Boundary-Constrained Optimization of Tilapia ( Oreochromis Niloticus ) Skin Hydrolysis for the Recovery of a Bioactive Hydrophobic Peptide-Enriched Fraction with Antioxidant, Antinociceptive, and Anti-Inflammatory Activities

This study optimized the enzymatic hydrolysis of tilapia (Oreochromis niloticus) skin using Aspergillus oryzae protease via response surface methodology. Under optimized conditions (pH 6.87, 55.50 °C, 3.70% enzyme-to-protein ratio), a maximum degree of hydrolysis of 28.75% was achieved. Downstream fractionation using AmberLite XAD-7HP macroporous resin successfully recovered a targeted hydrophobic peptide-enriched fraction (HPEF) via ethanol desorption with a 47.2% specific yield. Crucially, HPEF presented a significantly higher antioxidant capacity than the crude enzymatic protein hydrolysate (CEPH) and hydrophilic peptide-enriched fraction (LPEF) in both DPPH and FRAP assays. In preclinical murine evaluations, oral administration of the HPEF significantly attenuated acute inflammation and peripheral nociception, reducing inflammatory-phase paw-licking time by up to 58.8% and inhibiting histamine-induced paw edema by 46.3%. These findings demonstrate an efficient strategy for recovering highly functional biopeptides for biomedical and food industry applications.