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Pretreating Fruits
Pretreating is not necessary for most fruits. However, some fruits tend to
oxidize and turn brown more than others. Oxidation can also cause loss in
flavor and vitamins A and C. To reduce oxidation, place fruit in a holding
solution of ascorbic acid before drying. Pineapple, orange, lemon and lime
juice can all be used as a natural pretreatment. Ascorbic acid mixtures,
available from your supermarket, can also be used—follow the package
directions.
Pretreating Vegetables
Some vegetables need to be blanched. Blanching softens the cell structure,
allowing the moisture to escape more easily and also allows vegetables to
rehydrate faster. You can blanch vegetables by steaming them until they
are heated through, but not cooked. Vegetables should still be crunchy.
Drain and place immediately on dryer trays. See preparation guidelines
in the vegetable drying charts.
Drying Time
Drying times may vary, depending on the type and amount of food, thickness
and evenness of the slices, percentage of water in the food, humidity,
temperature of the air and the altitude. Drying times may also vary greatly
from one area of the country to another and from day-to-day, depending on
the climatic conditions. Record keeping helps you predict future drying times
for specific foods.
Testing For Dryness
Food must be carefully monitored near the end of the dehydration process
to prevent over drying. Over dried foods lose quality in texture, nutrition and
taste. To test for dryness, remove a piece of food, allow it to cool, and feel
with your fingers to determine dryness:
• Fruits should be pliable and leathery with no pockets of moisture. To
check if fruit is dry, tear a piece in half and watch for moisture beads
along the tear. If there aren’t any, it is sufficiently dry for long term storage.
• Fruit roll-ups should be leathery with no sticky spots.
• Jerky should be tough but not brittle.
• Dried fish should be tough. If the fish is high in fat, it may appear moist
due to the high oil content.
• Vegetables should be tough or crisp.
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