in drying foods at home is determining if and when the food item is
Judging when food is dry requires experience, but keep in mind that it
is better to overdry than to underdry.
be surprised to find a variety of suggestions for drying methods,
and lengths of time. When in doubt, continue drying for an additional
to 30 minutes, than check for doneness. Allow the product to cool
The length of time needed for drying will depend on the size and
number of pieces dried at one time. Drying fruit can take anywhere from
6 hours for very thin or small pieces such as apple slices or grapes to
10 hours for larger juicy fruits such as peach or apricot halves.
and humidity will also affect the drying time.
The drying process is simply
not as precise as canning and freezing because it involves so many
factors. Vegetables must be dried to about 5 percent water content and
fruits to 15 to 20 percent water content. Dried fruits are stable at a
higher moisture content than dried vegetables because the concentrated
natural sugars and acids in the dried fruit function as preservatives.
dried, allow 30 minutes to one hour cooling time. In general vegetables
are dry when they are brittle, fruits when they feel like leather. Too
long a cooling period allows moisture from the air to re-enter the food.
To determine if
vegetables are dry, remove some pieces near the end of the drying
This time will usually be after a minimum of 6 to 8 hours. Cool the
to room temperature. Vegetables are sufficiently dried when they are
and brittle or tough and leathery, depending on the vegetable. Edges
be sharp. Beans, corn and peas are hard and will shatter when hit with
a hammer. Leafy thin vegetables should be brittle. Larger chunks or
of vegetables should be leather.
To determine if
fruits are dry, remove a piece of fruit during the end of the drying
Cool to room temperature. Fruits are adequately dried when moisture
be squeezed from them. Most fruits will feel leathery and pliable when
properly dried. It should have no pockets of moisture.
Fruit leathers may
be slightly sticky to the touch but separate easily from the plastic
For long term storage, dry leathers until they are no longer sticky.
Herbs are dried
when brittle. Leaves shatter when rubbed together.
Meats should be
extremely dry unless they are to be refrigerated or frozen for
storage. Meat is sufficiently dried when it is dark in color, fibrous,
and forms sharp points when broken.
|Did You Know?
cryodesiccation) is a special dehydration process typically used to
preserve a perishable material or make the material more convenient for
transport. Freeze-drying works by freezing the material and then
reducing the surrounding pressure and adding enough heat to allow the
frozen water in the material to sublime directly from the solid phase
There are three stages in the complete freeze-drying process: freezing,
primary drying, and secondary drying.
If a freeze-dried substance is sealed to prevent the reabsorption of
moisture, the substance may be stored at room temperature without
refrigeration, and be protected against spoilage for many years.
Preservation is possible because the greatly reduced water content
inhibits the action of microorganisms and enzymes that would normally
spoil or degrade the substance.
Freeze-drying also causes less damage to the substance than other
dehydration methods using higher temperatures. Freeze-drying does not
usually cause shrinkage or toughening of the material being dried. In
addition, flavours, smells and nutritional content generally remain
unchanged, making the process popular for preserving food. However,
water is not the only chemical capable of sublimation, and the loss of
other volatile compounds such as acetic acid (vinegar) and alcohols can
yield undesirable results.
Freeze-dried products can be rehydrated (reconstituted) much more
quickly and easily because the process leaves microscopic pores. The
pores are created by the ice crystals that sublimate, leaving gaps or
pores in their place. This is especially important when it comes to
pharmaceutical uses. Lyophilization can also be used to increase the
shelf life of some pharmaceuticals for many years.