Study of physicochemical qualities of palm-rice bran composite oil during intermittent deep-frying.

The effect of rice bran oil addition to palm oil in deep frying was evaluated by comparing its physical and chemical characteristics during four days of intermittent frying. Regarding the parameter standards of oil deterioration, including color (lightness and yellowness index), viscosity, free fatty acid (%FFA) and Totox value, as compared with the control (ratio 100:0, PO:RBO %v/v), the decline of palm oil composites quality was inhibited by the presence of rice bran oil. After four days of intermittent frying, 90:10 (%v/v) palm-rice bran oil composite showed the most stable to polymerization and hydrolysis deterioration in frying, shown by the lowest yellowness index, viscosity and FFA value. Moreover, the lightness value of 90:10 (%v/v) palm-rice bran composite oil had no significant difference during 4 days of frying duration. For the oxidative deterioration, the palm-rice bran composite oil with the ratio of 90:10 (%v/v) also gave the lowest Totox value. However, for peroxide value parameter, the control was the most stable over hydroperoxides decomposition. In addition, 90:10 (%v/v) palm-rice bran composite oil also gave decreasing trend in terms of oil absorption into fried food.