Rôle of Viscosity in Milk Modification.

Abstract

A few years ago Brennemann 1 reported a notable study concerning the coagulation of cows milk in the stomach, in the course of which he had occasion to study the influence on curd formation of a number of different types of milk modifications. He states “that nearly all of the numerous devices that are used in infant feeding in adapting cow's milk to the infant are directed, consciously or unconsciously to modifying this curd so that it will be fine, soft, and flocculent as is that of breast milk.” Brennemann 1 found “that starch concoctions very radically influence the coagulation of milk in the stomach, and that the soluble carbohydrates, dextrins, milk sugar, cane sugar, and maltose have no appreciable influence.” Colloid enthusiasts are prone to explain the clotting of milk and the influence of different milk modifiers in inappropriate colloid terms. Alexander 2 first used colloid terminology in explaining milk clotting and since then many writers have ascribed to “colloidal protection” the influence of such modifiers as gelatin, tapioca, starch, barley gruel, gum arabic, etc. Palmer and Richardson 3 have indicated certain fallacies in Alexander's original claims, but do not offer any alternative theory to account for the commonly observed influence of such milk modifiers.

In a series of experiments, including both in vitro and in vivo observations, we have found no relation whatever between protective colloid value, as measured by gold number, and influence upon the nature of the milk curd. We have, however, found a direct correlation between the viscosity of the modified milk and the fineness of curd produced, and feel warranted in concluding that the term “protective colloid” is not strictly applicable in this connection. The important property, which is involved in producing fine, soft, flocculent curds, appears to be viscosity rather than protective colloid value.