208 CHEMICAL COMPOSITION 
Milk Sugar.—The milk sugar is present in per cent. corre- 
sponding with that of the original milk, times the degree of con- 
centration. A portion of it has undergone oxidation (carameli- 
zation) due to the high sterilizing temperatures. It gives to the 
evaporated milk a yellow to ight brown color. ‘he higher the 
sterilizing temperature and the longer the exposure of the evapo- 
rated milk to this heat, the darker is its color, 
Ash.—The mineral constituents also are present in nearly 
the same proportion to the other solids, as in fresh milk. ‘They 
are largely rendered insoluble by the sterilizing process. The 
lime constituents frequently are found in the bottom of the cans 
in the form of hard, whitish, insoluble granules. For discussion 
of relation of ash constituents to stability of casein, see Chapter 
XXIII on “Lumpy and Curdy Evaporated Milk.” 
Since the ash in normal fresh milk is practically constant, 
averaging about ./0 per cent., the per cent. of ash in the evapo- 
rated milk is frequently used as a factor in determining the 
degree of concentration. The results may, however, be very 
misleading, since, when the ash is precipitated in the form of 
granules, it is practically impossible to mix it back into the milk 
in order to obtain a representative sample for analysis. 
The Specific Gravity ranges from 1.05 to 1.08, according to 
the degree of concentration and the specific gravity of the origi- 
nal milk. It averages about 1.065. 
Plain Condensed Bulk Milk is of very varying composition, 
depending largely on the degree of concentration and the per 
cent. of fat present. It is usually made from partly or wholly 
skimmed milk and is condensed at the ratio of 3 to 4 parts of 
fresh milk to 1 part of condensed milk. ‘The same fact applies 
to the composition of concentrated milk. 
