Natural antioxidants enhance the oxidation stability of blended oils enriched in unsaturated fatty acids

Abstract BACKGROUND Rancidity causes unpleasant tastes and smells, and the degradation of fatty acids and natural antioxidants, so that an oil is unfit to be consumed. Natural antioxidants, including tocopherols, polyphenols (sesamol, canolol, ferulic acid, caffeic acid, etc.), β ‐carotene, squalene and phytosterols, contribute to delay the oxidation of vegetable oils. However, studies on the combination of natural antioxidants to lengthen the shelf life of unsaturated fatty acid‐rich blended oil have not been reported. RESULTS All of the composite antioxidants had the potential to significantly improve the oxidation stability of blended oil. Blended oil G with 0.05 g kg −1 β ‐carotene, 0.25 g kg −1 sesamol and 0.25 g kg −1 caffeic acid showed the best anti‐autooxidation. It is also effective in improving the oxidative stability of vegetable oils containing various fatty acids. The oxidation stability index of the blended oil containing the optimum composition of natural antioxidants was 2.17‐fold longer than that of the control sample. After the end of accelerated oxidation, the oil's peroxide value, p‐anisidine value and total oxidation value were 6.59 times, 12.26 times and 6.65 times lower than those of the control sample, respectively. CONCLUSION (1) The combination of natural antioxidants β ‐carotene (0.05 g kg −1 ), sesamol (0.25 g kg −1 ) and caffeic acid (0.25 g kg −1 ) enhances the oxidative stability of unsaturated fatty acid‐rich blended oils. (2) β ‐Carotene is the main antioxidant in the early stages of oxidation. (3) Sesamol and caffeic acid are the main antioxidants in the middle and late stages of oxidation. © 2023 Society of Chemical Industry.