FERMENTATION

From a
1909
cook book
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.

.....Fermentation in the wildest sense of the term includes all forms of decomposition
in both vegetable and animal substances when exposed to air and moisture at temp-
eratuures between the freezing and boiling point of water. But in common language,
the word fermentation is more often confined to those processes by which vegetable
juices are transformed into alcoholic liquors. These processes, however, are entirely
similar to putrefaction, or the decomposition of organic matter which sets free foul-
smelling gases; and decay, or the change by which without moisture, the trunk of a
tree molders into dust. Fermentation does not ordinarily take place much below 32 F.
or much above 140 F. It usually causes liquids to rise in temperature and to give off
gases with considerable internal motion, to become turbid, to form a scum and to
deposit a sediment.
.....Among the useful results of fermentation are the raising of bread with yeast; the
preparation of alcoholic beverages and certain food products, as sauerkraut; the
curdling of milk by means of rennet to form cheese; the manufacture of vinegar, etc.
.....Among the injurious results of fermentation are the souring of milk and vegetables,
the putrefaction of meat, the becoming rancid of fats and the decay of articles of wood
or textile fabrics.
.....Fermentation is caused by the vital action of microscopic plants, the germs of which
may be present in the fermenting substance, or may be deposited on their surface
from the air or from contact with water or other substances containing them. Or they
may be introduced intentionally, as when yeast is used for brewing, or for making
vinegar or bread. These small plants feed upon fermentable substances and bring
about various chemical changes. Thus the subject of fermentation has two phases:
i.e., (1) how to induce those forms of fermentation that are useful, and (2) how to
prevent those that are injurious.
.....The promotion of fermentation falls under such various subjects as fermented
beverages, the making of vinegar, cheese, bread, etc. The prevention of fermentation
falls under such subjects as the preservation of food, the preservation of timber, etc.
.....As fermentation occurs from the presence and development of germs, it is evident
that its prevention depends upon the destruction of any germs that are present, and
keeping away others, or the removal of conditions favorable to germ life. Hence, in
general, fermentation and putrefaction may be prevented by drying heat; by cooling
below the point at which fermentation takes place; by heating or cooking substances
to a point sufficient to kill the germs present, and then hermetically sealing them to
exclude others; and by the employment of various antiseptics, as alcohol, common
salt, saltpeter, sugar, syrup, smoke, borax, and many other substances.
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