Effect of High-Intensity Ultrasound and Dielectric Barrier Discharge Plasma on Physicochemical Properties of Egg White Protein and Its Binary Hydrogels with Xanthan Gum

Egg white powder (EWP) is widely used as a food ingredient due to its functionalities, such as foaming, emulsification, and gelation capacities. However, its low solubility and poor rheological properties have limited its application. This study aims to modify the properties of EWP for the development of binary hydrogels with xanthan gum (XG). The modification is achieved using a high-intensity ultrasound (HIUS) at powers of 100, 200, and 300 W and dielectric barrier discharge (DBD) plasma at intensities of 16, 18, and 20 kV. The effects of HIUS and DBD plasma treatments on the structural, physicochemical, and functional properties of EWP were analyzed. The results indicated that the treatments increased surface hydrophobicity and zeta potential, while reducing particle size and surface tension of EWP. These structural modifications improved the samples' foaming and emulsifying properties. The samples treated with HIUS at a power of 300 W and DBD plasma at an intensity of 20 kV were selected as the best candidates for developing binary hydrogels in different EWP to XG ratios (5:0, 4:1, 3:2, 2:3, 1:4, and 0:5). Analysis of the hydrogels' rheological properties showed that HIUS and DBD plasma treatments decreased the apparent viscosity and increased the elasticity. Further analysis of structural properties of the EWP confirmed the alteration of the protein's secondary and ternary structures toward an increase in beta-sheet and random coil and raising of disulfide bonds and hydrophobic interactions that ultimately led to increase of water holding capacity and firmness of the binary hydrogels. The study's results demonstrate that HIUS with the power of 300 W and DBD plasma with the intensity of 20 kV, along with different ratios of XG in binary hydrogels can provide diverse properties suited for specific applications.