What is roller/drum dried milk powder?
Dried milk may be considered the final stage in removal of water from liquid milk. Before the development of the spray dryer, milk was dried using double drum dryers, sometimes called a roller dryer. Today, because of the advances in large-scale manufacturing plants, the majority of milk powder is dried using the spray dried method.
In the roller/drum dried milk powder process, pasteurized milk is applied to rotating, steam heated drums. The water evaporates when the milk contacts the hot drum surface. The drum continues to rotate and after less than one full revolution, a thin sheet of dried milk is removed from the drum by a scraper knife. The dried sheet of milk powder is conveyed away from the drums using a screw auger and then moved to a hammer mill where the powder is broken into small particles. The powder particles consist of flakes of irregular, angular shape with a wrinkled surface and rough edges. The roller dried particles are flakes without vacuoles; no air cells are perceptible within the particles. The length and width of the flakes depend on the thickness of the film. The roller process creates a unique low density powder.