202 CHEMICAL COMPOSITION 



and this theory is frequently resorted to by condensed milk men 

 to explain why their milk is low in fat. It has been claimed by 

 some that the volatile fats (volatile fatty acids) are lost during 

 the process of condensation. This claim is not well founded, 

 since repeated experiments 1 have conclusively demonstrated that 

 condensed milk contains the normal amount of volatile fatty 

 acids. It has further been experimentally proven that the con- 

 densed milk, when made properly and from whole milk, contains 

 fat equal in amount to that found in the fresh milk used. A 

 reasonable allowance should be made, however, for loss of milk 

 due to spilling and wasting in pipes and retainers. Experience 

 has shown that this loss amounts to about fifty to one hundred 

 pounds of milk per average batch under normal conditions. 



Proteids. The per cent, of proteids in the condensed milk 

 varies with the per cent, of proteids in the original milk and 

 the degree' of concentration. It fluctuates usually between 7.5 

 and 9 per cent. The heating previous to condensing coagu- 

 lates a portion of the milk albumin and alters the casein to the 

 extent that it is not precipitated in the normal, way, when rennet 

 is added to the diluted condensed milk. 



While, in most analyses of sweetened condensed milk, the 

 per cent, of proteids nearly equals that found in the fresh milk 

 multiplied by the degree of concentration, there is a tendency 

 toward a slight loss of this constituent due to precipitation in 

 the forewarmers. 



Milk Sugar. Sweetened condensed milk contains from 

 about 12.5 to 15 per cent, of milk sugar, the amount varying 

 according to the degree of concentration and per cent, of milk 

 sugar in the fresh milk. The milk sugar is not known to undergo 

 any material changes as the result of the condensing process. If 

 condensed milk is recondensed, it assumes a darker color which 

 is largely due to the caramelizing of a part of the milk sugar, 

 caused by the action of prolonged exposure to heat. The milk 

 sugar in condensed, milk crystallizes very readily and causes the 

 condensed milk to become sandy and settled. Chemical anal- 

 yses of this sugar sediment show that it consists principally 

 of milk sugar. The primary cause of this property lies in the 



1 Hunziker and Spitzer, Indiana Agricultural Experiment Station Bulletin 

 No. 134, 1909. 



