acid foods are processed in a boiling-water
canner. The heat is transferred to the
product by the boiling water which completely
surrounds the jar and two-piece cap.
A temperature of 100° C (212° F) is
reached and it must be maintained for
the time specified. Always follow a
recipe with proven and tested processing
This method is adequate to kill molds,
yeasts, enzymes and some bacteria. This
method never reaches the super-high
temperatures needed to kill certain
bacterial spores and their toxins, which
can produce botulism, therefore, this
method cannot be used for processing
low-acid foods. See more about the Basic
Steps for this method, or learn
more about pressure
canning and low
Water bath canners are widely available.
You can use any big pot, however, if
it is deep enough for the water to cover
the tops of jars by several inches.
Allow 5 to 10cm (2 to 4 inches) above
jar tops for brisk boiling. The canner
must have a tight-fitting lid and a
wire or wooden rack. The jars must be
held off the bottom so the heat can
penetrate properly. The jars are divided
so they will not bump into each other
or tip over in the boiling water during
To ensure uniform processing of all jars with an electric range, the canner
should be no more than four inches wider
in diameter than the element on which
it is heated. However for flat top stoves,
canners should be no more than
2 inches wider than the diameter of
What Foods Use This Method?
foods like fruit
butters and spreads, fruit pie fillings, sauerkraut,
pickles and pickled vegetables, jams, jellies and
marmalades can be safely processed by boiling water
bath canning. The types of organisms that cause
in these foods are usually killed at boiling temperatures.
Use the boiling water bath method for canning acid
the hybrid varieties of modern tomatoes are on the
borderline between being acid and low-acid, tomatoes
and tomato products are no longer considered safe
for water bath canning methods without additional
Is a Science
canning is the only canning
method recommended for low-acid
foods like meat, poultry,
seafood and vegetables.
botulinum, the bacterium
that causes botulism food
poisoning, is destroyed
in low-acid foods when they
are processed at the correct
time and temperature
in pressure canners. Canning
low acid foods in boiling-water
canners is absolutely unsafe
because the botulinum bacteria
can survive this process.
If Clostridium botulinum
bacteria survive and grow
inside a sealed jar of food,
they can produce a deadly
toxin. Just a tiny taste
of food containing this
toxin can be fatal.
Put filled glass jars into canner of hot or boiling
water. For jams, preserves and raw packed fruits
or tomatoes, have water in canner hot but not boiling.
For pickles and hot packed fruits and tomatoes,
have water boiling. Add boiling water until it is
an inch or two over tops of containers; don't pour
boiling water directly on glass jars. Place cover
on the canner. See more
about the Basic Steps.
For most foods, you start to count processing
time when water in the canner comes to a rolling
boil. Processing methods for some pickles, such
as fresh-pack dill pickles, are slightly different
from the usual water_bath procedures. For these
products, start to count the processing time as
soon as you place the filled jars in the actively
boiling water. Follow instructions carefully for
the food you are canning.
Keep water boiling
gently and steadily during the time recommended
for each food. Add boiling water during processing
if needed to keep containers covered. Remove jars
from canner immediately when processing time is
up. Go to recipe links
with safe, proven and tested canning resources.