Freeze dryer (lyophilizer) is a technique that the use of the principle of sublimation drying that is dry the material to be fast at low temperatures to freeze, then vacuum in the appropriate circumstances, to freeze the water molecules directly sublimated into water vapor escape process. Freeze-dried product is called freeze-dried material (lyophilizer), the process is called freeze-drying (lyophilization).
Before drying the material is always in low temperature (frozen), and ice crystals evenly distributed in the material, the sublimation process will not occur due to dehydration and concentration phenomenon, to avoid the water vapor produced by the foam, oxidation and other side effects. Drying porous material was a dry sponge, the volume is essentially the same, easily soluble in water and restitution. The maximum extent possible to prevent drying, physical and biological degeneration.