Optimization of supercritical CO2 process for the concentration of tocopherol, carotenoids and chlorophylls from residual olive husk

In this paper the use of supercritical CO2 technology is studied as a means of streamlining olive husk extraction so as to obtain extracts with a high content of valuable compounds and without any residual solvent. Response surface methodology (RSM) was used to evaluate how pressure (25–35 MPa) and temperature (313–333 K) affected oil yield and the extract quality (expressed in terms of tocopherol, carotenoids and chlorophyll concentration). The effect of using ethanol as a cosolvent was also evaluated. Kinetic parameters were obtained for their use in the design and optimization of the extraction process and for scale-up steps in particular. Optimal extraction conditions were determined taking both maximum yield and recovery criterion into account. In these conditions the valuable compounds were from two to four times more concentrated than in classical hexane extraction.