A comparative study was undertaken to evaluate the antioxidant activities of irradiated phytic acid and commonly used antioxidants, including ascorbic acid, tocopherol and butylated hydroxyl anisole (BHA). Phytic acid was irradiated at 0, 10 and 20 kGy, and, after irradiation, radiolytic degradation and increments of antiradical and antioxidant activity were observed. Phytic acid irradiated at 20 kGy, showed significantly higher DPPH radical-scavenging capacity than ascorbic acid at the 800 muM level, while a scavenging effect was not seen in non-irradiated phytic. acid (P < 0.05). Ferric reducing/antioxidant power (FRAP) of phytic acid was significantly increased by irradiation; however, ascorbic acid, tocopherol and BHA showed higher FRAP values than phytic acid. Antioxidant activity of phytic acid in the lipid models was higher than that of the other antioxidants during storage and, especially phytic acid (800 muM) irradiated at 20 kGy showed the highest antioxidative ability among the antioxidants tested at 3 weeks of storage. (C) 2004 Elsevier Ltd. All rights reserved.