Effect of Mixed Culture Fermentations on the Aroma Compounds of ‘Cabernet Sauvignon’ Dry Red Wine Produced in the Eastern Foothill of Helan Mountain

This study investigated the effect of mixed culture fermentations with non-Saccharomyces strains and Saccharomyces cerevisiae on the aroma quality of ‘Cabernet Sauvignon’ wine from the eastern foothill of Helan Mountain in Ningxia in order to determine the optimum inoculation scheme for mixed culture fermentation. Three non-Saccharomyces strains were tested, including Hanseniaspora uvarum YUN268, Pichia fermentans Z9Y-3 and Pichia kluyveri C735. The proportions of mixed cultures were 10:1 and 1:1 between non-Saccharomyces and S. cerevisiae.Two inoculation schemes were used, namely sequential (48 hours apart) and simultaneous inoculation. Inoculation with S. cerevisiae alone was used as a control. The physicochemical and aroma properties of the resultant wine samples were evaluated. The results showed that compared with the control group, the mixed culture fermentation treatments increased the glycerol yield by 0.38–1.11 g/L and reduced the alcohol content by 0.33%–1.9%. In addition to ensuring successful completion of alcoholic fermentation, simultaneous inoculation of P. fermentans Z9Y-3 and S. cerevisiae at a mixing ratio of 10:1 significantly increase the dry extract content by 23.6% and the glycerol content by 4.6%. Moreover, this inoculation scheme maximized the ability of the two strains to produce aroma compounds, significantly increasing the contents of 30 different aroma compounds, including linalool, β-damascenone, ethyl octanoate, phenethyl acetate, methyl decanoate, isoamyl octanoate increasing the total amountof volatile compounds by 45%, and enhancing the berry-like, tropical fruit-like, floral and nutty aroma of wine. Therefore, this mixed culture fermentation scheme can be used as an ideal one for the production of ‘Cabernet Sauvignon’ wine in the eastern foothill of Helan Mountain.