Dehydration
- .
Drying or dehydration is the removal of the majority of water contained in the fruit or vegetable and is the primary stage in the production of dehydrated fruits and vegetables. Several drying methods are commercially available and the selection of the optimal method is determined by quality requirements, raw material characteristics, and economic factors.
There are three types of drying processes:
- Solar Drying
Atmospheric dehydration including stationary or batch processes (kiln, tower, and cabinet driers) and
Continuous processes
- Tunnel.
- Continuous belt
- Belt-trough
- Fluidized-bed
Explosion puffing, foam-mat
- Spray
- Drum
- Microwave-heated driers
- Sub-atmospheric dehydration (vacuum shelf, vacuum belt, vacuum drum, and freeze driers).
PRE-DRYING TREATMENTS
Pre-drying treatments prepare the raw product for drying or dehydration and include raw product preparation and color preservation. Raw product preparation includes selection and sorting, washing, peeling (some fruits and vegetables), cutting into the appropriate form and blanching (for some fruits and most vegetables). Fruits and vegetables are selected, sorted according to size and maturity. The final step in the pre-dehydration treatment is color preservation, also known as sulphuring. The majority of fruits are treated with sulphur dioxide (SO ) for its antioxidant and preservative effects.
2. CANNING
Canning is a method of preserving food in which the food contents are processed and sealed in an airtight container. Canning provides a typical shelf life ranging from one to five years, although under specific circumstances a freeze-dried canned product, such as canned, dried lentils, can last as long throughout the year in an edible state.
3. Freezing
Pickling
Pickling is a method to preserve vegetables and some fruits in spices, oil or in vinegar. Many vegetables and fruits can be preserved in this manner, including peppers, cauliflower, Mango, and gooseberry.
