Synergistic Effect Of Epigallocatechin Gallate And Flavonols And Flavonol Glycosides On Color Change In Vitro

Browning is easy to take place during the production and storage of green tea beverage.In order to clarify the browning mechanism of tea infusion,compounds(EGCG,flavonol and flavonol glycosides)which were mainly led to the deterioration of green tea infusion color were selected for analysis in this research.The interaction effects of EGCG and flavonol,EGCG and flavonol glycosides on the color changes were compared through the different simulations of tea infusion conditions.This paper is aimed at revealing the browning mechanism of tea infusion,and exploringthe effective ways of control methods.The main results are as follows:1.The color analysis was proved that EGCG and flavonol,EGCG and flavonol glycosides had the interaction effect on color changes.And change rule of color follows that EGCG and flavonol>EGCG and flavonol glycosides>EGCG>flavonol>flavonol glycosides.The combination of EGCG and flavonols,EGCG and flavonol glycosides could accelerate the color changes,and each of them assist this effect of the others.2.The correlation analysis showed that EGCG had an extremely significant correlation with the changes of chromaticity values(L*,a*,b*,BI)of each mixed solution.Flavonols had an extremely and strong correlation with the changes of chromaticity values(L*,a*,b*,BI value)of mixed solution of EGCG and flavonol.The correlation rule follows that myricetin>quercetin>kaempferol.There were different degrees of correlations between flavonol glycosides with the changes of chromaticity values(L*,a*,b*,BI)of mixed solution of EGCG and flavonol glycosides.The color change of correlation showed that myricetin glycosides>quercetin glycosides>kaempferol glycosides.Among of them,the rule of correlation between quercetin glycoside with the changes of chromaticity values(L*,a*,b*,BI)of the mixed solution of EGCG and quercetin glycosides follows that rutin>quercetin-3-O-glucoside.3.The visible spectrum analysis indicated that flavonol and flavonol glycosides(except for rutin)had no obvious absorption in the visible region,which did not have obviously change in heat treatment.EGCG had a prominently rise in absorption during the visible region.In a series of hybrid system of EGCG and flavonol,flavonol glycosides appeared a significant hyperchromic,and both of them had higher absorption value than EGCG.4.The analysis of HPLC showed that the addition of EGCG for flavonol and flavonol glycosides had a contribution of degradation,especially myricetin.Mixed solution had generated the interaction products at 480 nm.5.The interaction for color changes of EGCG and myricetin showed that the low concentration of EGCG had the few impacton myricetin,but a high concentration of EGCG had theimpact of color changes on myricetin for reddening and yellowing.Myricetin could accelerate the trend of reddening and yellowing for EGCG,and the variation tendency was related to the concentration of myricetin.The color change dynamics equation of EGCG and myricetin,proved that EGCG had a major role of yellowing and browning for mixed solution,and myricetin had a major role of reddening for mixed solution.6.Separation and identification of the red product by interacting between EGCG and myricetin were carried on: The collection of the products of EGCG and myricetin was used the SEP-PAKC18 column and HPLC.And the structural identification of red product was conducted by UV spectrum,UPLC-MS,NMR,IR etc.The results showed that the products were the dimers with the molecular weight of 608,668,764.