市販緑茶の個別カテキン類とカフェインの分析 Contents of Individual Tea Catechins and Caffeine in Japanese Green Tea.

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市販録茶試料7茶種85点の8種のカテキン類とカフェインの含有量を測定した。玉露,抹茶は煎茶,玉緑茶と比較してやや多くのカフェインを含む一方総カテキン量は少なかった。同じ茶種の中では,上級茶は一般に下級茶より多くのカフェインを含み総カテキン量は低かった。個々のカテキン類の中では,エピガロカテキンガレート(EGCg)の含有量が最も多く,総カテキン量の50~60%を占め,エピガロカテキン(EGC)と合わせた量は総量の約80%であった。遊離型カテキン(EC,EGC)の含有量は,エステル型カテキン(ECg,EGCg)の,煎茶,玉緑茶では半分以下,玉露,抹茶では1/3以下であった。玉露,抹茶では多くの試料からカテキン(C)が検出されたが,それ以外の微量カテキン類はほとんど検出されなかった。ほうじ茶のカテキン類は,加熱による変化を受けるためか量的にも少なく,その組成も他の茶種と大きく異なっていた。

Eighty-five samples of commercially available Japanese green teas were assayed for caffeine and the following eight catechins;epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECg), epigallocatechin gallate (EGCg), catechin (C), gallocatechin (GC), catechin gallate (Cg), and gallocatechin gallate (GCg). The tea samples were derived from the following types of tea; Gyokuro, Matcha, Sencha, Bancha, Hojicha, Kamairisei tamaryokucha, and Mushisei tamaryokucha. The total catechin content ranged from 9 to 18% except Hojicha and the caffeine content ranged from 2 to 4% of dry tea leaf. Four major catechins, EC, EGC, ECg, and EGCg, and caffeine were found in nearly all of tea, although some of the Hojicha samples did not have quantititative levels of EC. In addition, four catechins, C, GC, Cg and GCg, were detected in some samples.<BR>Gyokuro and Matcha, both of which are produced from leaves grown under a sunshade, contained more caffeine and less catechins compared to the other types of teas. In general, the higher grade teas contained more caffeine and the lower grade teas contained more catechins. More than half of total catechins contented in the teas was EGCg. The combined contents of EGC and EGCg comprised approximately 80% of total catechin content regardless of the tea type. The level of the free type catechins, EC and EGC, was less than half of the contents of ester type catechins, ECg and EGCg, in Sencha and the tamaryokuchas and less than one-third of ester type catechins in Gyokuro and Matcha. The level of catechins was much lower in Hojicha tea than in the other six types and the catechins composition was also different;probably due in part to the roasting of the tea during processing.

収録刊行物

  • 茶業研究報告

    茶業研究報告 1996(83), 21-28, 1996

    茶研報

各種コード

  • NII論文ID(NAID)
    130000736395
  • NII書誌ID(NCID)
    AN00143344
  • 本文言語コード
    JPN
  • ISSN
    0366-6190
  • NDL 記事登録ID
    4021973
  • NDL 雑誌分類
    ZR7(科学技術--農林水産--農産)
  • NDL 請求記号
    Z18-1171
  • データ提供元
    NDL  J-STAGE 
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