Certified Tissue Bank Specialist (CTBS) Practice Test

Which method is defined as freeze-drying?

1. Lyophilization

2. Cryopreservation

3. Desiccation

4. Disinfection

The correct answer is: Lyophilization

The method defined as freeze-drying is known as lyophilization. This process involves the removal of water from a substance, typically for preservation purposes, by freezing the material and then reducing the surrounding pressure to allow the frozen water to sublimate directly from the solid phase to the vapor phase. This technique is commonly used in the preservation of biological samples, pharmaceuticals, and food products, as it maintains the structural integrity and biological activity of the materials being preserved. In contrast, cryopreservation involves the preservation of cells or other biological constructs at very low temperatures to halt all biological activity, while desiccation refers to the removal of moisture from a substance without the use of freezing or sublimation. Disinfection is the process of eliminating or reducing harmful microorganisms, which is fundamentally different from methods that focus on preservation through dehydration. Therefore, lyophilization is the correct term associated with freeze-drying due to its specific method of processing that preserves substances in a stable and shelf-stable form.