Determination of antioxidant compounds and antioxidant activity in commercial oilseeds for food use

Different commercial edible oilseed samples were analyzed in order to evaluate the compounds involved in antioxidant activity. Fatty acids, triacylglycerols, tocopherols, chlorophylls, β-carotene, squalene, phenolic compounds and CIE L∗a∗b∗ coordinates were assayed. Strong chemical variability depending on the oilseed variety was observed. Antioxidant activity was evaluated for the oils, both for their methanol-soluble phase and the fraction insoluble in methanol. DPPH radical scavenging activity expressed in TEAC ranged between 0.45 and 2.30 mmol/l in peanut and maize oils, respectively. Free radical scavenging activity was mainly influenced by tocopherols content (r = +0.70) in oils and polyunsaturated fatty acids (r = +0.61) in the fraction nonsoluble in methanol. Variability of the correlation between the antioxidant activity and the composition of the oilseeds could be attributed to the differences in the squalene, chlorophylls, carotenoids, and phenols contents of the oils and their mutual interactions.