Question

Lyophilization or freeze-drying involves

• A. Freezing the cells in liquid nitrogen
• B. Sublimation of cells water by its drying under vacuum
• C. Making into powder by dry heat
• D. Wet heat and freezing of cells

Hint:

• Lyophilization = Freeze-drying.
• Process: Freeze the material \(\rightarrow\) Reduce pressure (vacuum) \(\rightarrow\) Ice sublimes (solid \(\rightarrow\) gas).
• Used for preserving sensitive biological materials, pharmaceuticals, food.

Answer 1

The Correct Option is B

Lyophilization, also known as freeze-drying, is a dehydration process typically used to preserve perishable materials and extend shelf life while maintaining their structural integrity. This method involves the following key steps:

• Freezing: The material is first frozen solid. This is a crucial step as it ensures that the structural integrity is preserved.
• Sublimation: Under a high vacuum, the frozen water in the material undergoes sublimation, which is the transition of water from a solid directly to a gas, bypassing the liquid phase. This effectively removes water content without damaging the material.
• Secondary drying: Any remaining moisture is further reduced to achieve the desired level of dryness using higher temperatures.

The correct answer is: Sublimation of cells water by its drying under vacuum. This choice accurately describes the core principle of lyophilization. The other options do not correctly represent the process or its distinct characteristics.