Relationship between cyclic voltammetry redox potential and total reducing power of tea extracts

The tea polyphenols contents and total reducing power of 28 kinds of green tea,oolong tea and black tea from different geographical regions were determined by means of Folin-Ciocalteu(FC) and ferricyanide reduction(FR) assays. The redox potentials of above tea extracts were analyzed by cyclic voltammetry(CV).The relationship among the determined results obtained from FC,FR and CV methods were studied. The difference in accuracy between the CV and FR tests were also evaluated.The results showed that the redox potential,total reducing power and content of the tea polyphenols were all interrelated.Compared with the FR assay,the CV method had vecovery and RSD of 100.3% and 1.10%,resbertively,suporior to the FR method(102.0% and 2.41%).Thus the CV method was move simple,convenient,time-effective and precise that the FR method.This research confirmed the feasibility of CV method to rapidly measure the total reducing power and evaluate the quality of tea,which would provide theoretical and methodological guidance for the evaluation of tea quality based on the total reducing power.