Food drying is a method offood preservation in which food isdried (dehydrated ordesiccated). Drying inhibits the growth ofbacteria,yeasts, andmold through the removal ofwater. 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.^[2] Water is traditionally removed throughevaporation by using methods such as air drying, sun drying, smoking or wind drying, although today electricfood dehydrators orfreeze-drying can be used to speed the drying process and ensure more consistent results.^[3]

Many different foods can be prepared by dehydration. Meat has held a historically significant role. For centuries, much of the European diet depended on driedcod—known assalt cod,bacalhau (with salt), orstockfish (without). It formed the main protein source for theslaves on theWest Indian plantations, and was a major economic force within thetriangular trade.Dried fish most commonly cod or haddock, known asHarðfiskur, is a delicacy inIceland, while driedreindeer meat is a traditionalSámifood. Dried meats includeprosciutto (Parma ham),bresaola,biltong andbeef jerky.

Dried fruits have been consumed historically due to their high sugar content and sweet taste, and a longershelf-life from drying.^[4]Fruits may be used and named differently when dried. The plum becomes aprune, the grape araisin.Figs anddates 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 andonion are often dried and stored with their stalksbraided. Edible mushrooms are sometimes dried for preservation or to be used as seasonings.

Home drying of vegetables, fruit and meat can be carried out with electrical dehydrators (household appliance) or by sun-drying or by wind.^[5] Preservatives such aspotassium metabisulfite,BHA, orBHT may be used, but are not required. However, dried products without these preservatives may require refrigeration or freezing to ensure safe storage for a long time.

Industrial food dehydration is often accomplished byfreeze-drying. In this case, food isflash frozen and put into a reduced-pressure system which causes the water tosublimate 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, andnutritional 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.^[6]

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.

Packaging ensures effective food preservation. Some methods of packaging that are beneficial to dehydrated food are vacuum sealed, inert gases, or gases that help regulate respiration, biological organisms, and growth ofmicroorganisms.^{[citation needed]}

There are many different methods for drying,^[7] each with its own advantages for particular applications. These include:

• Mendonca, Aubrey F., and Norman N. Potter. "Food Preservation." AccessScience, McGraw-Hill Education, 2016.

• National Center for Home Food Preservation, drying section