In milk, casein occurs as colloidal particles with an average size of about 100 nm. These are stabilized against flocculation by an outer layer of several thousands of κ-casein molecules. Stability of micelles is characterized by the magnitude of the Smoluchowskian flocculation rate constant, which during the renneting of milk nearly approaches the diffusion-controlled limit. The processes of the clotting of milk by rennet and the phenomena of age-thinning and age-thickening of ultra-high temperature-sterilized, concentrated milks bear interesting kinetic resemblances. Both processes are characterized by a lag phase during which viscosity decreases, followed by an explosive increase in viscosity. In the milk-clotting process, the decrease can be explained by the proteolytic action of the renneting enzyme. This strongly suggests that age-thinning and age-thickening are also caused by the action of a protease that survived the sterilization process. A quantitative check of this theory is difficult because of the apparently small amount of enzyme. © 1982, American Dairy Science Association. All rights reserved.
CITATION STYLE
Payens, T. A. J. (1982). Stable and Unstable Casein Micelles. Journal of Dairy Science, 65(10), 1863–1873. https://doi.org/10.3168/jds.S0022-0302(82)82431-4
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