Efficacy of enzymatic, preheating-enzymatic, and sonication-enzymatic treatments on water dispersibility of egg white powder

Egg white protein has great potential as a functional ingredient in foods and beverages. However, its application is often limited because of the poor dispersibility of spray-dried egg white powder (EWP). In this study, the efficacy of two methods of improving the water dispersibility of the EWP were investigated: heat-enzymatic hydrolysis (HE-EWP) and ultrasonication-enzymatic hydrolysis (UE-EWP). Specifically, the impact of these treatments on the water solubility, dissolution rate, and coefficient of stability (COS) of the EWPs was examined. The ultrasonication-enzymatic hydrolysis treatment (UE-EWP) reduced the particle size (190.10 nm), increased the absolute zeta potential (−24.83 mV), and improved the water solubility (95.81 %) of the egg white proteins. The heat-enzymatic hydrolysis treatment (HE-EWP) induced a greater degree of structural alteration and thermal aggregation of the egg white proteins, leading to the exposure of additional enzyme binding sites and internal groups on the egg white protein surfaces. Consequently, the HE-EWPs exhibited a higher degree of hydrolysis (DH), surface hydrophobicity (H 0 ), absolute zeta potential (−35.03 mV), and larger particle size (636.40 nm). This increase in particle size and H 0 resulted in a lower water solubility (82.14 %) and COS of the HE-EWPs than for the UE-EWPs. The results of the DSC analysis demonstrated that the complete hydrolysis of the ovotransferrin endowed the HE-EWPs with a relatively high thermal stability. • Both heat and ultrasonication improved efficacy of enzymatic hydrolysis. • Preheating-enzymatic treatment induced a greater degree of structural alteration. • HE-EWP samples exhibited the faster water dispersibility. • UE-EWP samples had the highest final water solubility and coefficient of stability. • HE-EWP showed higher thermal stability due to complete hydrolysis of ovotransferrin.