The present invention relates to a purified antioxidant polypeptide, a method of isolating and purifying said polypeptide, and method of enhancing antioxidant properties of a composition comprising addition of said polypeptide to the composition. The antioxidant is formulated alone as a nutritional supplement or is combined with other consumable products, such as foods, beverages, vitamins, herbal extracts, or other antioxidants. The present invention also relates to methods for identifying and quantifying the antioxidant polypeptide in food and beverages.