By extracting bioactive compounds from plant materials, scientists study their chemical composition, biological activity, and potential applications. Plant extracts can be used in functional foods and as additives that improve the quality and safety of products. New extraction methods offer sustainable and efficient technologies. This research featured maceration, ultrasonic extraction, microwave extraction, solvent extraction under pressure, and supercritical fluid extraction, as well as their advantages and disadvantages. The method of supercritical CO2 extraction made it possible to obtain target components from amaranth seeds. The input variables included the degree of fractionation and operating pressure while the temperature was a constant parameter. The degree of fractionation proved to be the key factor for the yield: the lower the fractionation, the higher the extract yield. A higher pressure increased the yield in the case of low particle dispersion. At 300 atm, the extract yield was lower for fractions of 0.31–0.56 and 0.16–0.31 mm than at 200 atm. The total extract yield ranged from 10.00 ± 0.20 to 18.20 ± 0.20% at 100 atm, from 10.54 ± 0.20 to 19.45 ± 0.20% at 200 atm, and from 11.64 ± 0.20 to 16.31 ± 0.20% at 300 atm. The amaranth extract demonstrated good prospects as an additive to vegetable oils, spreads, and cheeses.

The unique composition of lipophilic compounds, the presence of squalene, carotenoids, tocopherols, and unsaturated fatty acids in the CO2 extracts of amaranth seeds provide its high antioxidant activity. The aim of the study was to determine the antioxidant activity of CO2 extracts of amaranth seeds. As a result of supercritical CO2 extraction, different fractions of amaranth oil were obtained from different separators. The effect of the CO2 extraction process conditions, including oil separation conditions, on the antioxidant properties of the extracts, as well as the effect of amaranth oil storage conditions, was assessed. Antioxidant activity was determined by analyzing the ability of extracts to absorb DPPH radicals and by the ability to inhibit the oxidation of oleic acid. The best antioxidant activity was shown by the extract obtained under the following conditions: the lowest pressure at the separator outlet and the longest extraction time. This extract contains more squalene and unsaturated fatty acids. The extract obtained at the highest pressure and shorter exposure time showed lower activity. Under these conditions, fewer accompanying biologically active components are extracted, including squalene, and the ratio of unsaturated to saturated fatty acids changes. The results showed a decrease in the antioxidant activity of the amaranth extract by 3.8% when stored in the light for two months. The results of the studies are valuable for assessing potential sources of antioxidant compounds, the effect of extraction conditions and storage time of extracts on antioxidant properties, and for the purpose of obtaining functional products enriched with biologically active compounds.