Freeze drying technology

Freeze drying is a process of natural preservation of food products, by dehydrating them at very low temperature by a unique sublimation technique. The products intended to be preserved are first frozen to very low temperature ranging from -2^oC to -35 ^oC, using an Air Blast Freezing Equipment.

Freeze dried fruits are manufactured as follows:

Washing and Cleaning

Whole fruits procured from the field/market are separate out in perished, withered and other damaged fruits. The selected fruits are washed and cleaned.

Peeling and Skin removal

The fruits are separated from their skins by peeling or by knifed skin removal.

Slicing and Dicing

Depending upon the nature of the fruit and the specification of the buyer, the peeled fruits are either sliced or diced into cubes and bites.

Pre-freezing

The sliced or diced fruits are loaded onto the trays as per the density of loading. The fruits are frozen to a temperature of 20 ^oC.

Freeze Drying

The pre-frozen fruit trays are loaded into the drying chamber of the Freeze Dryer. The pressure in the chamber to a working level and the vacuum is maintained according to a prescribed thermal regime till about 98% of the moisture in the fruits is removed and the product is dry. The dried fruits are unloaded by pushing the trolleys with the trays out of the drying chambers.

Quality Control

The freeze dried fruits are subject to a quality control procedure to grade and separate the seconds.

• The freeeze dried fruits are normally bulk packed in 50lb. (about 23kg) fibre drums with special poly-liners, or any other packing specified by the Buyer.

• Freeze dried products are organic and porous in nature. The packing room should have a special type of dehumidifying arrangement, so that the ambient relative humidity is maintained at around 40%.

• The exposure time in packing should be minimum. Automatic filling through a closed chute arrangement is preferable.
• Freeze dried fruits or powders should be packed only in thin metallic pouches or similar impermeable non-reactive packing containers.
• The best condition for packing freeze dried products is either non-reactive packing containers.
• The best condition for packing freeze dried products is either under vacuum or in a nitrogen blanket. This keeps the products fresh for a long time.

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