Novel Pink Pigments Produced by Thermal Interaction of Theaflavins, Theanine, and Glucose: Color Formation, Isolation, and Structural Characterization

• DOI: 10.1021/acs.jafc.4c07072
• Publication Date: 2024-09-26T10:11:47Z
• Authors: Piaopiao Long; Shengxiao Su; Mingchun Wen; Chi-Tang Ho; Zisheng Han; Xiaobo Zuo; Yulan Jiang; Jia-Ping Ke; Guoping Lai; Mengting Zhu; Xiaochun Wan; Liang Zhang
• Keywords: Characterization; Theanine; Isolation

A color-deepening effect of theaflavins on the theanine-glucose thermal reaction model was revealed. Generated chromogenic intermediates in initial stage and an accelerated browning rate through promoted degradation Amadori rearrangement product intermediate final stages are responsible for effect. Four pink-to-red theaflavin-theanine were verified as theaflavinies referencing nuclear magnetic resonance liquid chromatography-mass spectrometry information l-theanine, including one accurately identified theaflavinie 4. Theaflavinie 4 showed two maximum absorption peaks at 401 506 nm with parallel intensities, which resulted a significant dichromic color change from pale pink to orange red. Theaflavinies also could undergo further reactions yield brown polymers under higher temperatures (130 140 °C). This research provided new insight into realizing thermally formed during black tea processing, may be by oxidation products amino acids or proteins non-enzymatic reactions.