Particle size determines foam stability of casein micelle dispersions

The role of interfacial properties and size of casein micelles aggregates on foam stability of casein micelle dispersions (CMDs) was examined. CMDs were prepared by redispersing casein micelles pellets obtained by ultracentrifugation. The size of colloidal particles could be controlled by differences in redispersing temperature. CMDs redispersed at 20 °C (CMD20 °C) and 4 °C (CMD4 °C) had average particle sizes of around 200 nm (micelles) and 500 nm (micelles and aggregates), respectively. At 3% total protein, the foam half-life, t½, of CMD4 °C was significantly higher than that of CMD20 °C and skim milk. No correlation between foam stability and surface rheological properties or protein composition could be observed. Foam stability was strongly related to the size of colloidal particles present in CMD. This was confirmed by the observation that the foam stability of CMD4 °C decreased to that of CMD20 °C when the aggregates were broken down by homogenisation.