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Freeze-drying, also known as lyophilization, is based on the physical phenomenon of water or organic solvent sublimation in frozen substances. This process involves the direct transition of the frozen solvent to vapor without passing through the liquid state. Typically, when dealing with food, proteins, or biological materials, the solvent to be removed is water. 300K has optimized this process to enhance the preservation, storage, and shipment of biological samples.


The goal of lyophilization is to produce a dry product that, when water or solvent is reintroduced, exhibits the same characteristics as the original product. Freeze-drying minimizes quality loss by preventing deterioration of the sample due to chemical reactions or enzymatic degradation. Lyophilization offers several advantages compared to other preservation methods:


  • Rapid regeneration of products.
  • Preservation of the original product’s shape and characteristics.
  • Ideal for drying thermolabile substances.
  • Protection of oxidizable constituents.
  • Achieves a very low final moisture level, typically less than 5% water content.


Freeze-Drying/Lyophilization process comprises three phases:


1- Freezing Phase

Freeze drying is easiest to accomplish using large ice crystals, which can be produced by slow freezing or annealing. However, with biological materials, when crystals are too large they may break the cell walls, and that leads to less-than-ideal freeze drying results. To prevent this, the freezing is done rapidly.


2- Primary Drying (Sublimation) Phase

Freeze drying’s second phase is primary drying (sublimation), in which the pressure is lowered and heat is added to the material in order for the water to sublimate. The vacuum speeds sublimation. The cold condenser provides a surface for the water vapor to adhere and solidify. The condenser also protects the vacuum pump from the water vapor. About 95% of the water in the material is removed in this phase. Primary drying can be a slow process.


3- Secondary Drying (Adsorption) Phase

Freeze drying’s final phase is secondary drying (adsorption), during which the ionically-bound water molecules are removed. Most materials can be dried to 1-5% residual moisture.