Select standard canning jars made of tempered glass that can withstand
high temperatures. The manufacturer's name or symbol in glass will
identify the product. With careful handling, jars last an average of
about 10 years. Avoid using antique jars because there can be hair-line
cracks not visible to the eye, causing jars to break.
Use canning jars in sizes suitable for the product canned and your
family's needs. Canning jars generally are sold in half-pint, pint and
quart sizes with wide and narrow mouths. Large-mouth jars are convenient
for packing such foods as whole tomatoes and peach halves. Quart jars
are convenient for vegetables and fruits where your family has four or
more members.
Examine the sealing edge of jars for nicks, cracks, or sharp edges that
would prevent a seal. Discard any with these imperfections.
One-trip jars from purchased canned foods should not be used because
they generally are not tempered to withstand the high heat required for
home canning, and may break when subjected to the heat. Tops of these
jars may not fit standard canning lids, thus preventing a good seal.
[Illustration: Home canning equipment.]
_Closures_--jar lids and rings come with new canning jars. The sealing
compound of lids recommended for one use only will not hold a seal
effectively after the first use.
Select lids appropriate for the jars being used. You may find the
two-piece units (flat lid with sealing composition and ring), one-piece
lids, or flats with separate gaskets made of metal or plastic. Always
follow the instructions for pretreatment as indicated on the box or
container by the manufacturer. If no name is indicated on the lid, use a
black wax marking pencil or crayon and mark the identity on each lid. If
there are problems, contact the manufacturer whose name and address is
on the box or container.
Screw ring bands may be reused if kept clean and dry in a protective
container with a tight-fitting lid. Never use bands with rust, or pried
up or bent edges.
If you have extra lids, store them protected in a dry, cool place.
One-piece zinc caps lined with white porcelain, with rubber rings, may
be used. The caps may be reused if they have not cracked, spread or bent
at the edges and are clean, like new. The rubber rings are effective
only once because they tend to dry and deteriorate with age, often
become porous, and sometimes crack.
If you have jars with bail wire clamps, sometimes called
"lightning"-type jars, be sure they are not in the "antique" class. Lids
for these jars are all glass, and rubber rings are used between the jar
and lid for sealing. A wire clamp holds the lid in place during
processing; after processing, the short spring wire of the clamp is
snapped down to complete the seal.
A _boiling water bath canner_ is needed for processing high-acid foods,
such as fruits, tomatoes, tomato and fruit juice, and pickles.
Water bath canners in several sizes are available on the market. The
container must be deep enough for a rack to hold the jars off the bottom
of the canner. The depth allows water to be over the jars of food by at
least 1 to 2 inches. Keep 1 to 2 inches of space above the water to
allow for boiling; this prevents water from boiling over.
The canner must have a tight-fitting lid. Or you can use a large kettle
with a tight-fitting lid, and a wooden or wire rack to hold jars off the
bottom. There should be free circulation of water to every part of the
surface of the jar and lid.
If you are going to buy a water bath canner, check the height, and the
lid to be sure it is tight-fitting. The rack preferably should have
dividers so jars will not touch each other or fall against the sides of
the canner or each other during processing.
A _steam pressure canner_ is absolutely essential in canning low-acid
foods, such as vegetables, and insures the destruction of spoilage
micro-organisms.
Ten pounds pressure is used for processing food in standard canning jars
at sea level. This pressure corresponds to 240° F.
The steam pressure canner is made of heavy metal that withstands high
pressure developed by steam. It consists of a kettle with a
tight-fitting lid equipped with an accurate weight or dial gage to
register the pounds of pressure in the canner. The lid must lock or seal
to prevent escape of steam.
The canner must have a safety valve, petcock or steam vent that can be
opened or closed to permit exhausting (venting), and a pressure gage. It
must have a rack to hold jars at least ½ inch from the bottom of the
canner.
A dial gage indicates pressure on a numbered instrument.
A weighted gage has no dial, but automatically limits pressure with
weights preset for 5, 10, and 15 pounds pressure.
[Illustration: Scalding tomatoes in a blancher.]
The pressure is adjusted for high altitude. For information on canning
at altitudes above sea level, see the later chapter by Carole Davis.
To insure the canner's proper working condition, check the dial gage for
accuracy each year--or if a canner or lid has been roughly handled or
dropped, the dial gage glass broken, or any parts are rusty. The
manufacturer or your county Extension office can give information on
testing availability. Study and follow the manufacturer's directions for
using your pressure canner.
Run through the process of operating the pressure canner on your range
in a trial run before you get into the canning season, to be sure
everything is working properly. Make a note of the dial setting of the
range if you use an electric range for holding pressure steady.
Trying to use a pressure canner obtained from garage, rummage, or
auction sales or handed down to you from someone's attic may prove
dangerous. You may not have any idea as to the care, handling, or
storage of the canner. A manufacturer manual on care, use and
replaceable parts usually is not available. Old-old canners did not have
complete information--manufacturer's name, address or model number--on
the appliance.
General kitchen equipment is helpful in any needed washing, peeling,
coring and slicing in the preparation of fruits and vegetables. Examples
are, a vegetable brush for cleaning vegetables, a blancher or wire
basket for scalding fruits and vegetables such as tomatoes and peaches
to loosen skins for peeling, and a colander for washing delicate fruits
such as berries.
A food mill is handy for making purees and straining fruits for making
juices, and a strainer for straining juice. A long handled fork or
plastic spatula aids in fitting and packing food and removing air
bubbles. A wide-mouth funnel is very convenient for filling jars, and a
jar lifter helps you avoid burns in handling hot jars. Use an automatic
timer to time processing accurately.
The number of pints of preserved food you will get from a given quantity
of fresh food depends on the quality, variety, and maturity of the fruit
or vegetable; on the size of the pieces, and on the packing method used.
Selection of good sound fruits and vegetables is of paramount
importance. The quality of canned fruits and vegetables will be no
better than quality of the raw food used. For best flavor retention,
preserve only those vegetables that are young, tender, and freshly
gathered.