Biological activity of egg-yolk protein by-product hydrolysates obtained with the use of non-commercial plant protease

Abstract

Enzymatic hydrolysis leads to improved functional and biological properties of protein by-products, which can be further used as nutraceuticals and protein ingredients for food applications. the present study evaluated AcE-inhibitory, antioxidant and immunostimulating activities in hydrolysates of egg-yolk protein by-product (YP), generated during industrial process of delipidation of yolk. the protein substrate was hydrolyzed using non-commercial protease from Asian pumpkin (Cucurbita ficifolia). the reaction was conducted in 0.1 M t ris-Hcl buffer (pH 8.0) at temperature of 37°c for 4 hours using different enzyme doses (100-1000 U/mg of substrate). the protein degradation was monitored by the determination of the degree of hydrolysis (DH), release of free amino groups (FAG) and by rP-HPLc. In the obtained hydrolysates we also evaluated biological activities. It was shown that the highest DH of substrate (46.6%) was obtained after 4h of reaction at the highest amount of enzyme. this hydrolysate exhibited antioxidant activity, including ferric ion reducing (FrAP) (56.41 μg Fe 2+ /mg), ferric ion chelating (695.76 μg Fe 2+ /mg) and DPPH free radical scavenging (0.89 μmol trolox eq /mg) as well as AcE-inhibitory (Ic 50 =837.75 μg/mL) activities. the research showed improved biological properties of enzymatically modified YP by-product.