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in place by a metal screw band
during processing. The flat lid is
crimped around its bottom edge
to form a trough, which is filled
with a colored gasket material.
When jars are processed, the lid
gasket softens and flows slightly
to cover the jar-sealing surface,
yet allows air to escape from
the jar. It is best to buy only the
quantity of lids you will use in a
year. Never reuse lids. To ensure
a good seal, carefully follow
the manufacturer’s directions in
preparing lids for use. Examine
all metal lids carefully. Do not use
old, dented, or deformed lids or
lids with gaps or other defects
in the sealing gasket. Follow
the manufacturer’s guidelines
enclosed or on the box for
tightening the jar lids properly.
• If screw bands are too
tight, air cannot vent during
processing, and food will
discolor during storage.
• Over-tightening also may
cause lids to buckle and
jars to break, especially with
pressure-processed food.
• If screw bands are too loose,
liquid may escape from jars during
processing, seals may fail, and the
food will need to be reprocessed.
Do not retighten lids after
processing jars. As jars cool, the
contents in the jar contract, pulling
the self-sealing lid firmly against
the jar to form a high vacuum.
Screw bands are not needed on
stored jars. They can be removed
easily after jars are cooled. When
removed, washed, dried, and
stored in a dry area, screw bands
may be used many times. If left
on stored jars, they become
difficult to remove, often rust, and
may not work properly again.
3. Canning methods: There are two
safe ways of canning, depending
on the type of food being canned:
the pressure canning method and
the boiling water bath method.
PRESSURE CANNING METHOD:
With the pressure canning method,
the jars of food are placed in 2 to 3
inches of water in a pressure cooker
and heated under pressure at a
temperature of 240 °F or above for a
specific length of time, which differs
for every recipe. Pressure canning
can be used to can all types of
food. It is also the only safe method
of canning low acid foods, which
have a ph greater than 4.6. Low-
acid canned foods are not acidic
enough to prevent the growth of the
bacterium Clostridium botulinum,
which may cause botulism. To
destroy the bacteria, foods must
be processed at a temperature
of at least 240ºF, which can only
be reached in a pressure cooker.
Processing foods under pressure
at a temperature of 240 ºF during
an adequate time ensures the
destruction of the largest number
of heat-resistant microorganisms
in home-canned foods. Low-acid
foods include all vegetables, meats,
poultry, and seafood. This method is
also recommended for canning such
items as soups, stews and chili.
Note: Although considered fruit,
tomatoes have a ph value close to
4.6. Therefore, you should typically
process them in a pressure canner.
WARNING: 240 ºF can only be
reached in a pressure cooker/canner.
Never attempt to can low acid foods
using the boiling water bath method.
Instructions for pressure
canning method:
Processing Instructions: Fill the
jars. Allow the proper headspace
according to processing directions
for specific foods. This is necessary
so that all the extra air will be
removed during processing, and a
tight vacuum seal will be formed.
To make sure that air bubbles have
not been trapped inside the jar,
run a bubble freer or any plastic or
rubberlike utensil around the edges
of the jar, gently shifting the food,
so that any trapped air is released.
After the air bubbles have been
removed, more liquid may need
to be added to the jar to ensure
proper headspace. Wipe off the
rims of the jars with a clean, damp
cloth. Screw on the lids, but not
too tightly — air needs to escape
during processing. Set the jars of
food on the rack and lower the rack
into the pressure cooker so steam
can flow around each jar. Add 2-3
inches of boiling water to the bottom
of the cooker (pour it between the
jars, not directly on them, to prevent
breakage). Put the lid on the cooker.
Once pressure is reached, keep
the pressure constant by regulating
the heat under the pressure cooker.
Do not lower the pressure by
raising or lowering the heat during
the processing. Keep drafts from
blowing on the pressure cooker.
Fluctuating pressure causes loss of
liquid from jars and underprocessing.
When the processing is completed,
carefully remove the pressure cooker
from the heat. If the pressure cooker
is too heavy, simply turn it off.
WARNING: Let the pressure in the
pressure cooker drop to zero using
the natural release method. Do not
use the cold water pressure release
method for pressure canning.
Never use the automatic release
method to hasten the reduction in
pressure when canning foods.
When the pressure cooker is
depressurized, unlock the lid and
tilt the far side up, so the steam
escapes away from you. Use a jar
lifter to carefully remove the jars from
the pressure cooker. Place the hot
jars on a rack, dry towels, boards or
newspaper, right side up to prevent
the jars from breaking on contact
with a cold surface. Leave at least
1inch of space between the jars. Do
not tighten the lids. Allow the jars to
cool, untouched for 12 to 24 hours.
BOILING WATER BATH METHOD:
The boiling water method is
safe for high-acid foods such as
fruits and pickles, as well as pie
filling, jam, jellies, marmalade and
other preserves. In this method,
jars of food are heated by being
completely covered with boiling
water (212 ºF at sea level).
CHEF INTERIOR 12-19.indd 28-29 12/19/11 9:14 AM
