Аntioxidant activity of peptide fractions obtained by membrane ultrafiltration of egg white protein enzymatic hydrolysates

Abstract

The objective of this research was a production of egg white protein hydrolysates with improved antioxidant properties. For this purpose, a thermal and ultrasound pretreated egg white proteins were intensively hydrolysed with a commercial food-grade bacterial protease Alcalase. Thus obtained hydrolysates were further separated by sequential ultrafiltration into four peptide fraction viz. Fraction I (> 30kDa), II (10 - 30 kDa), III (1 - 10 kDa) and IV (< 1kDa) which were investigated in terms of their antioxidant activity. The antioxidant activity of hydrolysates and peptide fractions were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical scavenging assays and measuring ferric reducing antioxidant power assay. Scavenging of 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) by Fraction III, prepared with ultrasound pretreatment (35 kHz - 30 min) was found to be significantly higher than other fractions (21.17 ± 2.01 % and 80.72 ± 1.32 %, respectively), while ferric reducing antioxidant power assay has proven to be the best for thermal pretreatment. The results show that the fractionated hydrolysates were superior to the original hydrolysate in the antioxidative activity tested and can be concluded that by combining ultrasound pretreatment hydrolysates with improved functional and antioxidant properties can be produced enhancing utilization of egg white in food products.