Freezers are laboratory equipment designed to perform dehydrofreezing or cryodrying processes by separating water or other solvents, without altering the qualitative or quantitative composition of the product. They are especially used to preserve a temporary food or make the material more convenient for transport.

Therefore, the lyophilizers are applied for the conservation of food and biological materials, such as: cells, tissues, bacteria and vaccines turning them into dry products, avoiding decomposition and enzymatic, biological and chemical changes.

Functions of Freezers

Freeze-drying is the mechanism of drying products, becoming the best organic and inorganic method, without altering its composition. It is done by vacuum and at low temperature and thus avoid denaturation of proteins.

This equipment carries out the drying processes by cryodrying and consists of three components:

• Dry or freeze-drying chamber with airtight closure: the product is frozen and then passed through the solid vapor.
• Condenser including cooling circuit: the vapor process is condensed and communicates with the dry chamber.
• A vacuum system: by means of the oil pump, the original air is separated from the dry chamber when the freeze-drying course is formed, helping in the sublimation process.

According to the above, freeze-drying processes are based on the physical change of the dissipation of water or an organic separator of aqueous-organic mixture that are frozen; this separator or solvent sublimes directly to steam without passing through the liquid state. In general, when working with food, protein or biological material, the solvent to be removed is converted into water.

Types of Lyophilizers

We have freeze dryers that are used in the food industry, whether it’s to make space food, military dairy products or dehydrated food. In addition, there are various equipment applied for the pharmaceutical sector, towards the conservation of vaccines and medicines.

Likewise, there are lyophilizers that are used in the performance of documents damaged by water, these are grouped by size in laboratory units, for the progress and increase of processes and devices of larger production size. Likewise, the lyophilizers can also be classified according to the type of product chamber:

• Freeze-driers, usually pre-frozen, in bottles,
• Freeze dryers with shelves in which the product is placed in a tray or directly on a shelf.
• Freeze dryers with units that prepare with both drying options.

Procedures for Freezing

For laboratories, samples of small quantities, round tubes capable of supporting the closures inside the freeze dryers are used, and at industrial level trays are used. To fulfill the cryodrying processes of the samples are done through the following steps:

• Freezing of the sample at low temperatures: the freeze-drying of the products directly affects the appearance and quality of the final product. The sample is usually placed in liquid nitrogen (-196°C) or in a carbonated snow bath and acetone (-78°C) until it is completely frozen.
• Drying of frozen product by sublimation: the sample is introduced into the containers of the sublimation chamber, closing the keys of each, open ours, and when it has reached the vacuum, open all the others.

Finally, the freeze-drying processes must be performed in reverse to break the vacuum of the sample very carefully, letting air in slowly. Otherwise, the solid sample may be subject to turbulence and may be scattered on the walls of the chamber. The stopcock is then closed, disconnected from the chamber, the vial removed and capped in order to prevent moisture entering the chamber.

Kalstein brand lyophilizers

We at Kalstein offer you the best laboratory equipment technology, and Freeze Dryers are the ideal drying processes for any sample. These belong to the YR series, have CFC-free cooling, LCD screen drying curves, English interface. Large condenser opening, condenser with pre-freeze function. HERE

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