Studies on the Colored Components in Black Tea Infusion

Part IV. Photometric evaluation of the quality of tea infusion

Abstract

The optical densities of theaflavin, thearubigin and water-soluble oxidized matter in black tea infusion were determined by the procedure ascribed by CASSON after several modifications and applied on the evaluation of the quality of black tea infusion.
The optical density values of theaflavin, thearubigin and also theaflavin plus thearubigin showed high positive correlations with the evaluation of the quality of tea, respectively, while water-soluble oxidized matter showed negative correlation.
Furthermore, it was thought that theaflavin, theaflavin plus thearubigin and water-soluble oxidized matter were likely to compose predominantly color of black tea infusion from the results of multiple regression analysis.
From these results, it was assumed that the rates of the optical density values of theaflavin plus thearubigin and water-soluble oxidized matter in total color of black tea infusion were effective to evaluating and classifying black teas.