The Effect of Bixin and Carotene on the Oxidation of Methyl Linoleate

While the coupled oxidation of carotene and oils has been studied in some detail (l-7), the r6le of other carotenoids in oxidizing oils is imperfectly understood. Indications that bixin is oxidatively destroyed in a manner similar to carotene were given in the study of lipoxidase by Sumner and Smith (8). Solutions of bixin were also observed to be vastly more stable than similar solutions of carotene. An alcoholic solution of bixin can be kept on the reagent shelf for months without significant deterioration. It was of interest, therefore, to investigate the destruction of bixin in contact with an autoxidizing or a photooxidixing unsaturated oil such as methyl linoleate and to compare the results with those of similar studies of a system containing the relatively unstable carotene. It was believed that such a study might give added information on the mechanism of similar coupled oxidations.