The agri-food industry generates large quantities of by-products of animal and vegetable origin, which are currently discarded or destined for low-value-added applications. Agrifood by-products contain a remarkable source of polyphenols, polysaccharides, and numerous other phytochemicals, including pigments, with many benefits for humans and their exploitation, can be an excellent opportunity for the food sector. Furthermore, new financial opportunities are created by using agrifood by-products as sources of valuable components that may serve as new foods or food ingredients, strengthening the circular economy.

Nowadays, different advanced green extraction techniques such as supercritical fluid extraction (SFE) are widely used to isolate valuable components from agrifood by-products. SFE provides a range of benefits, as well as offering routes to overcome some of the limitations that exist with the conventional methods of extraction such as low extraction efficiency, and high temperatures, which can promote the degradation of thermolabile compounds, and residual toxic reagents. In SFE, solvents above their critical pressures and temperatures are employed resulting in an easier diffusion through solid materials and therefore faster extraction yields. Usually, supercritical CO2 (SC-CO2) is used as a solvent in SFE due to its mild critical conditions, non-toxicity, and low cost. The phase separation can facilitate the collection of pure CO2 solvent (gas), such that it can be recirculated into storage, ready for re-use, thus reducing total energy costs (less CO2 collection required) thereby reducing energy consumption and increasing the overall sustainability of SCF-based extractions.

In AQUABIOPROFIT, the applications of SFE in the recovery of natural active substances from food processing by-products and underutilized biological resources have been reviewed by the University of Valencia, and Centro Tecnológico de la Carne de Galicia, Ourense, Spain.

Read the full review for more information: Zhou et al. (2021). The Application of Supercritical Fluids Technology to Recover Healthy Valuable Compounds from Marine and Agricultural Food Processing By-Products: A Review