Oryzanol as natural antioxidant for improving sunflower oil stability.

Sunflower oil is being made shelf stable by the
incorporation of synthetic antioxidants such as tertiary butyl
hydroquinone (TBHQ), while natural antioxidants like
oryzanol and tocopherols can also be used. The aim of the
current investigation was to evaluate the antioxidant effect of
natural oryzanol (Oz) concentrate (15.5 % oryzanol) and
purified Oz (80%oryzanol) on oxidative and thermal stability
of sunflower oil. Sunflower oil was incorporated with Oz
concentrate to provide 0, 0.12, 0.25, 0.50, 0.84, 1.0, 1.60,
2.0, 2.5 and 3.20 % oryzanol in the oil, stored for 5 weeks at
37 °C and oxidative stability was evaluated. It was found that
the oryzanol concentrate showed good antioxidant effect with
increase in concentration of oryzanol. In another set of experiments,
sunflower oil containing purified Oz at 1 % level
individually and in combination with 0.1 % α- tocopherol
(α-T) was heated at 120 °C for 24 h to evaluate thermal
stability. Sunflower oil containing 1 % Oz (80 % purity)
showed 98.40 % and sunflower oil containing 1 % Oz and
0.1 % α-T showed 108.75 % antioxidant effect compared to
TBHQ taken as 100 %. The study indicated that sunflower oil
containing 1 % Oz (80 % purity) and 0.1 % α-T combination
provides a synergistic effect in inhibiting primary and secondary
products and showed highest thermal stability. SFO containing
1 % Oz added as concentrate also showed good
antioxidant effect during storage. Hence, instead of using
synthetic antioxidants like TBHQ, we can add natural
oryzanol (purified or as concentrate) to sunflower oil to increase
its oxidative and thermal stability.