Characterization and Bioactivities of Gelatin Hydrolysates of Red Tilapia (Oreochromis spp.) Scale Byproducts

This study explores the production of gelatin hydrolysates with metal-chelating peptides derived from red tilapia scales and investigates their biofunctional properties. Gelatin was enzymatically hydrolyzed using Alcalase (Alc-GH), Flavourzyme (Flav-GH), or a sequential combination of Alcalase and Flavourzyme (Alc+Flav-GH). Alc-GH and Alc+Flav-GH were ultrafiltrated at 1 kDa cutoff. Alc+Flav-GH, characterized by a high proportion of small-sized peptides, exhibited superior metal-chelating ability, as determined by switchSENSE and was associated with enhanced antioxidant activity. Ultrafiltration improved the Fe 2+ -chelating properties of both fractions compared to their respective whole hydrolysates. All of the hydrolysates and their ultrafiltrates showed remarkable ACE inhibitory activity. Specifically, the ≤1 kDa Alc-GH fraction produced small-sized Fe 2+ -chelating peptides with ACE inhibitory activity, whereas the ≤1 kDa Alc+Flav-GH fraction efficiently generated Ni 2+ -chelating peptides with strong antioxidant potential. LC-MS/MS data showed peptides rich in Asp, Glu, Ser, Lys, and Arg, which may contribute to their metal-chelating and antioxidant properties.