Apparent ζ-potential as a tool to assess mechanical damages to the milk fat globule membrane

The apparent ζ-potential (ζap) of raw milk fat globules, either natural or mechanically damaged by homogenization or shear, was measured by laser Doppler electrophoresis. Upon homogenization, ζap increased in a non-linear way as a function of the surface coverage of the milk fat globule membrane (MFGM) with casein micelles and whey proteins (from −13.5±0.9 mV for natural globules to −20±1 mV for strongly homogenized ones). A model was calculated to estimate the MFGM deteriorations after mechanical stress, using ζap measurements. This new method to assess technological damages to raw milk fat globules can be considered as simple when comparing particle size distributions is not possible.