title: Prooxidant activity of oxidized alpha-tocopherol in vegetable oils.
abstract: 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 d 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 d of storage, respectively. 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.
authors.affiliation: Dept of Food Science and Technology, The Ohio State Univ, Columbus, OH 43210, USA.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Chapman
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: David B
authors.initials: DB
authors.lastname: Min
mesh_terms: D005227:Fatty Acids / Q000032:analysis; D005511:Food Handling / Q000379:methods; D006358:Hot Temperature; D007700:Kinetics; D008041:Linoleic Acids / Q000032:analysis*; D008042:Linolenic Acids / Q000032:analysis*; D009829:Oleic Acids / Q000032:analysis*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D017319:Photosensitizing Agents / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000032:analysis*; D024502:alpha-Tocopherol / Q000737:chemistry*
chemical_list: D005227:Fatty Acids; D008041:Linoleic Acids; D008042:Linolenic Acids; D009829:Oleic Acids; D017319:Photosensitizing Agents; D010938:Plant Oils; D017382:Reactive Oxygen Species; D024502:alpha-Tocopherol; D010100:Oxygen