Just as rust can damage a car, oxidation, or oxidative stress can damage the cells and may also contribute to aging. Antioxidants help prevent this oxidation and may help increase immune function and possibly decrease risk of infection and cancer. Antioxidants exist as vitamins, minerals and other compounds in foods.
With the increasing interest in the function and diversity of antioxidants in foods, several methods for measuring antioxidant activity of food, beverages and biological samples have been developed. Among them, the oxygen radical absorbance capacity (ORAC) assay has gained much attention because it deals with peroxyl radicals, the most abundant radicals in biological systems.
In a recent study, published in the November issue of Food Chemistry, the oxygen radical scavenging activity, i.e. the antioxidant activity of commercial red and white grape juices and wine vinegars, which are known to be rich in polyphenols, were determined by the ORAC assay using fluorescein as fluorescent probe. This study confirms grape juice, complex beverages and wine vinegar (seasoning ingredient) as good dietary sources of antioxidants.
This data could be used as an additional quality parameter for promoting the consumption of these grape products as sources of polyphenols and of other health-promoting substances.