Sustainable protein recovery from Sacha inchi press cake using cyclone separation: Functional and structural characterization

• Cyclone-based fractionation enriched protein content in Sacha inchi press cake. • F3 fraction showed superior solubility, water/oil-holding, and foam stability. • Antioxidant activity decreased, with no DPPH/ABTS radical scavenging detected. • Process is low-cost, scalable, and compatible with existing milling systems. • Further optimization and hybrid methods needed for better nutritional enhancement. Sacha inchi press cake, a protein-rich by-product, offers potential as a sustainable plant-based ingredient. However, its protein enrichment and functional properties are limited by dry processing constraints. This study evaluated cyclone-based dry fractionation after grinding and sieving (≤250 µm), producing four fractions (F1–F4). Key properties were assessed, including physicochemical composition, nutritional profile, amino acid composition, bioactive compounds, and techno-functional characteristics. Protein enrichment was modest, increasing from 53.06% in the starting material (SC-RM) to 56.62% in F3 and 57.12% in F4, with the highest yield in F3 (32.56%) compared to F4 (8.91%). Solubility was pH-dependent, ranging from 19.96% at pH 2 to 95.76% at pH 12. Functional properties showed varied results: F3 had reduced foaming capacity (from 11.38% to 3.95%), but improved foam stability (from 88.89% to 96.83%). Emulsifying activity and stability decreased slightly (from 87.70% and 78.87% to 76.52% and 70.09%, respectively), while gelation improved, with the least gelation concentration dropping from 18% to 10%. Bioactive compounds remained largely unchanged, with total phenolic content (TPC) ranging from 28.31–29.14 mg GAE/g and FRAP increasing from 64.04 to 79.94 µmol FeSO₄/g. The amino acid score was low (0.04), indicating limited protein quality. Overall, the fractionation resulted in minor changes to composition and functionality, highlighting trade-offs between yield, purity, and functionality. Further optimization of processing conditions and hybrid processing methods may improve enrichment and bioactivity.