Deposit layers arising during milk microfiltration have not yet been well described with regard to their structural build-up. Besides casein micelles forming the bulk of the deposit, whey proteins are integrated into the milk protein deposit. Both the deposited protein layer and the membrane are involved in the retention of both protein fractions. Therefore, this study focusses on the impact of whey proteins on casein micelle deposit compressibility and reversibility. Compressibility and specific fouling resistance of casein micelle deposits were reduced in the presence of whey proteins. In other words, the deposit layer becomes more open or more porous due to whey protein attachment to the casein micelle surface. Furthermore, diffusive removability of the deposit layers was affected by pH and whether or not whey proteins were present. Convective removal by fluid forces was found to be almost entirely independent of pH or the presence of whey proteins. This shows that deposit layers arising during milk microfiltration consist of three phases, a diffusively removable micro-porous deposit, a gel-like convectively removable layer and internal membrane fouling. (C) 2015 Elsevier B.V. All rights reserved.