Screening And Fragrance Effect Of Non-saccharomyces Cerevisiae In Yanqi Grape Production Area

The non-Saccharomyces cerevisiae in the winemaking process gives the wine a complex aroma,and the aroma of the wine is mostly in the form of a bound state.Instead of the enzymes produced by Saccharomyces cerevisiae during the brewing process,the wine can be combined in the wine.The degradation of the flavor material into a free small molecule material promotes the aroma of the wine.In this study,56 grape samples from 10 varieties in the main producing areas of Xinjiang wine grape were studied.The traditional identification and molecular biological identification methods were used to classify and identify the non-Saccharomyces cerevisiae.Then the typical non-Saccharomyces cerevisiae and industrial Saccharomyces cerevisiae were used to carry out mixed fermentation of Cabernet Sauvignon wine.The contribution of non-Saccharomyces cerevisiae to wine aroma was analyzed by GC/MS.The focus was on the abundance and species of typical non-Saccharomyces cerevisiae and wine aroma.The main contents and results are as follows:1.Isolation and identification of non-Saccharomyces cerevisiae yeast273 yeast strains were isolated from 56 grapevine grape skins by WL nutrient medium,and combined with 26S rDNA D1/D2 region sequencing.The results showed that the tested strains were divided into 10genera and 14 species,respectively,Cryptococcus,Sporidiobolus,Lodderomyces,Torulaspora,Clavispora,Rhodotorula,Hanseniaspora,Pichia,Kluyveromyces and Metschnikowia,indicating that the wine grapevines in the region are not diverse in non-Saccharomyces cerevisiae.2.Screening of enzyme-producing non-Saccharomyces cerevisaeUsing esculine?-glucosidase,pectinase,lipase,and protease screening medium,14 representative strains were selected from the above 9 genus yeasts,and inoculated in different screening media to screen for non-Saccharomyces cerevisiae Strains,and the tolerance of typical enzyme producing strains was studied.The results are as follows:?1?By inoculating 14 representative strains into the screening medium,the enzyme production results showed that 13 strains produced?-glucoside,of which CZ-3 had the highest activity of 110.65 U/mL;7strains produced pectinase.The enzyme activity of XL-14 enzyme activity reached 298.59 U/mL;5 strains produced lipase,of which strain MZ-2 lipase activity was the highest,the enzyme activity reached 146.23U/mL.There are 10 strains producing proteases,among which the strain CZ-10 has the highest protease activity,which is 105.30 U/mL;?2?The typical enzymes CZ-10,CZ-3,XL-14 and MZ-2 were selected for tolerance analysis.The results showed that strains CZ-10 and XL-14 were able to tolerate 110 mg/L of SO₂,CZ-3 and MZ-2 were able to tolerate 80 mg/L of SO₂;strains CZ-10 and CZ-3 were able to withstand pH 3.5,strains XL-14 and MZ-2 can tolerate pH 2.5;4 strains of tested yeast can tolerate 20%of glucose;strain CZ-10 can tolerate16%of ethanol,strains CZ-3,XL-14 And MZ-2 is able to tolerate 14%ethanol.Overall,the four tested yeasts were able to withstand the winemaking environment.3.Effect of non-Saccharomyces cerevisiae on wine aroma componentsIn order to further study the effect of non-Saccharomyces cerevisiae on wine aroma,high-yield non-Saccharomyces cerevisiae strains CZ-10,CZ-3,XL-14,and MZ-2 were mixed with Saccharomyces cerevisiae AWRI 796 to ferment Cabernet Sauvignon wines for winemaking.Yeast single-fermentation fermentation as a control.A total of 62 volatile aroma substances were detected from 5 wine samples by GC/MS analysis,including 23 esters,12 alcohols,10 acids,8 aldehydes,6 ketones,and phenols.Three kinds of terpenoids.It can be seen that the main volatile substances of Cabernet Sauvignon wines blended by five different yeasts are esters,followed by alcohols and acids,which account for 37.1%,19.4%and16.4%,respectively.The results of comparative analysis of various substances showed that different non-Saccharomyces cerevisiae had different effects on wine aroma,but the content of esters and alcohols in four mixed fermented wine samples was significantly improved compared with that of Saccharomyces cerevisiae.The content of ethyl acetate,isoamyl acetate,ethyl octanoate and phenylethyl alcohol increased;the content of acid compounds and aldehydes and ketones did not differ much,but the content of acetic acid in the four mixed fermentation wine samples was lower than that of the control group.Only three kinds of phenols and terpenes were detected and the content and threshold were lower.At the same time,non-Saccharomyces cerevisiae not only increases the content of volatile aroma substances in alcohols and alcohols,but also increases its unique aroma substances such as acetoin,linalool,citronellol,Malaysia.Aroma substances such as ketones not only enhance the aroma intensity of the wine,but also make the aroma substances in the wine more complicated.Principal component analysis was carried out on aroma substances with odor activity value greater than 0.1.The results showed that the cumulative contribution rate of the two principal components was87%.The mixed fermentation wine sample and the single-ferment fermentation wine sample were far apart in the main components PC1 and PC2,and There is a significant difference in the aroma between the wine samples.Among them,CZ-10 has an important contribution to citronellol and acetic acid;CZ-3 has an important contribution to ethyl acetate,ethyl octanoate,isoamyl hexanoate,palmitic acid,phenylethanol,furfural and acetaldehyde;XL-14 to acetic acid Ester,ethyl octanoate,methyl octanoate,isoamyl hexanoate,palmitic acid,phenylethanol and damascone have important contributions;MZ-2 is ethyl butyrate,isoamyl acetate,ethyl hexanoate,phenylethyl acetate,1-nonanol and octanoic acid have important contributions.