Supercritical carbon dioxide extraction and deacidification of rice bran oil

This study examined pilot-scale extraction and lab-scale deacidification of rice bran oil by using supercritical carbon dioxide (SC-CO2). Two purest gamma-oryzanols (γ-oryzanols) (>98 wt%) were initially obtained by preparative reverse-phase high-performance liquid chromatography. Supercritical carbon dioxide extraction at 300 bar and 313 K from 1.03 kg powdered rice bran indicated a total yield of oil of 15.7% with a free fatty acids content of 3.75%, obtained from 20.5 kg of carbon dioxide in 8 h. In the SC-CO2 deacidification, pressure ranged from 200 bar to 300 bar, temperature ranged from 343 K to 363 K and consumption of carbon dioxide ranged from 900 g to 2700 g: the efficiency of removal of free fatty acids from 13 g extracted oil in deacidification at 250 bar and 353 K reached 97.8% using 2700 g of carbon dioxide. Finally, three-factor center composite scheme of response surface methodology was employed in designing a SC-CO2 deacidification system, which demonstrated that the pressure and consumption of carbon dioxide are significant in retaining triglycerides and in removing free fatty acids from rice bran oil.