The total casein fraction is precipitated by lowering the
pH of the milk to about 4.7. It includes several types of
molecules (50% . αs -casein, β - 15% casein, and γ - 03%
casein). These compounds, PM 25, 000 closes, in the
monomer state, can be separated by electrophoresis and
ultracentrifugation. At pH 7 and 37°C, alpha and β caseins
are precipitated in the presence of Ca2+ ion during
coagulation. Other proteins remain in solution along with
the lactose and salts, forming the whey, caseins combine to
form micelles. When curdling milk (action of lactic acid
bacteria) there is a decrease in casein К with the formation
of the para-casein.