INFLUENCE OF EGG YOLK LIPOPROTEINS ON THE RHEOLOGY AND STABILITY OF O/W EMULSIONS AND MAYONNAISE 1. VISCOELASTICITY OF GROUNDNUT OIL‐IN‐WATER EMULSIONS AND MAYONNAISE

Abstract

Viscoelastic properties of groundnut oil‐in‐water emulsions stabilized by egg yolk and of mayonnaise have been deduced from their creep compliance‐time response to a constant low shear stress. The viscoelastic parameter values, emulsion stability and initial mean drop size were influenced by pH and NaCl, due to disruption of the egg yolk components. When carboxymethylcellulose was incorporated in the continuous phase of the O/W emulsions an egg yolk‐carboxymethylcellulose complex was formed and this affected the rheological properties of the emulsions and also their stability. Mayonnaises exhibited more pronounced viscoelasticity and greater stability than the O/W emulsions. At elevated temperature the micelles adsorbed around oil drops degrade. Their lipoprotein structure unfolds so that more segments on adjacent drops are then available for interlinking and network formation.