Recovery of oil components of okara by ethanol-modified supercritical carbon dioxide extraction

Recovery of the oil components of okara by ethanol-modified supercritical carbon dioxide extraction was investigated at 40–80 °C temperature and 12–30 MPa pressure. In a typical run (holding period of 2 h, continuous flow extraction of 5 h), results indicated that the oil component could be best obtained with a recovery of 63.5% at relatively low temperature of 40 °C and mild pressure of 20 MPa in the presence of 10 mol% EtOH as entrainer. Based on gas chromatography–mass spectrometry (GC–MS) analysis, the extracts consisted mainly of fatty acids and phytosterols, and traces of decadienal. Folin–Ciocalteau estimates of total phenols showed that addition of EtOH as entrainer increased the yield and the amount of phenolic compounds in the extracts. The amounts of two primary soy isoflavones, genistein and daidzein, in the extracts also increased with increasing amount of EtOH.