Initially simply as a sun dried form of goats' or other animals' milk, some form of milk powder or thick paste has been used as a food staple for centuries. Why? Because of the two main qualities these products still exhibit:
- Stability over long periods of dry, dark storage without spoilage or loss of nutritional value
- Lightweight and reduced bulk for ease of storage and transportation
These assets are the direct result of its low moisture content and were used by early travelers over long distances, particularly traders and armies. With the addition eventually of many varieties of dried dairy products developed besides those for personal nourishment, traders could also include the light weight products for barter along the way and at final destinations.
However, as the industrial revolution grew, sun drying gave way to artificially heated spray and drum for production from nonfat skim milk, whole milk, buttermilk, whey or other dairy products were reported and patented in the early 1800s. Various vacuum drying processes were also developed.
Today’s powdered milk products are mostly produced using a spray drying process. Initially the whole milk, nonfat milk, buttermilk, whey products or dairy blends are first concentrated by evaporation down to liquid volume containing about 50% solids. This concentrate is then finally sprayed into a heated chamber for almost immediate removal of the remaining water to form the final milk powder product.
A slightly different production method involves spraying the milk product into a quickly rotating, heated drum. The centrifugal force from rotation results in the formation of a thin film on the drum’s heated surface and evaporation leaves the powdered product for collection.
The process variables employed in these production methods determine physical properties these milk powders and determines their moisture content and particle size that ultimately determine storage bulk, stability and water solubility. In addition, temperature and duration of heating can significantly affect flavour.
However, in general nonfat dry milk powder typically contains carbohydrates (52% - mostly lactose), protein (36% including all twenty-one essential amino acids), minerals (mostly potassium and calcium) and vitamins. These individual percentages decrease by the presence of 26-40% fat, if whole milk is used.
For home and commercial uses milk powders are most frequently used in the preparation of infant formulas for child nourishment, in recipes for baking to prevent thinning of batter and in confectionery products to prevent dilution of “candy” ingredients.
Powdered milk’s ease of shipping and simplicity of storage make it an ideal protein supplement to other dried foods. This has been recognized for many years on a global basis with powdered milk products remaining a common item in UN food aid supplies for famine and disaster relief supplies.
The Australian Dairy Industry is a world leader in milk product preparation and has developed over a century into a modern industry operating as one of the most efficient and technically advanced producers of quality dairy products being provided not only domestically, but globally. In fact, new technologies introduced for the production of powders and the development of new product specifications have expanded the meet larger range of customer needs around the world.
Fulfilling these needs and ongoing changes in specifications has resulted in increased domestic sales and has allowed Australian and New Zealand dairy suppliers to capture nearly 50% of all internationally traded dairy products - particularly in the growing Asian markets.