In a study, performed by scientists of NIZO, Sorbonne Universités Paris, Stony Brook University New York and Utrecht University, an initial step was taken towards understanding the complex dynamics of stabilizing emulsions with, for example, plant proteins, which do not dissolve in water.

Understanding the process

In this study, the process of adsorption of an individual micro particle at a liquid-liquid interface was followed in real time. Liquid-liquid interfaces are found in food emulsions, between oil droplets and the water phase. Examples are mayonnaise and dressings. Traditionally, these emulsions are stabilized by using whey or egg protein, or label-unfriendly surfactants. However, the recent interest in the use of plant proteins has focused attention on another way of stabilizing food emulsions: by micro particles made from aggregated plant protein.

Emulsions are made by homogenization of a mixture of oil and water. The events on a microscopic scale during homogenization are determined by the shear rate imposed on the oil droplets and adsorbing particles. In order to optimize the process of homogenization, it is necessary to know how fast particles adsorb at the oil-water interface. This work was carried out to investigate this.

For technical reasons, the measurements were actually carried out not with oil-water interfaces, but water-water interfaces, because the adsorption at water-water interfaces (between a protein and a polysaccharide solution) is much easier to study. Understanding this complex process is crucial for making stable emulsions in the food and health industry.