Supercritical fluid extraction: Revalorization of agrofood by-products and other environmental applications.

Supercritical fluid extraction (SFE) is basically a liquid extraction of the compounds present in a solid or semisolid matrix, that takes place above the critical point. Solvents in supercritical state work as liquid solvent but maintains the mass transfer properties of real gases. CO2 is the most commonly used supercritical fluid due to its no flammability, no toxicity, is non corrosive and presents low critical point characteristics, besides it has been regarded as GRAS (generally recognised as safe) by the USFDA. All the social and legal tendencies allow us to present this technology as an extraordinary tool for the revalorization of agrofood by-products obtaining high added value raw materials for different productive cycles. Some of the most outstanding examples can be the extraction and fractionation of polyunsaturated fatty acids (PUFAs) from fish oil, obtaining of aromatic extracts and essential oils from different natural sources as orange peels, or the production of natural antioxidants from plants and vegetable by-products. All these products have a great market in pharmaceutical and cosmetic sector. On the other hand, SFE can also be used for the recovery of contaminated soils and detoxification of hazardous wastes. Among the different contaminants capable of being removed from different matrix. are the PAHs, PCB's and organoclorinated pesticides. Some of these applications, as detoxification of industrial waste waters, or treatment of petrol refinery wastes are implanted at industrial levels in some countries like USA. Applications in these two fields will be presented with some preliminary results of the fractionation and purification of PUFAs from different fish oils and the removal of organochlorine compounds from different environmental matrixes.