Freeze drying, also known as lyophilization, is a preservation method that removes water from materials through sublimation, transitioning frozen water directly to a gas without passing through the liquid phase.
This process is used to preserve food, pharmaceuticals, and other sensitive materials by reducing water activity, which inhibits microbial growth and prolongs shelf life.
It works by:
Freezing: The material is frozen to a low temperature.
Sublimation: A vacuum is created, and the frozen water (ice) is converted directly into vapor (sublimation), removing water from the material without melting it.
Secondary drying: Any remaining water is removed through evaporation and desorption.
It includes benefits like preservation, nutrient retention, quality preservation, etc.