The voluminosity of casein micelles was studied by means of static rheometry. In concentrated casein micelle suspensions with fluid-like flow properties to random-close packing, the reduced viscosity was obtained and linked via the Krieger-Dougherty model of volume fraction effect. The temperature dependency of hydration was fitted in a wide temperature (5 degrees C <= theta <= 35 degrees C) and mass fraction range (0.01 <= w <= 0.16). The results of our study suggested that the voluminosity of casein micelles decreased with increasing temperature and asymptotically reached a plateau (theta > 30 degrees C) as a consequence of the protein swelling and decreasing water immobilization. The obtained apparent voluminosity of native casein micelles dispersed in UF permeate was 5.0 ml g(-1) at 5 degrees C, 4.1 ml g(-1) at 20 degrees C, and 3.7 ml g(-1) at 35 degrees C. (c) 2012 Elsevier Inc. All rights reserved.