Rheology of spray‐dried egg yolk‐stabilized emulsions

Abstract

This paper deals with the influences that concentrations of oil fraction (65–77.5% w/w) and egg yolk (1–5% w/w), as well as temperature (5–35 °C), exerted on the droplet size distribution and rheological functions of concentrated oil‐in‐water food emulsions that were stabilized by a spray‐dried egg yolk product. This work must be considered as a preliminary study concerning the use of low‐in‐cholesterol egg yolk as emulsifier. In order to achieve this aim, steady‐state flow and dynamic viscoelasticity tests were done with emulsions processed with a rotor‐stator turbine. The same processing conditions were always maintained. All of the emulsions prepared showed a high stability. An increase in oil fraction yielded higher values for the rheological functions, and larger droplet diameters. The influence of processed egg yolk concentration was more complex. Thus, an increase in egg yolk content yielded lower values for the rheological functions, but, after a particular concentration, a further increase in emulsifier content yielded higher values for the rheological functions. The experimental results have been discussed taking into account the close relationship between rheology and emulsion structural parameters.