Effect of Different Harvest Time on Physicochemical Properties and Aroma Components of Vitis quinquangularis Rehd. ‘Yeniang No.2’ Wine

The study aimed to determine the influence of harvest date on ‘Yeniang No.2’ (Vitis quinquangularis Rehd.) wine basic chemical variables and aroma components. A series of three ‘Yeniang No.2’ wines were produced from grapes of different harvest dates, Harvest 1: 15 August, Harvest 2: 10 September and Harvest 3: 23 September. The physicochemical properties and aroma components were determined. Results showed that, the grapes of sequential harvest treatments showed an increase in total sugar and a decrease in titratable acidity. In the wines, alcoholic strength, phenol, tannin and flavonoid were enhanced with the sequential harvest, whereas residual sugar and acidity were decreased. there also existed significant difference among different harvest periods（P<0.05）. There were 89 aroma components identified in 3 wines, including 22 alcohols, 37 esters, 7acids, 5 aldehydes , 5 terpenes and 13 others. The highest concentration of aroma components was in the last harvest date, 852370.83 μg/L. The main aroma characteristics of ‘Yeniang No.2’ wines were fruity, caramel, fatty and floral aromas, but the odor activity value (OAV) of the same aroma component of wines harvested on different dates was different, which led to differences in their aroma characteristics. The higher OAV of isovaleric acid and octoic acid in wines harvested on 15 August gave the wine a higher fatty flavor. The higher OAV of phenylacetaldehyde, β-damastone and TDN in wines harvested on 10 September gave the wine more floral and caramel characteristics. The higher OAV of ethylcaproate in wines harvested on 23 September gave the wine a higher fruity aroma. The analysis results of the fruit quality and aroma characteristics showed that the best harvest period of the ‘Yeniang No.2’ grape was between 10 September and 23 September.