Freeze Drying is a conservation process whereby the deep-frozen product’s water content is removed by temperatures below 0°C and under high vacuum (0 bar) pressure.
This process makes the ice crystals sublimates, i.e. it evaporates without passing through the water phase. The Drying takes place as follows.
- Freeze the products below their eutectic point
- The system must be capable of evacuation to low pressure
- A controlled source of heat input to the product must be employed to drive the water vapour from the solid to the vapour state
Because only the water evaporates whilst the product remains frozen or at low temperature, the product retains all its nutrients, flavours, and colours – not obtainable with other drying methods
Keeping the Freeze-Dried production in airtight containers gives a long shelf life, and no refrigeration is needed.
Freeze drying can be helpful to produce all kinds of Starter Cultures.
As with Spray Drying, Freeze Drying is a costly way to preserve food on a small scale, but you shall know we have on the program.