Using Your Oven To Dehydrate Food In the Age of Covid-19

You can use your oven to dehydrate some foods.

You can use your oven to dehydrate foods thereby adding to your food security.

Dehydrated foods are compact, require no refrigeration, and store for long periods of time. You can make tasty dishes, snacks, sauces, soups, desserts, gifts, crafts, and more, with your home-dehydrated fruits, veggies, and herbs.

The "pros" of oven dehydrating:

1. It's possible

2. A convection oven has an inbuilt fan. Some even have a dehydration feature!

3. You likely own an oven

The "cons" of oven dehydrating:

1. It's not energy efficient

2. The oven won't hold as much food to dry

3. It will warm up your home

4. Not all ovens have low enough temperature settings

5. You'll have to re-position the food trays to achieve uniform drying

6. This may not be a safe option if you have small children

7. You won't be able to use your oven for at least a day

8. Most fruits take too long to dry by oven

Check that your oven's lowest heat setting can go below 150-degrees, ideally, otherwise you'll likely slow cook it instead of dehydrating it. Many ovens have a "keep warm" feature. Even if your lowest temperature is 200-degrees, the fact that the oven door is left slightly open, will mean that the inside temperature is less than 200. So give it a try and see. Less than ideal, but still possible.

Your oven will likely cycle on and off during the dehydrating process to try to maintain internal temperature when the oven door is slightly open, so not as energy efficient.

You want to keep the oven door slightly open to mitigate moisture which will prevent dehydration. A fan to circulate air means a better dehydration.

Okay let's get started. You'll need:

Some cookie sheets. Old battered ones are fine.

Some cooling racks (the ones used to cool cookies, etc.)

A fan

A chair or stool

Something to hold the oven door ajar

Cookie sheets and cooling rack combinations allow air to reach the underside of foods you're dehydrating.

Air circulation is of paramount importance for dehydration. Without a rack system of some type, as pictured above, you'll have to turn the food periodically.

A chair or stool, and a fan will help with air circulation around the foods your drying.

Position the fan so that it blows into the opening of the oven door as in the photo above.

You'll need something to keep the oven door slightly ajar. A garlic press, lemon reamer, whatever works.

The inbuilt "stop" feature of the oven door leaves too large a gap so most of the heat will escape. You want the oven to be slightly ajar by an inch or two; enough so that air from the fan enters, but most of the heat is still retained inside the oven. Dehydration may take six- to 18-hours, depending on the foods you want to dry.

Some foods need pre-treatment to prevent browning. Apples, pears, peaches, apricots, nectarines, and bananas need this. Although potatoes do need it, too, most other veggies do not. Many veggies will need at least a three minute steam blanching. Steam blanching also means that your dried foods are more tender when re-hydrated.

For that need an anti-browning pre-treatment, a dip in Fruit Fresh or acidulated water (to each pint of water add 1/2 cup lemon or line juice) does the trick. Again most veggies - except potatoes - don't need this.

There are some vegetables that don't need steam blanching. Mushrooms, onions, garlic, frozen vegetables, rhubarb, and most fruits.

I mentioned frozen vegetables. Frozen potatoes need no pre-treatment or steam blanching. Simple thaw and spread evenly over the drying racks. I also buy bags of frozen green beans and corn. My favorite frozen vegetables to dry are thawed packages of mixed veggies containing corn, green beans, diced carrots, and peas...sometimes there's lima beans in the mix also. I thaw them out and spread them over the drying racks. They're handy to tote along on camping trips, or to re-hydrate when I want to make veggie fried rice and don't have any fresh vegetables on hand.

Acidic fruits don't need a pre-treatment. Examples are citrus, pineapple, mangoes, strawberries, rhubarb, berries, and plums.

Foods need to be cut in 1/4-inch slices or cubes. Grapes, strawberries, cherries, cranberries, raspberries should be cut in half for oven drying. You may need to spray or rub a light coating of olive or other cooking oil onto the racks to prevent sticking.

Arrange the foods to be dried in single layers on the racks so they aren't touching. Set them into the oven, set the temperature, arrange your stool/fan combination, turn on the fan.

Every couple of hours or so you'll need to turn the racks 180-degrees and shuffle their positioning to insure even drying. Even so, you may find that the top of the food is drying faster than the bottoms of it. If this is happening use tongs to turn the food over so the bottoms are now better exposed to heat and air.

I used to oven-dry foods before acquiring my dehydrator. The dehydrator is so much more efficient in every way. However, the oven will get you started until you can acquire a dehydrator.

Onions, leeks, shallots, garlic, mushrooms, and peppers are some of the easiest items to oven-dry, and some you'll use most often when you're out of the fresh versions. They dry quickly and on those occasions when I find them on sale, I will still use my oven for the overflow.

When fruits are shrunken, dry, and malleable they should be finished. Low sugar fruits such as cranberries and rhubarb (actually a vegetable used as a fruit) that have little sugar content will tend toward crispness. It's hard to tell if foods are fully dehydrated when they're still hot, so allow them to cool a bit and check for doneness and dryness. They must be dry all the way through.

If your foods aren't dry at day's end you can turn off the oven, leave the foods in overnight, and simply turn on the oven again the next morning. I do this with my dehydrator, too, if I've waited until late afternoon to start it up. It won't harm the fruits or veggies to sit overnight in a cooling oven or dehydrator.

Don't do this with meats. I'm not giving instructions for dehydrating meats with an oven for food safety reasons. If you are adamant to oven-dry meats, the Teresa Marrone book, "Dried Foods" (see my previous post) will tell you how to do so. Dried meats should be refrigerated or frozen or they're likely to go rancid.

Store your dried foods in lidded jars or Ziploc baggies. Potatoes I store in paper bags due to their propensity to mold even if they appear dry.

Your dehydrated foods may need to be re-hydrated before using. My favorite method is to put veggies into a heatproof bowl or cup. Just cover with water then microwave for 30 or more seconds and allow to sit for 30 minutes. The liquid left over is great to use as a flavoring in sautees, soup stocks, or sip as a hot beverage.

If you're making soup, re-hydrated veggies may be sauteed in butter or oil, then added to the mixture for simmering. If a soup or stew is set to simmer for 40 minutes or more, the dried veggies may be added straight to the soup as they will re-hydrate sufficiently during cooking.

For recipes made with dehydrated vegetables that haven't been sauteed first, I like to add a pat of butter or a drizzle of oil before serving to add a mouthfeel of silkiness that only a bit of fat can give.

Dehydrated fruits may be used to make pies, cakes, added to nut mixtures, and eaten as is. Most fruits dehydrate to a sweet flexibility that makes them tasty as snacks with no preparation. Apples, bananas, pears, mangoes, pineapple,and peaches come to mind.

I like to make a muesli using my dehydrated fruits, pan-roasted nuts and seeds, and old-fashioned oatmeal. I take this camping in a Ziploc baggies. It makes a nice breakfast by adding some hot water or milk and letting it soak for about 15 minutes. I also make "overnight oatmeal by putting everything on to soak overnight. Add some hot milk and you have a nearly instant hot and satisfying breakfast.

Adding dehydrated foods to your food security-system is easy, compact to store, and you'll always having something to eat whether camping, traveling, when times get tough, or you run out of a fresh ingredient.