Ensuring Product Quality with Freeze Drying (Lyophilization)

Maintaining Optimal Quality and Integrity of Products


Freeze drying (lyophilization) is a low-temperature process used to remove water from foods, pharmaceuticals and other products to enable their easy storage and transportation without the need for constant refrigeration. It involves freezing the product at extremely low temperatures and then placing it in a vacuum environment. During the freeze-drying process, the frozen water content in the food undergoes sublimation, directly changing from a solid to gas.


Freeze drying offers distinct advantages over traditional heat-based methods for preserving food, pharmaceuticals, and other products. It maintains the original taste, texture, and nutritional value of food, ensures the effectiveness of pharmaceuticals, and preserves the quality of other products. Unlike heat-based methods that may lead to quality degradation, freeze drying ensures longer shelf life, safe food storage, better product stability, and superior quality.



This Application Note delves into how the selection of the right pump can optimize the efficiency and effectiveness of this critical preservation method. Discover the essential role of pumps in the freeze drying process by downloading the document. 

The Right Vacuum Pump: A Critical Choice for Freeze Drying


A reliable vacuum source is a critical part of the freeze drying process, ensuring that products retain their quality and effectiveness. Vacuum pumps create the vacuum needed for freeze dryers to operate effectively. The freeze-drying equipment must reach vacuum levels below 0.1 mbar. In some cases, it also needs to resist aggressive chemicals present in the solvent used. Two-stage rotary vane pumps and ChemStar Dry pumps meet these demanding requirements. 


If the lyophilization process seems like the solution you're looking for, we encourage you to download this Application Note and discover what a difference the right vacuum pump makes in the freeze drying processes. This comprehensive resource provides a deep dive into the key aspects of this efficient dehydration process to improve your understanding of this application. 


The Application Note includes:

  • An illustrative diagram that simplifies freeze drying into three easy-to-understand steps
  • A clear explanation of the process and the role that a vacuum pump plays in ensuring its efficiency
  • A breakdown of the broad range of Welch freeze dryer pumps to help you choose a solution to match your specific needs


Download the Application Note now to gain practical insights into lyophilization and discover how the right vacuum pump can make this remarkable dehydration method work effectively for you.



If you're in the market for a cutting-edge product for harsh chemical applications, look no further than ChemStar Dry pumps and Rotary Vane Vacuum Pumps. Check out Welch’s products for a reliable source of contamination-free vacuum that will help you make the most of your freeze-drying process.

Freeze Drying in Aerospace Applications


The cutting-edge realm of freeze-drying technology extends beyond everyday applications, such as fruit drying or instant coffee production. Welch Vacuum recently collaborated with Warsaw University of Technology, providing essential vacuum solutions for their laboratory freeze dryers. Within the university's labs, vacuum pumps play a pivotal role in creating the ideal low-pressure environment for aerogels. Recognized as the world's lightest solid, comprising up to 99.98% air, these materials have the potential to revolutionize industries such as aerospace.


Explore this partnership at the forefront of scientific innovation by reading the Case Study.




1. What is freeze drying?

Freeze drying, also known as lyophilization, is a process used to remove moisture from substances while preserving their natural structure and properties. It is a way to keep something in its original state but without the water. This unique preservation method is widely used to extend the shelf life of food, protect the potency of medicines or aid scientific research.

2. How does the freeze drying process work?

First, the material is frozen at extremely low temperatures, turning the water inside it into solid ice. Then, this frozen material is placed in a special chamber where the air is removed to create a vacuum.
In the vacuum, the frozen water within the material doesn't melt into a liquid when it warms up. Instead, it changes directly from a solid (ice) into a gas (water vapor). This transformation is called sublimation. During this process, the water vapor is drawn out of the material, leaving it dry. There are two phases to this process. In the primary drying phase, water is removed by sublimation. The secondary drying phase removes any residual water molecules.
What's remarkable is that the freeze dried substance retains its original structure and properties, just as if it were still frozen but without the moisture.

3. What is lyophilization, and how is it different from freeze drying?

Lyophilization is the formal term for freeze drying. They are essentially the same process, but lyophilization is the name commonly used in scientific and technical contexts.


4. Why is the selection of the right pump important for freeze dryers?

Choosing the right pump for freeze dryers is crucial because it affects how well the freeze drying process works. A well-suited pump also determines how long products maintain integrity, saves energy and money, ensures safety with chemicals, and keeps the freeze drying process consistent and reliable.


5. What types of freeze-drying equipment is there?

Freeze-drying equipment comes in different sizes and types. There are small benchtop units commonly used in laboratories for smaller-scale freeze drying experiments. You also have pilot-scale systems, which are larger and used for more significant quantities. There are also the industrial freeze dryers, the giants of freeze drying equipment, capable of handling large-scale production needs.


6. What are the components of the freeze drying equipment?

Freeze-drying equipment is a complex system with several key components, each with its own essential function.
First, there's the vacuum chamber that creates vacuum by removing air from the product. Then comes the condenser, which helps turn the moisture in the product into ice. The vacuum pump is the engine of the system. It maintains the vacuum and drives the process. Finally, there are the trays or shelves inside the chamber. These hold the products to be freeze-dried.


7. What are the key benefits of freeze drying?

One of its primary advantages is that this unique preservation method significantly extends the shelf life of products. Freeze dried foods can be stored for much longer periods without deterioration.
Another significant benefit is the preservation of product quality. Freeze drying helps retain the original taste, texture, and nutritional value of products, ensuring they maintain their intended characteristics even after long-term storage.
Additionally, freeze-dried products are incredibly easy to rehydrate. When needed, simply adding water restores them to their original state, making them convenient and versatile for consumers.
Due to these advantages, freeze drying finds extensive use in industries like pharmaceuticals, food, and biotechnology, where product integrity, long shelf life, and ease of use are critical considerations.


8. How can I access the Application Note on freeze drying?

You can download the Application Note by clicking the button below.