Impact of seed structure modification on the rate of supercritical CO2 extraction

Internal structure of soybeans was modified by the instantaneous controlled pressure drop process (DIC) when the material is heated by saturated steam for a short period of time and then rapidly evacuated. The bursting evaporation of moisture from all the mass of material caused by the pressure drop blows cavities in the material, breaks their walls and thus enhances subsequent extraction of oil from soybeans. Both the whole beans and milled beans and both the DIC-treated and non-treated beans were extracted with supercritical CO2 at 280 bar and 40 °C. The extraction yield was measured and simulated by three mathematical models and equilibrium and mass transfer parameters were evaluated. The pore size distribution was measured as well. The results show formation of micropores in the beans by the DIC treatment and a substantial increase in the rate of extraction controlled by intraparticle diffusion.