Extraction of rice bran oil using supercritical CO2 and compressed liquefied petroleum gas

This work focused on the extraction of rice bran oil using supercritical carbon dioxide (SC-CO2) and compressed liquefied petroleum gas (LPG). For the supercritical extractions, the influence of pressure and temperature on the extraction yield was evaluated from 150 to 250 bar and from 40 to 80 degrees C, whereas for compressed LPG extractions were performed at 5-25 bar and 20-40 degrees C. The antioxidant activity of the extracts was assayed by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method and the chemical composition by gas chromatography-mass spectrometry (GC-MS). The highest yields were 12.68 and 12.07 wt%, whereas the maximum antioxidant activities were 71.67 and 67.49% for extraction using SC-CO2 and compressed LPG, respectively. The chemical profile of fatty acids was similar for both solvents. The antioxidant compound found in both processes was the beta-sitosterol, which is one of the components of gamma-oryzanol. From kinetics analysis it was demonstrated that using LPG it is possible to decrease the solvent/feed mass by a factor of approximately 30, and extraction time by a factor of 15. Considering the slight difference in the yield and antioxidant activities of extracts between the solvents, compressed LPG is a more promising solvent than supercritical CO2 for extraction of rice bran oil, since the extraction period can be considerably reduced while lowering the energy required for solvent recompression. (C) 2015 Elsevier Ltd. All rights reserved.