Effect of Pre-fermentative Addition of Different Oak Chips on the Colour Based on the CIELab during Wine Aging

To explore the effect of adding different oak chips before fermentationon on the color of the wine,this experiment took the Cabernet Sauvignon grape from Heshuo,Xinjiang,as raw material. Five different toasting degrees(French-light,French-medium,French-medium plus,American-medium,American-medium plus)with three different dosages(2,3 and 4 g/L)were considered. The color parameters of the samples were determined by CIELab method at 1,3,6,9 months of aging. The results showed that,the addition of oak chips promoted the colour enhancement and stabilisation,reduced the brightness(L^*),enhanced the red hue value(a^*),slowed down the rising of the yellow color(b^*),which had contribute to maintain the purple hue of the new wine,increased the polymeric pigments content(PPC)during storage and improved the color of the wine. But the effects of different oak treatments on the color parameters were different. At 3 months of aging,2 and 3 g/L treatment with a^*,C_ab^*,PPC and total anthocyanins were significantly higher than the control group(P<0.05),3 g/L treatment with L^* was significantly(P<0.05)lower than the control,4 g/L treatment with L^* was significantly(P<0.05)higher than the control,and a^* was significantly(P<0.05)lower than the control. At 9 months of aging,the color indexes of each treatment were significantly(P<0.05)different from those of the control,but the 4 g/L treatment showed lower L^*,higher a^* and PPC. It was recommended that 2 or 3 g/L addition could be considered for the wines that only need short-term storage,4 g/L addition was better for the long-term aging wines.