Study On Maturity Index System Of Wine Grape In Tuha Region Of Xinjiang

The maturity of wine grapes is very important to the quality of wine.The indexes affecting the maturity of wine grapes are not only the basic physical and chemical indexes such as sugar and acid,but also polyphenols.However,for the determination of the harvest time of wine grapes in Xinjiang,most regions still use the content of fructose to judge,without considering the role of phenolic substances,and the taste and color of wine will be affected by phenolic substances.Therefore,this paper refers to the basic physical and chemical indicators and polyphenol indicators on the basis of four red wine grapes in Tuha region of Xinjiang.Grape varieties Cabernet Sauvignon(CS),Merlot(ML),Cabernet Gernischt(CG),Syrah(SR)and two white grape varieties Chenin Blanc(CB),Softclove(SC)carried out maturity control index system research to provide theoretical basis for timely harvest.The main research results are as follows:(1)The reducing sugar content in fruits increased gradually with the ripening of berries,while the acid content decreased gradually.The 100-grain weight of fruits increased gradually,and the 100-grain weight decreased at the later stage of harvest.There was no regularity in the change of polyphenol content in berry peel.For the polyphenol content in berry peel,Merlot fruit and Cabernet Sauvignon fruit showed the same trend of first rising and then falling;Syrah fruit and Cabernet Sauvignon fruit showed the same trend of first rising and then falling and then rising;for the polyphenol content in fruit seeds,Merlot and Serpentine Sauvignon Sauvignon showed the trend of first decreasing and then rising;Syrah fruit and Cabernet Sauvignon fruit showed the same trend of first rising.The upward and downward trend.(2)The content of polyphenols in wine increased gradually with harvesting time.SRW3?MLW2?CSW2?CGW2?CBW3?SCW2 had the highest content of phenols.The results of sensory analysis showed that SRW2,MLW2,CSW2,CGW2,CBW3 and SCW2 had the highest sensory evaluation.(3)According to the changes of the indices and components of fruits in different periods,the quality of fruits was analyzed by principal component analysis.The maturity control index system of red wine-making varieties in Loulan production area was established through the model.The first index of four red wine-making varieties was titratable acid;the second index of Syrah and Cabernet Sauvignon fruits was peel flavone,Merlot was total phenol of seeds and Serpentine Sauvignon.Peel flavanols;the third-level indicators of Syrah and Merlot are peel tannins,and the seed flavonoids of Cabernet Sauvignon and Snake Dragon Pearl are seed flavonoids.