the sterilization process. Salt precipitation, which appears as a crystalline or gritty
deposit on the side of the can, usually results from extended storage without inverting
the cans. To prevent salt precipitation, it is recommended that the cans be turned
(inverted) at monthly intervals and that the storage temperature be maintained between
32 and 72F (0 and 22C).
d. Other Defects. Other defects that may be found in evaporated milk are:
bacterial spoilage indicated by coagulation, gas formation, and bitterness; bulging of
appearing as sludge in the bottom of the can, usually resulting from long term storage.
Defects may also be caused by improper stabilization.
1-47. DRIED MILK PRODUCTS
a. Two Common Products. Dry milk (powdered milk) is milk from which a
major portion of the moisture has been removed. The two most commonly recognized
dry milk products are dry whole milk and nonfat dry milk. Dry whole milk has only the
water removed, while nonfat dry milk has both the water and butterfat (milkfat) removed.
The butterfat of the finished dry whole milk product, regardless of the drying process
used, is approximately 26 percent. Nonfat dry milk should have 1.25 percent or less
milkfat in the finished product.
b. Moisture Content of Dry Whole Milk. Dry whole milk manufactured for the
military services must be processed in accordance with USDA Standards for Grades of
Dry Whole Milk. The atmospheric roller process and the spray process are two
methods of processing dry whole milk. With the atmospheric roller process, the
moisture is reduced to approximately 4.0 percent. When the spray process is used, the
moisture content is reduced to approximately 2.25 percent.
c. Shelf Life of Dried Milk. Dry whole milk has a much shorter shelf life than
nonfat dry milk due to its relatively high fat content. This makes it very susceptible to
oxidative rancidity and the development of oxidized and/or tallowy flavors. The shelf life
of dry whole milk can be extended by reducing its moisture content to less than 3.5
percent, packaging it in hermetically sealed containers, and storing it under refrigerated
conditions. Nonfat dry milk, on the other hand, has a relatively long shelf life without the
need for special packaging or refrigeration, and, as a result, is used much more
extensively by the military.