| In this paper,the screening of functional bacteria in Daqu,the preparation of aroma-producing bran qu,the optimization of the solid state fermentation of baijiu,and the application of functional bacteria in small-scale and pilot test experiments were studied.The main conclusions are as follows:(1)Four strains of moulds with large clear circles were screened from saccharifying enzyme screening medium.The four molds were cultured in solid state with a fermentation medium.The glucoamylase activity was measured and a glucoamylase activity was screened out.The strong Aspergillus niger S3 was 1782.5U/g dry koji.At the same time,after screening with a screening medium containing tributyrin,5 colonies with larger clear circles were initially obtained.After repeated screening,a Monascus EM1 with strong esterification ability was selected,and the esterification power was 6.08 U/mL.Ten strains of yeast were screened from Daqu and their ester-producing and alcohol-producing properties were determined.Among them,Y3 and Y7 had the strongest ester-producing and wine-producing properties.Ethanol tolerance experiments were performed on these two strains of yeast,respectively,and they were found to grow almost normal at 10%,which can be applied to liquor brewing experiments.(2)Using the selected ester-producing yeast and the esterified red yeast rice as raw materials,the optimum conditions for the production of raw bran qu were determined by single factor and orthogonal experiments:the proportion of fine powder of the culture medium(bran)over the aperture 420?m sieve was 35%(w/w),the initial moisture content of the culture medium was 50%(w/w),and the inoculum volume of the spore suspension was 4%(v/w).After incubation at 32°C for 84 h,0.6 mL of yeast suspension was added per 1 g of koji(The cell concentration was 10~8 cells/mL),mix well,and dried at 35°C for 4 h to obtain dried koji,cooled and sealed.The total ester content in the artificial esterification system was 10.74±1.17 mg/100 mL,which was5.43 times higher than the blank control.(3)With the production practice as a guide,a solid state simulation fermentation system for liquor was established.The solid state fermentation cycle of white spirit was determined by the weight loss method of carbon dioxide for 25 days.According to the changes in the ethanol and substrate consumption of the fermentation product in the solid state simulation process,the solid state simulation fermentation kinetics of liquor was performed.In the study,the kinetic equation of the product formation was obtained as: y=1/(0.115+4.148e^(-t/4.207))The kinetic equation of the substrate consumption was: x=8.513+80.075/t The single factor experiment and Box-Behnken response surface analysis showed that the optimal combination of initial pH value,fermentation temperature and inorganic salt content was 7.05,28.15?,and 1.37%,respectively,and the response value Y reached a maximum of 10.101U.(4)Through the single-factor rotation experiment and Box-Behnken response surface analysis,the results showed that the best combination of saccharified bran added,aroma-producing bran qu,and brewing bran qu was 16.92%,8.34%,and 6.47%,respectively.The response value Y reached a maximum value of 250.01 mg/100 mL.In the validation test,the solid state simulated fermentation test was repeated 3 times in the best combination and the average fermentation power was determined to be 246.43mg/100 mL,which was close to the predicted value.(5)The fermentation process of Fen-flavor liquor was simulated in the tanker.The experimental group strengthened the microorganisms in the fermentation environment by strengthening the saccharified bran qu,the aroma-producing bran qu.The physicochemical indexes in the fermentation process were traced to find that the addition of the fortified bran qu facilitates the formation of flavoring substances.Chromatographic analysis of liquor found that the ethyl alcohol and ethyl lactate content of the original wine of the test group was higher than that of the control group. |
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