Studies on the Mechanism of the Oxidation of Tea Leaf Catechins

Part III. Formation of a Reddish Orange Pigment and its Spectral Relationship to Some Benzotropolone Derivatives

Abstract

A study is made on the oxidation of a mixture containing epigallocatechin and epicatechin with tea oxidase as well as a oxidizing reagent, in order to understand the formation of red pigments in tea manufacture. As the reaction proceeds a remarkable colored substance is formed, which can be obtained in reddish orange needles (from water) and is supposed to be a troponoid compound having a 3', 4'-dihydroxybenzotropolone nucleus as suggested by a tentative structural formula III from a consideration of its spectral characteristics.