Lyophilization is the process of drying by sublimation from frozen material. What is this process more commonly called?

• A. Freeze-Drying
• B. Desiccation
• C. Spray Drying
• D. Freeze-Thawing

Answer: (A)

Lyophilization is the removal of water by sublimation from a frozen material, so it is most commonly known as freeze-drying. In this process, the substance is frozen, then placed under vacuum so the ice converts directly from solid to vapor, bypassing the liquid phase. This allows water to be removed at low temperatures, preserving heat-sensitive components like biologicals and vaccines and yielding a porous, easily reconstituted dry solid. Desiccation is general drying by removing moisture, not necessarily from frozen material. Spray drying dries liquids into powders by contact with hot gas, not by sublimation of ice. Freeze-thawing is simply cycles of freezing and thawing, not a drying method.