@article{oai:nagasaki-u.repo.nii.ac.jp:00001597,
 author = {Morikawa, Hitomi and Okuda, Keita and Kunihira, Yuji and Inada, Aoi and Miyagi, Chika and Matsuo, Yosuke and Saito, Yoshinori and Tanaka, Takashi},
 journal = {Food Chemistry},
 month = {Jul},
 note = {Roasting of green tea causes oligomerization of tea catechins, which decreases the astringency. The aim of this study was to elucidate the oligomerization mechanism. 
The 13C NMR spectrum of the oligomer fraction showed signals arising from catechin and sugar residues. Heating of epigallocatechin-3-O-gallate with 13C-labeled glucose (150 °C for 2 h) suggested that condensation of sugars with catechin A-rings caused the oligomerization. The dimeric product obtained by heating for a shorter period (30 min)suggested cross-linking occurred between sugars and catechin A-rings. Furthermore, heating of phloroglucinol, a catechin A-ring mimic,
 with glucose, methylglyoxal, and dihydroxyacetone, confirmed that the basic mechanism included reaction of the catechin A-ring methine carbons with carbonyl carbons of glucose and their pyrolysis products., Food Chemistry, 285, pp.252-259; 2019},
 pages = {252--259},
 title = {Oligomerization mechanism of tea catechins during tea roasting},
 volume = {285},
 year = {2019}
}