It's possible to dehydrate vegetables, fruits, meats, herbs and even prepared meals. Drying is simple, safe and it offers delicious and lightweight options for campers, food gardeners or anyone with a surplus of fresh food. Teresa Marrone will help you get started with dehydrating in The Beginner’s Guide to Making and Using Dried Fruits (Storey Publishing, 2014). This excerpt, from Chapter 3, “Equipment,” provides tips and information that will help you get started with sun-drying fruit around your house.
Buy this book from the MOTHER EARTH NEWS store: The Beginner’s Guide to Making and Using Dried Fruits.
Sun-dried fruits are delicious; indeed, most raisins you buy in the store have been sun-dried, and commercial producers also sun-dry apricots, peaches, and other fruits. If you are blessed with clean air, low humidity, and an abundance of hot, sunny days, sun-drying is the least expensive method of dehydrating fruits and leathers. The advantages to sun-drying are obvious. The energy of the sun is absolutely free, requiring no outlay for electricity. There is no investment in equipment and just a handful of other expenses, since all the necessary materials can be assembled at home. Unlike other drying methods, there is no capacity limit in sun-drying. The only limit to the amount of food that can be dried at one time is the number of trays available and space to set them.
For reliable sun-drying at home, daytime temperatures must be 90 degrees F or above and the relative humidity must below 60 percent — the lower, the better. If the temperature is too low, the humidity too high, or both, spoilage will occur before the foods are adequately dry. The Southwest region of the United States has an ideal summer climate for sun-drying, but other regions are not so fortunate; for example, sun-drying should not be attempted in the humid Southeast. Summer conditions in the Northwest, Midwest, and Northeast are better but may still be marginal. Even if your location is marginal, however, you can use the sun when conditions are good, then fall back on a dehydrator or the oven to finish off a batch on those days when a sudden rainstorm or a low cloud ceiling hampers your sun-drying operation.
Although sun-drying vegetables, meats, and fish is a technique that was used for centuries, modern food science tells us that sun-drying at home should be used only for fruits, which are high in natural acids and sugar. (The exception to this is hot chile peppers, which can simply be strung together and hung in the sun.) Instructions are not given in my book, The Beginner’s Guide to Making and Using Dried Foods, for sun-drying vegetables, meats, or fish; should you choose to do so, the basic techniques are the same as those used for fruits. Remember that tomatoes are a fruit — not a vegetable — so they are safe for sun-drying.
To dry fruit in the sun, you’ll need drying trays and something to cover the fruit to protect it from insects and dirt. Baking sheets or homemade wooden trays may be used as drying trays, but drying is much more efficient if air can circulate freely around the fruit. Wooden frames covered with screens or other mesh-type material are a better choice. Many people use window frames that are being removed during remodeling projects; these can be cleaned up and fitted with new screens to use as your drying trays. If the windows date to 1978 or earlier, however, they may be painted with lead-based paint and should not be used unless you can confirm that the paint is lead-free. You can also make simple wooden frames, sealing the wood with food-grade mineral oil for durability.
The weight of the fresh food will cause large screens to sag, so keep openings fairly small — a foot square, or slightly larger — when building frames. For larger openings in existing frames, screw wooden strips into the frames at 2- to 4-inch intervals, or add a network of criss-crossed twine to the frame for additional support, stretching it tightly and stapling it to the frame before adding the screen.
Choosing material for the screens is the most challenging part of building the drying frames. Polypropylene screening sold for use in manufactured dehydrators is the ideal choice, but you’ll probably have to mail-order it; search online for “dehydrator screens” and look for polypropylene that is sold in rolls or rectangular pieces. Material used for replacement window screens is available at any big-box home center and most hardware stores, but not all of it is safe to use for food. Never use aluminum or galvanized screening or hardware cloth; these metals react with acids in fruits and will contaminate your dehydrated products. Nylon, plastic, and stainless steel screens are often available, but it can be hard to determine if they’re food-safe. The National Center for Home Food Preservation at the University of Georgia reports that Teflon-coated fiberglass window screen is safe for use in sun-drying racks; if the Teflon coating gets damaged, however, the fiberglass may shed minute particles, so keep an eye on it. As a final option, you can use a double layer of fine-mesh nylon fabric netting. This inexpensive material is sold by the yard at fabric stores (it is used for crafts, particularly for making “scrubbies” for dishwashing and showering). Nylon netting needs more support than other materials and is a bit more difficult to wash if it is permanently attached to the frames (however, if it’s simply lying on another screen that’s used for support, the netting can be removed and washed in the washing machine).
