| The aroma of wines not only depend on grape varieties and the brewing technology, but also closely related to the fermentation of yeast and other microorganisms. The quality of wine tends to be standardized and lack of unique and typicality when produced by Saccharomyces cerevisiae as a single starter, while co-fermentation with non-Saccharomyces cerevisiae can increase the complexity of the aroma. In this experiment, Cabernet Gerniscchet grapes in Hexi corridor of Gansu province were used as raw materials, the co-fermentation was conducted with VR and MGFSH-5 in the wine. In order to provide theoretical basis for producing the high quality of ’Cabernet Gernischet’ dry red wine with geographical features, the optimal process conditions of co-fermentation were obtained by response surface methodology and the aroma characteristics of wines were also analyzed in the study. The main results were as follows:1. Fermented with Cabernet Gerniscchet grapes, by Box-Behnken experimental design, the brewing factors were analyzed. By Box-Behnken experimental design, regression model for each factor was established. The results showed that inoculation ratio, initial p H and fermentation temperature had significant influence on the final contents of terpenes(p<0.01), while no significant changes were found in the influence of yeast polysaccharide(p>0.05). The optimal co-fermentation conditions were yeast mixing ratio 1:6, initial p H 3.6, fermentation temperature 26.0℃, yeast polysaccharide dosage 0.35 g/L.2. The analysis of aroma compounds in the wine samples under the optimum fermentation conditions showed that contents of terpenes and C13-norisoprenoids in the wines by co-fermentation and single fermentation were 200.85 and 167.66 μg/L, respectively, in which the content of β-Damascone and citronellol were highest. The contents of alcohols in both wine samples were 281.27 and 198.58 mg/L, respectively. 1-pentanol was highest in both wine of which concentrations were 143.81 and 130.87 mg/L. The esters contents of the in both wine were 231.68 and 180.29 mg/L, which showed ethyl octanoate was the highest, the concentration were 33.34 and 34.57 mg/L respectively. While contents of acids were12.48 and 15.66 mg/L, respectively.3. There were 29 and 25 kinds of aroma compounds that OAV larger than one in the wines by co-fermentation and single fermentation. The OAV values of linalool, trans-nerolidol, hexyl alcohol and heptyl alcohol in the wine samples fermented by single yeast showed less than 1 while in the co-fermentation mixed there were greater than one. The results of principal component analysis by OAV values of main aroma compounds showed that the cumulative contribution rate of PC1 and PC2 was 92.72%. Citronellol, β-ionone, trans-nerolidol, n-hexyl alcohol, heptyl alcohol, ethyl acetate, octyl acetate, benzene, ethyl acetate, ethyl propionate, ethyl caproate, diethyl succinate, 1-decanol, benzyl alcohol, n-octanol, acid methyl heptanoate, ethyl decanoate, isoamyl caprylate, caproate were the characteristic components on PC1, while 1-nonanol, 2-butanol, hexyl acetate were the characteristic components on PC2.4. Residual sugar, total acid, volatile acid, alcohol and other basic physicochemical indexes in the wines by co-fermentation and single fermentation have reached the national standard requirements. Total anthocyanins in co-fermentationed wine is 347mg/L, and in single fermentation wine is 397 mg/L.The sensory analysis in the two wines are difference.The aroma of co-fermentationed wine is more strong, the score is 8.7. The score of single fermentationed wine is 6.0. Acceptance degree of co-fermented and single fermented wine are high, the score respectively is 8.5 and 8.4. |
PDF Full Text Request