The Nature and the Origin of Polyphenols in Hôji-cha (Roasted Green Tea)

Abstract

The nature and the origin of major polyphenols in Hôji-cha were elucidated from the effects of heating on individual flavanols by using paper-chromatographic technique. Furthermore the direction of thermal transformation of each flavanol and the quantitative variation of major products and original flavanols were shown. The heating of flavanol solution resulted in epimerization, polymerization and decomposition, though the aspect of change was different with the kind of flavanol and thermal condition. Thus it was revealed that (-)-catechin, (-)- gallocatechin, gallic acid, phloroglucinol and two thermal products from flavanol gallates occurred characteristically in Hôji-cha.