Purification and characterization of antioxidant peptide fractions from protein hydrolysate of rainbow trout (Onchorhynchus mykiss) viscera

Abstract

This study was conducted to evaluate the purification of antioxidant peptides from the rainbow trout viscera using by enzymatic hydrolysis and to measure the amino acid profile of the peptide part with more antioxidant properties. Two concentrations of alcalase were used to hydrolyse fish viscera (1 % and 2 %). The hydrolyzate was fractionated and purified with ultra-filtration membranes (<30, <10, and < 3 kDa) and RP-HPLC (Reversed-phase high-performance liquid chromatography) and evaluation for antioxidant properties by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS⁺) radical scavenging assays. The degree of hydrolysis was measured in hydrolyzed fish viscera. Sections of F10, F11 and F12 in the chromatogram exhibited the highest DPPH radical scavenging activity with 80.41 ± 0.21 %, 79.71 ± 0.65 % and 78.83 ± 0.81 %, respectively. The amino acid profiles of sections F11, F12, and F10 confirmed that these sections contained adequate amounts of hydrophobic amino acids, increasing their antioxidant activity. The ratio of essential amino acids to total amino acids in selected samples was 37.51 % and also essential amino acids to non-essential amino acid ratio was 0.56. According to the results, the viscera of rainbow trout is a rich source of antioxidant peptides to replace with synthetic antioxidants.