People have been preserving food by drying them for generations. Just ask your grandmother. Campers have latched on to the idea of dehydrating food for space and convenience. Dehydrated foods take up less space than freeze-dried foods. That's because water is the heaviest part of food, so when it's evaporated the weight of the food is drastically decreased [source: Wild Backpacker]. Also it's easier and less costly to do it yourself than is freeze-drying.
However, more campers choose to purchase freeze-dried foods over purchasing dehydrated foods for one reason: freeze-dried food simply tastes better. Campers will need to cook and season dehydrated foods while camping on-site because they tend to lose their taste and texture through the dehydration process. Also, you can only dehydrate a single ingredient like rice while you can freeze-dry a whole entree, like a pasta casserole.
When you dehydrate food or dry food as it is often called, you are simply removing the water from it and preventing enzymes and bacteria from growing by circulating hot, dry air through the food [source: The Dry Store]. For years, people have dehydrated their foods using a variety of methods including air drying or putting food out in the sun.
However, you have to make sure that you have several sunny, low-humid days of at least 86 degrees Fahrenheit (30 degrees Celsius) in a row. You'll know the food is dry when it feels like leather, and you won't be able to spot a drop of water. A tip: it's not recommended to dry vegetables and meats in the sun because they are prone to spoil. After they dry, make sure the food is cool before putting them in glass jars, metal cans or freezer containers with tight lids [source: All Things Emergency Prepared].
You can also use an electric food dehydrator or an oven to dry foods, and this is particularly good for fruits and vegetables. Place them (washed and dried) on dehydrator trays and set the temperature to 140 degrees Fahrenheit (60 degrees Celsius). The process usually takes about eight to 12 hours. Check the food toward the end of the drying process. If the food feels dry when you touch it, then it's ready.