Steam pressure canning is the method used for home
canning of low acid foods, such as vegetables, meat,
poultry, seafood, and soup. Mixed vegetable recipes
that contain tomatoes are also considered low acid. In
steam pressure canning, you pack jars with hot or cold
food and place them on a rack in a pressure canner.
Then you add water as the manufacturer directs, seal
the canner, and heat it. The steam created is under
pressure and reaches the superheated temperature of
240 degrees F, which is capable of killing the harmful
byproducts of the botulism bacteria. Most vegetables
by be either cold or hot packed.
Remember too, that altitude can affect the pressure in
your steam pressure canner. Check the chart to find
what adjustments may be necessary at your altitude. If
your pressure canner has a weighted gauge, use 15
pounds pressure at all altitudes over 2,000 feet.
A pressure canner is a large, heavy metal utensil that
heats water under pressure to create steam. The steam
is hotter than boiling water and can cook food to the
240 degree F needed to kill dangerous botulism
bacteria. Although the initial expense of a steam
pressure canner may seem high, it should last you
through many, many years of gardening and canning. In
addition, it can be used for quick cooking may other
foods.
Steam pressure canners come in several sizes, ranging
from 8 to 22 quarts in capacity and holding 4 to 7 one
quart jars, or many more pint jars of food. You may
already have a pressure cooker, or saucepan pressure
cooker. You can use this for processing if it will
hold pint jars, if it has an accurate gauge, and if it
will maintain 10 pounds of pressure. Add 20 minutes to
the processing time given in the recipe if using a
regular pressure cooker, or saucepan pressure cooker.
Pressure canners and cookers differ slightly in
construction; one type has a dial gauge, another a
weighted gauge. Always follow the instructions that
came with your particular canner to the letter. Always
check the gasket and locking mechanism and clean all
parts as the manufacturer directs.
TESTING THE DIAL GAUGE Dial gauges must be checked
each canning season. The home economist at your local
Cooperative Extension Service Office can tell you
where and when you can have the dial tested. If the
dial varies more than 5 pounds per square inch either
way, get a new one. If the variation is less than 5
pounds, adjust pressure using the chart below.
Weighted gauges don't need to be tested, but they must
be kept clean.
If gauge reads low by 1 pound; Process at pressure
of 11 pounds.
2 pounds;
12 pounds.
3 pounds;
13 pounds.
4 pounds;
14 pounds.
If gauge reads high by 1 pound; Process at pressure
of 9 pounds.
2 pounds;
8 pounds.
3 pounds;
7 pounds.
4 pounds;
6 pounds.
Handle the dial gauges with care. NEVER rest the cover
on the gauge and never turn the cover upside down over
a full pan with the gauge attached, because moisture
could enter the gauge and rust it.
MAINTAINING PROPER HEAT LEVELS: Big pressure canners
may cover the range burners completely. Set the
pressure canner on the burner to be sure there's
enough air space to keep gas burners on or to prevent
the enamel of the range surface around the electric
unit from growing too hot. If a pressure canner seems
too snug against a burner, lift it up 1/4 to 1/2 inch
on asbestos blocks or an extra gas burner ring, so
that heat and air can circulate. (Make sure the
asbestos blocks or extra gas burner ring does not
itself cut down the air space of the gas burner or
block the heating of the electric unit.)
Source: Vegetable Gardening Encyclopedia Typos by
Dorothy Flatman 1995
