For the concentrate from the unheated milk, increasing the pH
of the milk increased the consistency coefficients of the milk
concentrate (Fig. 4A). This is also consistent with previous studies
on the apparent viscosity of milk concentrates and has been
attributed to an increase in the casein micelle voluminosity
(Snoeren et al., 1984a; van Hooydonk et al., 1986). However, unlike
changing the temperature, increasing the pH reduced the flow
behaviour index (Fig. 4C) indicating an increased shear thinning
behaviour. The reduction in flow behaviour index may indicate a
“loosening” of the micelle structure, allowing the micelle to be
compressed under high shear. This compression of the micelles
would reduce the viscosity of the system at high shear and account
for the observed shear thinning behaviour of the samples at high
pH.
For