258 UNSWEETENED CoNpENSED MiLx DeFEctTs 
exposure of the milk to the process. It consists largely of the 
mineral matter of milk, rendered insoluble and precipitated by 
heat. The use of lower sterilizing temperatures or the shorten- 
ing of the period of sterilization will help to avoid this defect. 
Evaporated milk in the condensation of which the “Continu- 
ous Concentrator” was used, has a tendency to show slight grainy 
condition, though this is barely perceptible. 
Separated and Churned Evaporated Milk. 
General Description.—This is a very common defect. <A 
portion of the butter fat of the contents of the hermetically 
sealed cans, has separated and appears in the form of lumps of 
cream or of churned butter, on top of the evaporated milk. While 
this separated evaporated milk is normal in quality and whole- 
someness, its appearance condemns it. 
Causes and Prevention.—As explained in Chapter IX on 
“Homogenizing,” the fundamental cause of separated and 
churned evaporated milk lies in the difference of the specific 
gravity between the butter fat and the rest of the milk constitu- 
ents. The fat globules, being lighter than the serum, tend to 
rise to the surface, forming a layer of thick cream. When this 
separated evaporated milk is subjected to agitation, as is the 
case in transportation, this cream churns into lumps of butter. 
This tendency of the fat to separate in storage and churn in 
transportation, increases with the increase of the size of the fat 
globules, because the larger the globules, the larger is their cubic 
content in proportion to their surface. This fact is based on the 
well known physical law, that the surfaces of two spheres are 
to each other as the squares of their diameters, and the cubic 
contents of two spheres are to each other as the cubes of their 
diameters. The cubic contents determine the gravity force, or 
buoyancy, while the surfaces control the resistance force. There- 
fore, the larger the fat globules the greater is their buoyancy 
and the weaker 1s the relative resistance which they must over- 
come in their upward passage. 
Effect of Locality and Season.—Since the predominating 
size of fat globules in milk, varies with breed and period of 
lactation of the cows, the ease with which evaporated milk 
