Influence of treatment-induced modification of egg white proteins on foaming properties

Abstract

Different treatment methods induce modification of egg white proteins (EWPs) in different ways, which can affect foaming properties. Recent findings on the effects of various treatments (heating, high hydrostatic pressure, high-pressure micro fluidization, ultraviolet irradiation, high intensity ultrasound, Maillard glycation, and enzymatic hydrolysis) on foaming properties of EWPs are reviewed. The review discusses how the treatment-induced modification of EWPs can alter foaming properties. Dry heating induces the partial hydrolysis of EWPs, allowing faster adsorption at the interface. In high hydrostatic pressure (HP) and high intensity ultrasound (HIU) treatments, foaming properties depend on ovomucin network degradation, protein unfolding, and aggregation. Under HP and HIU treatments, ovomucin degradation produces small particles with higher solubility and flexibility. These particles can quickly diffuse and adsorb at the interface. The mechanism by which ultraviolet (UV) treatment affects foaming properties can relate to fragmentation and aggregation levels. At lower UV dose, the adsorption of aggregates and fragments can increase viscoelasticity of the interface. UV treatment at higher dose improves foam stability by jamming of larger aggregates (non-adsorbed) in Plateau borders. Maillard glycation with polysaccharides can improve foaming properties because of partial protein unfolding and high solubility; however, the excessive attachment of polysaccharides can increase steric hindrance among the molecular chains of conjugates, resulting in lower foamability. Limited enzymatic hydrolysis can improve foaming properties; nevertheless, extensive hydrolysis may damage foaming properties because of the reduction of surface hydrophobicity. Moreover, the extensive hydrolysis increases peptide net charge, which can reduce adsorption and intermolecular attraction at the interface.