Supercritical CO2 Extraction as an Alternative to Organic Solvents in the Production of Soybean Oil

People nowadays generally expect to buy a high quality, minimally processed, "natural", additive-free food high in nutritional value. Furthermore, there is a growing interest in alternative processes that can minimize the environmental impact, decrease the toxic residues, more efficiently use the sub-products and also produce higher quality foods. The unique effects of pressure appear to be able to meet these requirements. Subjecting foods to pressures is now starting to be done by some of the world's leading food manufacturers. Organic solvents, mainly hexane, have been the preferred extraction solvent for soybean oil for a long time. Supercritical fluid technology is a viable alternative to current extraction methods. Supercritical CO2 is an ideal solvent because it is nontoxic, nonexplosive, inflammable, cheap, readily available and easily removed from extracted products. The oil extracted from soybeans with supercritical CO2 is of much higher quality than the hexane-extracted oil. It does not contain any phospholipids, thus eliminating the degumming step. The great advantage of the extraction of soybean oil with CO2 compared to the conventional extraction is that the refinement stages are simplified significantly and the solvent distillation stage is completely removed. In the terms of industry supercritical CO2 extraction still hasn't replaced hexane extraction. It may be not too long to wait before supercritical fluid extraction becomes routinely used for the production of soybean oil, thus it is very important to understand the effects of different process parameters on the yield of soybean oil as well as on the oil quality. The knowledge of these influences is not only useful for the optimization and economic evaluation of the process, but also for the ability to predict the extraction process, which is useful for scale-up as well as for the design and the optimization of industrial plant which is shown and elaborated in this paper.