Preparing Fruit for Dehydration

Pretreatment Methods from Acid Dips to Checking

Many fruits, especially apples, peaches, and pears, tend to darken during drying and storage. Pretreating preserves color. Pretreating by the steam blanch method also decreases loss of vitamins A and C and minimizes microbial spoilage and insect infestation. Figs and berries do not need pretreating unless you prefer to maintain color brightness. However, some berries need the extra step of checking (see below). These methods have all been tested by the US National Center for Home Food Preservation (NCHFP).

If using a frozen grocery store variety, pretreatment steps are not necessary as the fruit has already been pretreated before being frozen.

If you are preparing fresh fruit, Clean Your Produce before moving to one of these methods.

Ascorbic Acid/Vitamin C Method

Vitamin CAscorbic acid is the same as vitamin C. Volume for volume, it is the most effective of the pretreatment solutions. You can buy pure crystalline ascorbic acid or vitamin C tablets at grocery stores, drug stores, discount department stores, and some natural-food stores. Vitamin C tablets are finely crushed before mixing with water. Ascorbic acid is used most often with apples, peaches, apricots, nectarines, and pears. For apples, use 1 tablespoon of pure crystalline ascorbic acid for each cup of cold water. For peaches, apricots, nectarines, and pears, use 1-1/2 teaspoons for each cup of water. One cup of the solution will treat about 5 quarts of cut fruit. Sprinkle it over the fruit as it is peeled, pitted, cored, or sliced. Turn pieces over gently and sprinkle all sides to make sure each is coated thoroughly.


Citric Acid Method

Citric AcidIt takes three times as much citric acid as ascorbic acid for the same amount of fruit. Mix 1/4 cup of citric acid to each quart of cold water. Soak prepared fruit about 15 to 30 minutes. Drain well.


Lemon Juice Method

Lemon JuiceIt takes six times as much lemon juice as ascorbic acid to pretreat the fruit. Mix 1 to 1-1/2 cups of lemon juice to each quart of water. Soak prepared fruit about 15 to 30 minutes. Drain well.

I actually prefer to fill a mister bottle with straight lemon juice and spray the fruit as I am loading it on the dehydrator trays. This works well for me, especially in the case of bananas. Bananas get too soft if I soak them in an acid bath, so I prefer just to spray them on all sides.


Salt Solution Method

SaltPrepare a solution of 2 to 4 tablespoons of salt to 1 gallon of hot water. Stir the water until all the salt is dissolved. Allow the salt water to cool to room temperature. Soak the fruit 15 to 30 minutes; drain well.


Commercial Color Preservers

Fruit FreshThese mixtures contain crystalline ascorbic acid and sugar, or ascorbic acid, sugar, and citric acid. They are sold under various trade names like Ball® Fruit Fresh™ and Mrs. Wages® Fresh Fruit Preserver.

They are not as effective, volume for volume, as plain ascorbic acid, but they are readily available and easy to use. Follow the manufacturer’s instructions to process all your produce for greatest success.


Steam Blanch Method

Steam BlanchingWater blanching gives fruit a cooked flavor, so it is not generally recommended. Steam blanching does not give a cooked flavor. To steam blanch, put 1-1/2 to 2 inches of water in a double boiler or large pot; let water come to a boil. Place fruit loosely, not more than 1 inch deep, into the top of the double boiler or a colander or basket. Put it into the boiler, above the water, and cover with a tight-fitting lid. Follow directions in the chart below for the length of time required to blanch. When blanching time is up, immediately plunge the fruit into ice water for a rapid cool-down.

Steam Blanch Chart


“Checking” Fruits

Some fruits, like blueberries, grapes, and1-cranblues cranberries, need special consideration because of their thick skins. This is “checking” or “crazing”. To prepare these fruits, you may have three options.

  1. Dip the fresh fruit into boiling water for 90 seconds or until all the skins crack open and remove, instantly cooling in a cold water bath. Do a small amount at a time and only remove each berry after it cracks open. The point is to crack all of them. Dry the fruit before placing in the dehydrator on a tray.
  2. The fruit is pierced by a sharp needle, chopstick, ice pick, or onion holder. Make sure you pierce each one all the way through. Here is an excellent YouTube video by Christine Dresselhaus showing how to achieve this quickly and easily. Those that are not pierced will have no quick way to lose their water content – and therefore dehydrate slowly with a risk of case hardening. This is my preferred way of doing these fruits which I have found most successful.
  3. The fresh fruit is frozen before dehydrating. Make sure the fruit is thoroughly frozen (at least overnight) before removing, thawing, and rinsing. Dry the fruit before placing in the dehydrator on a tray.

You can opt to skip one of these methods if you cut the berries in half before drying. Place the berries in a single layer on the dehydrator tray with the skin side down.


Citrus Fruits

Photo credit: Dee Cee, Dehydrated tangerine

Photo credit: Dee Cee, Dehydrated tangerine

Citrus fruit (i.e., lemons, limes, oranges, and grapefruit) does not require pretreatment. However, many experience darkening of these fruits when dehydrating and/or storing. We have an article with a fix for that problem here. Lower temperatures for citrus, especially lemons, is necessary to help with this challenge.

Also, it is important to store citrus in an airtight container in a dark, cool place to prevent darkening during storage. Please note: this browning is not a sign of spoilage, but partly due to darkening of the sugars in the citrus. There really is no discernible taste difference and when you add the citrus to liquid they do lighten up again.


Roasting Fruit

Roasting concentrates a fruit’s natural sugars, deepening the flavor of the fruit and making under-ripe specimens sweeter. If you have a large crop of stone fruit like peaches, apricots, nectarines, cherries, or plums, this is a great recipe to make. Figs, grapes, apples, pears, quinces, and persimmons also all make excellent roasting candidates.

The Roasting procedure is described in this article: Roasted Peach Fruit Leather (Roll-ups).

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