Solubility of γ-oryzanol in supercritical carbon dioxide and extraction from rice bran

Abstract The γ-oryzanol is a complex mixture of triterpenic alcohols with ferulic acid esters of phytosterols, being an important nutraceutical in rice bran. In order to assess the ability of the supercritical carbon dioxide (scCO 2 ) to extract γ-oryzanol from rice bran, the solubility of γ-oryzanol in scCO 2 was measured at 40 °C, 60 °C, and 80 °C, and 200, 300, and 400 bar. A fractional extraction at 60 °C and 400 bar from rice bran containing 22.2% of oil with 1.55% γ-oryzanol was also performed. The mean solubility values ranged from 0.13 to 1.57 g γ-oryzanol/kg CO 2 , and a crossover pressure (CP) was observed at 300 bar. Below of the crossover pressure, the solubility decreased with increasing temperature and above, there is solubility increase with increasing temperature. Although Chrastil equation parameters have been correlated to experimental data, a high mean deviation of 9.0% was observed because it is a mixture of compounds. The presence of oil lowers the solubility of γ-oryzanol, which is the case of extraction from bran oil, showing that the nutraceutical is more concentrated at the final oil fraction or in the raffinate fractions.