Supercritical fluid extraction (SFE) techniques have garnered significant attention as green and sustainable methods for obtaining biologically active substances from a diverse array of plant byproducts. This paper comprehensively reviews the use of supercritical fluid extraction (SFE) in obtaining bioactive compounds from various plant residues, including pomace, seeds, skins, and other agricultural byproducts. The main purpose of supercritical fluid extraction (SFE) is the selective isolation and recovery of compounds, such as polyphenols, essential oils, vitamins, and antioxidants, that have significant health-promoting properties. Using supercritical carbon dioxide as the solvent, supercritical fluid extraction (SFE) not only eliminates the need for hazardous organic solvents, e.g., ethanol, and methanol, but also protects heat-sensitive bioactive compounds. Moreover, this green extraction technique contributes to waste valorisation by converting plant byproducts into value-added extracts with potential applications in the food, pharmaceutical, and cosmetic industries. This review highlights the advantages of SFE, including its efficiency, eco-friendliness, and production of residue-free extracts, while discussing potential challenges and future prospects for the utilisation of SFE in obtaining biologically active substances from plant byproducts.

Currant pomaces were valorised using food-grade supercritical CO₂ to examine how pre-drying (convective vs. freeze-drying) and species (black vs. red currant) shape extract composition and antioxidant readouts. Total phenolics (TPCs), DPPH capacity, tocopherols and fatty acids were determined; statistics employed included the Welch test with Holm adjustment and one-way ANOVA. Blackcurrant showed consistently higher TPCs than redcurrant, whereas DPPH responses were maximised in freeze-dried redcurrant. Freeze-drying increased PUFAs and concomitantly lowered SFAs within both species, with MUFAs varying within a narrower band and tending to be higher in blackcurrant. Tocopherol profiles in residues displayed homologue- and species-specific redistribution (e.g., α higher after convective drying in blackcurrant; γ/δ preferentially retained after freeze-drying), consistent with microstructure-dependent mass transfer and homologue-specific partitioning during SFE. Collectively, pre-drying emerged as the principal lever to tailor lipid class balance and antioxidant performance under fixed extraction conditions. Practically, freeze-drying is suited to PUFA-rich, antioxidant-active fractions, whereas convective drying favours more oxidation-resilient profiles. These results support process-informed ingredient design for clean-label applications and motivate yield-normalised mass balances and scale-up studies.

Fruit pomace, generated as a by-product of juice processing, is a valuable source of bioactive compounds but requires sustainable extraction approaches to enable its valorisation. Supercritical CO₂ extraction (SFE-CO₂) represents a promising green technology due to its efficiency, solvent-free character, and tuneable selectivity. In this study, the response surface methodology (RSM) was applied to evaluate the effects of pressure, temperature, and time on the recovery of fat, protein, and total phenolic compounds (TPCs) from blackcurrant (Ribes nigrum) and redcurrant (Ribes rubrum) pomace subjected to conventional- and freeze-drying. The highest protein content (14.5%) was obtained in freeze-dried blackcurrant at 400 bar, 60 min, and 30 °C, while the maximum TPCs (24.60 mg GAE/g d.w.) was reached at 500 bar, 60 min, and 40 °C. The redcurrant samples consistently showed lower extractable values across all the responses. Pressure and time were identified as the most influential process variables, enhancing the solvent density and mass transfer during extraction. These results demonstrate that both the drying pre-treatment and raw material type significantly affect the SFE efficiency and confirm the potential of optimised SFE-CO₂ as a viable strategy for converting fruit pomace into functional ingredients for food, nutraceutical, and cosmetic applications.