Drying fruit and vegetables at home: temperatures, prep, and storage

Drying works by removing enough water that bacteria, yeasts, and moulds cannot grow. Good results come from three things: steady low heat, moving air, and thin, even pieces.

Equipment

Electric dehydrator (best): a thermostat and a fan give even results.
Oven: possible if it holds 140°F; prop the door open a few inches for airflow, and expect drying to take longer and cost more energy. Keep children and pets away from an open, hot oven.
Sun drying needs several days of hot (85°F or more), dry weather and low humidity. It suits fruit in arid climates but is not recommended for vegetables.

Preparing fruit

Choose ripe, unblemished fruit. Overripe fruit makes good fruit leather instead.
Wash, peel if you like, and cut into even slices 1/4 to 1/2 inch thick.
Pretreat light-coloured fruit (apples, pears, peaches, apricots, bananas) to slow browning and vitamin loss. A common method is soaking for 10 minutes in 1 tablespoon ascorbic acid (vitamin C) powder dissolved in 1 quart of water.
Crack the skins of whole berries, grapes, and cherries by dipping them in boiling water for 30 to 60 seconds, then chilling. Waxy skins otherwise trap moisture.

Preparing vegetables

Most vegetables should be blanched (briefly boiled or steamed, then cooled) before drying. Blanching stops the enzymes that cause off-flavours and colour loss and shortens drying time. Onions, peppers, mushrooms, and tomatoes are commonly dried without it.

Drying and testing

Dry at about 140°F (60°C). Start a little higher if your dehydrator's manual recommends it for fruit, then lower to finish. Do not raise the heat to speed things up: the outside hardens (case hardening) and traps moisture inside.

Food type	Dry until	Typical final moisture
Fruit	Leathery and pliable, no moisture when cut	About 15 to 20%
Vegetables	Brittle or crisp	About 10% or less
Herbs	Leaves crumble	Very low

Test a few cooled pieces, as warm food feels softer than it is. The yield calculator estimates how much weight to expect.

Conditioning dried fruit

Pieces from the same batch dry unevenly. To even them out, pack cooled fruit loosely in a glass jar about two-thirds full, seal, and shake daily for 4 to 10 days. If droplets form inside the jar, return the fruit to the dehydrator.

Making fruit leather

Purée fruit, sweeten lightly if you like, and spread 1/8 inch thick on lined trays. Dry at 140°F until the centre is no longer sticky. Roll in plastic wrap to store.

Storage

Store dried food in airtight glass jars or freezer bags with the air pressed out, in a cool, dark, dry place. Most dried fruit keeps best quality for about a year at 60°F and about six months at 80°F; dried vegetables keep about half as long as fruit. Freezing extends both.

Check jars for moisture or mould now and then, and discard anything that looks or smells wrong. Find temperatures and prep for each food in the drying chart.

Food safety note. This guide summarises published USDA and NCHFP guidance. When in doubt, follow the source, and throw out food that looks, smells, or tastes wrong.