What is Lyophilization?

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  • Written By: Michael Anissimov
  • Edited By: Niki Foster
  • Last Modified Date: 26 August 2016
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Lyophilization is a process more commonly known as freeze-drying. The word is derived from Greek, and means "made solvent-loving". This process is a way of drying something that minimizes damage to its internal structure. Because it is a relatively complex and expensive form of drying, it is limited to those materials which are sensitive to heat and have delicate structures and substantial value. One of the only substances which cannot be preserved effectively by freeze-drying is mammalian cells, which are too fragile.

The preferred method of preservation in the biotechnology industry, lyophilization is regularly used to preserve vaccines, pharmaceuticals, and other proteins. Freeze-drying is also used to preserve special food products, eliminating the need for refrigeration. Freeze-dried food is eaten by mountain climbers and astronauts. Lyophilization is used by botanists to preserve flower samples indefinitely. Because the process of freeze-drying removes most of the water from the sample, freeze-dried materials become highly absorbent, and merely adding water can restore the sample to something close to its original state.


The energy and equipment costs of lyophilization are around 2-3 times higher than those of other drying methods. The drying cycle is also longer, about 24 hours. First, the temperature of the sample is lowered to near freezing point. Then, the sample is inserted into a vacuum chamber. The more energetic molecules escape, lowering the temperature further, while the extremely low pressure causes water molecules to be drawn out of the sample. Attached to the vacuum chamber is a condenser, which converts the airborne moisture into liquid and siphons it away.

Great care is taken throughout the process to ensure that the structure of the sample remains constant. For instance, the sample could merely be frozen by the vacuum rather than being frozen under atmospheric pressures, but that would cause shrinkage in the sample, damaging its structure irreversibly.

The primary mechanism that allows for freeze-drying is sublimation, whereby ice is directly converted to water vapor, without passing through the intermediary stage of a liquid. Rather than through heating, this is done by removal of pressure so that the ice boils without melting. The result is a sample whose structure is largely preserved, which can be stored at room temperatures and pressures.


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Discuss this Article

Post 15

what is the temperature used (in centigrade) and the pressure (in millibars) for freeze drying microorganisms (spores of a fungus) in the lyophilyzer?

Post 14

I am Dr Tunio and I have prepared bone graft material. How can i process bone samples for Leophylization? Thanks.

Post 11

What are the benefits of Lypholisation in medicines. Is this a process to make APIs sterile those who are not synthetically?

Adil, Lahore. Pakistan.

Post 9

"i bought a product, a muscular supplement which uses a form of lyophilization to deliver the supplement to the muscle quicker. my question is, is this a safe manner in which to deliver the supplement? i ask because i read in your article that it breaks down mammalian cells? Thank you for any help."

Answer: Lyophilization (or freeze drying) as a process damages mammalian cells. Not the product of lyophilization. Otherwise, all the astronauts would have died.

Post 8

Lyophilization is a process to store cultures for a long time and microorganisms are preserved by this process.

In our domestic process we are using freezing to preserve food material. With lyophilization we are also preserving microorganisms with foods. Do microorganisms grow with food? Why we are using freezing to preserve food material? -Arvind Bhandari, India

Post 7

is that lyophilization is the process of converting the ice in to vapour form without converting into vapour form? adidev, SOPS bhopal

Post 6

i have prepared a mixture of charcoal and BSA. Now i want to get the Pure BSA. How can i approach. can i go for lyophilisation.


Post 5

i bought a product, a muscular supplement which uses a form of lyophilization to deliver the supplement to the muscle quicker. my question is, is this a safe manner in which to deliver the supplement? i ask because i read in your article that it breaks down mammalian cells? Thank you for any help.

Post 4

what is the difference between lyophilization & freeze drying?

Post 3

what is the different between freeze drying, oven drying and tray drying? How does it affect dietary fiber properties?

Post 2

what are the applications of preservation in industrial microbiology?

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