Study On Control Of Higher Alcohols During Fermentation Process In Mulberry Wine

In this study,the mulberry wine special yeast with low yield of higher alcohols was screened and its fermentation conditions were optimized.On this basis,the changes of higher alcohols and main physicochemical indexes during the mulberry wine fermentation were studied,and the effects of exogenous additives on the content of higher alcohols in mulberry wine were studied,so as to further control the content of higher alcohols in mulberry wine.The quality of mulberry wine was evaluated by comparing the mulberry wine developed in this study with the commercial mulberry wine.The main research contents are as follows:1.A total of 35 strains were isolated from mulberry natural fermentation mash,and the mulberry wine yeast S-2 with good fermentation performance and low yield of higher alcohols was obtained by the preliminary screening with tubule fermentation,rescreening with ethanol production capacity,and three-stage screening with ethanol tolerance and SO2 capacity.The ethanol content of S-2 strain after fermentation was 10.56%,and the yield of higher alcohols was360.74mg/L,which was significantly lower than that of commercial yeast.2.Using single factor experiment and orthogonal test of mulberry wine fermented condition was optimized and get the best fermentation conditions for mulberry fruit wine:the initial sugar concentration 21°Brix,fermentation temperature 25?,7%yeast inoculation quantity,SO₂content of 50 mg/L.Under these conditions,the alcohol content of mulberry wine was 12.56%vol,the content of higher alcohols was 325.49mg/L,and the comprehensive score was 0.98.3.The mulberry wine fermentation conditions were optimized and the special yeast for mulberry wine was inoculated to ferment the mulberry wine.The results show that during the fermentation of mulberry wine,the content of total acid first increased,then decreased and then stabilized,the contents of residual sugar first decreased and then stabilized,and the content of yeast,alcohol,n-propanol,isobutanol,iso-amyl alcohol,phenyl alcohol and total higher alcohol first increased and then stabilized.After fermentation,the contents of each index were 6.62g/L total acid,4.4g/L reducing sugar,12.34%vol alcohol,7.83mg/L n-propanol,57.2mg/L isobutanol,220.34mg/L isoamyl alcohol,35.75mg/L phenyl alcohol and 321.12mg/L total higher alcohols.According to the correlation analysis of higher alcohols and main indexes,the change of main higher alcohols and total higher alcohols were significantly correlated with the change of yeast quantity,alcohol content and residual sugar content.The sensory evaluation showed that the mulberry wine on the 5th day of fermentation had the best sensory evaluation.4.During the mulberry wine fermentation,exogenous substances were added to study the effect of exogenous substances on the higher alcohol of mulberry wine.The results showed that Enzyme preparation?pectinase,glycosylase,cellulase?,metal ions(Mg²⁺,Ca²⁺,K⁺)and assimilable nitrogen sources?arginine,alanine,diammonium phosphate?besides glutamate could significantly reduce the content of higher alcohols in mulberry wine,among which cellulase,Mg²⁺,K⁺had the best effect in reducing higher alcohols.The response surface of cellulase,Mg²⁺and K⁺was optimized to obtain the optimal ratio of cellulase 0.2g/L,KCl 20.02mg/L and MgCl₂20.17mg/L.Under this condition,the content of higher alcohols in mulberry wine was282.34mg/L,and the content of higher alcohols in mulberry wine was 13.26%lower than that without adding exogenous substances.5.The main indexes,volatile substances,functional substances and antioxidant activities of mulberry wines were compared and analyzed.The results showed that the main indexes of mulberry wine developed in this study were in line with the industrial standard of mulberry wine?NY/T 1508-2017?.In addition,compared with the commercial mulberry wines,the content of higher alcohols of mulberry wine developed in this study was significantly decreased,the esters were abundant,the aroma was abundant,the flavonoids,anthocyanins and other functional substances were abundant,and the antioxidant capacity was strong.