Currants (Vitis vinifera L.) content of simple phenolics and antioxidant activity

Currant (Vitis vinifera L.) is a dried vine product, produced almost exclusively in Southern Greece and used in the Mediterranean diet. The three different commercial sub-varieties of currants, namely Vostizza, Gulf, and Provincial were investigated for their total polyphenol content, individual phenolic compounds, and total antioxidant capacity. Total polyphenol content was estimated with the Folin-Ciocalteau assay while identification and quantification of individual target polyphenolic compounds was performed by gas chromatography/mass spectrometry. Total polyphenol content ranged between 151 mg/100 g and 246 mg/100 g currants. Among the polyphenols studied, 17 were identified in Wand Provincial currants and 16 in Vostizza currants. The predominant polyphenolic compound in all currants was vanillic acid at mean concentration 1.21 +/- 0.23 mg/100 g currants. Caffeic acid, gallic acid, syringic acid, p-coumaric acid, protocatechuic acid, ferulic acid, and quercetin also predominated. The antioxidant activity of currants was assessed by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH center dot) radical scavenging assay. The amount of currants needed to scavenge 50% of DPPH radical (EC50) was similar for all sub-varieties ranging from about 4 mg to 6.5 mg. Total antioxidant capacity is in descending order Vostizza > Provincial > 6W. By the present work, the consumption of currants is considered to contribute to the intake of antioxidants. (c) 2006 Elsevier Ltd. All rights reserved.