Drying and Dehydration¡@
Drying removes the moisture from the food so that bacteria, yeasts and moulds cannot grow and spoil the food. It also slows down the action of enzymes, but does not inactivate them. Dried food items can be kept almost indefinitely, as long as they are not rehydrated.
The process of drying foods removes roughly 80 to 90 percent of the water content of fruits and vegetables. Drying food is a combination of continuous mild heat with air circulation that will carry the moisture off.
Because drying removes moisture, the food becomes smaller and lighter in weight. When the food is ready for use, the water is added back and the food returns to its original shape.
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Drying food loss only a little nutrition in the food.
Nutritional Losses by Selected Preservation Processes
| Preservation process | Normal loss of nutrition | Processing method |
| Canning | 60-80% | high temperatures |
| Freezing | 40-60% | water-logging and rupturing of cells |
| Comm'l Dehydrating | 5-15% | moderate heat and moderate air flow |
| In-home Drying | 3-5% | low heat and gentle air flow |
The disadvantages of this preservation method include the time and labor involved in rehydrating the food before eating. Moreover, rehydrated food typically absorbs only about two-thirds of its original water content, making the texture tough and chewy.
Examples: Various dried food products such as fruit, coffee, milk, soups, fish, meat and vegetables
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Dried coffee |
Dried soups |
Soup and milk are easy to dry and last for years.
Dried fruits are unique, tasty and nutritious. It might be argued that dried fruits are even tastier than fresh fruits. They have been called nature's candy. Dried fruit tastes sweeter because the water has been removed thus concentrating the fruit's flavor. Dried fruit can be eaten as a snack or added to cereals, muffins or ice cream.
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Drying tomatos |
Dried tomatos |
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