Fig. 11. Commercial drier with furnace.
The use of an electric fan is an effective means of Drying.
Fig. 15 shows how this household article is used. A motor fan run by
kerosene or alcohol serves the same purpose. Sliced vegetables or fruits are
placed on trays and the fan placed close to one end of the box holding the
trays, with the current directed along the trays, lengthwise. Insects must
be kept out by the use of cheesecloth or similar material. Drying by this
process may be done in twenty-four hours or less. With sliced string beans
and shredded sweet potatoes a few hours are sufficient, if the air is dry.
Rearrange the trays after a few hours, as the drying will be more rapid
nearest the fan.
As artificial heat is not used in fan drying it is important to
blanch or steam the vegetables for the full specified time. It is also
necessary that all fan-dried products be heated in an oven to 180°
F. for 10 or 15 minutes before storing.
DETAILS OF DRYING
As a general rule vegetables or
fruits, for Drying, must be cut into slices or shreds, with the skin
removed. In using artificial heat be careful to start at a comparatively low
temperature and gradually increase. Details as to the proper scale of
temperatures for various vegetables and fruits are given in the directions
in this Manual and in the timetable on page 28. To be able to gauge the heat
accurately a thermometer must be used. An oven thermometer may be bought at
slight cost. If the thermometer is placed in a glass of salad oil the true
temperature of the oven may be obtained.
Fig. 12. Simple tray drier made at home.
In the detailed instructions on pages
27 and 28, the
temperatures used are Fahrenheit. The temperatures indicated are for Drying
by artificial heat.
The actual time required for Drying cannot be given, and the
person in charge must exercise judgment on this point. A little experience
will make it easy to determine when products are sufficiently dried. When
first taken from the Drier vegetables should be rather brittle, and fruits
rather leathery and pliable. One method of determining whether fruit is dry
enough is to squeeze a handful, if the fruit separates when the hand is
opened, it is dry enough. Another way is to press a single piece; if no
moisture comes to the surface the piece is sufficiently dry. Berries are dry
enough if they stick to the hand but do not crush when squeezed.
Fig. 13. Electric range, useful for drying.
A sharp kitchen knife will serve every
purpose in slicing and cutting vegetables and fruits for Drying if no other
device is at hand. The thickness of the slices should be from an eighth to a
quarter of an inch. Whether sliced or cut into strips the pieces should be
small so as to dry quickly. They should not, however, be so small as to make
them hard to handle or to keep them from being used to advantage in
preparing dishes for the table such as would be prepared from fresh
Food choppers, crout slicers or rotary slicers may be used to
prepare food for drying.
Vegetables and fruits for Drying should be fresh, mature and in
prime condition for eating. As a general rule vegetables will dry better if
cut into small pieces with the skins removed. Berries are dried whole.
Apples, quinces, peaches and pears dry better if cut into rings or quarters.
Cleanliness is imperative. Knives and slicing devices must be carefully
cleansed before and after use. A knife that is not bright and clean will
discolor the product on which it is used and this should be avoided.
Fig. 14. Motor-fan, run by kerosene or alcohol.