3.5.5. Radical scavenging activity
Antioxidant is a substance which is capable of preventing or delaying the oxidation reaction during processing such
as heating or frying of foods. RBO contains natural antioxidants such as oryzanol, tocopherol and tocotrienol, which
were able to quench free radicals to some extent during heating and frying experiments. Results presented in Fig. 4 shows
that after 6 cycles of frying, the ability of oils to quench DPPH radicals changed from 53.5% to 37.9 and 39.8% for oils
subjected to heating and frying experiments, respectively. The loss of antioxidant activity in frying experiments was
marginally higher than in the heating experiments. The loss of antioxidant activity from heated oil may be attributed to
the volatilization of antioxidant through evaporation and or decomposition of the antioxidant. Additional loss of antioxidant activity in frying experiment occurs through steam distillation resulting from the introduction of water present in food, absorption and interaction of antioxidant with food (Augustin and Berry, 1983).