Effects of synthetic microbial communities replacing traditional Muqu on quality of high-temperature Daqu
Traditional high-temperature Daqu is produced by spontaneous fermentation,which has disadvantages including complex composition of microbial community and difficulty in controlling the com-ponents and content of required flavor.Wheat was used to prepare the solid microbial agents of Bacillus li-cheniformis BL44,Saccharomyces cerevisiae SCY62,Paecilomyces variotii PV3,Rhizomucor pusillus RP1 and Thermoascus crustaceus TC1 isolated and screened from the high-temperature Daqu to optimize the structure of microbial community in high-temperature Daqu and improve the quality of high-temperature Daqu.Two synthetic microbial communities were constructed with different addition ratios to replace the traditional Muqu(CK)in producing high-temperature Daqu.Brewing experiments in laboratory were con-ducted and analyzed.The results of high-throughput sequencing showed that the dominant fungal genus and the dominant bacterial genus of the three kinds of Daqu was Lichtheimia and Bacillus,respectively.The re-sults of measuring the physicochemical indexes of the Daqu showed that the liquefaction and saccharification abilities of the high-temperature Daqu inoculated with the synthetic microbial communities were significant-ly improved compared to CK.The results of analyses with gas chromatography-mass spectrometry showed that inoculating synthetic microbial communities instead of traditional Muqu significantly increased the con-tent of tetramethylpyrazine in Daqu and fermented grains.The content of tetramethylpyrazine in Daqu inocu-lated with synthetic microbial group 1 and microbial group 2 was 31.90 mg/kg and 56.73 mg/kg,in-creased by 2.80 and 4.99 times compared to that of CK.In the high-temperature stacked fermentation mash,the content of tetramethylpyrazine inoculated with synthetic microbial group 1 and microbial group 2 was 0.76 mg/kg and 2.74 mg/kg,increased by 4.03 and 14.61 times compared to that of CK.It is indicat-ed that the synthetic microbial community has potential application in directionally regulating the activity of enzymes in Daqu and the components and contents of some specific flavors in Baijiu.
synthetic microbial communityhigh-temperature Daquhigh-throughput sequencingphysical and chemical indexesvolatiles substancestetramethylpyrazine
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