Valorization of an agroindustrial soybean residue by supercritical fluid extraction of phytochemical compounds

Abstract

The present study proposes the valorization of an agroindustrial residue (expeller) obtained from soybean oil extraction by pressing operation. Two expeller samples, S1 and S2, were processed to obtain extracts by supercritical fluid extraction (SFE). The extractions were performed at 40 MPa and at 35 or 40 °C, using CO2 as solvent (5 kg CO2/kg expeller). Also, the expellers were impregnated with ethanol (25% w/w expeller), and then new SFE processes at 35 °C were performed for both S1 and S2. The extracts resulting from the ethanol impregnated samples showed the best antioxidant properties with values of total phenolics of 10.6 and 16.0 mg GAE/100 g d.m., flavonoids content of 65.0 and 31.3 QE/100 g d.m. and antioxidant capacity by DPPH values of 9.7 and 12.0 μmol TE/100 g d.m. for S1 and S2, respectively. Phytochemicals from soybean expellers may be recovered through green and safe technologies such as sc-CO2 extraction.