Milk powder contains a lot of protein and other temperature sensitive ingredients so too high temperature will cause its quality decline. The impact of high temperature (60-70℃) and dry air on the quality of milk powder has always been an unavoidable problem.The higher temperature leads to  the faster evaporation rate, but the difference in the content of protein, milk solids (whole milk powder, fat milk powder), etc. will cause the difference in the drying process, and result in the inconsistency of water content. Besides, there is the possibility of moisture absorption in the cooling (35-40℃) process of milk powder, which causes brown color.