Effect of Polar and Non‐Polar Compounds from Oxidized Oils on Oxidative Stability in Corn Oil

Abstract

The effects of polar and non‐polar compounds recovered from oxidized corn oils on oxidative stability in bulk oils are evaluated in the presence or absence of an antioxidant, tert‐butylhydroquinone (TBHQ). The balance of antioxidant and prooxidant compounds in oils is confirmed using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) spectroscopic method. Polar compounds accelerated the depletion of headspace oxygen content and increased the conjugated dienoic acid value and p‐anisidine value in oils with or without 200 ppm TBHQ, which implies that polar compounds from oxidized lipids are prooxidants. However, added non‐polar compounds showed no prooxidative properties in oils, irrespective of the presence of TBHQ. The antioxidant‐prooxidant balance (APB) value, which is calculated as the ratio of the loss of DPPH in isooctane to that in methanol, may reflect the content balance between antioxidant and prooxidative oxidized lipid products in oils. Low APB values indicate that oils are in a highly oxidized state.Practical Applications: Polar compounds from oxidized oils act as prooxidants. Therefore, it is necessary to determine the polar content in frying oils accurately. Using modified DPPH methods, not only the content of antioxidants but also prooxidative polar compounds in oils can be determined simultaneously. Modified DPPH methods can predict the oxidative stability of frying oil and help to extend the shelf‐life of fried foods in the food industry.Polar compounds from oxidized oils function as prooxidants. Non‐polar compounds do not act as prooxidants nor antioxidants. Modified 2,2‐diphenyl‐1‐picrylhydrazyl methods can predict the oxidative stability of frying oil.