Performance of Different Natural Antioxidant Compounds in Frying Oil.

In this study, the natural green tea extract, purified lycopene, purified resveratrol and purified γ-oryzanol were added into peanut oil and their antioxidant performances were evaluated during frying. Moreover, the sensory properties of fried dough were evaluated to determine the consumption feasibility. All natural antioxidants led to significant increase in the stability of the oil samples. The ranges of measurements in the treatment groups were as follows: free acidity 0.1-2.9 g of oleic acid per 100 g of oil, conjugated dienes 0.01-0.40 g per 100 g of oil, total polar material 8.8-73.8 g per 100 g of oil, total phenolics 0.1-4.2 mg of gallic acid equivalents per 100 g of oil, and antioxidant capacity 0.5-11.0 mM of Trolox equivalents per 100 g of oil. The fatty acid and sterol compositions indicated that antioxidant supplementation could slow the oxidative degradation of unsaturated fatty acids and reduce trans-acid formation. Frying oil enriched with purified γ-oryzanol had higher sterol levels than the other enriched oil samples. The obtained quality of oil protection was in descending order: purified γ-oryzanol, green tea extract and purified lycopene.