Abstract
The consumption of green tea in colorless and transparent pet bottles has increased recently. However, there is a problem of the discoloration of thegreen pigment (chlorophyll) in green tea by light. This study was carried out to investigate the effect of (-) -epigallocatechin gallate (EGCG) on the discoloration of chlorophyll-a (Chl-a) by light irradiation. EGCG inhibited the discoloration of Chl-a when its concentration was 10 times greater the Chl-a concentration. Moreover, the simultaneous addition of EGCG and ascorbic acid resulted in a synergistic inhibitory effect on discoloration of Chl-a by light irradiation. All Chl-a in the green tea ethanol solution was decomposed by light irradiation for 4 hours. In spite of the addition of EGCG (1mM) to the green tea solution, the inhibition of the discoloration of Chl-a was not as strong as that predicted in this study. The concentration of catechins in the green tea solution decreased slightly during light irradiation. Therefore, although the inhibitory effect of EGCG on the discoloration of Chl-a was noted, it was not clearly observed in the green tea solution.
