Changes Related to Casein Precipitation in Frozen Concentrated Milk

Abstract

During storage of frozen concentrated skhnmilk, lactose crystallization preceded protein precipitation. Cellulose acetate and free-boundaxy electrophoresis indicated that the precipitated protein was identical to normal casein. Casein precipitation was accompanied by losses of soluble calcium, phosphate, and citrate, but there was no change in the sodium or potassium content of centrifuged reconstituted milk. Precipitation occurred through interaction of the casein with colloidal tricalcium phosphate in the unfrozen portion.