Aggregation kinetics of heated whey protein-stabilized emulsions

Changes in the particle size of heated whey protein stabilized emulsions were followed using laser light scattering. Aggregation of the emulsions was more extensive, and proceeded more rapidly as the concentration of whey protein in the emulsions increased. Removal of non-adsorbed protein from the emulsion decreased the rate of the aggregation reaction by several times. A hypothesis is put forward that the aggregation mechanism involves interaction of adsorbed protein at the emulsion droplet surface with non-adsorbed heat denatured protein in the continuous phase. The non-adsorbed protein would act as a 'glue' holding the aggregated emulsion droplets together. The aggregation mechanism was found to best fit a reaction of order 1.5. This is also consistent with an aggregation mechanism where denaturation and aggregation of non-adsorbed protein is the major step.