Using abandoned unripe grape resources to solve the low-acid problem in the northwest wine region of China

Low acid is the main defect in the northwest wine region of China in recent years. The fermentation of unripe grape (UG) and wine grapes with low acid contents was carried out. Compared with control group (CK), the addition of UG addressed the core flaw that low acid grape bring to wine firstly, it significantly increased titratable acid, tartaric acid and malic acid while significantly decreasing alcohol and volatile acids in wine. Secondly, UG significantly improved wine color, the color parameters a*, b*, C* and L* were significantly increased to different degrees. At the same time, the addition of UG significantly improves other qualities of wine, including the phenolic substances and antioxidant capacity of wine. In addition, adding UGJ2% significantly improved the sensory quality, and pleasant volatile substances such as phenethyl alcohol, ethyl hexanoate, ethyl butyrate and isoamyl acetate were significantly increased, giving the wine more prominent floral and fruity aromas.