Flow properties of freeze-concentrated skim milk

The flow properties of freeze-concentrated skim milk, determined with a concentric cylinder viscometer; were well described by the simple power-law rheological model over the temperature range from -3.4 to +20 degrees C. High-total-solids freeze-concentrated skim milk (35-40% total solids) exhibited non-Newtonian behaviour while lower concentrations gave Newtonian flow properties. The magnitude of the flow behaviour inner was between 0.8 and 1.0. The Arrhenius model described well the effect of temperature on apparent viscosity in this temperature range. Statistical analysis showed that there was no difference in viscosity between condensed thermally evaporated skim milk and freeze-concentrated skim milk. However the viscosities of reconstituted skim milks were different: the reconstituted product made from evaporated milk had a slightly higher viscosity than that of freeze-concentrated milk. (C) 1997 Elsevier Science Limited.