Centrifugation

Centrifugal separation is a process used quite often in the dairy industry. Some uses include:

  • clarification (removal of solid impurities from milk prior to pasteurization)
  • skimming (separation of cream from skim milk)
  • standardizing
  • whey separation (separation of whey cream (fat) from whey)
  • bactofuge treatment (separation of bacteria from milk)
  • quark separation (separation of quarg curd from whey)
  • butter oil purification (separation of serum phase from anhydrous milk fat)

Principles of Centrifugation

Centrifugation is based on Stoke's Law. The particle sedimentation velocity increases with:

  • increasing diameter
  • increasing difference in density between the two phases
  • decreasing viscosity of the continuous phase

If raw milk were allowed to stand, the fat globules would begin to rise to the surface in a phenomena called creaming. Raw milk in a rotating container also has centrifugal forces acting on it. This allows rapid separation of milk fat from the skim milk portion and removal of solid impurities from the milk.