Han Pei-Jie, Luo Lu-Jun, Han Ying, Song Liang, Zhen Pan, Han Da-Yong, Wei Yu-Hua, Zhou Xin, Wen Zhang, Qiu Jun-Zhi, Bai Feng-Yan
College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Foods. 2023 Aug 2;12(15):2936. doi: 10.3390/foods12152936.
Daqu is a traditional starter for Baijiu fermentation and is produced by spontaneous fermentation of ground and moistened barley or wheat. The quality of Daqu is traditionally evaluated based on physicochemical and subjective sensory parameters without microbiological analysis. Here, we compared the physicochemical characteristics of qualified (QD) and inferior (ID) Daqu, their microbial communities based on plate counting and PacBio SMRT sequencing of rRNA gene libraries, and their impacts on Baijiu fermentation. The results showed that the glucoamylase and α-amylase activities of QD were significantly higher than those of ID. The counts of yeasts and relative abundances of functional microbes, especially the amylolytic bacterium and fungi and , were significantly higher in QD than in ID. The laboratory-scale Baijiu fermentation tests showed that the relative abundances of the amylolytic microbes were higher in the QD than the ID fermentation set, resulting in more efficient fermentation, as indicated by more weight loss and higher moisture content in the former. Consequently, more glycerol, acetic acid, ethanol, and other volatile compounds were produced in the QD than in the ID fermentation set. The results suggest that Daqu quality is determined by, and can be evaluated based on, its microbial community.
大曲是白酒发酵的传统酒曲，由研磨并湿润的大麦或小麦自然发酵制成。传统上，大曲的质量是根据理化和主观感官参数进行评估的，而不进行微生物分析。在此，我们比较了合格大曲（QD）和劣质大曲（ID）的理化特性、基于平板计数和rRNA基因文库的PacBio SMRT测序分析的微生物群落，以及它们对白酒发酵的影响。结果表明，合格大曲的糖化酶和α-淀粉酶活性显著高于劣质大曲。合格大曲中的酵母计数和功能微生物的相对丰度，尤其是解淀粉细菌以及真菌和，显著高于劣质大曲。实验室规模的白酒发酵试验表明，合格大曲发酵组中解淀粉微生物的相对丰度高于劣质大曲发酵组，前者发酵更高效，表现为失重更多、水分含量更高。因此，合格大曲发酵组比劣质大曲发酵组产生了更多的甘油、乙酸、乙醇和其他挥发性化合物。结果表明，大曲质量由其微生物群落决定，并可基于微生物群落进行评估。
