Freeze-drying is a process that aims to separate water (or other solvent) from a solution by freezing and then sublimating the ice under reduced pressure. Freeze-drying is the smoothest process for drying products and is the best method for drying organic or inorganic compounds without altering their qualitative or quantitative composition. The process of lyophilization is carried out under vacuum and at low temperature and thus, for example, it is possible to avoid the denaturation of proteins. Food and biological materials such as cells, tissues, bacteria and vaccines become dry products, avoiding the passage through their liquid phase, and consequently enzymatic, biological and chemical changes. 

The Lyophilizer is the device used to perform lyophilization. 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 refrigeration circuit: it communicates with the dry chamber and it is where the steam that is produced in the sublimation condenses and finally a vacuum system.

Freeze-drying is a drying or dehydrating process that is carried out through progressive sublimation of the solvent or water present in a sample. This process is characterized by using low temperatures which prevents some volatile elements from being lost, unlike in conventional drying processes. Progressive sublimation allows the direct passage of ice (solid) to gas (vapor) without passing through its liquid phase.