Effect of Cyclodextrins on the Thermal Epimerization of Tea Catechins

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The epimerization reaction of tea catechins was investigated at pH 5.5 and 120°C in the absence/presence of cyclodextrins (CDs). In the absence of CDs, a considerable quantity (∼20%) of products originating from reactions other than the epimerization ("other products") was formed during the epimerization of gallated catechins. In the case of (-)-EGCg, addition of β-CD to the reaction solution reduced the quantity of these other products to just a few percent, but other CDs with different cavity sizes had little effect. Generally, the addition of β-CD increased the ratio of non-epi type catechins, that is, [non-epi type catechin] / ([epi type catechin]+[non-epi type catechin]). Molecular orbital (MO) calculations using the PM3 method suggested that non-epi type catechins are more thermodynamically stable than their epi-type counterparts, moving the equilibrium position in favor of non-epi type catechins in the epimerization process.

The epimerization reaction of tea catechins was investigated at pH 5.5 and 120 °C in the absence/presence of cyclodextrins (CDs). In the absence of CDs, a considerable quantity (∼20%) of products originating from reactions other than the epimerization ("other products") was formed during the epimerization of gallated catechins. In the case of (-)-EGCg, addition of β-CD to the reaction solution reduced the quantity of these other products to just a few percent, but other CDs with different cavity sizes had little effect. Generally, the addition of β-CD increased the ratio of non-epi type catechins, that is, [non-epi type catechin] / ([epi type catechin]+[non-epi type catechin]). Molecular orbital (MO) calculations using the PM3 method suggested that non-epi type catechins are more thermodynamically stable than their epitype counterparts, moving the equilibrium position in favor of non-epi type catechins in the epimerization process.

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  • Food science and technology research  

    Food science and technology research 14(1), 83-88, 2008-01-01 

    日本食品科学工学会 = Japanese Society for Food Science and Technology / Karger

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各種コード

  • NII論文ID(NAID)
    10021184719
  • NII書誌ID(NCID)
    AA11320122
  • 本文言語コード
    ENG
  • 資料種別
    NOT
  • ISSN
    13446606
  • データ提供元
    CJP書誌  CJP引用  IR  J-STAGE 
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