Influence of ultraviolet irradiation on papers containing wasted tea leaves was studied. Ultraviolet irradiation generally caused reddish coloration. Irradiation under dry atmosphere caused stronger coloration than under ambient conditions. Presence of oxygen did not cause significant difference in coloration. Thin-layer chromatographic analysis showed disappearance of chlorophylls a and b, and did not disappearance of theaflavin by UV irradiation. The results strongly suggest that the coloration is caused by photochemical conversions of catechins to reactants (theaflavin-like compounds).
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