Freeze-drying in the coffee industry

Freeze-drying is a process used in food processing to remove water from foodstuffs, with the goal of increasing their shelf life. The process consists of various steps: At first product temperature is lowered, usually to about -40°C, thus causing freezing of the free water. Later, the pressure in the equipment is lowered and sublimation of the frozen water occurs (primary drying). Finally, the bound water is removed from the product, usually increasing product temperature and further decreasing the pressure in the equipment, thus reaching the target value of residual moisture (secondary drying).