Hirotsugu Kido

Semi-micro flow injection analysis method for evaluation of quenching effect of health foods or food additive antioxidants on peroxynitrite

A semi-micro flow injection analysis (SMFIA) method for evaluation of quenching effect of food additive antioxidants or health foods on peroxynitrite (ONOO(-)) is described. The injected sample was carried with phosphate buffer containing NaNO(2), mixed with a trigger solution to generate ONOO(-) and then detected CL generated after mixing with luminol solution. Selective chemiluminescence caused by ONOO(-) in this generation system was confirmed by catalase treatment. Ascorbic acid (ASA), Trolox and ascorbyl palmitate (ASP) were used as food additive antioxidants. EC(50) values of ASA, Trolox and ASP were 2.6, 6.4 and 43 µg/mL, respectively. The amount of reagents required for an assay by this SMFIA system could reduce the time by a third compared with the conventional method previously reported. Furthermore, as an application of the proposed method, the quenching effect of commercially available Noni (Morinda citrifolia) juices was evaluated.

Luminol Chemiluminescence Profile of O/W Emulsions during Thermal Oxidation

The luminol chemiluminescence (CL) profile of an oil-in-water (O/W) emulsion during thermal oxidation (60°C) was assessed using the luminol-K3[Fe(CN)6] assay, in which the oxidation species produced by the autoxidation of an O/W emulsion generated CL emission. Increased CL intensity was observed for O/W emulsions prepared using either linseed or corn oil, which was increased by the addition of Fe2+ to the O/W emulsion. The relationship between the CL profile and results obtained by conventional approaches, such as the peroxide value (PV) and thiobarbituric acid (TBA) methods, were compared. Owing to good correlation between the CL intensity and results obtained by the methods, the CL method might be applicable for estimating the oil oxidizing of an emulsion in thermal oxidation.