Concentrates from skim milk heated at pH 6.5 to 7.1 had viscosities that followed power law behaviour
and could be described by consistency coefficients (K) and flow behaviour indices (n). On evaporation to
40% total solids, milk heated at pH 6.5 produced concentrates with higher K than those from unheated
milk. Milk samples heated at pH 7.1 produced concentrates with lower K than those from unheated milk.
Above 40% totals solids, the K values of concentrates from heated milk were similar regardless of the pH
at heating, and were higher than those from unheated milk. It is proposed that denatured whey proteins
associated with the casein micelles increase the voluminosity of the micelles leading to an increased
viscosity and K at all milk concentrations. In contrast, denatured whey proteins and k-casein in the serum
only make a small contribution to the viscosity and K until the milk is at high concentrations.