53. Factors Affecting the Solubility of Milk Powders: I. The Effect of Heat on the Solubility of Milk Proteins

Abstract

No reliable information is at present available with regard to the effect of process of manufacture on the solubility of the protein of milk powders. Hunziker(1), it is true, gives a very well-balanced discussion of the subject, but it is apparent from his summary of the views of other workers that these are seldom based on adequate experimental evidence. In fact the only points on which there is general agreement among workers in this field are that the proteins of spray-dried powders are, on the whole, extremely soluble, while those of roller-dried powders are relatively insoluble. Moreover, even where experimental data are available, there remain many unexplained points. For example, Hunziker shows that the solubility of the proteins of a milk powder may vary according to the temperature at which the powder is reconstituted—a higher temperature giving a greater solubility. Such an observation cannot at present be brought into line with current theories regarding the properties of denatured proteins.