Lyophilised

Lyophilised, or freeze-dried, refers to a material that has undergone lyophilisation, a dehydration process used to preserve a wide range of substances by removing water while preserving structure and function. The process begins with freezing the material. The frozen product is then placed under a controlled vacuum, allowing ice to sublimate directly into vapor (primary drying). After most water has been removed, a secondary drying step desorbs bound water at slightly higher temperatures under vacuum. Conditions are carefully managed to minimize damage from ice formation and heat.

Lyophilisation offers several advantages. It yields products with very low residual moisture, improves stability at ambient or mildly elevated temperatures, reduces weight and volume for storage and transport, and often enables rapid reconstitution with water or a buffer. It is particularly valuable for heat- or moisture-sensitive materials, including many biological and pharmaceutical substances.

Common applications include pharmaceuticals (sterile injectable powders, vaccines, enzymes), biologics and diagnostic reagents, and research materials. In the food industry, lyophilised products such as coffee, fruit powders, and dairy powders retain flavor and nutrients and have extended shelf life. Lyophilised samples are also used in laboratories for long-term storage of proteins, nucleic acids, and other biomolecules.

Packaging typically involves moisture-impermeable vials or pouches, often with desiccants or barrier films to maintain low moisture content. Storage conditions vary, but many products remain stable at ambient temperatures when properly sealed.

Limitations include the higher cost and equipment needs, potential quality losses if the drying process is not properly controlled, and longer processing times. Reconstitution quality can vary and must be validated for each product.