Substances Adsorbed on the Fat Globules in Cream and their Relation to Churning. III. Analysis of the Adsorbed Protein

Protein constitutes the major part of the material adsorbed on the surface of the fat globules in cow's milk (1). The protein has'been identified by various workers as a glycoprotein (2), casein (3), albumin (4), a globulin-like protein (5), and a new milk protein (6). Some of the observed difference in composition may have resulted from the method used in the isolation of the material. A method whereby the stabilized fat globules in milk are freed from milk plasma by allowing the globules to rise through a single comparatively short column of water does not prevent the occlusion of plasma protein by the clusters of fat. A much more drastic procedure was used in the preparation of the material analyzed in the present study. The detailed method has been described in two preceding papers (1, 7). The general procedure was as follows.