•Condensed Milk and Milk Powder 121 



slight loss of this constituent due to precipitation in the fore- 

 warmers. 



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 analyses of this sugar sediment show 

 that it consists principally of milk sugar. The primary cause of 

 this property lies in the fact that sweetened condensed milk contains 

 so little water (about 26.5 per cent.) that the milk sugar is present 

 in the form of a supersaturated solution ; therefore, any condition 

 which favors sugar crystallization will tend to produce this defect. 1 

 Milk sugar requires from five to six times its weight of water at 

 ordinary temperatures for complete solution. In sweetened con- 

 densed milk the milk sugar has access to only about twice its weight 

 of water (12.5 to 15 per cent, lactose to 25 to 27 per cent, water). 



Ash. — The per cent, of ash is largely dependent on the degree 

 of condensation. It usually varies from 1.5 to 2 per cent. It is 

 quite constant in fresh milk (normal fresh milk contains uniformly 

 about .7 per cent. ash). The per cent, of ash in sweetened con- 

 densed milk may serve, therefore, as a reasonably reliable factor in 

 determining the degree of condensation. The heating of milk, 

 before condensing, precipitates and renders insoluble a portion of 

 the mineral solids, principally the lime salts. 



Sucrose. — The purpose of the presence of sucrose in this 

 product is to preserve it. Most of the sweetened condensed milk 

 on the market contains from 37 to 43 per cent, sucrose, or cane 

 sugar. Wider variations, however, are not infrequent. In some 

 cases analyses showed as low as 30 per cent, and in others as high 

 as 48 per cent, cane sugar. Cane sugar dissolves in one half its 

 weight of water, so that under normal conditions there is sufficient 

 water in the condensed milk to keep the sucrose in solution. The 



1 For further details on causes of settled sweetened condensed milk see Chapter XXIII, 

 page 146 



