Casein micelles surface potential

Surface (zeta) potential. It is not possible to measure the zeta potential of casein micelles at the assay temperature but measurements on heated micelles after cooling suggest no change in zeta potential, which is rather surprising since many of the changes discussed above would be expected to reduce surface charge. 

Since the micelles are closely packed, intermicellar collisions are frequent however, the micelles do not normally remain together after collisions. The micelles are stabilized by two principal factors (1) a surface (zeta) potential of c. —20 mV at pH 6.7, which, alone, is probably too small for colloidal stability, and (2) steric stabilization due to the protruding K-casein hairs. 

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