The effects of deamidation or fragmentation on the antioxidative activity of C hordein were investigated individually. Heat treatment at 70°C in 70% ethanol - 0.05 M HCl caused deamidation of C hordein with fragmentation. The antioxidative activity of C hordein was diminished by this deamidation. Trypsin digestion did not cause deterioration of the antioxidative activity of C hordein, whereas NBS fragmentation did. TGase deamidation also reduced the antioxidative activity of C hordein, as did fragmentation by N-bromosuccinimide. © 2003, Japan Oil Chemists' Society. All rights reserved.