Drying and Dehydrating

Heat and air

Drying preserves food by removing the water that molds and bacteria need; it also slows the food’s own enzymes ¹. Two things do the work: gentle heat and moving air.

Drying works best at about 140 °F. Much hotter and the food starts to cook instead of dry ¹; the outside hardens and traps water inside, which is called case hardening, and those pieces can mold later.

Equipment

• Electric dehydrator: trays, a heater, and a fan. Both horizontal (rear-fan) and vertical (stacked) types work ¹. Rotate trays if drying is uneven.
• Oven: only if it holds 140 °F. Prop the door open a little and set a fan blowing at the gap ¹. Good for an occasional small batch.
• Microwave: only for herbs ¹.
• Sun drying: acceptable for fruit only, not vegetables or meat, and hard to control; sun-dried food has to be pasteurized against insects ¹. In Wisconsin’s humid summers it’s rarely reliable.
• Air drying indoors: bundles of hot peppers and herbs hung in a ventilated room, loosely covered with a perforated paper bag against dust ¹.

Pretreating

Fruits that brown (apples, pears, bananas) look and keep better pretreated, soaked 10 minutes then drained ¹:

• ascorbic acid (vitamin C), 2-1/2 tablespoons per quart of cold water; or
• citric acid, 1 teaspoon per quart; or
• lemon juice and cold water, half and half.

Small fruits with skins (grapes, cherries, blueberries): dip in boiling water 30 to 60 seconds to crack the skins, chill in cold water, and dry on a cloth ¹.

Vegetables: most are blanched first in boiling water, which softens cell walls and helps drying: carrots 4 minutes, potatoes 7. Chill in cold water and drain before drying ¹.

Is it done?

• Fruit: about 20 percent moisture: pliable but not sticky. Fold a piece; it shouldn’t stick to itself, and you can’t squeeze out moisture ¹.
• Vegetables: about 10 percent: brittle or crisp ¹.

Times vary from hours to more than a day with the food, the slice thickness, and the humidity; even, thin slices (about 1/4 in.) dry together.

Conditioning and storage

Pieces dry at different rates, so fruit gets conditioned ¹:

1. Let it cool.
2. Pack it loosely into clean jars or covered containers, and close them.
3. Leave at room temperature 7 to 10 days, shaking daily.
4. If condensation appears, back into the dehydrator it goes.

Then store dried food airtight, in a cool, dark place; the freezer extends storage further.

Venison jerky

Jerky is dried meat, and it needs one extra step for safety, since a dehydrator’s 140 °F doesn’t reliably kill pathogens in meat. Heat it to 160 °F, either ¹:

• Before drying: bring the strips to a boil in their marinade and boil 5 minutes (longer for strips over 1/4 in.), check with a thermometer, drain, and dry; or
• After drying: heat the dried strips on a baking sheet in a 275 °F oven for 10 minutes.

Use lean meat (trim venison fat, which goes rancid), slice 1/4 in. thick, and dry until a piece cracks but doesn’t break when bent. Jerky keeps about two weeks at room temperature; refrigerate or freeze the rest ¹. Illinois’s basic marinade for 1-1/2 to 2 lb of meat: 1/4 cup soy sauce, 1 tablespoon Worcestershire, 1/4 teaspoon each black pepper and garlic powder, 1/2 teaspoon onion powder, 1 teaspoon hickory-smoked salt, 1-2 hours or overnight in the refrigerator ¹.

Try it

Dry a dehydrator load of apples: half pretreated with ascorbic acid, half untreated. Dry at 140 °F until pliable, condition in jars for a week, and compare color and texture a month later.

What to take from this

Dry at about 140 °F with moving air; hotter case-hardens food. Use a dehydrator or a 140 °F oven with the door ajar and a fan; sun-dry only fruit. Pretreat browning fruit 10 minutes in ascorbic acid (2-1/2 Tbsp per quart), crack skins on grapes and cherries, and blanch vegetables. Fruit is done pliable and not sticky (about 20%), vegetables brittle (about 10%). Condition fruit in closed jars 7-10 days. Heat jerky to 160 °F before drying or for 10 minutes at 275 °F after.