Serbian aromatized wine "Bermet": Electrochemical, chemiluminescent and spectrophotometric determination of antioxidant activity

Abstract

Serbian aromatized wine "Bermet" from grapes grown on Fruška Gora Mountain has been in production since the 15th century. Ten commercial Bermets produced according to the traditional procedure by different manufac­turers, and six prepared within the scope of this study were assessed for anti­oxidant (AO) activity using electrochemical, chemiluminescent and spectro­photo­metric AO assays. Direct current polarographic assay based on the dec­rease of anodic current of [hydrogen(peroxido)(1-)]hydroxi­domercury(II) com­plex formation in alkaline H2O2 solution at potential of mercury oxidation, chemiluminescent H2O2 scavenging assay, as well as commonly used spectro­photometric assays (2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) based Trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing anti­oxidant power (FRAP)) were used. Total phenolic content (TPC) was det­er­mined by Folin–Ciocalteu assay. The results obtained were correlated using regression analysis, ANOVA and F-test. An integrated approach to AO cap­acity determination allowed a more comprehensive comparison between samples. The approach is based on the introduction of the relative antioxidant capacity index, calculated by assigning each AO assay equal weight, and by PCA analysis. In addition, the intro­duct­ion of phenolic antioxidant coefficients, calculated as the ratio between indi­vidual AO capacity and TPC, enabled a better understanding of their relation.