Summary and ImplicationsGround beef with 10, 15 or 20% fat were added with none, 0.05% ascorbic acid + 0.01% α-tocopherol, or 0.05% ascorbic acid + 0.01% α-tocopherol + 0.01% sesamol, and irradiated at 0 or 2.5 kGy. The meat samples were displayed under fluorescent light for 14 days at 4° C. Irradiation increased both lipid oxidation and total volatiles, especially aldehydes, but decreased redness of ground beef over the 14 days storage period regardless fat content. The production of alcohol greatly increased in nonirradiated ground beef during storage due to microbial growth. Adding antioxidants such as ascorbic acid + α-tocopherol was effective in minimizing lipid oxidation, volatile production and color changes in irradiated ground beef, but fat content had little effect on the quality parameters of irradiated and nonirradiated ground beef. Therefore, up to 20% fat would not affect quality changes of irradiated ground beef if ascorbic acid + α-tocopherol is added.