Milk is an oil-in-water emulsion with the globules in a continuous skim milk phase however , if raw milk were left to stand the fat would rise and from
A cream layer . homogenization is a mechanical treatment of the fat globule in milk while hot , which is brought about by passing milk under high pressure through a tiny orifice , which results in a decrease in the average diameter and an increase in number and surface area of the fat globules. The net result , from a practical view , is a greatly reduced tendency for creaming of fat globules. Three factors contribute to this enhanced stability of homogenized milk : a decrease in the mean diameter of the fat globules ( a factor in stokes’ law ,see also under separation above) a decrease in the size distribution of the fat globules (causing the speed of rise to be similar for the majority of globules such that they do not tend to cluster during creaming) and an increase in density of the globules (bringing them closer to the density of the continuous phase) due to the adsorption of a protein membrane. In addition, heat pasteurization breaks down the cryo-globulin complex , which tends to cluster fat globule causing them to rise