FORMATION OF ALPHA-TOCOPHEROLQUINONE AND ALPHA-TOCOPHEROLQUINONE EPOXIDES IN PLANT OIL

The antioxidative activity of alpha-tocopherol in oil is necessary for the inhibition of lipid peroxidation. If no regeneration of antioxida nts is possible in foods, oxidation products are formed to a measurabl e extent. The aim of this study was to investigate oxidation products of a-tocopherol in plant oil. The oxidation of alpha-tocopherol in pla nt oil leads to alpha-tocopherolquinone and to two epoxides (alpha-toc opherolquinone-2,3-epoxide, alpha-tocopherolquinone-5,6-epoxide). Thes e three reaction products were identified and quantified in plant oil. The 2,3-epoxide is formed at lower temperatures (90 degrees C) wherea s at high temperatures (180-220 degrees C) only the 5,6-epoxide appear s. The kinetics show that the 5,6-epoxide is produced as long as alpha -tocopherol is present. With longer reaction times the concentration o f the 5,6-epoxide starts to decrease. alpha-Tocopherolquinone is found at substantially lower concentrations.