Relationship between photon emission and chemopreventive potential of tea

Photon emission from tea (610–670 nm) in the H2O2/KHCO3/MeCHO system and the utility of the photon detection system in tea evaluation were investigated. Photon intensity of tea depended on manufacturing method as follows: green tea (1202 ± SD 173.51 cd/m2) > oolong tea (834 ± SD 237.44 cd/m2) > black tea (222 ± SD 87.65 cd/m2). Photon intensity corresponded with polyphenol content (r2=0.8810) rather than catechin content (r2=0.7759) and showed a high correlation with chemopreventive activities against H2O2 (r2=0.7516), O2− (r2=0.7998) and DPPH radical (r2=0.7516). Photon intensity from green tea leaves at each manufacturing process step gave the same decreasing curve as DPPH radical scavenging activity. Chemiluminescence of tea, which gives information on the polyphenol content and chemopreventive potential, is a useful technique for tea evaluation.