Environmental and Physicochemical Characterization and Fungal Community of Two Batches of Chinese Luzhou-Flavored Daqu

Abstract

The environmental and physicochemical characteristics and fungal communities of two batches of Chinese Luzhou-flavored Daqu were investigated during the fermentation stage and storage period. The Daqu was processed on July 1, 2018 and August 1, 2018, and was identified as middle-temperature and middle and high-temperature Daqu, respectively. At the genus level, the dominant fungi were Aspergillus during the fermentation stage and Candida after three months of storage. Principal component analysis (PCA) and the unweighted pair group method with arithmetic mean (UPGMA) analysis revealed that the fungal community could be divided into two primary groups based on the fermentation and storage stages. Each large fungal population could then be divided into two smaller groups according to the batch. Notably, LEfSe [line discriminant analysis (LDA) effect size] analysis did not find any significantly different fungal populations between the two batches. Redundancy analysis showed that during the entire culture stage of two batches of Daqu, water content and fermenting power were positively correlated with Aspergillus and Wickerhamomyces, while water content correlated negatively with Rhizopus. During fermentation, environmental humidity correlated negatively with Wickerhamomyces in the two batches of Daqu. This study increases the theoretical understanding of Daqu preparation, especially function of the storage period and the fungal differences between batches of Daqu. Such information potentially enables the quality control of Daqu in order to improve quality by controlling the fungal community via the processing conditions and the addition of Candida.