Before 1878, the separation of cream from milk occurred through nothing more than the force of gravity. This process took time and was also inefficient since it limited the amount of cream that could be processed from the milk. Cream is formed when the lighter fat molecules of cream rise to the top of the milk through its heavier water-based fraction. This process happens naturally in raw milk when it is left to settle for a period of at least twenty-four hours. Cream can then be skimmed off or the milk can be drained from underneath, leaving only the cream behind.
Fortunately, help was at hand for the dairy industry. Stockholm Institute of Technology graduate Carl Gustaf de Laval (1845-1913) had been experimenting with centrifugal force as a way of separating fluids. In 1878 he invented a steam-driven device that spun raw-milk sample at 4,000 revolutions per impute. Under the force exerted through the centrifugal fluids. In of the device, heavier fraction is spun toward the outside of the rotating vessel while the lighter cream is kept in the center. Not only did Gustaf's machine extract cream faster than the conventional method, it was also more efficient, leaving less than 0.1 percent of cream in the milk.
Gustaf was a prolific inventor, perhaps owing to his background in both mechanical engineering and chemistry, and he went on to create many useful devices, including a miniature steam turbine and milking machines (first patented in 1894), with which his name is still associated. Laval's company, Alfa Laval, marketed the first commercially viable milking machine in 1918, five years after the inventor's death. But most importantly Laval invented a device that made making ice cream easier.
