Amino acid composition and antioxidative properties of hydrolysed pumpkin (Cucurbita pepo L.) oil cake protein

Abstract

Pumpkin oil cake protein isolate (POCPI) was hydrolysed using two food-grade enzymes alcalase and trypsin. Alcalase-hydrolysed POCPI (POCPH1) was selected as the optimum treatment based on the DPPH radical scavenging, total antioxidative, and ferrous ion chelating activities. Amino acid composition showed a direct relationship between the antioxidative activity of POCPH1 and the amount of hydrophobic amino acids that formed 33.49% of its total amino acids. Surface hydrophobicity decreased as a result of hydrolysis and potent thermal and pH stability was observed in POCPH1 (p ˂ 0.05). In terms of molecular weight distribution, size exclusion chromatogram indicated that the majority of peptides possessed molecular weight less than 6.5 kDa. Based on the results, POCPH1 could be employed as a natural antioxidative agent with strong pH and thermal stability.