Basic Principles of Freeze Drying

Virtis and FTS Systems, SP Scientific brands, have authored a highly informative reference white paper for all people interested in the Basic Principles of Freeze Drying. To access a copy of ’Basic Principles of Freeze Drying’ - available in English, Chinese, French, German, Portuguese or Spanish - please visit www.spscientific.com/LyoLearn-Tech-Brief.aspx.

Freeze drying, also known as lyophilisation, is a process whereby a product is rendered chemically inactive by freezing, and the ice is then removed by sublimination with the intent of being able to store the product at a higher temperature than the original freezing point, while retaining chemical inactivity.

Lyophilisation requires the development of a unique recipe or cycle based on the thermal and physical characteristics of the product along with consideration of temperature and pressure relationships, phase changes and heat transfer.

A basic understanding of the theory behind freeze drying is essential for any scientist to begin to design a working lyophilisation process.

This authoritative new white paper provides an overview of all of the steps involved in freeze drying including product freezing, primary drying (sublimation) and secondary drying (desorption).

Also introduced are the concepts of critical temperature (eutectic and glass transition), thermal treatment (annealing), vapour pressure of ice, product collapse, determination of completion of primary drying and cycle optimisation. Common freeze dryer equipment designs are reviewed along with their typical components and sub-systems.