Antioxidant Activity of South African Red and White Cultivar Wines: Free Radical Scavenging

Abstract

The free radical scavenging activity of South African red (n = 46) and white (n = 40) cultivar wines was determined using 2,2‘-azinobis(3-ethylbenzothialozinesulfonic acid) radical cations (ABTS^•+) and 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH^•). The total antioxidant activities (TAA) of red and white wines using ABTS^•+ were 14.916 and 0.939 mM Trolox, respectively, at corresponding total phenol (TP) contents of 2339.0 and 273.8 mg of gallic acid equiv/L. Ruby Cabernet wines had the lowest TAA_ABTS (13.177 mM Trolox) of the red wines, whereas the TAA_ABTS values of Chardonnay and Chenin blanc wines were the highest (1.060 mM Trolox) and lowest (0.800 mM Trolox) of the white wines. The TAA_DPPH values were of the same magnitude as the TAA_ABTS values, and similar trends were observed. TAA correlated (P < 0.001) with total phenol content of red (r = 0.935) and white (r = 0.907) wines, as well as flavanol content of red wines (r = 0.866) and tartaric acid ester content of white wines (r = 0.767). Canonical discriminant analysis using phenolic composition and antioxidant activity was applied to differentiate between red and white cultivar wines. Keywords: ABTS radical cation; DPPH radical; free radical scavenging; antioxidant; total antioxidant activity; phenolic compounds; polyphenols; anthocyanins; wine