Glossary
Lyophilisation
Freeze-drying — removing water from a frozen solution under vacuum by sublimation, leaving a dry, stable cake.
Lyophilisation freezes a peptide solution and then removes the ice directly as vapour under vacuum, without passing through a liquid phase. The result is a dry, porous cake that is far more stable for storage and transport than a solution, because the water that drives most degradation has been removed. Peptides are shipped lyophilised for this reason and are dissolved again (reconstituted) in the laboratory when needed. The appearance of the cake is itself a quality indicator: a collapsed, shrunken, or melted-looking cake can signal a problem with the freeze-drying or with subsequent moisture ingress.
Covered in depth in Storage and stability.
Related terms
- Vial cake
- The solid, porous mass of freeze-dried material left in a vial after lyophilisation, whose appearance is a quality indicator.
- Reconstitution
- Dissolving a lyophilised (freeze-dried) material back into a liquid using a suitable solvent in the laboratory.
- Stability
- How well a material retains its identity and purity over time under defined storage conditions.
- Excipient
- An inactive substance included alongside the peptide, such as a bulking agent added before freeze-drying.
- Loss on drying
- A method that measures the total mass lost when a sample is dried, used as an estimate of residual moisture and volatiles.