Identification of alpha-tocopherol oxidation products in triolein at elevated temperatures

The effect of high-temperature treatment on the stability of alpha -tocophe rol (1) in triolein tvas assessed under a reduced-pressure atmosphere (4-40 mbar) simulating the deodorization step of the refining of vegetable oils. A marked degradation of 1 was observed, which increased with increasing te mperature (180-260 degreesC) and heating time (20-80 min). The degradation of 1 in triolein at 240 degreesC was inhibited by the:addition of the synth etic antioxidant TBHQ or when heating was performed under nitrogen atmosphe re, indicating oxidative degradation. The oxidation products were isolated and identified as alpha -tocopherolquinone (2), 4a,5-epoxy-alpha -tocophero lquinone (3), and 7,8-epoxy-alpha -tocopherolquinone (4).