Recent advances in subcritical water and supercritical carbon dioxide extraction of bioactive compounds from plant materials

Background: Subcritical water (SWE) and supercritical carbon dioxide extraction (SCCO2) are novel extraction techniques for recovering compounds with food-enhancement and health promoting properties, from various plants and biomaterials. These extraction techniques are efficient, economical and promising routes for resource recovery without compromising the quality of the extracted products. Scope and approach: Here, the theoretical background, practical application and recent trends associated with the use of SWE and SCCO2 in the recovery of bioactive compounds from plant sources are presented. The paper is organised to allow a refreshed understanding of the main features, benefits, challenges, and possible solutions involving SCCO2 and SWE based on the enormous number of scientific publications and the very few industrial applications in the public domain. The utilisation of these methods are advantageous in selective extraction of better-quality compounds at lowest potential environmental impact. Furthermore, two research publication databases were queried using specific criteria to show the progress and growth in interest on SWE and SCCO2. Key findings and conclusions: Subcritical water and supercritical carbon dioxide are viable extraction techniques for recovery of bioactive compounds. These techniques, standalone or combined sequentially or with other extraction methods, enhance yield and quality of thermally liable compounds. Mathematical models having a strong correlation with experimental data can also be used to predict and monitor the process kinetics. Our findings should be beneficial for professionals concerned with the application of technology in the development of new and existing food products, their storage and marketability.