THE ANTIOXIDANT CAPACITY OF COMPLEX-MIXTURES BY KINETIC-ANALYSIS OF CROCIN BLEACHING INHIBITION

The capability of a compound or of a mixture of compounds to quench pe roxyl radicals was measured by analyzing the kinetics of the competiti on of a parallel reaction where peroxyl radicals bleach the carotenoid crocin. This kinetic approach, originally described for the analysis of antioxidants reacting with hydroxyl radicals in water, was modified by both decreasing the polarity of the solvent, thus allowing the ana lysis of lipophilic compounds, and by substituting a source of peroxyl radicals for the hydroxyl radical generating system. Single compounds as well as complex mixtures were analyzed by kinetic data processing. Overall antioxidant capacity, relative to that of a-tocopherol or of its soluble analog Trolox C, was calculated. As examples of the use of this test, the antioxidant capacities of a crude rosemary extract, Ma illard reaction products, and virgin olive oils were measured.