| Strong-Flavor liquor is one of the basic flavors of Chinese liquor,and its unique fermentation process leads to the formation of special microbial flora in Daqu.The study of microbial flora is conducive to the control of flavor and quality of Strong-Flavor liquor.In this study,samples of 3d-90 d Strong-Flavor liquor Daqu were collected from a StrongFlavor liquor enterprise in Hebei province,and high-quality yeast strains were screened.The yeast strains were used to prepare the complex bacterial solution,and the optimal ratio of yeast addition amount in the complex bacterial solution was analyzed,which could be applied to the preparation of fortified Daqu.Moreover,the volatile components in the fortified Daqu were analyzed.In addition,the protection process of lyophilized yeast was optimized,the storage and fermentation properties of lyophilized yeast powder were tested,and the feasibility of lyophilized yeast from separation and purification was explored.The results provided a reference for the separation and purification of high quality yeast in Strong-Flavor liquor Daqu,the preparation of fortified Daqu and the preparation of lyophilized yeast powder.The results are as follows:(1)from Strong-Flavor daqu liquor purification out 91 yeast strains advantage,9strains for the production function of the yeast,select four strains produce gas and acid excellent performance,high temperature resistant,resistant to ethanol high-quality yeast,the yeast fermentation JM-3 good performance is significantly higher than other strains(p < 0.05),yeast JM-4 esterification performance is good,JM-1 and JM-2 were preliminarily identified as Ogataeapolymorpha,JM-3 as Saccharomycescerevisiae and JM-4 as Komagataellapastoris by sequence comparison.(2)According to the analysis of the optimal complex ratio of yeast addition amount in the complex bacteria solution,the results showed that the total ester content of liquor prepared by simulated solid state fermentation was 224.29±0.35mg/100 m L with 3% yeast JM-1,5% yeast JM-4,3% yeast JM-3 and 4% yeast JM-2 in the functional complex bacteria solution.Fortified Daqu was prepared by adding functional compound bacteria solution.It was identified that Daqu had good quality,uniform color and texture in cross section and no disease.(3)GC-IMS technology was used to analyze the content of volatile organic compounds in fortified Daqu and ordinary Daqu.By spectra than qualitative 51 kinds of volatile organic compounds,including two kinds of daqu of alcohol compounds,esters content have obvious difference: the qualitative results showed that the improved daqu sample 2-methyl-1-propanol,methyl acetate,propyl acetate,1-hexanol and amyl alcohol,butyl alcohol,propylene glycol,ethyl formate content is significantly higher than ordinary daqu.(4)Through single factor tests on yeast lyophilization centrifugation rate,centrifugation time,type and concentration of protective agent,balance time between protective agent and bacterial solution,and ratio between protective agent and bacterial solution,the optimal lyophilization process of yeast was determined as follows: The yeast liquid was centrifuged at a centrifugation rate of 6000 rpm for 15 min,and 7% sucrose was used as a protective agent to fully mix with yeast somatic cells 1:1 for 30 min before vacuum freeze-drying.The cell survival rate of yeast lyophilized powder was 36.41%after 3 months of storage,and the fermentation performance was not significantly different from that of fresh yeast liquid,showing good fermentation performance. |
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