Relationship Between Condensed Tannin Properties And Astringency In Cabernet Sauvignon Wine From Different Regions

Condensed tannins in wine come from grapes and are immersed in wine during the inpregnation process.The climatic conditions in different regions have a significant influence on the properties of tannins in berries and directly affect the quality of wine.In particular,the sensory quality and astringency of wine are closely related to tannin properties.At present,the quantitative relationship between condensed tannin properties and sensory quality and astringency in wine is not yet clear.In order to explore the regional differences in the tannin properties of wine grapes and wine tannins in different regions of China and establish the relationship between wine sensory quality and astringency,the experiment was conducted in2016 in nine vineyards in Shaanxi,Shanxi and Ningxia to collect Cabernet Sauvignon grapes at commercial maturity.Next,wine samples were obtained using small container brewing method.The basic physical and chemical indicators,the content of phenolics,the properties of condensed tannin of Cabernet Sauvignon grape and wine in different regions are determined,and wine samples were evaluated for sensory quality and astringency.The main conclusions based on our research are as follows:（1）There are obvious regional differences in the properties of condensed tannins in Cabernet Sauvignon grapes and wine.The percentage of epicatechin-3-O-gallate extended subunit（ECG-Ext）,the sum of catechin extended subunit and terminal subunit（C-Ext+C-Term）,and epicatechin-3-O-gallate extended subunits and terminal subunits（ECG-Ext+ECG-Term）in the skin tannins in Shaanxi region was significantly higher than that of the other two regions.The molecular mass of seed tannin in Shaanxi region was significantly lower than that of the other two regions.The percentage of catechin terminal subunit（C-Term）,the sum of catechin extended subunit and terminal subunit（C-Ext+C-Term）of seed tannin in Shaanxi region was significantly higher than that of the other two regions,but the percentage of epicatechin extended subunit（EC-Ext）,the sum of epicatechin extended subunit and terminal subunit（EC-Ext+EC-Term）of seed tannin in Shaanxi region was significantly lower than that of the other two regions.The percentage of epicatechin-3-O-gallate terminal subunit（ECG-Term）of seed tannin in Ningxia region was significantly higher than that of the other two regions.The percentage of catechin extended subunit（C-Ext）,epicatechin extended subunit（EC-Ext）,the sum of epicatechin extended and terminal subunits（EC-Ext+EC-Term）of wine tannin in Shaanxi region was significantly higher than that of the other two regions,but the percentage of epigallocatechin extended subunit（EGC-Ext）of wine tannin in Shaanxi region was significantly lower than that of the other two regions.The content of wine tannin in Ningxia region was significantly higher than that in the other two regions,but the percentage of catechin terminal subunit（C-Term）,the sum of catechin extended subunit and terminal subunit（C-Ext+C-Term）of wine tannin in Ningxia region was significantly lower than that of the other two regions.The mean degree of polymerization（m DP）of skin tannins in Shanxi region was significantly higher than that in Shaanxi region,and there was no significant difference between Ningxia regions and other two regions.The mean degree of polymerization（m DP）of seed tannins in Ningxia region was significantly higher than that in Shaanxi region,and there was no significant difference between Shanxi regions and other two regions.（2）The astringency intensity of wine increased with the increase of the tannin molecular mass and the percentage of epigallocatechin extended subunit（EGC-Ext）.The regression equation of the astringency intensity and tannin propertiess of wine was:y=0.002X _{tannin molecular mass}（R²=0.594,P≤0.05）.（3）There was a significant negative correlation between the astringency intensity of the wine sample and the percentage of epicatechin terminal subunit（EC-Term）of the seed tannin;There was an extremely significant negative correlation between astringency and p H value of wine,and there was no significant correlation between astringency and other basic physical and chemical indexes and phenolics content.