Corn germ oil extraction with compressed propane compared with Soxhlet extraction

Abstract

The extraction of corn germ oil was evaluated using pressurized propane as solvent in semi-batch process as an alternative approach to organic solvent extraction. The effect of temperature (20, 40, 60 °C), pressure (20, 60, 100 bar), particle size and confinement time were studied. Moreover, the extraction kinetics for the pressurized solvent were determined. Temperature and pressure had no effect on the extraction yield. Consequently, the lowest temperature and pressure involved in this study (20 °C and 20 bar) could be used without implications on yield. An increase in confinement time had a positive effect and the increase of particle size had a negative effect on the yield. The extracted oils were characterized by physicochemical properties, total phenolic content (TPC) and antioxidant activity. In general, pressure exerted a positive effect on these properties for propane-extracted oils, indicating that the pressure may be managed to improve the quality of the extracted oil. The antioxidant activities of propane-extracted oils, which seemed to be correlated with their corresponding TPC value, were closer to those obtained with hexane. For propane extracts, the highest TPC of 29.89 mg GAE/100 g of oil was obtained by extracting wet-milled corn germs at 60 °C and 100 bar. The highest extraction yield with propane was 38.4 ± 1.2 wt% at 20 °C, 20 bar, 30 min and 0.95 mm particle size.