Is a process to separate water (or other solvent) from a solution by freezing and then sublimating the ice under reduced pressure. Freeze-drying is the gentlest process for drying products and is the best method for drying organic or inorganic compounds without changing their qualitative or quantitative composition. The freeze-drying process is done under vacuum and at low temperature and thus, for example, it is possible to avoid the denaturation of proteins. The freeze-dryer is the apparatus used to carry out freeze-drying. It consists of the following parts: dry chamber or freeze-drying chamber: it is the place where the substance to be freeze-dried is placed, condenser with cooling circuit: it communicates with the dry chamber and it is there that the steam produced in the sublimation is condensed and finally a vacuum system.

Freeze Dryer is a drying or dehydration process that is carried out by progressive sublimation of the solvent or water present in a sample. This process is characterized by the use of low temperatures which avoids that some volatile elements are lost, contrary to conventional drying processes. In the progressive sublimation we manage to pass directly from ice (solid) to gas (vapor) without passing through its liquid phase.