Composition Variations Of Anthocyanins During Grape Ripening And In Wine Of Merlot From Different Production Areas Of Hexi Corridor

Anthocyanin, as the main coloring substance in dry red wine, is constantly accumulated and transformed in grape ripening stage and during wine fermentation, and eventually determines the color characteristics and area-specific representation of wine. Merlot is one of the fine grape species that were widely planted in the Hexi Corridor. In current study, grapes of Merlot, being collected from different producing areas(Banqiao, Gaotai, Huangyang town and Jiayuguan) of Hexi Corridor, were used to examine the composition of anthocyanins and their variations, by using HPLC, before and after grape maturation and wine fermentation. Main results are summarized as follows:1. Contents of nine anthocyanins of Merlot from different areas of Hexi Corridor exclusively accumulated in grape ripening stage. Malvidin-3-O-glucoside content of grape had the highest value in all the producing areas, comparing with other anthocyanins, and which was relatively higher in Gaotai than in other areas. Anthocyanins in Jiayuguan attained their peaks when veraison reached to 40 d, while 50 d for other areas.2. Though PCA, we found that Peonidin-3-O-glucoside and Peonidin-3-O-(6-O-acetyl)-glucoside had a major contribution to the composition of anthocyanins of grapes collected in Banqiao town, while they were Delphinidin-3-O-glucoside and Petunidin-3-O-glucoside for Gaotai, Malvidin-3-O-(6-O-coumaryl)-glucoside for Huangyang town, Malvidin-3-O-glucoside and Malvidin-3-O-(6-O-acetyl)-glucosidefor Jiayuguan.3. The content of anthocyanins varied during wine fermentation between different producing areas, but generally shared the similar tendency. The relative content of delphinidin derivatives、cyanidin derivatives、petunidin derivatives and peonidin derivatives decreased, while it increased for malvidin derivatives. Non-acylated derivatives showed an increase, while a decrease for coumaroylglucoside derivatives.4. According to PCA, delphinidin derivatives, cyanidin derivatives, petunidin derivatives, peonidin derivatives and malvidin derivatives had a relative higher contribution to PC1, suggesting that the composition these 5 derivatives anthocyanins varied before and after fermentation and was obviously different among producing areas. However, Anthocyanins grouped as a function of their C-ring substitution pattern, no significant differences were found in non-acylated derivatives and acetylglucoside derivatives among producing areas.5. Anthocyanins in Merlot wine inherits the characteristics of raw materials from each producing area. delphinidin derivatives were more stable in Banqiao town than in other areas. Delphinidin-3-O-glucoside in Gaotai showed the higher value comparing with that in other areas. The content of Cyanidin-3-O-glucoside was very low in grape skin from Huangyang town, and was not detected in the wine and malvidin derivatives in Huangyang town showed relatively high stability comparing with that in other areas, and The content of Malvidin-3-O-(6-Oacetyl)-glucoside was higher in Jiayuguan than in other areas, and the composition of anthocyanins was area-specific.In conclusion, Merlot grape ripening stage and the wine, being collected from different producing areas(Banqiao, Gaotai, Huangyang town and Jiayuguan) of Hexi Corridor, accumulated in the characteristics of producing area.