According to http://www.sciencedaily.com/ low-level irradiation (which has no known side effects) and refrigeration of grapes before they are made into wine can magnify the healthful effects of drinking red wine. This apparently makes the good source of antioxidants two or three times more potent.

These findings are reported in the Journal of Agricultural and Food Chemistry. Lead researcher from the Spanish Council for Scientific Research in Murcia, Francisco Tomas-Barberan, says that low levels of ultraviolet irradiation can boost amounts of resveratrol which has antioxidant and anticancer properties. He says that these results contradict a previous study that used higher levels of irradiation and grapes picked before they ripened. According to the research, irradiating grapes before they are turned into wine could raise resveratrol levels from one milligram per glass of wine to more than three milligrams, therefore raising the level of antioxidants. Antioxidants protect against the damaging effects of oxygen and nitrogen in the human body, helping prevent high cholesterol, heart disease and Alzheimer's disease. Tomas-Barberan also noted that elevated levels of resveratrol in red wine are generated during the fermentation process, so the additional benefits of irradiation are less significant for grapes used to make grape juice. For the full story visit www.sciencedaily.com/releases/2000/11/001102072111.htm