Determination of Antioxidant Power of Some Various Grape Juices by Voltammetric Method and Its Correlation with Polyphenolic Content

Objective: Due to rich resources of phenolic components such as anthocyanin and flavonoids, grape has grabbed lots of attention. Antioxidants are the frontline of the human immune system against free radicals and they are of high importance for the human health. Methods: In order to determine antioxidant activities, the amount of phenols, anthocyanin and ascorbic acid of 2 grapes’ varieties ("white seedless" and "red seedless" as two famous verities of Qazvin's grapes) have been studied with cyclic voltammetry including, DPPH and Folin-Ciocalteo reagent at room and refrigerator  temperature, before and after pasteurization process. Results: The results of this study has shown that the two verities of grapes did not have a meaningful difference in total antioxidant concentration; and cyclic voltammetry method has been more or less able to define the type of antioxidant according to the results of this study. Moreover, the two types of grapes had a significant difference in concentration of ascorbic acid and anthocyanin so that concentration of ascorbic acid in white grape juice in room temperature was 53ppm while at the same situation it was 24ppm in red grape juice.