University of Vermont
Department of Plant and Soil Science

gmg logo Fall News Articleline

DRYING APPLES

Dr. Leonard Perry, Horticulture Professor Emeritus
University of Vermont
   
Visiting an orchard, either to buy pre-picked or pick-your-own apples, makes a great fall outing.  Even if you can't visit an orchard, fresh local apples can be found in farmstands, farmers' markets, and many grocers.  Drying is an easy way to stock up on fresh apples, in several forms, to enjoy through the long winter months.
   
Drying is simply removing the water from fruit that food-spoiling microorganisms and enzymes require.  It is one of the simplest, and oldest, means of food preservation.  It is much less precise than canning, allowing more flexibility.  Unlike canning, containers or food storage bags of dried produce can be opened and closed repeatedly.
     
There are three main methods of drying.  Solar drying is just that, using the heat from the sun.  Unless you use the back window ledge of a closed car for 3 or 4 days, this likely wont dry fast enough in the fall.  Oven drying works if your oven can be set below 200 degrees (F), preferably 130 to 150 degrees.  If you plan to dry many fruits or vegetables in this and coming years, you may wish to invest in (or make) a dehydrator.
   
A dehydrator is simply a box unit with many solid mesh shelves (usually plastic) to allow air to flow.  It has a fan and a gentle source of heat that is adjustable on better units.  They are much more efficient than ovens, requiring much less energy and drying in half the time or less, so saving money.  Food from a dehydrator is less brittle, lighter, and more flavorful than that dried in an oven. 
   
Start by choosing ripe fruit, then wash and cut off any blemishes.  Don't oversoak as this will lead to some nutrient loss, and fruits will be water-soaked and take longer to dry.  Peels may be left on, but they may become bitter or discolor upon drying.  Then core, and cut the fruit as you wish into sections or slices.
   
Pre-drying treatments aren't necessary as they are for some vegetables, as fruits have higher levels of sugar and acid that prevent decomposition by enzymes.  However, pretreating can prevent discoloring in some varieties of apples, and can lower loses of flavor and vitamins A and C.  Just realize if you soak apples in a solution, plan on longer times for drying.
   
A common dip for apples is ascorbic (also known as citric) acid, which also increases the vitamin C content.  You can find this commonly among canning supplies in stores.  Follow directions for mixing with water, stir the fruit until evenly coated, then remove after about 5 minutes. If you don't find such a product, you can make your own dip by dissolving three crushed tablets (500-milligram) of vitamin C in a quart of water.  Some use the juice from citrus fruits, but this is weaker and less effective.
   
Another dip that you can use, similar to that used in commercial products, is with sulfite compounds.  Follow directions on products you find for sale for this purpose.  Don't use if you or others who will consume the fruit, particularly those with asthma, are allergic to sulfites,.
   
For sweet fruit, you may wish to pretreat with sugar syrup or honey.  You can use up to one part sugar to 2 parts water, bringing this to a boil.  Add the fruit, simmer for 5 minutes, then drain.  A honey dip, in addition to sweetness, can lessen browning and softening.  Use one part honey to 4 parts water, soak the fruit, then drain well. Obviously these apples will taste of honey.   

Place apple slices or sections in a single layer on trays, and dry until leathery or crisp with no moist centers.  Figure on 6 to 12 hours, but check periodically.  Since some pieces may be drier than others, it is a good idea to "condition" fruits prior to storage.  Fruits have higher moisture than vegetables when dry, so the need to condition them for best storage. This distributes moisture evenly among fruit, minimizing the chance for spoilage, and gives you a check to make sure they are sufficiently dry.
   
To condition apples, as with any fruits, loosely pack the cooled and dried fruit into plastic or glass containers, filling about two-thirds full.  Cover containers tightly, and shake daily for about 2 to 4 days.  This allows moisture from wetter pieces to be absorbed by drier ones.  If water forms on the lid inside, the fruit aren't dry enough and should be placed back in the dehydrator. Place dry and conditioned fruit in containers or freezer bags.  Even if not freezing, the latter are more resistant to moisture than normal plastic bags.  Store in dark, cool and dry, such as an unheated closet or garage, or even a refrigerator if space.
   
Another fun option for apples is to make fruit leathers-- great for small quantities, bruised or overripe fruit, and popular with children.  They can be made from cooked or uncooked fruit.  Wash and prepare fruit as for drying, then if cooking use a double boiler or microwave until fruit are soft, stirring occasionally.
   
Once cooked, or if uncooked once cut into sections or slices, add one tablespoon of lemon or citrus juice per quart of fruit.  Prepare a thick puree, as in a food processor or blender.  You may add spices or sweeteners to taste. Pour the puree onto special trays for this, or else a lightly oiled piece of heavy plastic, spreading to about one-quarter inch thick.  Make sure the tray isn't covered totally with the plastic so air can circulate.
   
Dry until the fruit leather is sticky, about 6 to 8 hours at 140 degrees (F).  If properly dried it will peel away readily from the plastic.  If too dry it will be brittle, but is still edible.  Leave whole, or cut into slices or strips that can be rolled up.  Store cool, dark, and dry in airtight containers as you would for dried fruit.
   
The University of Maine has an excellent series of 13 publications on preserving apples and many other fruits and vegetables, including details of canning (www.umext.maine.edu under the food and health section).     More details on drying apples, and information on drying other fruits and vegetables also can be found in a publication available online from Pacific Northwest Extension (www.cals.uidaho.edu)


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