of boiling water
(212 deg. F.); but, if the bacteria are spore producers, cooking must be
continued for an hour or more to insure their complete destruction.
Generally speaking, in order to kill the spores the temperature must be
higher than that of boiling water, or the article to be preserved must
be cooked for about two hours at a temperature of 212 deg. F., or a
shorter time at a higher temperature under pressure. Yeasts and their
spores are, however, more easily destroyed by heat than bacteria spores.
Hence, fruits containing little nitrogenous material are more easily
protected from fermentation than nitrogenous foods in which in general
fermentation is caused by bacteria. Of course, it is not possible to
know what kinds of organisms are in the food one is about to can or
bottle; but we do know that most fruits are not favorable to the growth
of bacteria, and, as a rule, the yeasts which grow in fruits and fruit
juice can be destroyed by cooking ten or fifteen minutes at a
temperature of 212 deg. F. If no living organisms are left, and the
sterilization of all appliances has been thorough, there is no reason
why the fruit, if properly sealed, should not keep, with but slight
change of texture or flavor, for a year or longer, although canned
fruits undergo gradual change and deterioration even under the most
favorable conditions.

When fruit is preserved with a large amount of sugar (a pound of sugar
to a pound of fruit) it does not need to be hermetically sealed to
protect it from bacteria and yeasts, because the thick, sugary sirup
formed is not favorable to their growth. However, the self-sealing jars
are much better than keeping such fruit in large receptacles, from which
it is taken as needed, because molds grow freely on moist, sugary
substances exposed to the air.

MOLDS AND MOLDING.

Every housekeeper is familiar with molds which, under favorable
conditions of warmth and moisture, grow upon almost any kind of organic
material. This is seen in damp, warm weather, when molds form in a short
time on all sorts of starchy foods, such as boiled potatoes, bread,
mush, etc., as well as fresh, canned, and preserved fruits.

Molds develop from spores which are always floating about in the air.
When a spore falls upon a substance containing moisture and suitable
food it sends out a fine thread, which branches and works its way over
and into the attacked substance. In a short time spores are produced and
the wo