Skimming consists in removing the fat content contained in the milk (cream).
Traditionally, cream was separated from milk through the gravity skimming technique. The raw milk was poured into low and wide containers made of wood or copper (called conche) that were placed in a cool, dark place. Depending on the temperature of the room, the cream would rise to the surface after one or two days in the form of a dense layer of white tending to yellow. With a special spoon (the skimmer) the layer of cream was collected to be then worked, and this process consists of the skimming of the milk.
Today, to skim milk, we use machines that exploit centrifugal force, thanks to which the cream, which is lighter, gathers around the rotation axis of the skimmer to be collected.