A Simple and Sensitive Evaluation Method of Antioxidant Activity by the Measurement of Ultraweak Chemiluminescence

Abstract

As we reported previously, the oxidation of oils and related foods was accompanied by emission of ultraweak chemiluminescence. It was expected that the retardation of oxidation rate by the addition of antioxidants would reduce the emission intensity of oils. Therefore, we attempted to examine the antioxidant activity by the measurement of the emission intensity. Chemiluminescence was measured at 100°C by using a single photoelectron counting system ("CHEMILUMINESCENCE ANALYZER"). Apparent decreases in their emission intensities were observed when fatty acid methyl esters prepared from rapeseed oil were mixed with antioxidants (BHA, BHT, α-, γ- and δ-tocopherols) in 0.02%. In comparison with the results of AOM (Active Oxygen Method) and Oven Tests of the same sample esters, the emission intensity was closely correlated with AOM hours, except α-tocopherol, which could have the most significant quenching effect of singlet oxygen among tocopherols. With new antioxidants (5-bromo-3, 4-dihydroxy benzaldehyde and rosemary extracts), the antioxidative activity was also detected as the decreased chemiluminescence. This new method is very simple in the procedure and very sensitive, by which even 1mg of antioxidative materials can be tested. Accordingly we expect to use this method as a preliminary test for the screening of antioxidants.