OBSERVATIONS ON THE SEASONAL-VARIATIONS IN THE SALT BALANCE OF CONCENTRATED MILK

Seasonal variations in the salt balance of raw bulk milk and its 3:1 c oncentrate were studied ovo a one-year period. A marked increase in th e level of colloidal calcium was found between December and February i n raw milk, whereas the other components remained unchanged. Evaporati ve concentration shifted the soluble-colloidal equilibrium towards the colloidal phase as the Ca, PO4, Mg ald citrate content increased. The rmal stabilization of the concentrates by pH adjustment or Na2HPO4 add ition had little effect on salt balance at any time of the year. The c olloidal Ca/PO4 ratio was the only compositional parameter that could be correlated to the heat stability of concentrated milk.