What Does Freeze Drying Entail?

Starters and cultures freeze drying has proven to be an effective way of storing perishable material. The procedure is also widely used when one is looking to transport such material. A lot of beneficial products have seen the light of day, and many more are being manufactured thanks to the procedure. What exactly happens when a product is marked for freeze drying? Let’s find out.

What is Freeze Drying?

Freeze drying is a dehydration process in which the material of interest is frozen, and the frozen water is allowed to sublime. The anti-rabies vaccine was among the first products from the procedure. This took place in the early 1900s when the process was introduced into the world of science. It has since crossed borders and is widely applied in a host of fields. During World War II, advances were made in the process as soldiers looked for efficient ways of storing their medical supplies. Freeze drying has grown in popularity in biological circles and is the widely used preservation technique.

Steps Involved in Freeze Drying

Products go through some processes before they become ready for preservation. Starters and cultures freeze drying usually involves pretreatment, freezing, primary drying and eventually secondary drying. Pretreatment is done to maintain the product quality once freeze drying is complete. The cycle time of the process may also require that the product is pretreated. There is no limitation to the methods used in this step.

The material is then frozen to temperatures which will ensure that sublimation takes place in the subsequent processes. A walk-in freezer or shell freezer is used depending on the size of the material. The end product is a crystal which is then exposed to primary drying. Larger crystals are preferred as they can easily be freeze-dried.

Primary drying is done to facilitate sublimation of the ice. Controlled pressure is used to guarantee the efficiency of this process. Caution needs to be taken at this stage as the structure of the material may be jeopardized. The final step, secondary drying, is carried out to ensure that no moisture remains in the product. The material is later sealed once an inert gas has taken care of the vacuum created. The elimination of moisture from the product ensures that microorganisms which are responsible for the degradation of material do not thrive.


Though starters and cultures freeze-drying was designed for preservation, it is still applied for commercial purposes. The pharmaceutical and food processing industries are the largest users of this technique with widely popular products being manufactured. Synthetic skin and ceramics have also been manufactured using the technique and feature prominently in the semiconductor industry. The procedure has been adopted in a lot of fields as the nutritional content, and chemical structure of the products remain intact.