| In this paper,sweet potato and rice are used as raw materials for wine making,dried Aspergillus oryzae and rice wine active dry yeast are used as saccharification starters,and sweet potato sake is brewed by liquid fermentation process.The relevant research results are as follows:1.Research on koji making technology.Aspergillus oryzae is used to make rice koji,and the best conditions for rice koji preparation are determined according to the activity of glucoamylase.Finally,it was determined that the inoculum was 1.0%,the culture time was 72h,the culture temperature was 32℃,the p H of the rice soaking water was 4.5,and the glucoamylase activity was 430.8001U/g under these conditions.2.Research on the fermentation technology of sweet potato sake.First,the composition of sweet potato and rice was tested,and the crude protein,crude fat,ash,moisture and starch content in sweet potato and rice were determined.It was determined that the combination of sweet potato and rice was feasible as a raw material for sweet potato sake brewing.Secondly,determine the p H and sugar content during the fermentation process,determine that the pre-fermentation time is 12 days,determine the total sugar,total acid,alcohol content and amino acid nitrogen during the fermentation process,and determine the total fermentation time to be 28 days.Thirdly,through the analysis of the physical and chemical indexes and sensory evaluation of the finished sweet potato sake,the effects of four factors,namely the ratio of material to water,the ratio of material to koji,the amount of yeast and the amount of sweet potato added,on the quality of sweet potato sake were studied;the sensory score was used as the evaluation of the orthogonal test.Indicators,on the basis of single factor experiment,L9(3~4)is used for orthogonal optimization experiment,and the best parameters for brewing sweet potato sake are obtained:the ratio of material to water is 1:2,the amount of sweet potato is 40%,and the ratio of material to koji is 2:1.The amount of yeast added is 0.2‰,and the influencing factors of sensory evaluation are the ratio of material to water>the amount of sweet potato>the ratio of material and koji>the amount of yeast.Finally,the parameters of optimized fermentation conditions were used for the verification test of sweet potato sake.Under these conditions,the total acid of sweet potato sake was 0.5460g/100m L,the total sugar was 5.3661g/100m L,the alcohol content was 14.6%vol,and the amino acid nitrogen was 0.5254g/L;3.Research on quality characteristics,active substances and DPPH of sweet potato sake.First,SPME and GC-MS were used to determine the aroma components in sweet potato sake,rice sake and Japanese sake.A total of 26 aroma components in sweet potato sake were detected,including 3 alcohols,20 esters,and 2 aldehydes.,1 kind of phenol;20 kinds of aroma components in rice sake were detected,including 5kinds of alcohols and 15 kinds of esters;23 kinds of aroma components in Japanese sake were detected,including 3 kinds of alcohols and 19 kinds of esters One kind of aldehydes.Second,use the electronic tongue to analyze the sour,sweet,bitter,astringent,fresh,salty,aftertaste A(astringent aftertaste),aftertaste B(bitter aftertaste),and abundance in sweet potato sake,rice sake,and Japanese sake.Compared with Japanese sake,the 9 kinds of tastes tested have significant differences(p<0.05).Compared with rice sake,the aftertaste B(bitter aftertaste)and abundance are not It is significant(p>0.05),and the rest have significant differences(p<0.05).Thirdly,the content of flavonoids and polysaccharides in rice sake and sweet potato sake were compared.The flavonoid content of sweet potato sake was 1.3437mg/m L and the polysaccharide content was 11.3154mg/m L;the flavonoid content of rice sake was 0.8381mg/m L and the polysaccharide content was 8.5140mg/m L;the content of DHEA in sweet potato sake was determined by HPLC,and DHEA was not found in sweet potato sake.Finally,1g/L Vc and BHT were used as positive controls to determine the DPPH free radical scavenging rate of rice sake and sweet potato sake.When the sample dosage was 200μL,the rate of removal of sweet potato sake was 20.13%and that of rice sake was14.88%. |
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