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SET UP & USE
PRETREATING
Enzymes in fruit and vegetables are responsible for color and fl avor changes during
ripening. These changes will continue during drying and storage unless the produce
is pretreated to slow down enzyme activity.
Blanching can be used in the pretreatment of vegetables, as it helps set color and
hastens drying by relaxing tissues. Blanching may also prevent undesirable changes
in fl avor during storage, and improve reconstitution during cooking.
Many light-colored fruits (especially apples, apricots, peaches, nectarines, and pears)
tend to darken during drying and storage. To prevent this darkening, the fruit may
be pretreated by blanching or by a suitable dip, but effectiveness of pretreatment
methods varies.
Fruits may be dipped in one of the following:
• Pineapple or lemon juice as a natural alternative to other pretreatments to reduce
browning. Slice fruit directly into juice. Remove promptly (about 2 minutes) and
place on trays. Fruits may also be dipped in honey, spices, lime or orange juice, or
sprinkled with coconut to give them a snappy dried flavor. Use your imagination
and make your own fl avorful dip.
• Sodium Bisulfi te: Ask for food safe, (USP) grade only. Dissolve 1 teaspoon of
sodium bisulfi te in one quart of water. Prepare small amounts of fruit and dip for 2
minutes in the solution. This helps prevent loss of Vitamin C and maintains a bright
color. Sodium bisulfite may be obtained from a local pharmacy.
• A solution of table salt.
• A solution of ascorbic acid or citric acid. Commercial antioxidant mixtures
containing ascorbic acid may also be used, but often are not as effective as pure
ascorbic acid.
Fruits may be steam-blanched. However, blanched fruits may turn soft and become
difficult to handle.
Syrup blanching may help retain the color of apples, apricots, fi gs, nectarines,
peaches, pears and plums. A sweetened candied product will result.
Fruits with tough skins (grapes, prunes and small dark plums, cherries, fi gs and some
berries) may be water-blanched to crack the skins. This will allow moisture inside to
surface more readily during drying.
Before drying pretreated food, remove any excess moisture by placing the food on
paper towels or clean cloths. Drying trays should be loaded with a thin layer of food
as directed. If needed, clean cheesecloth can be spread on the trays to prevent food
pieces from sticking or falling through.
The amount of food being dried at one time should not exceed roughly 3/4 of each
tray‘s surface area and a 1/4“ thick.
