Study On The Fermentation Process Of Purple Yam Wine And Analysis Of Its Quality

Dioscorea alata-A medicinal homologous,one year or perennial tuber plant,is a kind of purple meat yam varieties.Based on the study of Su Ying 1th dioscorea alata from the experimental base of Jiangsu Agricultural Sciences Academy,the optimum technological conditions and saccharification conditions for the enzymatic hydrolysis of dioscorea alata were determined by response surface method and orthogonal test.The optimum fermentation conditions of dioscorea alata wine were optimized by orthogonal test,and the most suitable clarifying agent and proportion were determined.Finally,the nutritional composition analysis and antioxidation of dioscorea alata wine before fermentation,after fermentation and after aging were studied and the finished products were inspected.The main research and results were as follows:(1)Dioscorea alata ingredient analysis:moisture 75%(fresh weight),fat 2.8%,protein 8.76%,ash 3.4%,total sugar 64 mg/g(dry weight);A total of 12 fatty acids were measured,of which the content of unsaturated fatty acid was as high as 60.537%,and that the content of single unsaturated fatty acid with oleic acid is 11.253%,the total content of polyunsaturated fatty acids with linoleic acid and a-linolenic acid was 49.284%,palmitic acid content is 29.285%;The total amount of amino acid in dioscorea alata was up to 6.325g/100g,amylopectin was 64.47%,amylose was 23.31%,total starch was 87.78%,anthocyanin content was 23.8mg/100g.(2)The effects of a-amylase addition,pH,temperature and time on the enzymatic hydrolysis of dioscorea alata starch were investigated by using reductive sugar release rate(DE),and the process parameters were optimized by response surface method.The best enzymatic hydrolysis conditions of dioscorea alata starch:a-amylase addition 23 u/g,75?,pH 5.5,77 min.Under this condition,the DE was 27.17%,Vm= 4.141 mg/(mL min),Km=4.329 mg/mL,the kinetic equation of enzymatic hydrolysis was:v=6.98[S]/(7.94+[S]),R2=0.9966.The effects of the amount of glucose,temperature,pH and time on the saccharification effect were investigated by using the content of reducing sugar,and orthogonal experiment was used to optimize the saccharification technology of dioscorea alata starch and the digestion characteristics during the simulation.The optimal saccharification process condition:glucoamylase addition 240 u/g,55 ?,pH 4.5,60 min.In vitro digestion simulation test showed that the soluble sugar release rate and reducing sugar release rate of dioscorea alata were significantly lower than that of enzymatic hydrolysis process.(3)Influence degree of fermentation technology of dioscorea alata wine was as follows:amount of inoculation>addition of SO2>temperature>time.Optimum fermentation conditions were as follows:0.09 g/kg SO2,0.5%inoculation amount of active dry yeast,28?,8 days.The effects of 4 kinds of clarifying agents such as chitosan,bentonite,gelatin and PVPP on the single and compound clarification test of dioscorea alata wine were investigated,and the stability of the dioscorea alata wine was studied.The test results showed that the single clarifying agent was as follows:chitosan>bentonite>gelatin>PVPP;When the compound clarifier test,1%chitosan and 1%bentonite compound use,its clarification effect was superior to other compound clarifying agent,however,1%chitosan and 3%bentonite compound use,the light transmittance was as high as 99.65%,and the dioscorea alata wine stability was better.(4)GC-MS and HPLC were used to compare the aroma components and organic acids of dioscorea alata wine before fermentation,after fermentation and after aging,and to explore the antioxidant activity of three different periods at the same time.Finally,the finished wine was tested for the factory inspection.The results showed that the esters increased significantly after aging,and the heterocyclic material decreased significantly,which showed that aging could not only increase the aroma of wine,but also remove the bad odor.The content of organic acids were as follows:after aging>after fermentation>before fermentation,and the content of organic acids decreased after aging.With the extension of time,the dioscorea alata wine DPPH · and O2-· were significantly increased,,the ability to clear OH· was strongest after fermentation,after aging,but decline.Finished wine factory test results showed that:dioscorea alata wine was color purple,clear and transparent,dioscorea alata taste,taste micro-acid,entrance supple,with a typical dry-type fruit wine style;alcohol precision 9.8(20?)%V/V,total sugar 3.76 3.76 g/L,titration acid 4.875 g/L,volatile acid 34.2 g/L,free sulfur dioxide 97.5 mg/L,dry extract 42.1 g/L.This paper has established the brewing technology of dioscorea alata wine,which lays a theoretical foundation for the development and application of high value-added products of dioscorea alata.