Study on the color effects of (-)-epigallocatechin-3-gallate under different pH and temperatures in a model beverage system

The effects of pH (2.2–8.0) and temperature (25–100 °C) on the instrumental color a model beverage containing (−)-epigallocatechin-3-gallate (EGCG) were investigated. As increased, lightness (L*) decreased while redness yellowness (a* b*, respectively) increased. Using spectral scanning, it was possible to verify that changes might be related structural rearrangement EGCG aqueous solution in system under alkaline heating conditions. There 6 key substances identified solutions, among which (2R)-2-Hydroxy-3-(2,4,6-trihydroxyphenyl)-1-(3,4,5-trihydroxyphenyl)-1-propanone 2-O-gallate (m/z 473.0720) theacitrin C/dehydrotheasinensin AQ 911.1340) as coloring substances. Color did not decrease antioxidant activity model. These results provide new insights mechanism change during storage green tea beverages, enable understanding contributors browning infusions beverages for first time.