Lyophilization, also called freeze drying, is by far the gentlest product drying method. It is based on the physical phenomenon of sublimation, which means a direct transition from the solid state to the vapour state without passing through the liquid state. The frozen products are dried under vacuum without thawing. This method offers a wide spectrum of potential applications:
- for preserving the characteristics of the original substances (e.g. pharmaceutical products or coffee)
- for preserving the original form (e.g. animal preparations, archaeological objects, flowers or books)
- for conditioning the material (e.g. freeze-dried fruit in yoghurt)
- for the sample preparation for chemical or biochemical analysis (e.g. investigation of trace elements in foods, sludge or soil)
Freeze dryers are generally divided into two categories: those for batch operation and those for continuous operation. Systems for batch operation are commercially available with capacities from 2 kg to approximately 1 tonne per drying cycle.Christ focuses on this product segment and is the only manufacturer in the world that covers the full spectrum from standard laboratory (2kg - 24kg ice capacity), Pilot freeze dryers (4kg to 12kg) to large production systems (12kg to 500kg).