Freeze Drying
- Freeze-drying is a method of drying food materials by sublimation, using low temperatures and reduced pressures. It is generally employed where heat-sensitive materials must be processed to a dry state.
- The principle used is freezing the food products and subsequently drying the same.
- The material to be dried is frozen in various cut shapes and sizes like slabs or pellets.
- The frozen material is then subjected to a high vacuum which is below the vapor pressure of water at the temperature of the material to be sublimed. Under these condition the ice (or frozen material) sublimes from the frozen mass and is collected on a cooled condenser whose temperature is such that the vapor is de-sublimed.
Major Phases
- Freezing
- Primary drying:- The removal of the frozen free moisture by a process of sublimation the conversion of ice to vapour without passing through the liquid phase
- Secondary drying
The process of further drying by desorption
Frozen raw product is cut down to the desired piece size and spread evenly onto trays that are stacked and stored in freezers. The sized product freezes at an even colder temperature, reaching an optimal state at which the original shape of the product can be retained.
The trays are then loaded into a refrigerated freeze-drying chamber that seals tightly shut. The chamber’s vacuum system removes ice from the product and converts it directly to a vapor without moving through the liquid state, in a process called sublimation. Since the water is removed from the product in a frozen state, cell structure remains intact and finished product bears close resemblance to its fresh counterpart, thus retaining its piece identity.
NSSPL has experience in setting up such plants as an OEM. We are having experienced service team for installation, testing, commissioning and training of your staff.
All most all type of fruits, vegetables, sea foods could be freeze dried while preserving its color, essence, taste and nutrients. This process also prolong the storage life and reduce the transportation cost including storage handling.
The advantages of our system are:
- Low energy consumption
- Compact and modular design
- Simple and reliable operation
- Stainless steel construction
- PLC control
- Easy loading and unloading
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