Major factors influencing antioxidant contents and antioxidant activity in grapes and wines

Abstract: Phenolic compounds in wines, especially in red wines, possess strong antioxidant activity, have the largest effect in decreasing atherosclerosis by both hypolipemic and antioxidant mechanisms. The long-term uptake of red wine has a positive impact on antioxidant activity (AA) of blood plasma in rats in vivo and increases AA by 15%–20% compared to a control group. In the article the effect of total phenolics (TP), total anthocyanins (TA), individual anthocyanins, procyanidins and phenolics contained in red grapes, musts, grape seeds and skins and wines on the AA is discussed. Significant impact of varieties, viticultural regions and locations, climate conditions and vintage has been shown. Likewise, the ways and individual stages of the vinification technology process, and storage conditions affect color, TP, TA, and AA and health aspects of produced wines. Resveratrol, another free radical scavenger mainly contained in the skins of grapes, inhibits the risk of cardiovascular diseases. Higher amounts of trans-resveratrol (RES) have been found in wines from cool and wet climate regions and lesser amounts are typical for warm and dry regions. Changes in the TP content and AA affected by grape variety, vineyard location and winemaking process in white and blue varieties from different vineyards of the Czech Republic were studied. Significant differences in TP among varieties were found. Analysis of variance showed statistically high differences among red and white wines and growing locations. Wines differed significantly in TP content and AA increased significantly during the winemaking process. Statistically significant differences in AA values were found among growing areas, wines and varieties. Significant positive correlations between TP and AA were determined. Total antioxidant status (TAS) of white and red wines (white and blue vine varieties) determined by DPPH and ABTS assays revealed significant differences in AA between white and red wines. Moreover, differences were ascertained between individual varieties of red wine. The results obtained supported the assumption that variety plays a considerable role in TAS; the blue vine varieties showed a much higher TAS. Analysis of variance in AA showed statistically high significance between red and white wines. AA increased during the winemaking process, the highest increase was determined during fermentation and maturation stages of red wine.

Keywords: wine, grape, antioxidants, antioxidant activity, DPPH, ABTS, extrinsic and intrinsic factors