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 antiox-
idants such as oryzanol, tocopherol and tocotrienol, which
were able to quench free radicals to some extent during heat-
ing 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 antiox-
idant 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).