Preparation of antioxidant peptides from grass carp protein by response surface methodology and evaluation of their activities

Grass carps were hydrolyzed by five different proteases to extract antioxidant peptides,respectively.It was found that papain hydrolysates showed the highest DPPH·free radicals scavenging activity(IC50=2.66±0.41mg/mL),Alcalase 2.4L hydrolysate exhibited the highest hydroxyl radical scavenging ability(IC50=1.81±0.44mg/mL) and pancreatin 6.0 demonstrated the highest super superoxide anion radical scavenging activity(IC50=8.57±0.32mg/mL).The hydrolysis conditions optimized by response surface methodology(RSM) were as follows:[E/S]=0.68×103U/g protein,time 3.83h and temperature 51.41℃.The IC50 value for hydrolysates prepared under this condition was 155.89±11.21μg/mL,which was in accordance with the value estimated by RSM(146.22μg/mL).It proved that RSM could be well used in the optimization of hydrolysis conditions.In addition,the hydrolysates optimized by RSM had strong reducing power and lipid peroxidation inhibition activity.