Influence of pH and ionic strength on the thermalinduced transitions of egg yolk dispersions

Abstract

Thermal-induced transitions of egg yolk were studied by using Differential Scanning Calorimetry (DSC) and temperature controlled Small Amplitude Oscillatory Shear (SAOS). The influence of composition (pH and electrolyte concentration and type) was analyzed. The results obtained under DSC measurements suggest a continuous evolution in protein denaturation which depends on pH and salt content. Slope temperature measured by SAOS allowed the analysis of the evolution of the viscoelasticity functions during the gelification process. Viscoelasticity functions showed a dramatic increase and were affected by the pH, ionic strength and salt type. SAOS was also used to obtain the mechanical spectra of egg yolk dispersions and gels as a function of composition. The influence of pH and ionic strength on line ar viscoelastic properties and microstructure may be explained in terms of the model for the formation of gel networks of globular proteins

Keywords

• differential scanning calorimetry
• egg yolk
• gelation
• linear viscoelasticity
• ph