CHEMICAL COMPOSITION 203 
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. 
Milk sugar requires from five to six times its weight of water 
at ordinary temperatures for complete solution. In sweetened 
condensed 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. Jt usually varies from 1.5 to 2 per cent. 
Tt is quite constant in fresh milk (normal fresh milk contains 
uniformly about .7 per cent. ash). The per cent. of ash in 
sweetened condensed milk may serve, therefore, as a reason-. 
ably 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 44 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 amount of sucrose in milk does not appreciably 
affect the power of the milk to dissolve milk sugar, nor does 
the per cent. of lactose present materially affect the power of the 
milk to dissolve sucrose. 
When the sweetened condensed milk has a concentration 
of about 2.5:1, the manufacturer usually aims to have it contain 
about 40 per cent. sucrose. When it is condensed sufficiently 
only to contain 28 per cent. milk solids it is necessary to add 
sufficient sucrose to bring the percentage of sucrose up to about 
44, in order to insure the necessary keeping quality. 
1¥For further details on causes of settled sweetened condensed milk see 
Chapter XXII. 
