Dehydrating fruit means reducing its moisture with moderate heat, dry air and good circulation. The process slows many forms of spoilage, but it does not sterilize food or by itself guarantee the removal of bacteria or mould.
This guide applies only to fruit. Meat, poultry, fish, vegetables and herbs require specific procedures and must not automatically be processed using these directions.
How to prepare fruit
Choose fresh, fully ripe and sound fruit. Discard any bruised, decayed or mouldy fruit, then wash the sound fruit thoroughly.
Cut pieces to an even thickness. Peeling, pretreatment and size depend on the fruit: use an official fruit-specific table and the appliance instructions.
Arrange pieces in a single layer without overlap so that air can circulate.
Sun-drying fruit
Outdoor drying is not a universal method. The National Center for Home Food Preservation limits it to high-sugar, high-acid fruit when the weather remains hot, dry and breezy.
Use food-safe racks and protect fruit from insects, birds, dust and contamination. Bring it under shelter at night because cool air can add moisture back. If conditions are unsuitable, use an oven or food dehydrator.
Drying fruit in an oven
Colorado State University gives 60 °C (140 °F) as the reference temperature for pretreated fruit in an oven or dehydrator. Check that the oven can hold a low, stable temperature and provide adequate airflow.
There is no universal six-hour duration: the same source ranges from about 6 hours for thin apple slices to 36 hours for peach halves. Fruit, thickness, humidity and equipment all matter.
Do not leave the oven door ajar unless the manufacturer allows it. Turn pieces when required by the selected method and monitor them closely near the end.
Using a food dehydrator
A food dehydrator provides more consistent control of heat and airflow, but it does not make the process automatic or identical for every fruit.
Set temperature, pretreatment and duration according to the appliance manual and a fruit-specific guide. Check regularly and do not decide that drying is complete only because a fixed number of hours has passed.
How to test fruit for dryness
Cool a few pieces to room temperature before testing: warm fruit feels softer and moister than it really is.
Fruit should generally be pliable and leathery with no visible moist pockets; it should leave no moisture on the hand and pieces should spring apart. The exact test depends on the fruit.
Conditioning and storage
After cooling, loosely place the fruit in clean, dry containers and close them. NCHFP recommends conditioning for 7–10 days, shaking daily and checking for condensation.
If condensation appears, return the fruit to the dehydrator. After conditioning, pack in tightly closed containers and store in a cool, dark and dry place.
Discard fruit with mould, off odours or other signs of spoilage. Drying also causes some nutrient loss, so it is inaccurate to say that every nutritional property remains unchanged.
