Preserving Summer Produce with Dehydration
Posted Aug 7, 2012
Practically anyone can find satisfaction in a day of drying fruits and vegetables. This has nothing to do with cooking skill; rather, with temperament.
Folks who love to putter at home will find that once they prep the produce, they'll be left with hours for gardening, good books or crafting, with only the occasional check on the food to interrupt. Multitaskers, on the other hand, will have a chunk of time to tackle loads of laundry or a week's worth of cooking. Food drying even accommodates trips to the supermarket or several hours of errands.
As for skill, it's mostly common sense, said more than one expert.
"It's not such an exacting science," said Ken Love, a certified food preservation instructor.
Nutritionist Joannie Dobbs, who's long been dehydrating food, agrees. "It is a relatively simple process," she said.
Drying is the oldest form of food preservation, going back some 12,000 years, said Love, to "when people had to save food to wander around until they could find a place to grow food."
A big bonus is that most of the nutritional content of dried food is retained.
Dried produce can be eaten as is for a healthful, preservative-free snack or reconstituted and treated as fresh. Dried vegetables are often added to soups or stews.
The most obvious way to dry food is to set it out in the sun and wind. Dobbs said that when she lived in the African bush, she would wrap her food in cheesecloth and screen and hang it on a clothesline in the direct sun.
Hawaii's mild, sunny weather makes it a great place to set out dry boxes. Other means include an oven or a dehydrator.
Love said he used his mom's oven as a boy. "I'd set it on its lowest temperature and leave the door open 1 inch."
The recommended temperature for drying food is 140 degrees, as heat beyond 150 or 160 degrees will cook (and burn) food rather than dry it. Because ovens use lots of energy and the drying process usually takes twice as long in an oven as in a dehydrator, cost is relatively high.
But if the oven is the appliance of choice, keep the oven door open several inches and place a fan near the door to move the air. Drying requires both heat and air circulation. Use a kitchen thermometer to monitor temperature.
Love's recommendation, however: "Go buy the cheapest dehydrator you can find."
Once you've got the appliance, advice centers more on guidelines than specific directions.
Case in point: How long will dehydrated produce last?
"That depends on environmental moisture, which can vary dramatically," said Dobbs. "I used to keep dried fruit in a can with crackers because the moisture was soaked up by the crackers. Some fruit can last two years in the refrigerator. It also depends on things like cleanliness."
"Listen, you cannot leave this stuff in a car for a week," because there are no preservatives, Love said.
"If it's moldy or has a rancid taste or bad smell -- if something is funny -- just don't take a chance. It's better to be safe than sorry."
Both recommend a container with a tight seal or, to maximize shelf life, vacuum-sealing the food in bags and then refrigerating or freezing.
Love said you can dry almost anything, and that's one of the best reasons for taking on the task.
"You can dry things that you don't commonly see in a store," he said. "Lots of times, dehydration brings out the sugar in fruit, so stuff like kumquat, lychee and longan are amazingly sweet. Try slicing a lemon and drying the disks. They're incredible."
DRY IT YOURSELF
--Select healthy produce in good condition. Bruised items are already spoiling, and enzymes and gases will continue the process. They will not dry evenly or keep well.
--Wash and peel produce if necessary. Slice; be consistent in thickness so drying time is consistent. Food preservation instructor Ken Love recommends slicing no thicker than 1/4 inch.
--Produce must be "pretreated." For fruit this means dipping slices in lemon or other citrus juice to prevent darkening. All but a few vegetables must be blanched or steam-blanched, which deactivates enzymes that lead to spoilage.
--Season produce if desired. Sprinkle fruit with li hing powder. On veggies, try different salts, garlic powder or nutritional yeast.
--Place food in single layer on baking sheet or dehydrator rack. Check periodically. After one or two hours, if slices are easily lifted from the rack, turn them over. Switch positions of sheets or racks as lower racks dry at a different rate than higher ones. Food dries faster at the end of the drying time, so check more often then.
--Doneness in fruit: Fruit feels softer and less dry when warm, so cool before testing. Fruit should be between chewy and crispy, with a leathery texture. Sufficiently dried fruit will have no visible moisture when cut and squeezed, and a handful should fall apart when squeezed and released. High-sugar fruits such as mango, pineapple, figs and cherries will feel slightly sticky.
--Doneness in vegetables: Most are brittle or crisp when properly dried. Some vegetables will shatter if hit with a hammer.
--Storing dried fruit: Dried fruit must be "conditioned" to equalize any remaining moisture, which reduces the risk of mold. Pack fruit loosely, about 2/3 full, in plastic or glass container with a tight seal. Let it stand for a week to 10 days, shaking the container daily to separate pieces. If condensation appears, return fruit to the dehydrator.
--Fruit leathers: Puree fruit until smooth, adding 2 teaspoons lemon juice and honey or sugar if desired. Line dehydrator rack with plastic wrap, or line cookie sheet, and spread puree evenly to a thickness of 1/8 inch. If you like, add spices, flavorings or garnishes, such as cinnamon, ginger, citrus peel, vanilla extract, shredded coconut, chopped nuts or seeds. Drying time in dehydrator ranges from 6 to 8 hours, up to 18 hours in oven and 1 to 2 days in the sun.
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