How cream is made

A dairy does not skim anything. It spins milk so hard that the fat leaves through its own pipe.

stations: 5
things upstream: 1
raw source: 1
step from the ground: 1

The short version

Butterfat is lighter than the rest of milk, and left alone it floats to the top. Dairies speed that up with centrifugal separators, which split whole milk into cream and skim in a continuous stream. The cream is then adjusted to a legal fat grade, heat-treated and packed, from half and half up to heavy cream.

Spin the whole milk

Milk runs into a fast-turning centrifugal separator. The less dense butterfat collects apart from the skim milk, and the two leave separately. Before these machines, milk sat in a container until the fat rose and could be skimmed by hand, sometimes going sour first.

Goes in
Raw milk
Eject the bowl sediment

Any solids in the milk gather as sediment in the separator bowl. Modern bowls throw this out by themselves, which lets the machine be cleaned in place without taking it apart.
Set the fat grade

Fat level decides what the product can be called. In the United States, half and half holds 10.5 to 18 percent fat, light cream 18 to 30, and heavy cream at least 36. Skim is blended back until the batch lands in its band.
Heat-treat the batch

The cream is pasteurized or sterilized at ultra-high temperature to kill microbes and extend its life. French rules allow the words crème fraîche only on pasteurized cream packed on site within 24 hours.
Fill and keep cold

Chilled cream is filled into cartons or tubs and stays in the cold chain until sale. Some goes on to other dairy lines in tankers instead, to be churned or cultured.

End of the lineCream Next it goes into butter, ice cream, cream cheese and 2 more.

Worth repeating

Cows on natural pasture can give faintly yellow cream, because separation concentrates carotenoid pigments from the plants they eat.
Whisking turns cream into a soft solid only when it holds more than 30% fat.
Goats and water buffalo give pure white cream.