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Supercritical CO2 extraction has shown great potential in separating vegetable oils as well as removing undesirable oil residuals from natural products. The influence of process parameters, such as pressure, temperature, mass flow and particle size, on the mass transfer kinetics of different natural products has been studied by many authors. However, few publications have focused on specific features of the raw material (moisture, mechanical pretreatment, bed compressibility, etc.), which could play an important role, particularly in the scale-up of extraction processes. A review of the influence of both process parameters and specific features of the material on oilseed extraction is given in Eggers (1996). Mechanical pretreatment has been commonly used in order to facilitate mass transfer from the material into the supercritical fluid. However, small particle sizes, especially when combined with high moisture contents, may lead to inefficient extraction results. This paper focuses on the problems that appear during scale-up in processes on a lab to pilot or industrial plant scale related to the pretreatment of material, the control of initial water content and vessel shape. Two applications were studied: deoiling of wheat gluten with supercritical carbon dioxide to produce a totally oil-free (< 0.1 % oil) powder (wheat gluten) and the extraction of oil from rose hip seeds. Different ways of pretreating the feed material were successfully tested in order to develop an industrial-scale gluten deoiling process. The influence of shape and size of the fixed bed on the extraction results was also studied. In the case of rose hip seeds, the present work discusses the influence of pretreatment of the seeds prior to the extraction process on extraction kinetics

Interfacial properties exert a fundamental influence on fluid/liquid separation processes, with the interfacial tension being an important quantity associated with mass transfer and mutual solubility of participating compounds. A better understanding of transport phenomena is achieved by obtaining interfacial tension data under different conditions of pressure and temperature and as a function of time. Generally, interfacial tension decreases with increasing pressure due to increased adsorption of the compressed fluid at the interface. In the case of considerable mutual solubility, interfacial tension further decreases with time as mass transfer into the bulk phase proceeds. Prediction of colloidal behaviour in a separation process requires acquisition of additional information on the presence of surfactants.