| Maotai-flavored Daqu is the koji used for the brewing of Maotai-flavor liquor,and its production accounts for up to 50%of the raw materials for brewing.It is the most important factor affecting the quality of Maotai-flavor liquor.For Maotai-flavored Daqu making,wheat crushing degree has a significant impact on the whole process conditions of Daqu-making.Previous related studies only used wheat crushing degree as one of the many influencing factors to conduct descriptive research,and failed to reveal that it is the most important factor in Maotai-flavored Daqu koji making.The essential characteristics and laws of high temperature accumulation process control and regulation.Therefore,in this study,the monitoring of the production process of Maotaiflavored Daqu-making,the sequencing of Daqu-forming bacteria 16S rDNA(V3+V4 region)and fungal ITS region,physical and chemical tests and headspace combined gas chromatography(HS-GC)determination of Maotai-flavored Daqu quality and other research methods,to study the relationship between wheat fragmentation and Maotaiflavored Daqu quality and microbial diversity,to explore the technical nature of the koji-making process from the production conditions of Maotai-flavored Daqu,and to try to improve the quality of Maotai-flavored Daqu technology.The theory is initially constructed.The details are as follows:(1)To study the characteristics of Maotai-flavored Daqu with different wheat crushing degrees:After stacking and fermenting Maotai-flavored Daqu with different wheat crushing degrees,it was found that A3 Maotai-flavored Daqu had the highest curvature,that is,when the wheat crushing degree was 38.42%,its water retention coefficient It is 0.2182 min/g,the thermal conductivity is 0.2149℃/min,the top temperature of the first stage is 63.6℃,the moisture loss is 10.03%,the top temperature of the second stage is 57.9℃,the moisture loss is 7.68%,the top temperature of the third stage The temperature is 49.6℃,the moisture loss is 7.04%,and the highest curvature is 85%;(2)Based on the sequencing of bacterial 16S rDNA(V3+V4 region)and fungal ITS region,the fungal and bacterial microbial composition of Maotai-flavored Daqu with different wheat crushing degrees was analyzed:A total of 4 fungal phyla and 32 fungal genera were detected in 6 groups of different wheat crushing degrees in Maoxiang Daqu,mainly Ascomycota(99.61%)at the fungal phylum level,and the main flora at the genus level are Aspergillus(82.55%),Monascus(12.07%),Trichomonascus(1.77%)and Fusarium(0.91%);6 groups of wheat with different degrees of crushing sauce.A total of 32 bacterial phyla and 394 bacterial genera were detected in Daqu,among which Firmicutes(80.23%),Actinobacteria(9.13%)and Proteobacteria(4.36%)were the main phyla at the bacterial phylum level;Genus,Virgibacillus(24.27%),Staphylococcus(23.80%),Kroppenstedtia(15.64%),Scopulibacillus(9.00%),Brevibacterium(3.33%)and Bacillus(2.49%).(3)Analysis of the quality of Maotai-flavored Daqu with different wheat crushing degrees:The quality of A3 Maotai-flavored Daqu was the best,that is,when the crushing degree of wheat was 38.42%,the moisture content of Maotai-flavored Daqu was 14.20%,pH is 5.60,acidity is 1.21 mmol/10g,starch content is 54.93%,saccharification power is 261.6 U/g,liquefaction power is 0.52 U/g,cellulase activity is 7.65 U/g,protease activity is 190.55 U/g,the content of acetoin was 232.14 mg/g,and the content of 2,3,5,6-tetramethylpyrazine was 352.52 mg/g.(4)Preliminary research on the mechanism of wheat crushing degree affecting the quality and microbial diversity of Maotai-flavored Daqu.It can be found that the wheat crushing degree directly affects the water retention and thermal conductivity of the koji.The temperature of Qudui and the moisture content of koji will affect the growth and metabolism of microorganisms,and the bioheat generated by the growth and metabolism of microorganisms will increase the temperature of Qudui.The three work together and affect the quality of Maotai-flavored Daqu. |
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