A comparative study on some properties and antioxidant activity of Hypophthalmichthys molitrix (Valenciennes, 1844) protein hydrolysates produced by different hydrolysis methods

Some functional, physicochemical and antioxidant properties of Hypophthalmichthys molitrix protein hydrolysates produced by alcalase (SCPH-alcalase), acid (SCPH-acidic) and alkaline (SCPH-alkaline) were investigated. No significant difference was observed for degree of hydrolysis (DH), L*, a* and b* values among all types of hydrolysate samples (p>0.05). The highest protein recovery, protein and essential amino acids content were observed in SCPH-alcalase. All protein hydrolysates displayed antioxidant activities, that enhanced by increasing the hydrolysates concentration. The chemical hydrolysates had the highest DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging activity, while SCPH-alcalase showed the highest ABTS (2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) radical-scavenging activity and FRAP (Ferric reducing antioxidant power) (p<0.05). The highest solubility and the lowest fat adsorption were observed with the SCPH-alcalase (p<0.05). Increased numbers of hydrophilic groups of SCPH-alcalase are supported by FTIR spectra. The results showed the significant effect of different hydrolysis conditions on hydrolysates properties and indicated alcalase enzyme might be more suitable to produce hydrolysates with desirable functional, nutrition and antioxidative properties.