The antioxidant activity of South African wines in different test systems as affected by cultivar and ageing

[摘要] ENGLISH ABSTRACT: Phenolic compounds in wine, due to their antioxidant activity, are reportedlyresponsible for the health-promoting properties of wines. The effect of cultivarand in-bottle ageing on the antioxidant activity of South African wines indifferent types of antioxidant assays was, therefore, investigated.The antioxidant activity of commercial South African red (CabernetSauvignon, Ruby Cabernet, Pinotage, Shiraz, Merlot) and white (Sauvignonblanc, Chenin blanc, Chardonnay, Colombard) cultivar wines was comparedusing the 2,2'-azino-di-(3-ethylbenzothialozine-sulphonic acid) radical cation(ABTS·+) scavenging, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·)scavenging and microsomal lipid peroxidation (MLP) assays. The red wineswas more effective than the white wines on an 'as-is and an equal totalphenol content. The total antioxidant activity (TAAABTS and TAADPPH) of RubyCabernet was the lowest of the red wines, but the antioxidant potency (APABTSand APDPPH) of red wine phenolic fractions did not differ (P ³ 0.05). RubyCabernet and Pinotage were the least effective inhibitors of MLP, while Merlotwas the most effective of the red wines. Pinotage phenolic fractions hadlower (P < 0.05) APMLP than that of other red wines. Of the white wines,Chardonnay and Chenin blanc had the highest and lowest effectivityrespectively according to all antioxidant parameters. Ascorbic acid present insome wines increased and decreased their TAA and % MLP inhibitionrespectively. TAA and % MLP inhibition correlated well (r ³ 0.7, P < 0.001)with total phenol content of red and white wines, as well as with flavanolcontent of red wines and tartaric acid ester content of white wines. The% MLP inhibition also correlated well with flavanol content of white wines. Nocorrelation (P > 0.01) was obtained between TAA or % MLP inhibition andmonomeric anthocyanin content of red wines. In the deoxyribose assay, redwines were more pro-oxidant and exhibited lower hydroxyl radical scavengingand metal chelating abilities than white wines.The effect of in-bottle ageing on antioxidant activity of wines wasdetermined using the ABTS·+ and DPPH· scavenging assays. The TAA andtotal phenol content of experimental red (Pinotage and Cabernet Sauvignon)and white (Chardonnay and Chenin blanc) cultivar wines, decreased(P < 0.05) during 12 months of storage at 0, 15 and 30 ºC. The TAAABTS ofCabernet Sauvignon and Chardonnay, stored at 30 ºC were lower (P < 0.05)than at 0 ºC. The APABTS and APDPPH of most wines also decreased duringstorage. The monomeric anthocyanin content of red wines decreased(P < 0.05) rapidly at 15 and 30 ºC. The flavanol content of wines (exceptChenin blanc) increased during the first 9 months, decreasing again after 12months, while minor changes in the flavonol and tartaric acid ester content ofboth red and white wines were observed. The TAAABTS exhibited a goodcorrelation (r ³ 0.7, P < 0.001) with total phenol content of red and whitewines, as well as with flavonol and tartaric acid ester content of red and whitewines and flavanol content of white wines. The monomeric anthocyanincontent of red wines correlated (r = 0.50, P < 0.001) weakly with TAAABTS.The decrease in the TAAABTS of wines could thus be mainly attributed to adecrease in their total phenol content.

[发布机构] Stellenbosch University