quality indicators highlighted their role in HTD quality. Lactococcus, Candida, Pichia, Paecilomyces, and protease activity played a crucial role in the formation of isovaleraldehyde. Acidic protease activity had the greatest impact on the microbial community. Moisture promoted isobutyric acid generation. Furthermore, the comprehensive quality evaluation standard system was established by the entropy weight method combined with multi-factor fuzzy mathematics. Consequently, this study provides innovative insights for comprehensive quality evaluation of HTD during storage and establishes a groundwork for scientific and rational storage of HTD and quality control of sauce-flavor baijiu.