The freeze drying/dehydration technology allows you to save delicate aromas while drying the frozen product under vacuum, producing a premium quality product. The ice contained in the product is sublimated, hence transformed from a solid to a gas and then trapped inside the condensation system.
Freeze drying is the drying of an already frozen product in a vacuum below the “triple point” (6.2 mbar + 4.6 torr). Water will only be present in two phases: Ice and vapor. The vacuum allows the ice to turn directly into vapor without first passing through the water stage, in the sublimation process.
Freeze drying is applied to a vast number of food products like fruit, vegetables, meat, seafood, soup blocks, poultry, rice and more; this preserves the products original shape, color, taste, aroma and important nutrients.
The freeze drying/lyophilization cycle is divided in three phases:
The initial IQF freezing process, carried out in a way that:
- The product exhibits the desired crystalline structure
- The product is frozen below its eutectic temperature
A primary drying (sublimation) phase during which:
- The partial pressure of the vapor surrounding the product must be lower than the pressure of the vapor from the ice, at the same temperature
- The energy supplied in the form of the heat must remain lower than the products eutectic temperature (the highest allowable product temperature during the conditions of sublimation)
A secondary drying aimed at eliminating the final traces of water which remain due to absorption, and where:
- The partial pressure of the vapor rising from the product will be at its lowest levels
At the completion of the process the treated product will have retained is original form, volume, physical, chemical, and biological properties. It can then be stored for an almost indefinite period of time with the reduction of the moisture. As the product is porous, it can be re-dissolved by a simple addition of a proper solvent.