Quantification of ascorbyl adducts of epigallocatechin gallate and gallocatechin gallate in bottled tea beverages. (30th September 2018)

• Record Type: Journal Article
• Authors: Hung, Wei-Lun; Wang, Siyu; Sang, Shengmin; Wan, Xiaochun; Wang, Yu; Ho, Chi-Tang
• Is Part Of: Food chemistry. Volume 261(2018)
• Page Start: 246
• Page End: 252
• Publication Date: 2018-09-30
• Subjects: Epigallocatechin gallate -- Gallocatechin gallate -- Tea beverages -- Ascorbic acid -- Ascorbyl adducts; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2018.04.050
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Ascorbic acid is usually added to tea beverages to protect catechins from oxidation. Ascorbyl adducts of epigallocatechin gallate were formed in the aqueous solution. Ascorbyl adducts of catechins were quantified in green tea and oolong tea drinks. 8C-ascorbyl adducts of catechins were the major adducts in tea drinks. Abstract: 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.