Supercritical Fluid Extraction to Valorise Fruit and Vegetable by-Products.

The global transition toward a circular bioeconomy requires the urgent valorization of agro-industrial by-products, specifically fruit and vegetable residues, which represent a significant environmental burden but also a rich source of high-value bioactive compounds. This review critically examines Supercritical Fluid Extraction (SFE) using carbon dioxide (CO2) as a highly efficient and versatile technological platform for the sustainable recovery of specialty lipids and secondary metabolites. By analysing the thermodynamic foundations of the supercritical state, the study explores how the tuneable density and transport properties of supercritical CO2 (SC-CO2) facilitate molecular preservation compared to conventional solvent-based methods. The discussion focuses on the mechanistic aspects of the process, including the role of green co-solvents in overcoming polarity barriers and the application of kinetic models to describe mass transfer phenomena in complex matrices. Unlike general surveys, this work integrates technical-economic considerations with critical analysis of SFE's role within a multi-stage biorefinery framework, essential for aligning economic profitability with the ecological mandate of strategic molecular recovery.