On-vine drying (passerillage) improves the quality of "Hutai No. 8" table grape wine: Focusing on phenolics, aromas, color and sensory attributes

On-vine drying (passerillage) was employed for Hutai No.8 table grapes with different water loss rates and that are used for winemaking to alter the qualities of wine. Results showed that on-vine drying increased sugar content, thereby elevating alcohol and glycerol contents in the resulting wine. A moderate drying treatment (D2, 18 % water loss) produced wine with optimal red color characteristics. The D2 wine contained abundant individual phenolics such as caffeic acid, salicylic acid, resveratrol, p-coumaric acid, and proanthocyanidin B1, which exhibited strong positive correlations with color parameters (a*, C*(ab) and triangle E*(ab)). Similar trends were observed in aroma compounds, with ethyl acetate, ethyl caproate, diethyl succinate, geraniol, linalool, 4-terpinenol, alpha-terpineol, and beta-ionone contents showing significant increment in D2, aligning with enhanced sensory evaluations of wines. Thus, improvement of wine quality can be achieved through moderate on-vine drying (18 % water loss), serving as a valuable reference for table grape winemaking.