PLAIN CONDKNSED BULK MILK 165 



li.shed density, usually condense the milk to a point slightly 

 beyond that desired. Then, after superheating, they determine 

 the amount of water required to reduce the finished product, and 

 then add the required amount of water before the condensed milk 

 is cooled. It is advisable to use destilled water for this purpose. 

 Ratio of Concentration. The ratio of concentration varies 

 largely with the fat content of the milk, although the locality 

 and season of year are also influencing factors. Whole milk is 

 condensed at the ratio of about three parts of milk to one part 

 of condensed milk, while the ratio of concentration for skim 

 milk is about 4 to 1. The proper density varies somewhat with 

 locality and season of year. Roughly speaking, whole milk has 

 reached the proper density when the Beaume reading at 120 de- 

 crees F. is about 10 decrees P>. and skim milk has reached about 



o o 



the proper density when the Beaume reading at 120 degrees F. 

 is about 14 degrees 15. When the ratio of concentration exceeds 

 4 to 1, there is danger of gritty condensed milk due to the pre- 

 cipitation, in this concentrated product, of crystals of milk sugar 



Cooling. The plain condensed bulk milk is- usually drawn 

 into 40 quart milk cans, placed in cooling tanks containing re- 

 volving cogwheels, as described in Chapter VI, under ''Cooling 

 Sweetened Condensed Milk." and is cooled to as near the freez- 

 ing point as facilities permit. 



Recently this crude and laborious method of cooling has 

 been superseded in many of the larger condenseries by more 

 modern ways. While the plain condensed bulk milk becomes 

 too thick and sluggish during the process of cooling to make 

 possible the use of surface coolers, and internal-tube coolers, it 

 can be readily cooled in vats equipped with revolving discs, or 

 in horizontal coil vats especially constructed for this purpose 

 and in which the lower part of the vat is constricted and the coil 

 sets very low in this constricted part, so as to agitate the milk 

 vigorously and at the same time prevent the incorporation of air, 

 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 expels, rather than incorporates, air. 

 from the condensed milk. 



When cooled the condensed milk is rcadv for the market. 



