Antioxidant properties and bioactive components of Norton (Vitis aestivalis) and Cabernet Franc (Vitis vinifera) wine grapes

Three wine grapes, Norton (Vitis aestivalis), Cabernet Franc clone1, and Cabernet Franc clone313 (Vitis vinifera), collected from a Virginia vineyard were evaluated and compared for their antioxidant properties and phenolic profile. All grape extracts exerted remarkable antioxidant activities. Their oxygen radical absorbance capacity (ORAC) values were not significantly different from one another, ranging from 22.9 to 26.7 mu mol TE/g of fresh weight. The Cabernet Franc clone1 had the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH center dot) radicals scavenging activity (8.8 mu mol TE/g) compared to the Norton or Cabernet Franc clone313 grape extracts (7.9 mu mol TE/g and 5.4 mu mol TE/g, respectively). The Norton grape contained significantly higher total phenolic, anthocyanin, and flavonoid content than the Cabernet Franc grapes (p < 0.05). The hydroxybenzoic acids, in particular gallic acid, were the major phenolic acids in all the grape extracts. The Norton grape variety was found to be rich in malvidin-diglucoside and malvidin-glucoside, while the malvidin-diglucoside was negligible in the Cabernet Franc grapes. The results suggest a remarkable impact of grape genotype on its antioxidant properties and phenolic composition in Virginia-grown wine grapes. (C) 2009 Elsevier Ltd. All rights reserved.