Characterization of packed beds of plant materials processed by supercritical fluid extraction

The particle size distributions of crushed plant materials obtained using different types of comminuting machines were analysed. The Rosin–Rammler–Bennett model was used, as an appropriate description for these data. Some characteristics of raw materials and packed columns were determined using different simple measuring methods (sieving, air pycnometry, traditional solvent Soxhlet-extraction). Furthermore, simple empirical equations were used to determine as many other parameters (density, viscosity, solubility, diffusion coefficient, mass transfer coefficient in the fluid phase) as possible. The usage of data was demonstrated by modelling the supercritical fluid extraction (SFE) of corn germ, pumpkin seed, calendula and paprika. The suitability of Sovová’s model for description the extraction curves was proven. A comparison of measured data to model predictions showed that extraction yields and concentration profiles in packed columns may be evaluated by using the same model parameters.