Spray drying has been found the most suitable process for removing the last part of the water, since spray drying can convert milk concentrate into a powder while still keeping the valuable properties of the milk.

The principle of all spray dryers is to transform the concentrate into many small drop-lets which are then exposed to a fast current of hot air. Because of the very large surface area of the droplets (1 1 of concentrate will be atomized to 1.5 x 10¹⁰ particles of 50µ with a total surface of 120 m²) the water evaporates almost instantaneously and the droplets are transformed into powder particles.