Food drying is a method of food preservation in which food is drying (dehydrated or desiccation). Drying inhibits the growth of bacteria, , and mold through the removal of water. Dehydration has been used widely for this purpose since ancient times; the earliest known practice is 12,000 B.C. by inhabitants of the modern Asian and Middle Eastern regions. "Historical Origins of Food Preservation". Accessed June 2011. Water is traditionally removed through evaporation by using methods such as air drying, sun drying, smoking or wind drying, although today electric or freeze-drying can be used to speed the drying process and ensure more consistent results.
Dried fruits have been consumed historically due to their high sugar content and sweet taste, and a longer shelf-life from drying. may be used and named differently when dried. The plum becomes a prune, the grape a raisin. ficus and date palm may be transformed into different products that can either be eaten as they are, used in recipes, or rehydrated.
Freeze-dried vegetables are often found in food for backpackers, hunters, and the military. Garlic and onion are often dried and stored with their stalks braided. Edible mushrooms are sometimes dried for preservation or to be used as seasonings.
Industrial food dehydration is often accomplished by freeze-drying. In this case, food is flash freezing and put into a reduced-pressure system which causes the water to sublimate directly from the solid to the gaseous phase. Although freeze-drying is more expensive than traditional dehydration techniques, it also mitigates the change in flavor, texture, and nutritional value. In addition, another widely used industrial method of drying of food is convective hot air drying. Industrial hot air dryers are simple and easy to design, construct and maintain. More so, it is very affordable and has been reported to retain most of the nutritional properties of food if dried using appropriate drying conditions.
Hurdle technology is the combination of multiple food preservation methods. Hurdle technology uses low doses of multiple food preservation techniques in order to ensure food is not only safe but is desirable visually and texturally.
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