Enhancement of emulsification properties by modulation of egg white protein fibril structure with different heating times

Abstract

Egg white protein (EWP) has poor emulsification ability due to the hydrophobic groups buried in the molecular structure. In contrast, the protein fibrils produced by acidic heat treatment are able to expose the hydrophobic groups and firmly adsorb to the surface of oil droplets. Therefore, the preparation of egg white protein fibrils (EWPF) can broaden the range of applications of EWP, such as low-fat emulsion-based foods. Since the heating time affects the growth condition of the fibrils and thereby the properties of their stabilized emulsions. The effect of treatment time on the structure properties and emulsification properties of EWP during fibrillation, also the effect of different environments on the stability of EWPF emulsion were investigated. The EWPF content increased with heating time. During the heating of EWP under acidic condition, proteins were hydrolyzed into peptides, subsequently peptides aggregated unidirectionally to form fibrils due to electrostatic repulsive forces at low pH. Compared with EWP, EWPF had larger particle size, higher ζ-potential, higher β-sheet content and greater surface hydrophobicity. In addition, the emulsifying activity and emulsification stability of the EWPF emulsion increased nearly two-fold compared with that of the EWP emulsion. Furthermore, it had smaller droplets, higher ζ-potential, and better thermal and ionic stability. This study could provide insights into the improvement of EWP emulsifying properties and fibril-modified EWP as stabilizing ingredients for emulsion-based foods. • EWP rich in acidic amino acids is an excellent material for fibrils preparation. • EWPF morphology gradually prolonged and aggregated with heating time. • The fine curled structure of EWPF can better encapsulate the oil droplets. • EWPF had the best emulsification properties when heated for 8 h. • Thermal stability and ionic stability of emulsion with EWPF were increased.