Recovery of Bioactive Peptide Fractions from Rainbow Trout (Oncorhynchus mykiss) Processing Waste Hydrolysate

Aims Bioactive peptides with antioxidant properties derived from fish by-products and wastes by enzymatic hydrolysis have become a topic of great interest for pharmaceutical, health food, and processing/preservation industries. Materials & Methods This study aimed to characterize peptide fractions with antioxidative activity recovered from rainbow trout gelatin hydrolysate. Four peptide fractions (<3 kDa, 3–10 kDa, 10–30 kDa, and >30 kDa) were obtained from gelatin hydrolysate by subjecting them to centrifugal ultrafiltration using successively a 30 kDa, 10 kDa, and a 3 kDa membrane. The 10–30 kDa fraction was characterized in terms of amino acid composition. The antioxidant activity of all fractions was monitored by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging as well as reducing power activity. Findings The free amino acids in 10–30 kDa fraction were dominated by Gly, Pro, Ala, and Hyp; the total hydrophobic amino acid of 10–30 kDa fraction was also 61.5%. All hydrolysate and peptidic fractions demonstrated high antioxidant activities. Moreover, 10–30 kDa fraction exhibited the highest DPPH and ABTS radical scavenging activity (2, 5, and 10 mg ml−1) and reducing power (10 mg ml−1) compared to other fractions (p<0.05). Conclusion These results revealed the potential of peptide fractions recovered from rainbow trout skin gelatin as source of natural antioxidants for use in food products.