%T LC-MS and GC–MS analyses reveal that amino acid-induced ammoniation of EGCG in different tea types enhances its structural stability
%L uneatlantico17836
%P 146024
%X Epigallocatechin gallate (EGCG) is the most abundant polyphenol in tea. Owing to the different fermentation degrees, differences in polyphenol composition of water extracts of green tea, white tea, oolong tea, and black tea occur, and affect health value. This study revealed that the content of EGCG decreases with the increase in the degree of fermentation. In tea with a high fermentation degree, EGCG was stably present in the form of ammoniation to yield nitrogen-containing EGCG derivative (N-EGCG). The content of N-EGCG in tea was negatively correlated with the content of EGCG. Furthermore, the content of l-serine and L-threonine in tea was positively and negatively correlated with N-EGCG and EGCG levels, respectively, suggesting that they may participate in the formation of N-EGCG as nitrogen sources. This study proposes a new fermentation-induced polyphenol-amino acid synergistic mechanism, which provides a theoretical basis for the study of the biotransformation reaction mechanism of tea polyphenols.
%A Yuxuan Zhao
%A Jingyimei Liang
%A Wanning Ma
%A Mohamed A. Farag
%A Chunlin Li
%A Jianbo Xiao
%D 2025
%V 493
%J Food Chemistry
%R doi:10.1016/j.foodchem.2025.146024