熷乌龙茶－经反覆烘焙与陈放转化出的精制乌龙茶.PDF

農林學報 63(2): 83-90 (2014) - 83 - Journal of Agriculture and Forestry, 63(2) : 83 -90 (2014) 熷烏龍茶－經反覆烘焙與陳放轉化出的精製烏龍茶 王美琪[1] 陳盈潔[1] 曾志正[1]* 摘 要 台灣烏龍茶一直是家喻戶曉、中外馳名的特產，其特有的色、香與回甘滋味廣受飲茶人士的愛好。本文定義「熷烏 龍茶」為台灣現在市面上常見的烏龍茶再經專業的反覆烘焙及陳放所轉化出風味完全不同的精製茶品。就分子成份而言，經此 轉化，原茶湯中水溶性主要成份，包括游離胺基酸、咖啡因、兒茶素類、黃酮醇配醣體等的含量均明顯減少。然而，沒食子酸 的含量顯著提升，推論主要為酯型兒茶素(帶有沒食子酸結構的兒茶素分子)於烘焙時裂解所產生；且新產生楊梅黃酮、檞皮素 與山柰酚等黃酮醇成份，推論為此三類黃酮醇配醣體於烘焙時去醣降解所產生。此外，原茶湯中含量豐富且具揮發性的長鏈烷 類與長鏈酸類分子會顯著降解，但新產生多種吡咯衍生物，例如，2-乙醯基吡咯與 2-甲醛基吡咯等具烘焙風味的成份，此類成 分可能貢獻熷烏龍茶特有的香氣，推論此揮發性成份應於烘焙時由胺基酸轉化而來。就台灣烏龍茶產業的升級觀點，研發適當 的烘焙技術及其正確的陳放條件，將有助於發展多元且別具特色的客製化熷烏龍茶。 關鍵詞 ：陳放 、烘焙 、熷烏龍茶 。 Tzen Oolong Tea Converted from Oolong Tea by Baking and Aging Periodically Miki M. C. Wang[1] Ying-Jie Chen[1] Jason T. C. Tzen [1]* ABSTRACT Taiwan oolong tea has long been a representative and well -known tea product worldwide. Its unique color, flavor and umami taste broadly attract the tea-loving population. Here we defined Tzen oolong tea as a totally different type of tea refined from conventional oolong tea after baking and aging periodically. At the molecular level, the major soluble constitutes, including free amino acids, caffeine, catechins, and flavonol glycosides, in the original oolong tea degraded significantly after the tea conversion. However, gallic acid was found accumulated substantially in Tzen oolong tea, and presumably released from (-)-epigallocatechin gallate (EGCG) during the baking process. Moreover, the unique occurrence of three flavonols, myricetin, quercetin and kaempferol were presumably resulted from deglycosylation of their glycoside derivatives in fresh oolong tea after repeated baking. The abundant long - chain hydrocarbons and fatty acids in the fresh oolong tea were not found