Effect of pre- and post-heat treatments on the physicochemical, microstructural and rheological properties of milk protein concentrate-stabilised oil-in-water emulsions

The effect of heat treatment on the physical stability of milk protein concentrate (MPC) stabilised emulsions was investigated; 3% (w/w) MPC dispersions were preheated at 90 °C for 5 min at neutral pH prior to emulsification. Heat-treated (120 °C, 10 min) emulsions stabilised by preheated MPC had slightly fewer droplet–droplet interactions than that stabilised by unheated MPC because the whey proteins were pre-denatured (∼90% denaturation of the total whey proteins), which led to a reduction in subsequent heat-induced droplet–droplet and droplet–protein interactions. Emulsions stabilised by calcium-depleted MPC were also investigated. The presence of some non-micellar casein fractions gave better emulsification and may have conferred a protective stabilising effect on whey protein aggregation, in both the dispersed phase and the continuous phase during the secondary heat treatment. It was concluded that calcium manipulation and thermal modification of MPC can be utilised to control the functionality in oil-in-water emulsions.