Effect of Temperatures Higher than 100°C on the Rheological Properties of Spray-Dried Egg White

Abstract

Spray-dried egg white (EW) suspensions of 10, 20, 30 and 40 weight% were heated for 5 min at 100, 120, 140 and 160°C. The rheological properties of the heat-induced EW gels were investigated by stress-relaxation testing. The obtained stress-relaxation spectra were analyzed with four-elements of the double Maxwell model in parallel. The four elements and two relaxation times, E₁, E₂, η₁, η₂, τ₁, and τ₂ (τ₁>τ₂) were each determined, where E1 reflects the dynamic properties of the three-dimensional network structure of a gel. The value of E₁ increased logarithmically with increasing EW concentration, but was not affected by the temperature. The τ₁ rapidly increased from 140°C to 160°C, while τ₂ decreased with decreasing EW concentration. The changes in the rheological properties at high temperature strongly depended on the EW concentration.