Antioxidant activity and functional properties of grey mullet (Mugil cephalus) protein hydrolysates

Abstract

Grey mullet protein hydrolysate possessed high antioxidant activity and was prepared using neutrase. The hydrolysis conditions were optimised by the response surface methodology (RSM): enzyme to substrate ratio 5.8:1 (U of enzyme/mg of substrate), pH 7.3, 51°C, and 3.5 h. The hydrolysate obtained under the optimal conditions (HGM) possessed superior radical scavenging activity (IC50 values: 0.786 mg/mL for DPPH; 1.294 mg/mL for superoxide anion radical) to that of unhydrolysed grey mullet protein (GM). HGM also possessed better ferric-reducing power and higher ferrous ion-chelating activity. Electrophoretic analysis indicated that HGM mainly consisted of peptides with molecular weights below 10 kDa. The amino acid composition indicated a high nutritional value for HGM. The solubility, foamability, and emulsion activity index of HGM were improved as compared to those of GM. These results indicated that HGM has potential as a bioactive ingredient in the formulation of functional foods.