Abstract
•Antioxidant peptides from CGM protamex hydrolysis were prepared and optimized.•Comprehensive balance method of orthogonal design to optimize variables used.•CGM oligopeptides fraction is mainly responsible for the antioxidant activity.•CGM peptides are efficient in scavenging DPPH radical and reducing power.•Amino acids and Alanyl-Tyrosine have a role in peptide antioxidant activity.
Protamex catalyzed corn gluten meal (CGM) hydrolysis peptides (CHP) were prepared. Orthogonal design L16 (45) was used to optimize processing variables of CGM concentration, CGM heat pretreatment (121°C) time, and enzymolysis pH, temperature, and time. Degree of hydrolysis (DH), undigested residue ratio, molecular weight (MW) distribution and DPPH radical inhibition were selected as analysis indicators. Optimum variables were CGM concentration of 18%, heat pretreatment time of 40min, and enzymolysis pH, temperature and time of 7.5, 55°C and 24h, respectively. Verification test showed that CHP IC50 for scavenging hydroxyl radical was the best and then followed by reducing power. Oligopeptides improved after hydrolysis at the expense of di- and tripeptides, suggesting formation of soluble aggregates from low MW peptides. The increase in the DH, oligopeptides, Alanyl-Tyrosine, and antioxidant free amino acids coincided with the improvement in the antioxidant activity of CHP.