Fruits impart palatability and flavour to other foods and exercise a
favourable influence upon the digestive organs, though their food
value is low. They contain a high percentage of water and only a small
percentage of nutrients. Most fruits are eaten raw and are exceedingly
valuable to the body because of the fresh acids they contain. Cooking
softens the cellulose of the fruit and, therefore, renders some fruits
more easy of digestion. The cooking of fruit is of value chiefly for the
purpose of preservation.
_The drying of fruits._--Fruits are dried so that they may be preserved
for use. Bacteria and moulds, which cause the decay of fruits, need
moisture for development and growth. If the moisture is evaporated, the
fruits will keep almost indefinitely. Fruits and vegetables can be
easily and inexpensively dried. When dried fruits are to be used for the
table, they must be washed thoroughly and soaked for several hours, or
overnight, in water, so as to restore to them as much water as possible.
They should be cooked, until soft, in the same water in which they are
soaked.
_Canning and preserving._--Other methods of preservation are desirable,
in order that vegetables and fruits be made of value for a longer period
of time than through their ripening season. Canning is one of the
methods most commonly employed in the home, being both easy and
satisfactory. Fruit which is to be canned is first sterilized by boiling
or steaming, in order to destroy all germs and spores. This can be
adequately accomplished by boiling for twenty minutes, but a shorter
time is sometimes sufficient. In order to ensure complete success, all
germs must also be destroyed on the cans and on everything which comes
in contact with the food. This will be effected by boiling or steaming
for twenty minutes. The jars, covers, dipper, and funnel should all be
placed in cold water, heated until the water comes to the
boiling-point, boiled five minutes, and left in the water until just
before sealing. As for the rubbers, it will be sufficient to dip them
into the boiling water. After the fruit has been put into the can, it
must be sealed so that it is perfectly air-tight. In order to do this,
it is necessary to have good covers, with new, pliable rubbers, and to
see to it that they fit tightly.
When the jar is to be filled, it should be placed on a board or wooden
table, or on a cloth wrung out of hot water, and should be filled to
overflowing.
Sugar is not essential to sterilization and is used only to improve the
flavour. Both fruits and vegetables can be canned without sugar.
However, fruits canned with a large amount of sugar do not spoil
readily, for germs develop slowly in a thick syrup.
_Methods of canning._--The simplest method of canning is the
"Open-kettle Method" employed for small, watery fruits, such as berries,
grapes, tomatoes, etc. The fruit is boiled in an open kettle (which
permits of the evaporation of some of the water in the fruit) and
transferred at once to a sterilized jar, which is immediately sealed.
Another and safer method, which secures more complete sterilization
without serious change of flavour in the fruit, is that known as the
"Cold-pack Method". After being transferred to the cans, the vegetable
or fruit is subjected to an additional period of heating of considerable
length, or to three periods of briefer length on three successive days.
If the three periods of sterilization are used, the process is known as
the "Intermittent Method".
The Single Process Method is described in the recipe for canned beets.
The Intermittent Process proves more satisfactory for canned beans.