| Traditional Chinese liquor brewing is an extremely complex natural fermentation process.The brewing process is a process of saccharification,fermentation,distillation,storage and blending molding with koji as a saccharifying agent.In the process of brewing liquor,there are many microorganisms,and there is an unclear mechanism of action between microorganisms.In this paper,we use the pure rhizomes of Rhizopus oryzae and Aspergillus niger to cultivate self-made high-quality koji as saccharifying agent.Using sorghum,rice,glutinous rice,wheat and corn as raw materials,and using the four strains of Saccharomyces cerevisiae,Hansenula,Acetobacter baumannii and Lactobacillus plantarum to optimize the brewing process.The main research results are as follows:1.Cultivation of Rhizopus oryzae and Aspergillus niger using pure seed culture techniques.The liquefaction enzyme and glucoamylase activity were used as indicators to optimize the quality of the koji and the quality of the koji was determined by the sweet rice wine saccharification and fermentation experiments combined with the initial enzyme activity.The liquefaction enzyme activity of Rhizopus oryzae increased by 179.5%compared with the A plant koji,and increased by 163.1%compared with the B plant koji;the glucoamylase activity of Aspergillus niger was 12.4%higher than that of the A plant koji,and122.1%higher than that of the B plant koji.The saccharification and fermentation experiment showed that the content of reducing sugar was 11.9%higher than that of A plant liqueur and169.2%higher than that of B plant.The fermentation alcohol was 6.4%higher than that of plant A,and 30.1%higher than that of plant B.2.According to the brewing rate,total acid and total ester content combined with sensory evaluation,the brewing process conditions of multi-grain liquor were optimized.The ratio of multi-grain is 40%sorghum,30%rice,10%corn,10%glutinous rice and 10%wheat,and the dry weight of multi-grain is 40g.When the ratio of material to water is 4:2,it is suitable for multi-grain liquor brewing.When Aspergillus niger:Mycorrhizal is 1:30,the amount of splicing is 10%,and the saccharification time is 1d,the higher the alcohol yield is81.5%,the total acid is 0.26g/L,and the total ester is 2.70 g/L.The brewing rate of multi-grain liquor is 23%higher than that of the A plant.3.In the study of optimizing the external factors of multi-grain liquor brewing,it was found that when the fermentation time was 13d,the acid,alcohol and ester in the wine could reach a good balance.n the slow-temperature fermentation process with a temperature gradient of 30℃,28℃and 26℃,the alcohol content after distillation was 30.1%vol,the total acid content was 0.26 g/L,and the total ester content was 2.72 g/L.The brewed multi-grain white wine smells fragrant and has no peculiar smell.It looks like the wine is translucent,the taste is mellow,and the spicy taste is less.4.Investigating the effects of strains on the brewing of multi-grain liquor,it was found that the inoculation method and inoculum of the strains affected the brewing results.When the inoculation amount of the single strain Saccharomyces cerevisiae was 7.5×10~7 CFU/mL,the alcohol content was up to 33.1%vol.In the multi-grain liquor brewing between the two strains,the simultaneous inoculation method was adopted when the inoculation ratio of S.cerevisiae to Hansenula was 1:1,and the fermentation alcohol and ester-producing ability were the highest,respectively 30.0%vol and 2.43g/L;When the inoculation ratio of Saccharomyces cerevisiae and A.faecalis is 1:1,the fermentation alcohol content is 31.0%vol,and the ethyl acetate content can reach 313.50 mg/L.In the brewing process,1d aerobic fermentation was carried out,the total ester reached 2.80 g/L,the fermented alcohol was 31.1%vol,and the ethyl acetate was up to 373.52 mg/L,which was 18.5%higher than that of anaerobic fermentation.The inoculum of Lactobacillus plantarum is 7.5×10~5 CFU/mL.The distilled white wine looks translucent.It smells natural and tastes spicy.The fermented alcohol is30.6%vol and the ethyl lactate is 109.1 mg/L,the total ester was 2.78 g/L.In the experiment of multi-grain mixed fermentation and brewing multi-grain liquor,it was found that the multi-bacteria has a complex effect in the brewing process,and we can determine the combination of strains according to the quality of the liquor required.5.In the factors affecting the brewing quality of multi-grain liquor,the aeration time,the inoculum amount of Acetobacter baumannii and the pre-fermentation time were orthogonal experiments.When aerated for 12h,fermentation at 30℃for 12d and Acetobacter aceti inoculation was 2.5?10~7 CFU/mL,alcohol content from 31.50%vol to 32.2%vol,alcohol increased by 2.2%;The content of ethyl acetate was from 243.47 mg/L to 328.62 mg/L,and the content was increased by 35.0%;the total ester content was from 2.62 g/L to 2.73 g/L,and the content was increased by 4.2%.The experiment is better.The accelerated fermentation experiment of 200g dry weight of multi-grain raw materials further verified the reliability of the optimization results.6.Through optimization of brewing raw materials,strain combination and fermentation process conditions,under the semi-solid fermentation mode,controlled multi-bacteria can be used to brew high-quality white wine,which provides a new technical method for automatic fermentation of large tanks. |
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