🔄 Separation

Separation means splitting whole milk into cream and skimmed milk. Fat is lighter than the rest of the milk. If milk is left to stand, the cream rises to the top by itself in 12–24 hours. This was done for centuries: the risen cream was skimmed off with a spoon, or the milk was drained from below. A separator — a centrifuge — does the same thing in seconds.

At the dairy, milk is warmed to about 55–65 °C and fed into a fast-spinning drum fitted with discs. The heavy skimmed milk moves to the edge, and the light cream gathers near the centre. Each stream leaves through its own outlet. Only about 0.05% fat is left in the skimmed milk. Cold separation is also possible: it saves energy and holds back the growth of bacteria.

Separation is the basis of many products. Cream is made into butter, sour cream and ice cream. Skimmed milk goes into low-fat products and milk powder. Cream and skimmed milk are often mixed again later in the right ratio to get milk with a set fat content. This step is called standardization.