Increasing the heat stability of whey protein-rich emulsions by combining the functional role of WPM and caseins
Résumé
The heat stability of whey protein emulsions remains a real challenge due to the rapid denaturation/
aggregation of native whey proteins on heating. The use of heat-stable Pickering-like whey protein
microgels (WPM) makes it possible to develop heat-stable emulsions in a large range of whey protein
concentrations. In this study, emulsion heat stability was evaluated with a special focus on the contribution
of WPM adsorbed at the fat droplet surface and in the continuous phase of the emulsion. Dairy
emulsions were prepared with 30% milk fat and 70% suspension of WPM in the dispersed phase of milk.
The protein interfacial load and the composition of the fat droplet surface were determined immediately
after emulsion formation, and the heat stability of the emulsions at 120 C was assessed visually and at
microscopic scale. WPM are heat stable in the continuous phase of the emulsion, but the presence of
WPM at the surface of the fat droplets is responsible for a rapid gelation of the emulsions. In the heated
emulsions, the fat droplets seemed to be crosslinked by WPM. The presence of caseins instead of WPM at
the fat droplet surface allowed the heat stability of the emulsion to recover at low and high whey protein
concentrations. This study shows that it is possible to prepare heat-stable whey proteinerich emulsions
by using whey proteins previously aggregated as heat-stable WPM and a sufficient amount of caseins in
order to fully cover the fat droplet surface. These results will contribute to the development of heatstable
whey proteinerich emulsions.