| The Xiangning County, Shanxi Province is a nascent producing area for grape and wine, and being focused on by a great number of grape and wine researchers due to its unique condition in geography and climate. However, its wine industry is still at an initial stage and everything is being fumbling for. The purpose of this study was to provide academic guidance for local wine production. In this research, two genotypes of grape varieties, Cabernet Sauvignon (sampling at Sep. 16, 21, 26 and 30, Oct. 6 and 15, 2010) and Merlot (sampling at Sep. 16, 21, 26 and 30, Oct. 6 and 9, 2010) were chosen as experimental materials, and used to make dry wine (about 12%) through the same technology. In addition, the physicochemical propoties of these wines were detected. Then, the grape skins, seeds and wine from these two varieties harvested at different time were studied for their phenolic compounds, such as total phenolics, total flavonoid, total flavanol and total anthocyanin, and antioxidant activity using several assays based on different characteristics, such as DPPH scavenging capacity, cupric reducing power, Potassium ferricyanide reducing activity, hydroxyl radical scavenging activity and metal chelating capacity. And optimal harvest time about the two varieties in Xiangning County was identified through analyzing all these indicators using the principal component analysis. Moreover, it was found that the berry shrivel (BS) phenomenon, which has aroused great concern, also occurred in Xiangning County. In this research, the BS was studied for its impact on phenolics and antioxidant capacity of grape berries. The primary conclusions were as follows:(1) Phenolic compounds were extracted from grape skins and seeds using acidified methanol (1 M HCl in 80% methanol), respectively. The extracts solution was used to analyze total phenolics, total flavonoid, total flavanol and total anthocyanin, and antioxidant activity using several assays mentioned above. Then combined with basic physicochemical composition, we applied the method of the principal component analysis to make comprehensive evaluation of the quality of each grape sample from different harvest time. The results show that grape quality was in the decreasing order as follows: Cabernet Sauvigon, CS 9-16,CS 9-21,CS 9-26,CS 10-15,CS 9-30,CS 10-6; Merlot, ML 10-6,ML 10-9,ML 9-30,ML 9-26,ML 9-21,ML 9-16.(2) All wine samples were used to analyze penenolic compounds and antioxidant activity using several assays mentioned above. Then combined with basic physicochemical composition in each wine sample, we applied the method of the principal component analysis to make comprehensive evaluation of the quality of each wine sample from different harvest time. The results show that wine quality was in the decreasing order as follows: Cabernet Sauvigon, CS 9-16,CS 9-21,CS 10-6,CS 10-15,CS 9-30,CS 9-26; Merlot, ML 10-9,ML 10-6,ML 9-16,ML 9-30,ML 9-21,ML 9-26.(3) Cabernet Sauvignon is a late-mature cultivars, however, the optimal harvest time for Cabernet Sauvignon is about Sep. 16 according with the study on grape and wine mentioned above. It is more beneficial to wine quality that Cabernet Sauvignon was harvested earlierly when it is impossble to reach complete maturity. Merlot is middle-late mature varieties, and the optimal harvest time for Merlot is about Oct. 6～9 according with the study on grape and wine mentioned above.(4) Berry shrivel (BS), a berry development disorder, appears soon after veraison. It occurs worldwide and affects the quality of grape berries and wine. However, it had not been reported in China until recently. This study aimed to investigate the changes in berry composition and antioxidant activity of Cabernet Sauvignon grapes from Xiangning Valley, Shanxi Province, China, during BS. Shrinkage contributed to an increase in the concentration of basic grape ingredients such as sugar and acid. An appropriate degree of shrinkage was apparently helpful in improving the phenolic content and increasing the antioxidant activity, but the berries that continued to shrivel showed a low antioxidant activity. Further, the results indicated distinct differences between the berries harvested from the southern side of the canopy and those harvested from the northern side, presumably due to variations in sunlight exposure. |
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