Except water evaporation, Is any other change made for production of industrial powdered milk. Is any material added?
Powdered milk or dried milk is a manufactured dairy product made by evaporating milk to dryness. One purpose of drying milk is to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated, due to its low moisture content. Another purpose is to reduce its bulk for economy of transportation.
There are various powdered milks such as dry whole milk and nonfat dry milk. Generally, milk powders contain all twenty-one standard amino acids, the building blocks of proteins, and are high in soluble vitamins and minerals the contents vary according to the type of powdered milk though.
Concerning differences, among others, commercial milk powders are reported to contain oxysterols (oxidized cholesterol) in higher amounts than in fresh milk (up to 30 μg/g, versus trace amounts in fresh milk).
Dear.. Heydari.. I agree with Zelalem Yilma answer,
Please see the definition of milk powder, it may contain added calcium chloride,citric acid and sodium citrate, sodium salts of orthophosphoric acid ad polyphosphoric acid by not exceeding 0.3% by weight, Butylated Hydroxy anisole is also permitted to an extent of 0.01% by weight of the product. other than these additives, no extra additives are permitted.
Obviously fresh milk has got superior flavour and taste, one can definitely notice it. Bioactive components are more in fresh milk as compared to milk powder.
There are reports indicating the loss of essential amino acid Lysine upon drying by Maillard browning mechanism. There is another report saying nutritive value of proteins gets reduced to an extent of 8%. However, deleterious effect of heat has not been elucidated completely. Modern methods of drying are meant to preserve the nutritive value of milk powder to great extent.
In dried milk one can expect differences concerning mainly heat induced changes, such as taste, nutritional properties (vitamins, ...) and protein denaturation. Even with optimized spray drying processes the previous heat concentration steps remain effective in promoting changes in milk components, with advantages or disadvantages according the milk powder further utilization.
There are various drying processes like spray drying, drum drying, freeze drying etc. The process of powder manufacturing also has effect on the final composition of powder because drying temperature varies in each process such as drying temperature in spray drying process is around 55 degree C while in freeze drying drying temperature is below zero degree C. So, the volatile /heat liable components in milk will definitely get destroyed based on the processing temperature applied for drying the milk.
Further, as mentioned by Laxmana Naik, sometimes to increase the shelf of whole milk powder it is required to add some antioxidant compounds in milk after condensing and before drying. This will also change the composition of final product.
Fresh milk more nutritive and tastier than reconstituted milk.
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