Influence of some experimental variables and matrix components in the determination of antioxidant properties by β-carotene bleaching assay: experiments with BHT used as standard antioxidant

The beta-carotene bleaching assay belongs to the oldest and continuously commonly applied methods of estimating the antioxidant activity of compounds and mixtures. In this method, the antioxidant activity of the examined substance is evaluated by the spectrophotometric measurement of beta-carotene concentration changes in beta-carotene/peroxyl radicals (LOOaEuro cent) systems with and without antioxidant. Yet a little is known about factors influencing the value of inhibition percent of the investigated antioxidant, estimated by this method. The paper shows that both the antioxidant solvent type and the amount of the antioxidant solvent in the measuring system significantly influence the inhibition percent value for butylohydroxytoluene (BHT), used as standard antioxidant in the performed experiments. Moreover, the results shown in the paper prove the essential influence of hydrogen and metal ions on the results of antioxidant assay. The relationships discussed in this paper indicate the necessity of standardizing beta-carotene method and reveal the complexity of the problem of estimation of adequate antioxidant activity of examined substances.