Lyophilization, also known as freeze-drying, is a process that involves removing water or other solvents from a substance by freezing it and then subjecting it to a vacuum. Lyophilization helps extend product shelf life, maintain quality, and facilitate easy storage and transportation.
The process involves three main steps: freezing the substance, reducing the surrounding pressure to create a vacuum, and applying heat to allow the frozen water or solvent to sublimate directly from solid to gas, leaving behind a dry and stable product.
Lyophilization is particularly beneficial for heat-sensitive substances, as it minimizes damage and loss of potency. It is widely employed in producing vaccines, enzymes, antibiotics.
Lyophilization Phases
1. Freezing Phase
The first step in lyophilization is freezing the material. The temperature is lowered to around -40°C to -50°C to solidify the water or solvent in the product. This freezing process helps convert the liquid phase into a solid phase.
2. Primary Drying Phase (Sublimation)
After the material is frozen, the vacuum is applied, and heat is introduced to initiate sublimation, where the frozen water or solvent transitions directly from a solid to a gas without passing through the liquid phase. The temperature is maintained at around 0°C to -20°C).
3. Secondary Drying Phase (Desorption)
Following the primary drying phase, some residual moisture may still be present in the material. In the secondary drying phase, the temperature is increased slightly, usually around 20°C to 40°C to facilitate the removal of any remaining moisture.
4. End of Drying, Stoppering and Sealing
Note :
It’s important to note that the exact temperature and duration of each phase can vary depending on factors such as the specific product being lyophilized, the formulation, and the equipment being used. Process parameters are carefully optimized to ensure effective drying while preserving the integrity and stability of the product.
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