Vacuum deaeration has been used successfully to expel dissolved air and finely dispersed air bubbles from milk. Preheated milk is fed to an expansion vessel, in which the vacuum is adjusted to a level equivalent to a boiling point about 7 – 8°C below the preheating temperature. If the milk enters the vessel at 68°C, the temperature will immediately drop to 68 – 8 = 60°C. The drop in pressure expels the dissolved air, which boils off together with a certain amount of the milk. The vapor passes a built-in condenser in the vessel, condenses, and runs back into the milk, while the boiled-off air, together with non-condensable gases (certain off-flavors) is removed from the vessel by the vacuum pump.