124 EvaroraAtiép Mu,K—HoMmocENIZING 
tailed directions on calculations of concentration and on exact 
method for standardizing, the reader is referred to. Chapter 
XXIX on “Standardization.” 
CHAPTER IX. 
HOMOGENIZING. 
Purpose.—The object of homogenizing is to avoid the separa- 
tion of the butterfat in the evaporated milk after manufacture. 
The butter fat is present in milk in the form: of minute 
globules. These fat globules are lighter than the rest of the 
ingredients of the milk. They, therefore, show a strong ten- 
dency to rise to the surface and to form a layer of thick cream 
in the cans. When these cans are subsequently subjected to 
agitation, as is the case in transportation, this cream churns, 
forming lumps of butter. ‘his tendency of evaporated milk to 
separate in storage and churn in transportation is especially 
noticeable with milk rich in fat and in which the large fat glob- 
ules predominate. In Jersey and Guernsey localities, it is more 
difficult, therefore, to manufacture evaporated milk that does not 
separate, than in Holstein and Ayrshire localities. While sepa- 
rated and churned evaporated milk is perfectly sound and in 
every way as valuable as a food, as it would be without this 
separation, it does not sell in this condition. It is rejected on 
the market. 
This tendency toward fat separation can be minimized and 
frequently entirely prevented by increasing the viscosity of the 
evaporated milk. This can be accomplished by superheating the 
milk in the pan or after it leaves the pan, and by prolonging 
the sterilizing process, raising the heat very slowly or stopping 
the reel of the sterilizer at certain stages of the process. How- 
ever, there are conditions when even these precautions do not 
permanently avoid separation of the fat. In such cases, the 
proper use of the homogenizer furnishes a reliable means to 
guard against this difficulty. 
Principle of the Homogenizer.—The principle of the homo- 
genizer is to force the milk under high pressure through exceed- 
ingly small, microscopic openings. By so doing the fat globules 
are broken up so finely that they fail to respond to the gravity 
