The changes of microbial community and metabolic components during the storage of traditional Daqu (B-Daqu) and fortified Daqu (F-Daqu) were revealed by polyphasic examination. The results indicated that the ability of saccharifying was increased, the contents of volatile component and the microbiota of α-diversity index changed alternating in B- and F-Daqu. The fermenting ability of B-Daqu and the content and types of volatiles in F-Daqu was increased, while the liquefying power and esterifying ability of B-Daqu were decreased. The optimal storage time for B-Daqu and F-Daqu were 60-90 and 90-120 d, respectively. The α-diversity indexes of bacteria in F-Daqu were higher than that of B-Daqu, without fungi. Weissella, as dominant bacteria in B-Daqu, was negative correlated with Pichia and Rhizomucor. Bacillus, as the dominant bacteria in F-Daqu, was positively correlated with most fungal genera. Volatile components were closely related with Bacillus, Thermomyces, Thermoascus, Rhizomucor, Saccharopolyspora and Pichia. Carbohydrate metabolism ability was stronger when inoculation of Bacillus licheniformis, and the content of tetramethyl pyrazine and 2, 3-butanediol was increased. This study provides the foundation that can be used to for determine the optimal storage period of Daqu.
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