Production of bioactive peptides using enzymatic hydrolysis and identification antioxidative peptides from patin (Pangasius sutchi) sarcoplasmic protein hydolysate

• Patin sarcoplasmic proteins were hydrolysed using papain and Alcalase.
• The antioxidant activity of protein hydrolysates was examined.
• Four steps of purification were executed to obtain the active peptide.
• The antioxidant peptides were identified as DPQHPVMPR, LVVDIPAALQHA and GVDNPGHP.

Patin sarcoplasmic protein was hydrolysed with Alcalase and papain. The antioxidant activities of sarcoplasmic protein hydrolysates (SPHs) were assessed by evaluating 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical-scavenging activities, reducing power and metal chelating activity. The Alcalase hydrolysate was purified by ultrafiltration, ion exchange and gel filtration chromatography and RP-HPLC. The most potent fraction (SI 3) obtained from RP-HPLC showed DPPH radical-scavenging activity by 1.83 times higher than SPH. Three antioxidant peptide sequences, Asp-Pro-Gln-His-Pro-Val-Met-Pro-Arg, Leu-Val-Val-Asp-Ile-Pro-Ala-Ala-Leu-Gln-His-Ala and Gly-Val-Asp-Asn-Pro-Gly-His-Pro, were identified by HPLC connected to electrospray ionisation-time-of-flight mass spectrometer (ESI-TOF MS/MS). The presence of a hydrophobic amino acid (Val), hydrophilic amino acids (His and Pro) and an acidic amino acid (Asp) in the peptide sequences is believed to contribute to high antioxidant activity of SPH. Hence, antioxidative peptides from patin protein may be produced for development as natural antioxidant ingredients in functional foods.