A Kinetic Model Describing Antioxidation and Prooxidation of β-Carotene in the Presence of α-Tocopherol and Ascorbic Acid
β-Carotene oxidation in the presence of both lipophilic α-tocopherol and hydrophilic ascorbic acid was experimentally studied in a biphasic oil–water system. Ascorbic acid in the water phase had two opposite effects of promoting and suppressing α-tocopherol consumption in the oil phase and indirectly participated in the antioxidation and prooxidation of β-carotene in the oil phase. The drastic antioxidation of β-carotene by stopping the consumption of α-tocopherol was caused by the depletion of oxygen in the system due to the oxidation of ascorbic acid. A kinetic model was constructed by incorporating the oxidation of ascorbic acid itself in the water phase, the regeneration and consumption of α-tocopherol by ascorbic acid at the oil–water interface, and the oxygen mass transfer across the gas–oil interface and the oil–water interface. The model well described the antioxidation and prooxidation behavior of β-carotene in the presence of α-tocopherol and ascorbic acid and the oxygen concentration profiles in each phase. The model was able to effectively determine the appropriate amounts of lipophilic and hydrophilic antioxidants to prevent β-carotene oxidation under various conditions.
KeywordsLipid oxidation Antioxidant Antioxidation Prooxidation Kinetic model Biphasic oil–water system
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