ABSTRACT
In recent years, increasing demand for superior quality and safety of foods and medicines, as well as concern for environmental pollution during their commercial production, have triggered stringent regulations on the toxin levels in foods and medicines as well as on the discharge of pollutants to the environment. In addition, there has been increasing consumer preference for natural substances. All these factors have given strong impetus to development of cost-effective new technologies, such as the one for eco-friendly extraction from natural substances employing
green and safe solvents. In recent years, supercritical fluid extraction (SCFE) has emerged as a highly promising environmentally benign technology for production of natural extracts, such as flavors, fragrances, spice oils, and oleoresins; natural antioxidants; natural colors; nutraceuticals; and biologically active principles. The state of a substance is called supercritical when both temperature and pressure exceed their critical point values. A supercritical fluid (SCF) combines the twin beneficial properties, namely high density (which imparts high solvent power) and high compressibility (which permits high selectivity due to large variability of solvent power by small changes in temperature and pressure). In addition, it offers very attractive extraction characteristics, owing to its favorable diffusivity, viscosity, surface tension, and other thermo-physical properties.
