Milk powder is obtained by dehydration of milk, this is done so as to increase shelf life of milk without using refrigerator. There are several types of milk powders based on requirement like: whole, skimmed, buttermilk etc,. Milk powders are widely used around the world for its various applications. From infant formulas to desserts, milk powders have found its way to be one of the biggest market players in the world. Apart from food industry, milk powder is widely used in the field of biotechnology also for its research purposes.
The first step is separation and standardization. The raw milk from the dairy factory is pasteurized and separated into skim milk and cream using centrifugal cream separator. It must be ensured that there is 26-30% fat in the milk powder. This step is followed by preheating, where milk is heated to 75 – 120 °C. The milk is held at this temperature for a few minutes. The milk is preheated so as to control denaturation of whey proteins in the milk and destroys bacteria, inactivates enzymes, generates natural antioxidants and imparts heat stability. The next step is evaporation. In the evaporator, the preheated milk is concentrated in stages” from around 9.0% total solids content for skim milk and 13% for whole milk, up to 45-52% total solids. This is achieved by boiling milk below 72 °C and removing water as vapour. This vapour can be recycled again. The next step is spray drying, involving atomizing of milk concentrates from evaporator to fine droplets. This is performed in a large drying chamber with facilities for flow of hot air. The milk droplets are then cooled by evaporation, leaving a fine powder with around 6% moisture content with a mean particle size typically of <0.1 mm diameter. Final or “secondary” drying takes place in a fluid bed, or in a series of such beds, in which hot air is blown through a layer of fluidized powder removing water to the point of amoisture content between 2-4%. Final stage is packaging. Milk powders are enormously more stable than fresh milk but protection from moisture, oxygen, light and heat is needed in order to preserve their quality and shelf life. Milk powder is packed into either plastic-lined multi-wall bags or bulk bins.
Milk powders are nowadays widely used for research purposes. For example, Fat-free powdered milk is used as a saturating agent to block nonspecific binding sites on supports like blotting membranes.
Milk powders have longer shelf life than regular milk and thus can be a very good substitute for milk. Milk powders contain all 21 amino acids and thus have high nutritional value. And because of this, It is very good for remote areas or the parts of world where there is no or very little milk.
Milk powders are widely used in cosmetics and in skincare industry. It is used as a whitening agent.