Study On The Composition And Content Of Tannin Extract In Different Organs Of Quercus Variabilis

As an important tanning plant,the tannin content of acorn cup of Quercus variabilis is very high,so it is very important raw materials to tannin extract.Q.variabilis ’ bark,leaves and branches also contain a certain amount of tannin,and as green renewable resources,they also have the very broad application prospect.Studying on the composition and content of tannin extract in different organs of Q.variabilis can help to determine the best harvest period and the feasibility of using other organs for extract production.So that can provide a certain basis for making better use of Q.variabilis resources and expanding its resource utilization.This paper researched Q.variabilis in the north slope of Qinling Mountains to analysis how different organs,different collecting time and DBH to effect tannin content by LY/T1082-2008 tannin extract analysis methods and UV Spectrophotometry.The results showed that:1.The extract ingredients of different organs of Q.variabilis in the north slope Qinling were not the same,and trend for soluble content、tannin content and non-tannin content were similar:acorn cup>bark>leaf>branch,the trend for total dry substance is:acorn cup>leaf>bark>branch,the trend for insoluble content is:acorn cup>leaf>branch>bark.2.Brak total dry substance content were 10.07%-14.97%,bark soluble content were 9.16%-12.98%,bark insoluble content were 1.01%-1.99%,bark tannin content were 7.21%-9.12%,bark non-tannin content were 1.95%-3.86%.Leaf total dry substance content were 11.22%-17.83%,leaf soluble content were 7.69%-12.66%,leaf insoluble content were 3.53%-5.17%,leaf tannin content were 6.04%-9.06%,leaf non-tannin content were 1.65%-3.60%.Branch total dry substance content were 7.90%-12.66%,branch soluble content were 6.98%-10.06%,branch insoluble content were 1.01%-3.71%,branch tannin content were 5.12%-7.86%,branch non-tannin content were 1.86%-3.23%.Acorn cup total dry substance content were 33.58%-42.46%,acorn cup soluble content were 25.97%-34.11%,acorn cup insoluble content were 7.61%-9.35%,acorn cup tannin content were 19.18%-25.12%,acorn cup non-tannin content were 6.18%-8.99%.So acorn cup and other parts of Q.variabilis could also be used as raw material for the production of tannin.3.There was significant influence on tannin products when harvested in different time,the content of tannin in the bark,branches and changed with the harvest time basically consistent,and tannin content was lower in the spring and summer compared with the content in autumn and winter.Therefore the raw material could be harvested in autumn to make better use of Q.variabilis resources.The process of turning brown affected other components,resulting in the decline of the quality of vegetable tannin extract so the acorn cup should be harvested in the middle of September or early October as soon as possible.4.The tannin content in different organs of Q.variabilis was increased with the growth trend of diameter at breast height.It was better to choose individuals of 28 and 32 diameter class as raw materials in this area and make a directional cultivation and protection for the 20 size class of Q.variabilis individuals.