Efficient Recovery of Biologically Active Substances from Currant Pomace—Pre-Drying Effects on Supercritical CO2 Extracts

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.