Canning of Fruits and Vegetahlcs. ^Much has beeen written
on the proper method of canning fruits and vegetables, but our
best authority comes from the srovernment. . Government ex-
perts have made a very careful study and investigation of this
subject, and their report is the most scientific and reliable ma-
terial that we have. In their l)ulletins (see the list) the subject
is carefully discussed. The followino; material is largely taken
from these bulletins.
Tlie Meaning of Sterilization. The secret of canning lies in
complete sterilization. The air we breathe, the water we drink,
all fruits and vegetables, contain minute forms of life which
we call bacteria or germs. These germs are practically the sole
cause of decomposition. The exclusion of air from canned ar-
ticles, which Avas formerly supposed to be so important, is un-
necessary, provided the air is sterile or free from germs.
Germs which cause decay may be divided into tl'i'ce ^lasses:
yeast, mold, and bacteria. All of these are miscrosc/opic plants
of a very low order, and live on plants of a higher order. Every
housewife is familial' with the yeast plant. It thrives in sub-
stances containing sugar and it is the wild yeast that causes a
large part of the difficulty in canning fruits. However, yeasts
are easily killed, so that fruits are easier to can than vegetables.
The molds, as a general rule, are likely to attack jellies and pre-
serves, but these are easily killed. The bacteria are the class
of microscopic plants which we have to deal with in the canning
of vegetables and are the hardest to kill.
Bacteria are more resistant to heat than any of these other
minute plants. They reproduce themselves with amazing rapidity
and by two processes. The bacteria either divides itself into
two parts, thus making two where one existed before, or repro-
duces itself by spores. These spores may be compared to seeds
of a plant, and they are the chief difficulty in canning. The
parent bacteria is readily killed at the boiling temperature, but
the spores retain their vitality for a long time even at that tern-
36 Bulletin of tlie University of Texas
peratnre. and upon coolintr may oerminate and produce new
bacteria. Tn oi'der to completely sterilize a vegetable we must
cook it for a long time (about four or five hours) or for two
or three days in succession. The process of boiling upon suc-
cessive days is the one that is 8m.i)loyed in scientific work and
is much to be preferred. It is called the intermittent method
of canning, or the method of fractional sterilization, and is the
one Avhich is thoroughly recommended by all persons interested
in vegetable canning. By this method any vegetable may be
canned with success. Fruit may also be canned by this method,
but the one day cooking is sufficient for fruits. Also the open
kettle method is often used. Here the fruits are cooked in a
syrup, put into sterilized cans, sealed and put away in a cool
place.
The kind of jars. The first requisite for successful canning
is a gootl jar. Glass is the most satisfactory. However, tin cans
which are lacquered on the inside to prevent the juice from
comiuiT into contact with the tin, are used with success in many
factory canning plants.
Page 12
Presented as published in 1916. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
AI-modernized reading of the original text
Canning of Fruits and Vegetables. Much has been written on the proper method of canning fruits and vegetables, but our best authority comes from the government. . Government experts have made a very careful study and investigation of this subject, and their report is the most scientific and reliable material that we have. In their bulletins (see the list) the subject is carefully discussed. The following material is largely taken from these bulletins.
Tlie Meaning of Sterilization. The secret of canning lies in complete sterilization. The air we breathe, the water we drink, all fruits and vegetables, contain minute forms of life which we call bacteria or germs. These germs are practically the sole cause of decomposition. The exclusion of air from canned articles, which Avas formerly supposed to be so important, is unnecessary, provided the air is sterile or free from germs.
Germs which cause decay may be divided into three classes: yeast, mold, and bacteria. All of these are microscopic plants of a very low order, and live on plants of a higher order. Every housewife is familiar with the yeast plant. It thrives in substances containing sugar and it is the wild yeast that causes a large part of the difficulty in canning fruits. However, yeasts are easily killed, so that fruits are easier to can than vegetables. The molds, as a general rule, are likely to attack jellies and preserves, but these are easily killed. The bacteria are the class of microscopic plants which we have to deal with in the canning of vegetables and are the hardest to kill.
Bacteria are more resistant to heat than any of these other minute plants. They reproduce themselves with amazing rapidity and by two processes. The bacteria either divides itself into two parts, thus making two where one existed before, or reproduces itself by spores. These spores may be compared to seeds of a plant, and they are the chief difficulty in canning. The parent bacteria is readily killed at the boiling temperature, but the spores retain their vitality for a long time even at that temperature
36 Bulletin of tlie University of Texas
temperature, and upon cooling may germinate and produce new bacteria. Tn oi'der to completely sterilize a vegetable we must cook it for a long time (about four or five hours) or for two or three days in succession. The process of boiling upon successive days is the one that is employed in scientific work and is much to be preferred. It is called the intermittent method of canning, or the method of fractional sterilization, and is the one Avhich is thoroughly recommended by all persons interested in vegetable canning. By this method any vegetable may be canned with success. Fruit may also be canned by this method, but the one day cooking is sufficient for fruits. Also the open kettle method is often used. Here the fruits are cooked in a syrup, put into sterilized cans, sealed and put away in a cool place.
The kind of jars. The first requisite for successful canning is a gootl jar. Glass is the most satisfactory. However, tin cans which are lacquered on the inside to prevent the juice from coming into contact with the tin, are used with success in many factory canning plants.