Composition of Ultrafiltrates from Milk Heated at 80 to 230° F. in Relation to Heat Stability

Summary Analyses of ultrafiltrates collected from milk at temperatures up to 230° F. indicated that temperature changes affect the inorganic composition of milk much more drastically than has previously been demonstrated from the analyses of cooled milks. At 200° F., the amount of calcium passing into the ultrafiltrate was approximately 50%, and the phosphate about 82%, of that found at 80° F. On the other hand, the hydrogen ion concentration of ultrafiltrate collected at 200° F. was at least double that of ultrafiltrate Collected at 80° F. Similar tests made with solutions of calcium and phosphate indicated that these changes in the inorganic composition of milk can be explained entirely on the basis of changing solubility and composition of the insoluble calcium phosphate salts. No change in the dissociation of calcium citrate with temperature could be detected. No correlation was observed between the changes induced by heat and the heat stability of various samples of milk