202 CHEMICAL COMPOSITION 
and this theory is frequentiy 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! 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. cf 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 1s 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, 
