Pectic Substance in Green Tea and its Quantitative and Qualitative Change by Heating

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  • 緑茶のペクチンと加熱による変化
  • リョクチャ ノ ペクチン ト カネツ ニヨル ヘンカ

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Abstract

Pectic substance in green teas or tea leave were extracted fractionally to be determined by a colorimetric method of pectin with carbazole-sulfuric acid.<BR>The pectic substance content of Hoji-cha (roasted green tea) was specially higher than that of other green tea, i.e. Gyokuro, Sen-cha and Ban-cha.<BR>By heating Sen-cha at 170C, water solble pectin increased rapidly for from 5 to 8 minutes and then decreased slowly, while hydrochloric acid soluble pectin (protopectin) decreased continuously. The content of natrium hexametaphosphate soluble pectin in Sen-cha did not vary by heating.<BR>Furtheomore, the molecular weight of water soluble pectin of Sen-cha decreased to 10000 or 40000 from 150000 by heating at 170C for 24 minutes.<BR>The degree of esterification of Sen-cha pectin was 40-50% which decreased a little by heating at 170C.

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