132 CONCENTRATED MILK 



by being completely submerged, or in circular vats equipped 

 with a vertically suspended coil. The vertical coil vat has the 

 further advantage in that it eliminates from the milk, all bear- 

 ings and glands and it expells, rather than incorporates air, 

 from the condensed milk. 



When cooled the condensed milk is ready for the market. 

 If held in the factory, it should be placed in a cold room or should 

 be otherwise protected against temperatures sufficiently high to 

 cause it to sour. When kept at 40 F. or below the danger from 

 souring is largely eliminated. If transported long distances during 

 warm weather, it should be shipped in refrigerator cars. 



CHAPTER XIII. 

 CONCENTRATED MILK 



Definition. Concentrated milk is cow's milk, either whole 

 milk, or partly or wholly skimmed milk, condensed at the ratio 

 of three to four parts of fresh milk to one part of concentrated 

 milk. It is not condensed in vacuo, but in open vats by passing 

 currents of hot air through the milk. It is sold largely in pint 

 and quart bottles for direct consumption. It is not sterile and 

 therefore keeps for a limited time only. Its keeping quality is 

 similar to that of a high grade of properly pasteurized milk. The 

 process by which the concentrated milk is manufactured is 

 known as the "Campbell Process." This process was invented 

 by J. H. Campbell of New York City, in 1900 and patented in 

 1901. 



Apparatus Needed. The principal parts are : the evap- 

 orating vat with hot water jacket and coils, and air blast registers 

 or nozzles near the bottom of the vat ; an air blower which 

 fxirnishes the air blast; an air heater through which the air 

 blast passes and from which the heated air is conducted into the 

 milk; a water pump circulating hot water through the jacket and 

 coils ; an auxiliary evaporating tank for completing the evapora- 

 tion ; and a spray pump which throws the spray of milk drawn 

 from the bottom of the main evaporating vat into the auxiliary 

 tank and for transferring the partly condensed milk from tank 1 

 to tank 2. 



Operation of Campbell Process. The milk is heated to about 

 100 degrees F. and allowed to flow into evaporating tank 1 



