A major part of the solids in milk are milk proteins. The most important from a quantitative point of view is casein and whey proteins. By membrane filtration of skim milk it is possible to fractionate the milk proteins, which are discharged at a solids content of about 30 %. Due to the high content of proteins in the concentrate, it is not possible to concentrate it further before final drying. The preferred spray drying process is with nozzle atomization in a plant equipped with a bag filter to minimize powder loss.
The milk proteins are easy to dry, and a plant like the Integrated Filter Dryer IFD™ or the Multi-Stage Dryer MSD™ is chosen, as they are equipped with after-dryers and bag filters to ensure a good drying economy.