164 CHEMICAI, COMPOSITION 



repeated experiments 1 have conclusively demonstrated that con- 

 densed milk contains the normal amount of volatile fatty acids. 

 It has f.urther been experimentally proven that the condensed 

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

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

 able 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 coagul- 

 ates 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. In early spring when 

 the majority of the cows supplying the condensery freshen, 

 there is a tendency of the jacket and coils in the vacuum pan to 

 become coated more or less heavily with a layer of semi-solid 

 milk. This very probably is due to the relatively high per cent, 

 of albumin which sticks to the heating surface. This thickened 

 milk, when mixed with and stirred in water, usually dissolves 

 without much difficulty. See also "Defects of Sweetened Con- 

 densed Milk," page 202. 



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 



1 Hunziker and Spitzer, Indiana Agricultural Experiment Station Bulletin 

 No. 134, 1909. 



