Supercritical Fluid Extraction of Bioactive Compounds from Botanic Matrices: Experimental Data, Process Parameters and Economic Evaluation

This review discusses the recent developments in supercritical fluid extraction (SFE) of bioactive compounds from botanic matrices during the period of 2007-2012. The main operational parameters affecting the extraction yields that are presented and discussed include: pressure, temperature, extractor geometry, average size of particles, extraction time, solvent flow rate and use of cosolvents. Emphasis is given to extractor geometry. The data compiled herein show the influence of the vessel height vs. internal diameter ratio on the overall extraction curves. Several extractor volumes (2 cm3 to 2×104 cm3) and height to internal diameter ratios (1.9 to 63.6) were used for SFE of substances from several types of raw materials. The study of extractor geometry is important when plant scale up is proposed. To succeed in scale up, similar profiles for the extraction curves obtained for SFE of plants with different bed geometries must be obtained. Hence, the process parameter calculations are exhibited by comparing equations available in scientific literature and explaining the use of these equations in different extraction situations. Aspects concerning the cost of manufacturing a product are described and also discussed. Various recent studies that mention the economic feasibility of extracting components from solid matrices in pilot or larger plants using supercritical technology are summarized. These works also present some specific costs in investment and raw material as the dominant costs for the process, indicating that the cost of manufacturing of target substances decreases when the extraction vessel capacity increases.