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. 2013 Mar;1(2):184-95.
doi: 10.1002/fsn3.27. Epub 2013 Feb 14.

Biological and functional properties of proteolytic enzyme-modified egg protein by-products

Affiliations

Biological and functional properties of proteolytic enzyme-modified egg protein by-products

Marta Pokora et al. Food Sci Nutr. 2013 Mar.

Abstract

Enzymatic hydrolysis led to improve functional properties and biological activity of protein by-products, which can be further used as protein ingredients for food and feed applications. The effects of proteolytic enzyme modification of egg-yolk protein preparation (YP) and white protein preparation (WP), obtained as the by-products left during the course of lecithin, lysozyme, and cystatin isolation on their biological and functional properties, were evaluated by treating a commercial Neutrase. The antihypertensive and antioxidative properties of YP and WP hydrolysates were evaluated based on their angiotensin-converting enzyme (ACE)-inhibitory activity and radical scavenging (DPPH) capacity, ferric reducing power, and chelating of iron activity. The functionality of obtained hydrolysates was also determined. Neutrase caused a degree of hydrolysis (DH) of YP and WP by-products: 27.6% and 20.9%, respectively. In each of them, mixture of peptides with different molecular masses were also observed. YP hydrolysate showed high levels of antioxidant activity. The scavenging capacity, ferric reducing power, and chelating capacity were observed at the level: 0.44 μmol/L Trolox mg(-1), 177.35 μg Fe(2+) mg(-1), and 549.87 μg Fe(2+) mg(-1), respectively. YP hydrolysate also exhibited significant ACE-inhibitory activity, in which the level was 59.2 μg. Protein solubility was significantly improved as the DH increased. WP hydrolysate showed high water-holding capacity of 43.2. This study indicated that YP and WP hydrolysates could be used in foods as natural antioxidants and functionality enhancers.

Keywords: Antioxidant activity; bioactive peptides; egg proteins; hydrolysis.

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Figures

Figure 1
Figure 1
The degree of hydrolysis (DH) of egg-yolk (YP) and egg-white (WP) protein preparations treated by Neutrase.
Figure 2
Figure 2
Changes in free amino groups contents (FAG) in egg-yolk (YP) and egg-white (WP) protein preparation treated by Neutrase.
Figure 3
Figure 3
Peptide profiles of (A) egg-white (WP) and (B) egg-yolk (YP) protein preparation hydrolysates (reversed-phase high-performance liquid chromatography [RP-HPLC]).
Figure 4
Figure 4
Peptide molecular weight repartition for (A) egg-white (WP) and (B) egg-yolk (YP) protein preparation hydrolysates.
Figure 5
Figure 5
DPPH (2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl) scavenging activity of egg-yolk (YP) and egg-white (WP) protein preparation hydrolysates.
Figure 6
Figure 6
The ferric reducing ability (FRAP) of egg-yolk (YP) and egg-white (WP) protein preparation hydrolysates.
Figure 7
Figure 7
Ferrous ion-chelating activity of egg-yolk (YP) and egg-white (WP) protein preparation hydrolysates.
Figure 8
Figure 8
Water solubility profiles of egg-white (WP) and egg-yolk (YP) protein hydrolysates.
Figure 9
Figure 9
Emulsifying capacity of egg-white (WP) and egg-yolk (YP) protein preparation hydrolysates at pH 6.5.

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