Lyophilisation (freeze drying) is still the preeminent process technology for the dehydration and preservation of sensitive biologicals.
Lyophilisation is performed at extremely low pressure (high vacuum), upto 1000 times less than normal atmosphere pressure. This creates an environment that eliminates the ability of water to exist as a liquid and maintains it as solid ice which then gently sublimates over time into water vapour which is condensed @ -40c away from the product.The primary benefits of lyophilisation are: - Retention of original shape, size and colour of tissue
- Retention of cellular structure and strength
- Consistent appearance and preservation
- Achievement of low activity of water values to provide excellent product
 stability. - Provides excellent porosity and surface area to permit rapid reconstruction
- Freedom from contamination
Products suitable for dehydration by lyophilisation included:- Biological extractives for nutritional or pharmacntrical use
- Dehydrated foods that require stable preservation and rapid rehydration with full retention of flavour, colour and texture
- Flowers for decoration
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