碩士 / 國立中興大學 / 生物科技學研究所 / 101 / Tea is widely consumed for over several thousand years in Mandarin China. Up to these days, tea has become the most consumed beverages around the world. In Taiwan, oolong tea is the most popular tea because of its unique flavor and taste. Astringent taste is considered to be one of the characteristics that lower the quality of oolong tea. The main substances causing astringent taste in oolong tea are catechins. Catechins can be further divided into two subgroups, non-gallate-type catechins and gallate-type catecins. It has been shown that gallate-type catecins are far more astringent than non-gallate-type catechins. In tea trees, the main non-gallate-type catechins are (-)-epicatechin (EC) and (-)-epigallocatechin (EGC), and the main gallate-type ones are (-)-epicatechin gallate (ECG) and (-)-epigallocatechin gallate (EGCG). Oolong tea produced from leaves of Camellia sinensis L. cultivated at higher altitude are generally tasted less astringent than those grown at lower altitude because of lower polyphenol contents, but fewer researches have been focused on the non-gallate-type catechins and the gallate-type catechins contents in tea trees grown at different altitudes. In my research, I collected fresh tea leaves and oolong tea products from tea trees cultivated at different altitudes, and analyzed their catechin contents by HPLC analysis. The degrees of galloylation on these two types of catechins, designated as ECG/(EC+ECG) and EGCG/(EGC+EGCG) were also discussion. It seems that less cathion contents and less galloylation of catechins in tea leaves cultivated in higher altitude may partly lead to the less astringency of oolong tea infusion. My observation may provide useful information for both tea tree cultivation and oolong tea manufacture in the future.
| Identifer | oai:union.ndltd.org:TW/101NCHU5111022 |
| Date | January 2013 |
| Creators | Sin-Jie Lee, 李欣潔 |
| Contributors | 曾志正 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 51 |
Page generated in 0.0145 seconds