Perfect prevention of oxidation of material with biological activity using regeneration reaction of lipid soluble antioxidant with catechin

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The purpose of this research is to evaluate the antioxidant activity of catechin and to construct a novel method for preventing the oxidation of desired materials with biological activity in the actual food system using a regeneration reaction of lipid soluble antioxidant with catechin. In 2002, the oxidation experiments of β-carotene, an active oxygen quencher, were performed in an inert n-decane solvent with addition of epigallocatechin gallate (EGCG) or epicatechin gallate (ECG). In both cases, the induction period, in which the β-carotene concentration decreased slightly, was observed and the oxidation was suppressed. The induction period became longer with increasing the ECG concentration, whereas the period had a maximum at a certain EGCG concentration. EGCG containing pirogallol group is known to oxidize itself to produce activated oxygen. Therefore, EGCG was considered to have a progressive activity of the oxidation as well as the antioxidant activity.β-Carotene is commonly dis … More solved in the oil in water emulsion when used as a food additive. Catechin haying amphiphilic property is more easily dissolved in the water phase. The reaction of β-Carotene and lipid-soluble antioxidant, α-tocopherol, with catechin occurs on the oil-water interface. In 2003, the oxidation experiments in the presence of α-tocopherol were performed in the biphasic oil-water system having a definite interfacial area. In the biphasic system, the time for which α-tocopherol remained was longer than that in the single phase of n-decane. Since the β-carotene oxidation was suppressed during a-tocopherol remained in the oil phase, the existence of water phase was effective for the suppression of β-carotene oxidation. α-Tochopherol was consumed by its oxidation as well as the antioxidative protection of β-carotene. The peroxyl radical of α-tocopherol concerned with the chain oxidation was easy to dissolve in the water. This phenomenon seemed to contribute the restrain of α-tocopherol consumption, resulting in the suppression of β-carotene oxidation. A kinetic model was constructed by considering the transfer of the α-tocopherol peroxyl radical into the water phase in addition to the oxidation and antioxidation mechanisms of β-carotene. The model quantitatively described the oxidation behavior of β-carotene in the biphasic system over a wide range of the initial α-tocopherol concentrations. Less