Freeze drying: it IS rocket science!

Lyophilisation — the process by which water is gently removed from materials to make them more stable and lengthen their shelf life — is a technology used in food, pharmaceuticals and biotech products.

It’s vital in the production of so many products, but the technology itself hasn’t changed in over 50 years and is very costly.

American researchers have set out to improve freeze-drying technology to make it safer and more affordable. And they are applying the principles of rocket science to do it.

Purdue University in Indiana has created a new lyophilisation consortium, LyoHUB, led by academics from the university’s Industrial and Physical Pharmacy and Aeronautics and Astronautics faculties. The team believes that if they can successfully reduce manufacturing costs through technological innovation, it could mean more jobs and benefit to the US economy.

The lyophilisation process requires big pieces of equipment that create a low-temperature and -pressure environment to push water into the vapour phase, so that it leaves the material and collects on condenser coils. Since the equipment is sealed it is impossible to check on a process while it is occurring, except through information from one or two sensors. Processing one batch of material can take a few days, which means time is lost if something goes wrong, according to Elizabeth Topp, head of Purdue’s Department of Industrial and Physical Pharmacy.

The conditions required for lyophilisation are similar to those in outer space, and the Purdue team plans to apply aerospace engineering principles to the project.

“Inside the lyophiliser the conditions are a rough vacuum, similar to that at 50 to 100 km altitude in the Earth’s atmosphere, and the fluid dynamics, heat transfer and certain molecular effects are different from what we see under normal conditions,” said Alina Alexeenko, an associate professor of aeronautics and astronautics.

“Lyophilisation is rocket science. We need to approach the equipment design the same way we approach a new spacecraft design — by first understanding in detail all of the forces and mechanics involved and using some of the special physical effects of the rarefied environment to our advantage.”

The development of new sensors that are less bulky and better distributed within the system is one approach to help control the processing. Advancing process analytical technologies and sensors for process development, monitoring and control are one of the initial focuses of the consortium, as well as developing standards for lyophilisation equipment performance, testing and validation.