Tannin in wine provides two things: structure and ageability. Found in the grape’s skins, seeds, and stems, tannin is a natural preservative. Red wines, with considerably more tannin than white, can thus age longer. Tannins belong to a class of complex compounds called phenols, powerful antioxidants believed to give red wine its reported health benefits. Some scientists believe that antioxidants offer a way to also slow fresh food spoilage by reacting with chemicals that cause oxidation. Paul Kilmartin, a professor of wine chemistry at New Zealand’s University of Auckland, discovered that plastics impregnated with discarded grape solids during the manufacturing process retained the tannin’s antioxidant benefits. Testing their effect on packaging for various edible oils, Kilmartin was able to extend the oil’s shelf life up to 30%.