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ANSWER: Pressure cookers have less metal, are
smaller in diameter, and will use less water than
pressure canners. The result is that the come-up
and come-down times will be less than for the standard
pressure canner. The come-up and come-down times
are part of the total processing time that was used to establish
a reasonable margin of safety, which is 12D (the
amount of heat required to cause a 12 log reduction
in bacteria.) for low-acid foods.
In the early years of canning in the 1940s pressure saucepans were considered
an alternative for home canning and it was thought
that adding 10 minutes to the process would keep
food safe. That proved not to be the case, the problem is that there
are several sizes of pressure saucepans and they
weren't adequately tested.
Hence, in the late 1980s the USDA recommendation was
not to use them for home canning. Unfortunately,
that option sometimes is included in current literature
by individuals not qualified to discuss safety considerations.
But we should not endorse use of this non-canning
equipment for canning.
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MSU University News; August 02, 2002 -- Updating
your recipes Some people may think that any recipe can be
canned at home, but that is not the case. You cannot
whip up a batch of your favorite soup, pour it into
canning jars, drop them into a canner and then serve
it up without placing your family at risk of food
poisoning. Safe canning recipes are thoroughly evaluated
in a food testing lab where the ingredients are
tested for pH factors that will determine
the correct processing time.
“There
are many chances for creativity in cooking, but
canning is not one of them,” says Paul. Safe recipes
require testing to prevent botulism. So, even though
its tempting to try home-canning your special
soup or sauce, she encourages everyone to play it
safe and stick with tested recipes from reliable
sources. It is not safe to guess on what processing
time and pressure to use.
Sources on canning typically
very widely. Someone might still be using grandma’s
high school, domestic-science textbook, copyright
1918. Maybe you have an old USDA pamphlet dating
from the 1940s or your mom's favorite heirloom recipes. Putting Food By, first published
in 1973 is also still found in rummage sales and
thrift stores. All of these sources were reputable
in their day, but they are considere4d unsafe by
today's standards. Everyone wants to know, “What’s
wrong with them now?”
The USDA dramatically changed the canning guidelines
and instructions in 1989 to incorporate the current,
modern methods and improvements in food safety, so be sure
your recipes are current and dated after that year.
Food preservation is more
precise, and therefore much safer than it was years ago. The
most accurate, up-to-date, and dependable guidelines
are in the current bulletins put out by the USDA,
available free or at a small cost from your local county
extension office. Read these pamphlets carefully,
and follow their instructions to the letter.
Canning summer produce is a family tradition
for some—for others, it may be a first attempt.
But either way, creativity and canning aren’t
a safe combination, says Lynn Paul, a food and nutrition
specialist at Montana State University Extension.
While many people may want to follow in the
old heirloom canning recipes used by their grandparents,
but canning requires current, tested recommendations
and the right type of equipment. These recommendations
are based on the food safety and quality, says Paul,
but safety is by far the top priority.
Finally, Paul notes that what may seem to be
a daunting list of do’s and don’ts is really meant
to provide tasty and safe food. “Learn what you
need to know and have fun this summer canning your
produce.”
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Tomato canning recipes now require lemon juice
or citric acid because some varieties of tomatoes
may have lower acid levels than those we used in
the past. See more about acidification.
Paraffin wax seals are no longer recommended
because they will not prevent mold growth in jams
and jellies. Use canning jars with seals and lids,
and follow the directions from a recommended recipe.
Don’t use microwaves for home canning, even though
you may find a few microwave-canning recipes in
magazines. Microwaves can be extremely dangerous,
especially with low-acid foods, because botulism
bacteria could survive. Other unsafe canning methods
include crockpots, ovens, dishwashers, open-kettle canning (where food
is heated and poured into jars).
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