Improvement of antioxidant properties of egg white protein enzymatic hydrolysates by membrane ultrafiltration

The production of bioactive peptides from egg white proteins (EWPs) and their separation are emerging areas with many new applications. The objective of this study was to compare antioxidant activity of three distinct EWP hydrolysates and their peptide fractions prepared by membrane ultrafiltration using membranes with 30, 10 and 1 kDa molecular weight cut-off. The hydrolysates were obtained by thermal and ultrasound pretreated EWPs hydrolyzed with a bacterial protease, Alcalase. It appeared that the pretreatment significantly affected peptide profiles and antioxidant activity of the hydrolysates measured by ABTS, DPPH and FRAP methods. The hydrolysate prepared using alcalase and ultrasound pretreatment at 40 kHz - 15 min has shown to be the most effective in scavenging both DPPH and ABTS radicals (28.10 +/- 1.38 and 79.44 +/- 2.31%, respectively). It has been noticed that this hydrolysate had a nutritionally more adequate peptide profile than the other hydrolysates with a much lower amount of peptides lt 1 kDa (11.19 +/- 0.53%) and the greatest content of the peptide fraction in the molecular weight (MW) range of 1-10 kDa (28.80 +/- 0.07%). This peptide fraction has shown the highest DPPH and ABTS antioxidant activity compared to all other fractions having a potential to be used as a functional food ingredient.