All fresh fruits, vegetables, and meats are perishable.
With the exception of some fruits and a few vegetables,
fresh foods must be prepared and served soon after harvesting
or they begin to spoil, to change color and flavor,
and ultimately to decompose. This is nature's plan.
A few day's storage in the refrigerator will delay these
processes, but it takes something drastic to halt them
completely. Canning does this by heating food in sealed
containers. The heat destroys the troublesome organisms
and the sealed containers prevent recontamination of
the processed food.
Pressure canning is the only way to safely can low-acid
foods such as beans, corn and carrots as well as meat,
fish and poultry. Meat, fish, poultry and all common
vegetables except tomatoes should be canned in a steam-pressure
canner. NEVER can these foods in a boiling water_bath
canner, an oven, a steamer without pressure or an open
kettle. The pressure canner is the only method of home
canning that will heat these foods enough to kill the
dangerous bacterial spores of Clostridium botulism within
a reasonable time.
In order to kill all bacteria,
their spores and the toxins they produce, low-acid foods
must be super-heated to a temperature of 240F and held
there for a specified time. Because the steam inside
the canner is pressurized, it's temperature exceeds
the boiling point of water.
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 degrees
C (212 degrees F) is reached & must be maintained
for the time specified. 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