Q. Explain Spray-dried milk powder?
The milk which is concentrated by the process of spray drying contains about 40- 45% total solids. Do you know how the dried milk powder is prepared? The milk is repasteurized and then atomized into a drying chamber of hot air where the hot air is made to flow, depending on the design, in the same, opposite or a combination of directions relative to the flow of the atomized milk particles. The drying air is heated to temperatures up to 1 50-260°C. The moisture is removed as particles move through the hot air and collects at the base of drying chamber. The dried powder is cooled to 38-400o as it moves from the drier. The large clumps are separated in a 'sifter' and then packed.
The spoilage of dried milk depends upon the type of organisms present initially in the raw milk and the conditions of sanitation in the processing. Micrococcus flavus and Bacillus subtilis are the common thermbduric organisms found in raw milk which can withstand drying temperatures.