Optimization of Enzymatic Preparation of Antioxidant Peptides from Protein Hydrolysate of the Marine Microalgae Nannochloropsis by Response Surface Methodology

Protein from the marine microalga Nannochloropsis was extracted and hydrolyzed with pepsin to prepare antioxidant peptides. The effects of enzyme-to-substrate ratio, substrate concentration, hydrolysis temperature and pH on the degree of hydrolysis (DH) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of hydrolysates were investigated and the process conditions were optimized using one-factor-at-a-time (OFAT) method and response surface methodology (RSM). The optimal hydrolysis conditions were determined as follows: substrate concentration, 5.0 mg/mL; temperature, 32℃; pH, 1.36; and enzyme-to-substrate ratio, 6%. The hydrolysate prepared under these conditions could scavenge 51.85% of DPPH free radical. © 2018, China Food Publishing Company. All right reserved.