To sterilize a substance or thing is to destroy all life and sources of
life in and about it. In following the brief outline of the structure
and work of bacteria, yeasts, and molds, it has been seen that damage to
foods comes through the growth of these organisms on or in the food;
also that if such organisms are exposed to a temperature of 212° F.,
life will be destroyed, but that spores and a few resisting bacteria are
not destroyed at a temperature of 212° F., unless exposed to it for two
or more hours.
Bacteria and yeasts, which are intimately mixed with food, are not as
easily destroyed as are those on smooth surfaces, such as the utensils
and jars employed in the preparation of the food.
Since air and water, as well as the foods, contain bacteria and yeasts,
and may contain mold spores, all utensils used in the process of
preserving foods are liable to be contaminated with these organisms. For
this reason all appliances, as well as the food, must be sterilized.
Stewpans, spoons, strainers, etc., may be put on the fire in cold or
boiling water and boiled ten or fifteen minutes. Tumblers, bottles,
glass jars, and covers should be put in cold water and heated gradually
to the boiling point, and then boiled for ten or fifteen minutes. The
jars must be taken one at a time from the boiling water at the moment
they are to be filled with the boiling food. The work should be done in
a well swept and dusted room, and the clothing of the workers and the
towels used should be clean. The food to be sterilized should be
perfectly sound and clean.
As in this bulletin we have only to do with fruits, it will not be
necessary to say anything more about long cooking at a high temperature.
In canning fruits it is well to remember that the product is more
satisfactory if heated gradually to the boiling point and then cooked
the given time.