Viscosity and Non-Newtonian Behaviour of Concentrated Milk and Cream

The effect of the composition of milk solutions on their viscosities over the temperature range of 20–60°C was investigated using previously reported data and new experimental data. Low-fat milk of known composition was concentrated to obtain samples with 9 to 50% total solids content and the viscosity was measured. At concentrations up to 20% total solids, the liquid was Newtonian, but above 30% concentration skim milk concentrates exhibited pseudoplastic (shear thinning) behaviour, which is consistent with previous studies. The previous and new data were analysed to determine the fit to a recently proposed equation. The contributions of lactose, fat, casein, and whey protein were determined so that the viscosity of a liquid dairy product could be calculated from its composition over the entire experimental range.