Effect of adding a third polysaccharide on the adsorption of protein microgels at the interface of polysaccharide-based water in water emulsions

Abstract

HypothesisWater-in-water (W/W) emulsions are formed by mixing aqueous solutions of incompatible polymers and can in some cases be stabilized by addition of particles. The adsorption of particles at the interface of W/W emulsions is dictated by the interfacial tension between the two aqueous phases and between the particles and each phase. It should therefore be possible to induce and fine-tune adsorption by adding small amounts of a third polysaccharide that is compatible with one or both phases. ExperimentsW/W emulsions were formed by mixing aqueous solutions of pullulan (PUL), amylopectin (AMP), and protein microgels (MG). The microstructure and positioning of the MG were monitored using confocal laser scanning microscopy. The effect of adding small amounts of other types of polysaccharides on the adsorption of the MG at the interface and their partitioning between the phases was studied. FindingsThe addition of all polysaccharides led to a progressive shift of the MG from the PUL phase to the AMP phase and to adsorption of the MG at the interface when the partition was not extreme. The partition could be fine-tuned to be equal, in which case particles adsorbed at the interface even very close to the binodal. The findings were confirmed for another type of emulsion and particle.