The influence of calcium ions, ionic strength and pH of the integrity
of the calcium caseinate particulate structure under pressure treatmen
t of up to 300 MPa has been investigated. The colloidal integrity of t
he calcium caseinate aggregates is disrupted through pressure treatmen
t. The changes in turbidity as a result of pressure treatment are depe
ndent on the applied pressure and the concentration of calcium in the
system, and less dependent on the duration of pressure treatment, espe
cially at low calcium concentrations. The disruptive effect of high hy
drostatic pressure appears to be a consequence of shifts in the equili
brium between colloidal and soluble calcium as increasing concentratio
ns of calcium in the soluble phase reduced the tendency of the aggrega
ted system to be disrupted through the application of pressure. The ef
fects are specific to calcium and not a consequence of changes to the
ionic strength of the system. Increasing the ionic strength by using s
odium instead of calcium showed an adverse effect on the turbidity rea
dings, indicating that a calcium-depleted system is more prone to pres
sure-induced structure disruption. A reduction of pH resulted in an in
creased stability of the colloidal system to pressure-induced changes,
particularly at higher calcium concentrations.