Methods used to separate the colloidal and soluble phases

1 Methods used to separate the colloidal and soluble phases 

Ultrafiltrates obtained using cellophane or polysulphone membranes at 20°C and a transmembrane pressure of c. 100 kPa are satisfactory, but the concentrations of citrate and calcium are slightly low due to sieving effects which are accentuated by high pressures. Dialysis of a small volume of water against at least 50 times its volume of milk (to which a little chloroform or azide has been added as preservative) at 20°C for 48 h is the most satisfactory separation procedure and agrees closely with results obtained 

The partition of salts between the soluble and colloidal phases is summarized in Table 5.5. In general, most or all of the sodium, potassium, chloride and citrate, one-third of the calcium and two-thirds of the magnesium and about 40% of the inorganic phosphate are in the soluble phase. 

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