Innovative gourmands have found lots of clever ways to dehydrate food: posh dehydrators, oven warming drawers and carefully arranged electric space heaters. Most of these, however, require power and patience in equal measure. If you're looking for a more rustic method, take a page from pioneer history and dehydrate your food mostly gadget-free.
"Without Heat" Is a Misnomer
While you can certainly dehydrate food without plugging in to power or turning on the gas, some form of gentle heat is a necessary element in the process. After all, the basic principle of dehydration involves heat: essentially, it's the movement of warm air around the subject of the drying, whereby the warm air rises and brings moisture with it.
The gentle heat required for dehydration -- around 100 degrees Fahrenheit, according to the University of Illinois at Urbana-Champaign College of Agriculture -- varies according to the thickness and native moisture content of the food. For example, drying paper-thin strips of meat into jerky will require less warmth and less time than drying big grapes into raisins. The idea is to find a level of heat that dries the food without cooking it; when the outside of the food dries too quickly, the dry "shell" traps moisture inside the food.
The drying food must have steady, gentle air flow around it in order to move the moisture away. Sometimes, this requires a fan set to low; however, strong airflow is likely to either blow the food away or blow dust onto the food, so don't overdo it.
Solar drying is the simplest non-gadget-requisite method of dehydration. Best suited for arid climates, solar drying involves slicing the food into the thinnest possible pieces, arranging them in a single layer on screens or thinly stretched cloth, then placing the screens in full sun. The food must be covered at night to protect it from gathering dew and watched during the day to scare off snacking wildlife.
To dry food in a warm indoor environment, you can use the same methods as Native Americans and medieval housewives did. Herbs, leafy greens and flowers can be bunched, covered lightly with cheesecloth or mesh, and hung from the ceiling. Alternatively, stretch bedsheets tightly between mooring points to dry greens and paper-thin slices of fruit and vegetables. Another method is to "sew" slices on a long thread, making sure to leave space between each piece for the air to move through.
Meat and Fish Safety
Unless you're in Arizona and it's the middle of July, you will need something hotter than a room-temperature environment to safely dry meats and fish: otherwise, insects will lay eggs in the food. If you're unwilling or unable to dehydrate using power, dry these foods close to fire and pre-salt the pieces. When the meat or fish becomes brittle, it's ready to store.