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It was aimed to study the effects of different concentrations (50,100 and 200ppm) of β-carotene on the oxidative stability of the purified soybean oil undergoing either autoxidation (at 60℃, for 5days) or photosensitized oxidation (erythrosine 100 ppm; 1,800 Lux fluorescent light irradiation; at 60℃ for 5days). The oxidative stability of a control and substrates was estimated on the basis of the peroxide and conjugated diene value development. The results were as follows; The autoxidation of the soybean oil was slightly promoted by 50-200ppm β-carotene added. The oxidation products of β-carotene also accelerated the autoxidation. The photosensitized oxidation, however, was prevented by 50-200ppm β-carotene. The antioxidant activity of β-carotene seemed to depend both on its action as quencher of singlet oxygen and also as filtering agent against incoming light. It appeared, however, that β-carotene was more effective as a singlet oxygen scavenger than as a filtering agent. The decomposition temperature of β-carotene was determined with a differential scanning calorimeter and found to be 161.2℃. The decomposition of the β-carotene in the substrates seemed to be caused by the cumulative action of the atmospheric oxidation, light, and oxidative products present, but not by the action of temperature.
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