The food industry is always looking for the best separation technology to obtain natural compounds of high purity, healthy products of excellent quality with several industrial applications. The conventional extraction process for those compounds has some limitations regarding the solvent toxicity, flammability and wastefulness. Research into energetically less costly technologies with respect to the environment is required. Supercritical fluid extraction (SFE) is a relatively new extraction process that has attracted great interest in many industries. Supercritical fluid properties are used selectively to extract specific components. This paper overviews the applications of supercritical fluid technology in food processing using carbon dioxide as the ideal supercritical fluid because of its non-flammable, non-toxic, non-polluting and recoverable characteristics. A summary of commercial applications and examples of recent developments illustrate the different possibilities that SFE has in industrial food processes.

SUMMARYEffective diffusion coefficients (D ef ) and mass transfer coefficients (k m ) in essential oil extraction processes from vegetal porous matrices using high-pressure carbon dioxide have been determined. The experimental data available for these calculations are extracted mass curves as functions of time for the extraction process of lemongrass essential oil (Cymbopogon citratus Staupf) using supercritical carbon dioxide as solvent extracting fluid. The mathematical model employed is based on Fick's second law, which has been solved using the finite element method and computer programs specially designed to evaluate the transport properties D ef and k m . A set of routines based on the modified Marquardt method to evaluate the optimum values of such properties were written and coupled with the finite element method code. The results show that the model employed and the computer programs developed are adequate to evaluate the transport properties and the extraction curves.