38. Although, as has been explained, the selection and preparation of
foods require much consideration from the housewife who desires to get
good results in cookery, there is still one thing to which she must give
attention if she would keep down the cost of living, and that is the
care of food. Unless food is properly taken care of before it is cooked,
as well as after it is cooked--that is, the left-overs--considerable
loss is liable to result through its spoiling or decaying. Both uncooked
and cooked food may be kept wholesome in several ways, but before these
are discussed it may be well to look into the causes of spoiling. With
these causes understood, the methods of caring for foods will be better
appreciated, and the results in buying, storing, and handling foods will
be more satisfactory.
39. To come to a knowledge of why foods spoil, it will be well to note
that nature abounds in _micro-organisms_, or living things so minute as
to be invisible to the naked eye. These micro-organisms are known to
science as _microbes_ and _germs_, and they are comprised of _bacteria,
yeasts_, and _molds_, a knowledge of which is of the utmost importance
to the physician and the farmer, as well as the housewife. Just in what
ways these are beneficial to the farmer and the physician is beyond the
scope of the subject of cookery, but in the household their influence is
felt in three ways: They are the cause of the decay and spoiling of
foods; they are of value in the preparation of certain foods; and they
are the cause of contagious diseases. It will thus be seen that while
some microbes are undesirable, others exert a beneficial action.
40. It is only within comparatively recent years that the action of
micro-organisms has been understood. It is now definitely known that
these minute living things seize every possible chance to attack
articles of food and produce the changes known as fermentation,
putrefaction, souring, and decay. Micro-organisms that cause
fermentation are necessary in bread making and vinegar making, but they
are destructive to other foods, as, for example, those which are canned
or preserved. Organisms that cause putrefaction are needed in the making
of sauer kraut, salt rising bread, and cheese. Molds also help to make
cheese, but neither these nor putrefactive organisms are desirable for
foods other than those mentioned. It should be remembered, however, that
even those foods which require micro-organisms in their making are
constantly in danger of the attacks of these small living things, for
unless something is done to retard their growth they will cause food to
sour or decay and thus become unfit for consumption.
Some foods, of course, withstand the attacks of micro-organisms for
longer periods of time than others. For example, most fruits that are
protected by an unbroken skin will, under the right conditions, keep for
long periods of time, but berries, on account of having less protective
covering, spoil much more quickly. Likewise, vegetables without skins
decay faster than those with skins, because they have no protective
covering and contain more water, in which, as is definitely known, most
micro-organisms thrive.
41. If food is to be kept from decaying, the housewife must endeavor to
prevent the growth of micro-organisms, and she can best accomplish this
if she is familiar with the ways in which they work. It is for this
reason that, whether she possesses a scientific knowledge of bacteria or
not, an understanding of some practical facts concerning why food spoils
and how to keep it from decaying is imperative. In this part of cookery,
as in every other phase, it is the reason why things should be done that
makes all that relates to the cooking of food so interesting. In all
parts of the work there are scientific facts underlying the processes,
and the more the housewife learns about these, the more she can exercise
the art of cookery, which, like all other arts, depends on scientific
principles.
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