Stretch your screening material tightly over the frames and staple it in place; if using nylon netting, roll-fold the edges so you’re stapling through a heavier layer. You’ll have to wash the screens with a hose and soft brush after each use, and if you’re not careful you can easily pull out the staples or rip the material. For additional security, nail strips of wooden molding over the edges of the screens.
Because sun-drying takes days rather than hours, the fruit will be exposed to potential bacterial growth for a longer period of time, so pretreating is more important than when drying in a dehydrator.
After pretreating, spread the fruit in a single layer over the drying trays and place them in a well-ventilated spot in full sun. The trays need to be raised off the ground for ventilation and cleanliness; it’s also easier to tend to the trays when they’re not down on the ground. Cement blocks work well as supports; so do benches, sawhorses, or stacked bricks. If you have large sheets of aluminum or tin, lay them on the ground under the raised trays; the sunlight will reflect off the metal and radiate back up to the trays. A concrete surface also provides some radiant heat.
The trays must be covered with a layer of material that lets light and moisture pass through but keeps out insects, twigs, dust, and other unwanted materials. The easiest option is to set another screen-covered tray of the same dimension on top of the one that is holding the fruit; set the top tray upside-down to prevent its screen from touching the fruit. If there are gaps between the frames of the two trays, weight the corners with bricks to keep them pressed together tightly.
Another covering option is to drape open-weave fabric over the entire tray, propping the fabric up so it isn’t resting directly on the fruit and wrapping it around the edges so insects can’t sneak through gaps in the side. Cheesecloth is often recommended for this use, but it can be difficult to work with because it gets caught on rough surfaces, unravels and leaves threads on the fruit, and wads up into a hopeless ball when laundered. Fine-mesh nylon netting discussed above is a better choice; it’s cheap, doesn’t fray, and doesn’t tangle up during washing. If the netting seems too open and insects are able to get through, use a double layer.
Stir or turn the pieces of fruit several times a day to expose all surfaces to the sun. Take the trays inside at night to prevent the fruit from absorbing moisture from dew and to discourage nocturnal critters.
All drying times given for sun-drying specific fruits are rough estimates, since the time required will vary depending on the temperature, the amount of sunshine, the humidity in the air, the amount of air movement, and the amount of moisture in the food. Any time out of the sun, of course, is “down time” and is not included in the drying-time estimates. Sun-dried fruit should always be pasteurized to kill any minute insect eggs that may have been deposited on the fruit while it was outside. Also be sure to wash your drying screens and any fabric you used to cover them.
Tips for Sun-Drying
You may want to try sun-drying a test batch of fruit to see how it works in your area. For a quick and easy setup, use a cake-cooling rack set over a rimmed baking sheet rather than worrying about building a large screen. Place your prepared fruit on the rack, using a screen, cheesecloth, or nylon netting if necessary to keep it from falling through. Wrap cheesecloth or nylon netting over the setup to keep out insects, propping it up with jars, cans, or blocks of wood to prevent it from touching the fruit.
If you do use wooden trays, sand them well and seal them with food-grade mineral oil; also note that the odors of such woods as pine and cedar will transfer to the food being dried on them.
You may be able to buy a used dehydrator that no longer works at a yard sale or online auction site and then use the trays for sun-drying. After adding the fruit, cover the trays with screening material as described above.
If you’re using cheesecloth to cover your drying trays, buy it at a fabric store. The material will be wider than the kind sold in small packages at the supermarket, and it will also cost a lot less per yard.
To intensify the sun’s heat, prop a pane of glass above the drying tray, allowing enough room for adequate ventilation. Take precautions to prevent the glass from getting bumped or knocked off, and remember that the edges may be quite sharp. For even more efficiency, combine the pane setup with the aluminum reflectors mentioned above.
Want to learn more about how to sun-dry specific fruits? Read Dehydrating Plums: What You Need to Know for tips on preparing and drying plums.
Alternative Spaces for Sun-Drying
If you have a greenhouse, solarium, or sun space that isn’t currently filled with plants, you can set up drying trays inside it. The food will be protected from critters, and the clear roof allows plenty of sunlight in. As with all sun drying, if the weather turns cloudy or rainy, you may have to finish drying in a dehydrator or your oven. Some people also put small amounts of food on trays, or even baking sheets, and then place them in the back window of an automobile that won’t be moved for a few days.
Reprinted with permission from The Beginner’s Guide to Making and Using Dried Foods by Teresa Marrone and published by Storey Publishing, 2014. Buy this book from our store: The Beginner’s Guide to Making and Using Dried Foods.