Oxidative Stabilities of Oils

September 23/Life Science Weekly -- According to recent research published in the Journal of Food Science, "The effect of oxidized alpha-tocopherol on the oxidative stabilities of soybean, corn, safflower and olive oils and the oxidation of oleic, linoleic and linolenic acids were studied. The 0, 650, 1300, and 2600 ppm oxidized alpha-tocopherol were added to soybean, corn, safflower and olive oils and 10000 ppm oxidized alpha-tocopherol to the mixture of oleic, linoleic and linolenic acids."

"Samples in the gas-tight vials were stored in the dark for 6 or 35 days at 55 degrees C. The oxidative stabilities of oils were determined by headspace oxygen with GC and peroxide value. Fatty acids were determined by GC. As the concentration of oxidized alpha-tocopherol in soybean, corn, safflower and olive oils increased, the depletion of headspace oxygen and the peroxide values of oils increased during storage. The prooxidant effects of oxidized alpha-tocopherol on soybean and corn oils with about 55% linoleic acid were greater than those on safflower and olive oils with about 12% linoleic acid, respectively (P < 0.05). The changes of fatty acids during storage showed that the oxidation ratios of oleic, linoleic, and linolenic acids were 1:2:3, 1:12:26, and 1:8:16 after 5, 30, and 35 days of storage, respectively," wrote T.M. Chapman and colleagues, Ohio State University.

The researchers concluded, "The oxidation of alpha-tocopherol in oil should be prevented and the oxidized alpha-tocopherol should be removed to improve the oxidative stability of oils."

Chapman and colleagues published their study in the Journal of Food Science ("Prooxidant Activity of Oxidized alpha-Tocopherol in Vegetable Oils." Journal of Food Science, 2009;74(7):C536-C542).

For additional information, contact D.B. Min, Ohio State University, Dept. of Food Science & Technology, 2015 Fyffe Rd., Columbus, OH 43210.

From the September 28, 2009, Prepared Foods E-dition