Impact of heat treatment, casein/whey protein ratio and protein concentration on rheological properties of milk protein concentrates used for cheese production

In fresh/hard cheese manufacture, a high casein concentration is desired, whereas, for quark production, a high total protein concentration and a high degree of whey protein denaturation is needed. However, concentration impacts inevitably the concentrate's viscosity-particularly after heat treatment. Our research question was therefore, which mechanisms are responsible for changes in viscosity upon increasing the total protein concentration, varying the casein/whey protein ratio, and heating. In order to answer this question, we investigated the viscosity of unheated and heated milk protein concentrates (3-14% total protein) and three casein/whey protein ratios (85:15, 92:8, 98:2). It turned out that a 37% whey protein depletion was sufficient to 1) inhibit the impact of the casein micelles' repulsive forces on the viscosity; 2) achieve the highest polydispersity and, therefore, particle packing density of all concentrates; and 3) allow up to 95% whey protein denaturation without changing the viscosity of the concentrates after heating.