Sedimentation of Casein Micelles During the Storage of Ultra-High Temperature Milk Products—a Calculation

¹ Agricultural Research Service, USDA, Department of Nutrition and Food Sciences, Utah State University, Logan 84322-8700

Calculations have been made tendency of casein micelles in stored milk to sediment under the force of gravity in the absence of stirring effects such as convection or mechanical agitation. The calculations show that even native micelles have a tendency to sediment during several months of storage and to produce a small layer of sedimented material; the effect of diffusion is insufficient to compensate for this sedimenting tendency. Sedimentation is especially pronounced in concentrated milks. The effect of even small increases in the molecular weight of the casein micelles is to increase the sedimentation rate significantly. Possible consequences of the formation of sediment in this way are discussed.

Key Words: ultra-high temperature • sedimentation • casein micelle • coagulation

Submitted on April 10, 1991
Accepted on August 27, 1991