烏龍茶種植海拔高度與其茶湯澀度的關聯性

Correlation between Cultivation Altitudes of Oolong Tea Plants and the Astringency of Their Tea Infusions

李欣潔(Sin-Jie Lee) ； 陳冠亨(Guan-Heng Chen) ； 曾志正(Jason T. C. Tzen)

《農林學報》 63卷2期 (2014/09) Pp. 107-113

https://doi.org/10.30089/JAF.201409_63(2).0005

摘要

澀度高低乃決定茶飲品質好壞的重要指標之一，而茶湯澀味大多源自於其所含的多酚類（主要是兒茶素類）物質。茶葉所含的兒茶素成份主要有四個，包括兩個非酯型兒茶素，表兒茶素（epicatechin EC）與表沒食子兒茶素（epigallocatechinEGC），以及兩個酯型兒茶素，表兒茶素沒食子酸酯（epicatechin gallate ECG）和表沒食子兒茶素沒食子酸酯（epigallocatechingallate EGCG）。酯型兒茶素乃由非酯型兒茶素經酵素作用，額外鍵結一個沒食子酸而產生，相較之下，其引起澀味程度明顯比非酯型兒茶素高出許多。台灣地理條件及氣候適宜茶樹生長，因此不論海拔高低，均有茶園的分布。種植於中部山區的青心烏龍品種所製成之高山烏龍茶，因具有獨特的香氣與滋味，普遍受到大眾的喜愛。這些種植於中部山區不同海拔的青心烏龍茶樹與其製作出的清香型高山烏龍茶，提供了一組可供探討種植海拔高度對烏龍茶澀度影響的好題材。分析結果發現以下兩個趨勢：第一，總兒茶素含量隨種植海拔高度的提升而逐漸減少；第二，澀味強度較高的酯型兒茶素含量比例也隨種植海拔高度的提升而遞減。總兒茶素含量降低及酯型兒茶素含量比例降低，均能減少茶湯的澀度。就此推論，此兩項趨勢乃造成種植於海拔較高的茶樹所採栽製成的烏龍茶之茶湯澀度較低的主因。

關鍵字

澀味 ； 海拔 ； 沒食子酸酯型化

並列摘要

Astringency caused by polyphenolic compounds, such as catechins, is a major factor for the quality of tea. Tea infusions mainly comprise two non-gallate type catechins, epicatechin (EC) and epigallocatechin (EGC), as well as two gallate type catechins, epicatechin gallate (ECG) and epigallocatechin gallate (EGCG). Gallate type catechins are derived from non-gallate type catechins via incorporation of a molecule of gallic acid by a specialized enzyme, and induce a relatively high astringent taste. Fresh tea leaves and their corresponding oolong tea granules prepared by Chin-Shin Oolong plants cultivated at different altitudes of Center Taiwan provide adequate sources to evaluate the effects of cultivation altitude on the characteristics of oolong tea. In our analysis, catechin contents in oolong tea infusions were found inversely correlated to the cultivation altitude. The degrees of catechin galloylation in both oolong tea infusions and their fresh tea leaves were also found inversely correlated to cultivation altitude. It seems that catechin contents and the degree of its galloylation largely account for the inverse correlation between astringency of oolong tea and cultivation altitude.

並列關鍵字

Astringency ； cultivation altitude ； galloylation of catechins