Overview
Freeze drying is to directly transform the moisture or other organic solvents in the material from a solid state into a gas through sublimation, thereby removing the moisture or other solvents in the material. Freeze drying must be frozen at low temperature and carried out in a vacuum state, so it is also called vacuum freeze drying. Sublimation refers to the process in which a solvent changes directly from a solid state (such as water, like dry ice) to a gaseous state without passing through the liquid state. The product obtained by freeze-drying is called lyophilisate. Traditional drying will cause the material to shrink and destroy cells, while the freeze-dried material structure will not be destroyed and can effectively retain the biological and active integrity of the product.
Working principle
The working principle of vacuum freeze-drying is to first freeze the wet material below the eutectic point temperature, so that the water becomes solid ice, and then sublimate the ice into water vapor under the appropriate temperature and vacuum degree, and then use the water trap (water vapor condenser) of the vacuum system to condense the water vapor, thereby obtaining the technology of drying products. The drying process is a process of phase change of water and movement of matter. Since this change and movement occurs at low temperature and low pressure, the basic principle of vacuum freeze-drying is the mechanism of heat and mass transfer at low temperature and low pressure.
The basic process of vacuum freeze-drying can be divided into three stages: pre-freezing, sublimation drying and analytical drying.
Technical parameters
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