Final answer:
The correct option is B. Lyophilization, or freeze-drying, is a preservation method that involves rapidly freezing material and dehydrating it under vacuum, allowing water to sublime from solid to gas. This process preserves the structural integrity and composition of the material, making it suitable for long-term storage.
Step-by-step explanation:
Lyophilization, also known as freeze-drying, is a process used to preserve a perishable material. The process involves rapidly freezing the material and then reducing the surrounding pressure to allow the frozen water in the material to sublime directly from the solid phase to the gas phase. This combination of low temperature and low pressure ensures minimal damage to the material's structure and composition, making lyophilization an effective method for preserving biological samples, such as microbial cultures, as well as food. Once the process is completed, the lyophilized material can be sealed and stored at room temperature, significantly extending its shelf life.
Role of Vacuum in Lyophilization
The use of a vacuum in freeze-drying speeds up the dehydration process by reducing the air pressure around the substance being dried. This lower pressure decreases the sublimation point of water, allowing it to sublimate at lower temperatures. As a result, the temperature of the substance being lyophilized drops because the process of sublimation requires heat from the substance itself, hence the material cools as the water vaporizes.