RESUMO
Antioxidant activity of ethanolic extracts obtained from two amaranth species was evaluated in a beta-carotene-linoleic acid model system. The addition of amaranth extracts in the range of 0.01-0.1% inhibited degradation of a beta-carotene in a model emulsion during incubation at 60 degrees C; 0.05% addition of amaranth seeds extract was proposed as practically applicable. The total content of phenolic compounds was estimated by the Folin-Ciocalteu method and ranged from 39.17 mg/100 g of Amaranthus caudatus to 56.22 mg/100 g of A. paniculatus seeds. Free phenolic acids contained in ethanolic extracts of amaranth seeds were purified and isolated by solid-phase extraction (SPE) and identified by reversed-phase high-performance liquid chromatography (RP-HPLC). The technique involved gave a good separation of the free phenolic acids in the amaranth seeds. Significant differences in phenolic acids profiles of both amaranth species were observed.