Optimisation of Microwave-Assisted Extraction of Squalene from Amaranthus spp. Seeds

Squalene is a triterpene of pharmaceutical interest, due to its antioxidant and anticancer properties. Amaranth oil is a source of plant origin with high squalene content which is extracted by conventional methods that involve high cost, time-consuming and create large amounts of waste by-products or CO₂ emissions. In this study, the microwave-assisted extraction (MAE) was used to obtain amaranth oil rich in squalene under closed conditions. The optimization of squalene yield (SQ) was conducted using response surface methodology by a Box-Behnken design (BBD) with 3³ factors: time (20, 25, 30 min), solvent–co-solvent (50:50, 60:40, 70:30 v/v) and temperature (40, 60, 80 °C). The effect of factors on yield was measured by gas chromatography-mass spectrometry followed by a comparison of the yield and chemical composition than those obtained by Soxhlet extraction (n-hexane during 6 h). Optimal conditions produced a squalene yield of 16,456 mg·100g⁻¹ oil versus 7,967 mg·100g⁻¹ oil for conventional extraction. The ratio solvent and heating time significantly affected the yield, but the chemical composition and quality of extract were not affected, there were no oxidation products derived from the heat treatment. MAE has proven to be an environmental-friendly option with a significant reduction in time, energy and avoids solvent consumption.