Why we use centrifugation to separate milk and cream
Answers
A newly invented appliance for separating cream from milk was described in the German trade journal “Milch-Zeitung” dated the 18th of April 1877. This was “a drum which is made to rotate and which, after turning for a time, leaves the cream floating on the surface so that it can be skimmed off in the usual fashion”.
After reading this article, a young Swedish engineer, Gustaf de Laval, said, “I will show that centrifugal force will act in Sweden as well as in Germany.” The daily newspaper “Stockholms Dagblad” of 15th January 1879 reported: “A centrifugal separator for cream skimming has been on show here since yesterday and will be demonstrated every day between 11 a.m. and 12 noon on the first floor of the house of number 41, Regeringsgatan. The machine can be likened to a drum which is driven round by a belt and pulley. The cream, which is lighter than the milk, is driven by centrifugal force to the surface of the milk and flows off into a channel from which it is led into a collection vessel. Under it, the milk is forced out to the periphery of the drum and is collected in another channel, whence it is led to a separate collecting vessel.”
From 1890, the separators built by Gustaf de Laval were equipped with specially-designed conical discs, the patent on which had been granted in 1888 to the German Freiherr von Bechtolsheim and had been acquired in 1889 by the Swedish company AB Separator, of which Gustaf de Laval was part-owner.
Today, most makes of similar machines are equipped with conical disc stacks.