HOMOGENIZED MILK 397 



The production of certified milk involves identically the same 

 factors as mentioned in the production of clean milk, with the 

 exception that each point is carried to a greater degree ; thus the 

 cows must be a little cleaner, the stable atmosphere a little freer 

 of dust, the milkers' hands cleansed before the milking of each 

 cow, all pails and cans thoroughly sterilized and the milk cooled 

 at once to 50 degrees or below. 



In the past an immense amount of unnecessary expense has 

 been incurred in the production of certified milk. Millionaires 

 of good intentions have lavished their wealth upon cow stables 

 and bottling outfits with the result that there was no profit in 

 the industry when the interest on the money invested was 

 taken into account. Often, too, the cooling and bottling ma- 

 chines were so elaborate as to be difficult of cleaning. This 

 naturally resulted in the production of an article considerably 

 inferior to that which could be produced by means of a simple 

 and less expensive outfit. It is gratifying to note that there 

 is now a tendency away from the unnecessary dairy refinements 

 with a more tenacious clinging to the points essential in clean 

 milk production. In Chapter XXVI are given the chief rules 

 and regulations laid down for the production of certified milk. 



Homogenized milk is milk rendered homogeneous, or uni- 

 form, throughout. Homogenization of milk involves not only 

 the pulverization of the fat globules, as originally thought, but 

 also the breaking up of the casein shreds as well. The process 

 may, and usually does, also involve pasteurization, since milk 

 may be more readily and rapidly homogenized at a compara- 

 tively high temperature. The homogenizer is a machine con- 

 sisting essentially of three or more pumps which force the milk 

 through a small aperture against a hard surface under a pressure 

 of from two to five thousand pounds per square inch. In prac- 

 tice homogenization is now employed most largely by ice cream 

 manufacturers and the pressure and temperature employed vary 

 with the use to which the cream or milk is to be put. Unsalted 

 butter and skim milk may easily, by the aid of this machine, be 

 emulsified into a milk or cream of any desired fat percentage. 

 Thus it may be employed in cream and ice cream making in the 

 winter season when fresh cream is scarce and high priced. 



