Progressive effect of water on prevention of β-carotene oxidation in biphasic oil-water system with addition of an antioxidant α-tocopherol

Oxidation experiments of β-carotene in the presence of α-tocopherol were conducted in a biphasic oil-water system having a definite interfacial area. The induction period in which the β-carotene concentration slowly decreased was about 1.6 times longer than that in the single oil phase system when the initial α-tocopherol concentrations were the same. The existence of the water phase suppressed the α-tocopherol consumption, resulting in a delay in the progress of the β-carotene oxidation. A kinetic model was constructed by modifying the oxidation and antioxidation mechanisms of β-carotene in the single oil phase and incorporating the reaction of the α-tocopherol peroxyl radical with the oxonium ion at the oil-water interface. The model quantitatively described the oxidation behavior of β-carotene in the biphasic system over wide ranges of temperature, initial α-tocopherol concentration and interfacial area.