192 STORAGE 
few days at ordinary temperatures and should, therefore, be sold 
and used as soon as possible after manufacture. If their storage 
is unavoidable, they should be held as near the freezing point 
as possible. For prolonged storage it might be advantageous to 
freeze them. However. reliable data on this phase of the indus- 
try are lacking. 
Evaporated milk, sold in hermetically sealed cans, is sup- 
posed to be entirely sterile. and. if made properly, will keep in- 
definitely. here is a constant tendency, however, for the fat 
to separate out. which naturally is augmented by prolonged 
storage. Again, the lactic acid in the evaporated milk gradually 
acts on the can. causing the tinplate to become dull and the 
contents to acquire a disagreeable metallic favor. \When stored 
for an excessively long time this chemical action may be sufh- 
cient to cause the evolution of considerable quantities of hydro- 
gen gas. swelling the cans. 
Sweetened condensed milk which is preserved by about 40 
per cent of sucrose, will keep apparentiy unchanged for a con- 
siderable length of time. It is best, however, when fresh. Bac- 
teriological examinations have shown that, while moderate age 
does not change the outward appearance of this condensed milk, 
the bacteria in it gradually increase and the milk gradually de- 
velops a stale flavor. White and yellow “buttons.” lumps, or 
nodules of a cheesy texture and flavor, due to fungus growth, 
are also prone to appear in the condensed milk. -\ge, also, causes 
it to become darker in color. These defects are especially ap- 
parent in old milk which has not been kept at a low temperature. 
Again, sweetened condensed milk made in May and June has a 
strong tendency to thicken with age and to hecome entirely solid. 
In some cases a part of the sweetened condensed milk made 
during the summer months is stored in large cylindrical wooden 
or iron tanks sunk into the ground, or installed in the basement 
of the factory, where the condensed milk remains at an even tem- 
perature. As the demand for the product increases and. the 
supply of fresh milk decreases, condensed milk is drawn from 
these tanks to fill the increasing orders. 
Effect of Storage Temperature.—-Most, 1f not all the changes 
which condensed milk is prone to undergo in storage are retarded, 
if not entirely prevented, when stored at the proper temperature. 
