Carol W. Costenbader - Food Drying Techniques

Carol Costenbader

Drying was one of the earliest methods of preservation humans found to save food from times of bounty to use when food was scarce. As far back as pre-biblical times, fishermen dried and smoked fish, and farmers dried olives and dates in the hot, dry climate of the Middle East.

Drying is by far the simplest and most natural way of preserving food. Little in the way of equipment is needed, but climate is everything. If you are fortunate enough to live in a warm, dry region, all you need is fresh food and a little time. The faster food can dry without actually cooking, the better its flavor will be when its reconstituted. If you live in a relatively moist climate, you will want to learn to use a more active drying method a dehydrator, your oven, or in some cases the sun. As always, the finished product will be only as good as the original, so start with the very best fresh food.

The concept of drying food is quite simple. When all the moisture is removed from the food, the growth of organisms that spoil food is stopped. Bacteria, mold, and yeasts can be supported only in an environment that has adequate water for them to grow. Properly dried fruits have about 80 percent of the water removed, and properly dried vegetables have about 90 percent of the water removed. Thus you can count on keeping your home-dried foods for six months to two years, depending on the storage temperature (see chart on pages 1819). Remember that cooler storage temperatures are better. Food kept at 70F does not keep as long as food stored at 52F.

Use only blemish-free fruits and vegetables. Fruit should be fully ripe but not overly ripe. (Save overly ripe fruit for sauces or for making fruit leathers; see pages 1112.) The smaller the piece of food to dry, the less time it will take to dry properly. Try to keep all the pieces about the same size, so each piece will dry at the same rate.

Proper blanching, which heats the food without actually cooking it, deactivates the enzymes that cause food spoilage. For use in the drying process, steam-blanching is the only method recommended for vegetables.

The method of dipping produce in boiling water, used in many areas of the world, is not recommended because it adds more water to the produce and therefore increases drying time. Because the food is heated longer and at a hotter temperature, it also robs the food of nutrients and does not fully protect the produce from spoilage organisms. If you must boil fruits and vegetables, use about 3 gallons of water to every 1 quart of food, drain and chill the pieces in ice water to stop the cooking and then pat dry.

To steam-blanch, place produce in a steamer basket in a pan over at least 2 inches of water.

To cool, pour produce into an ice-water bath. When cool, transfer to a towel to dry.

To blanch using the steam method, youll need a steamer, a large Dutch oven, or your canner with lid. Use a wire basket with legs, a basket that fits in the top of the pot, or a colander that will allow 2 or more inches of water to boil without touching the produce. Steam 1 minute longer than the time given if you live 5,000 feet or more above sea level (see chart on pages 1819 for steaming times). After blanching, drain the food, then chill in ice water to stop the cooking. Drain again and dry on towels.

Blanching can be done in a microwave oven, but only in small quantities. Wattages vary, so consult the manufacturers instructions.

To improve the chances for good color retention, dip the fruit slices in a prepared solution (see dipping chart on page 4). This is only partially effective, however. Steam-blanching for both fruits and vegetables is still the best way.

For decades, many people used sulfur to pretreat dried fruits to preserve color. Fruit pretreated with sulfur must be dried by the sun method. Sulfuring of fruits is not a good practice for use with a home dehydrator.

While sulfuring preserves the color and vitamin C of many fruits, it may cause allergies or asthma. Sulfur is now banned as a preservative for produce in supermarkets and in restaurant salad bars.

Drying meat and produce involves the simple process of exposing the food to mild heat and moving air. This can be done by placing food in the sun, in a dehydrator, in the open air, or in an oven.

The process of air-drying is very similar to sun-drying. Puffs of dry air circulate around the food, absorb the moisture, and carry it away. Keep the food out of direct sun to prevent loss of color.

Try air-drying steam-blanched green beans by stringing them on a cotton thread and hanging them under the eaves of the house or porch or in a well-ventilated attic. Depending on the conditions, in two or three days you will have dried, pliable leather britches, great for adding to soups. Bring the beans inside at night to prevent dew from collecting on them. Keep them out of direst sun: It will make them lose all color.

To dry mushrooms, first thread them onto a clean string.

To dry mushrooms, wipe them clean, string using a needle and thread, and hang in an airy location. Or you can place clean mushrooms on several thicknesses of newspaper; turn them several times as the day progresses, and change the newspapers as moisture is absorbed. Place the mushrooms in a dry, airy spot (in direct sun if you wish, but dont forget to bring them in at night.) In one or two days the mushrooms will be almost brittle.

After the drying process, both the green beans and the mushrooms must be heated in a 175F oven for 30 minutes to destroy insect eggs. Condition the produce (see Post-Drying Methods, page 9) and then store in a cool, dry place for up to six months.

Because sun-drying takes more time, pretreating the produce by blanching or another method is much more important. The ideal temperature is about 100F with low humidity. If you are blessed with a climate like that, do try sun-drying. In other climates, use caution. Low temperature and high humidity is the perfect combination for spoilage to occur before drying can be accomplished.

Staple cheesecloth or fabric to a picture frame to make a good drying frame.

Sun-Drying Equipment. To make sun-drying equipment, I like to use old picture frames purchased from flea markets. First, clean the frames with a cloth dampened with soap and water. Then seal the frames with mineral oil. Stretch a clean, 100 percent cotton sheet or cheesecloth over a frame and secure with a stapler. Some people use screens from their windows. This is fine, but dont use a screen with galvanized wire as it can impart off-flavors to the food. Arrange the prepared produce on the cloth, then place the frames in direct sun, bracing them so that air can circulate on all sides. (Bring them in at night to prevent dew from collecting on them.) You can turn the produce over halfway through the drying process (after about two days). In about two to four days you will have leathery but pliable produce. This is great for sun-dried tomatoes.