Wei-Lun Hung, Siyu Wang, Shengmin Sang, Xiaochun Wan, Yu Wang, Chi-Tang Ho (2018). Quantification of ascorbyl adducts of epigallocatechin gallate and gallocatechin gallate in bottled tea beverages. Food Chemistry, 261, 246-352.
Citrus Research and Education Center, Department of Food Science and Human Nutrition, University of Florida, Lake Alfred, FL 33850, USA
Department of Food Science, Rutgers University, 65, Dudley Rd., New Brunswick, NJ 08901, USA
Laboratory for Functional Foods and Human Nutrition, Center for Excellence in Post-Harvest Technologies, North Carolina Agricultural and Technical State University, North Carolina Research Campus, Kannapolis, NC, USA
State Key Laboratory of Tea Plant Biology and Utilization, School of Tea & Food Science, Anhui Agricultural University, Hefei, Anhui, China
International Joint Research Laboratory of Tea Chemistry and Health Effects, Hefei, Anhui, China
Catechins are the major bioactive compounds existing in tea leaves (Camellia sinensis). Dehydroascorbic acid is (DHAA) a reactive dicarbonyl species and previous studies have demonstrated that catechins could effectively trap DHAA to form ascorbyl adducts of catechins, especially epigallocatechin gallate (EGCG). Since catechins in the aqueous solution are unstable due to their structural features, ascorbic acid (AA) is usually added to bottled tea beverages to protect catechins. However, whether ascorbyl adducts of catechins are formed in bottled tea beverages remains unclear. In this study, formation of ascorbyl adducts of EGCG increased along with increased incubation time when EGCG and AA were dissolved in the aqueous solution. Next, 6C-DHAA-EGCG and 8C-DHAA-EGCG were detected in both green tea and oolong tea beverages, and their concentrations ranged from 0.23 to 1.95 µM and 0.28 to 1.97 µM, respectively. Furthermore, an 8C-ascorbyl adduct derived from gallocatechin gallate was also found in some tea beverages.