dessiccation

Desiccation, sometimes spelled dessiccation, is the process of removing moisture from a substance or environment, resulting in a dry state. The term is used in fields such as food science, materials science, biology, archaeology, and meteorology.

Common methods include heat drying, air drying, spray drying, oven drying, and vacuum drying. Freeze-drying (lyophilization) freezes material and removes water by sublimation under reduced pressure. Desiccants such as silica gel or molecular sieves can adsorb moisture at ambient conditions.

In biology, desiccation refers to extreme dryness, a state that many organisms experience in dry habitats. Some organisms are desiccation-tolerant and employ protective molecules and cellular vitrification to survive. Desiccation can damage membranes and proteins if water removal is excessive or rapid.

In preservation and laboratory practice, desiccation is used to stabilize samples and prevent spoilage. Desiccators maintain low humidity, and moisture content is often quantified by gravimetric loss or by moisture analyzers. Equilibrium moisture content depends on temperature and ambient relative humidity.

Applications include food preservation, pharmaceutical stability, archaeological preservation of artifacts, and the study of drought effects in ecology. The term is often contrasted with hydration or moistening and with rehydration processes.