The CDC estimates that foodborne diseases cause approximately
76 million illnesses, 325,000 hospitalizations, and
5,000 deaths in the United States each year, these figures
do not include mild cases of food poisoning were patients
did not seek medical care, or misdiagnosed cases. Most cases
of food poisoning are associated with inadequately
processed, home-canned foods.
The most serious and deadly form of foodborne illness
is botulism, a severe type of food poisoning
caused by the ingestion of foods containing a potent
toxin that affects the nervous system. Although incidence of the
disease is low, the mortality rate is high. This toxin is destroyed
in low-acid foods when
they are processed at the correct time and temperature
in pressure canners.
Don't taste or use food that shows any kind of spoilage.
Look closely at all jars before opening them. A bulging
lid or leaking jar is a sign of spoilage. When you open
the jar, look for other signs, such as spurting liquid
and off-odors or mold. Spoiled canned foods should be
discarded in a place where they will not be eaten by
humans or pets. Spoiled meats, seafood and low-acid
vegetables, should be detoxified to destroy any poisons
that might be present before they are discarded because
the contents are lethal and could cause life threatening
illness or even that to people who might com in contact
with it later.
Before eating canned foods,
be sure of the following:
- Food was
processed following a current, tested recipe following
the recommendations from University
Extension services, the USDA or the latest edition of
the Ball Blue Book.
- Food was
processed in a pressure canner with a gauge that was
checked at the beginning of the canning season.
- Time and
pressure were properly adjusted for altitude.
- Ingredients or proportions of a tested and approved
canning recipe were NOT added, altered or changed.
times and pressures matched the size of jar, style of
pack and kind of food being canned.
- Jar lid
is firmly sealed and concave (curved inward).
has leaked from the jar.
- No liquid
spurts out when jar is opened.
- No unnatural
or "off" odors can be detected
Look closely at all jars of food before
opening them. Do not eat food which shows signs of spoilage. Do not taste foods
that show signs of spoilage or foods from a jar with unsealed lids. All
suspect jars of spoiled low-acid foods, including tomatoes, should be treated as
containing botulism toxin.
Growth of spoilage bacteria and yeast produces gas
which pressurizes the food, swells lids, and breaks
jar seals. As each stored jar is selected for use, examine
its lid for tightness and vacuum. Lids with concave
centers have good seals. Next, while holding the jar
upright at eye level, rotate the jar and examine its
outside surface for streaks of dried food originating
at the top of the jar. Look at the contents for rising
air bubbles and unnatural color. While opening the jar,
smell for unnatural odors and look for spurting liquid
and cottony mold growth (white blue, black, or green)
on the top food surface and underside of lid.
discard any jar of spoiled food to prevent possible
illness to you, your family, and pets. Detoxify unsealed, open, or leaking jars of food before disposal to prevent
the spread of toxin
- If suspect glass jars are still sealed, place
them in a heavy garbage bag. Close the bag, and
place it in a regular trash container or bury it.
- If suspect jars are unsealed, opened or leaking,
detoxify (destroy bacteria and toxin) as follows
before disposal. Place suspect jars of food, including lids, on
their sides in an 8-quart volume (or larger) stock pot. Wash your hands
thoroughly in hot soapy water. Carefully add water to the pan until it is at
least one inch above the containers. Avoid splashing
the water. Place a lid on the pot. Heat to boiling,
and boil rapidly for at least 30 minutes to insure detoxification and destroy
all bacteria and toxin. Cool and drain water and
dispose of the containers, lids and food in the
trash, or bury in soil to prevent accidental poisoning.
- Thoroughly scrub all counters, containers, and
equipment that may have touched the food or containers, and other equipment or utensils used in the process
with a solution of 1 part chlorine bleach to 5 parts
water. Wet the surface with this solution and let
stand 5 minutes before rinsing.
clothing in hot water and soap.
- Wash hands thoroughly in hot water and soap
- Place sponges , wash cloths and towels that were used in clean-up in a
plastic bag and discard them in the trash. Boil all items in the water for 30
minutes. Cool and discard jar contents in garbage
or bury in soil. This will prevent accidental poisoning.
Improperly canned low-acid foods can contain botulinum toxin
without showing signs of spoilage. Low-acid foods are considered improperly
canned and not safe if any of the following are true:
- The food was NOT processed in a pressure canner.
- The gauge of the canner was inaccurate.
- Up-to-date researched processing times and pressures were NOT used for the
size of the jar, style of pack and kind of food being processed.
- Ingredients were added that were NOT in an approved recipe.
- Proportions of ingredients were CHANGED from the original approved recipe.
- The processing time and pressure were NOT correct for the altitude at which
the food was canned.
Because improperly canned low-acid foods can contain botulinum toxin without
showing signs of spoilage, they should also be detoxified and then discarded.
Time, energy and money are lost when food spoils. There are several reasons
home-canned foods spoil. The most common ones are: failure to heat process the
filled jars, processing by an incorrect method, processing for insufficient
time, and failure of lids to seal.
When you can low-acid vegetables and meat, you must use a pressure
canner. Because the pressure canner keeps steam confined until it builds up
pressure, it can build up temperatures above the boiling point. You need these
high temperatures to destroy botulism spores that can cause food poisoning in
low-acid foods. At 10 pounds pressure at sea level used in home pressure
canning, you will get a temperature of 240 degrees F. Adjustments need to be
made as altitude increases. You must maintain the recommended pounds of pressure
throughout the processing period. If at any time during processing the
pressure drops, the food will not be adequately processed. Whenever pressure
drops below the recommended processing level, bring it back up and re-time for
the entire period needed for the particular food.
In many old canning books, there are no instructions for heat processing jars
of food after filling. The older books describe a canning method called
"open-kettle canning", and spoilage with this method is quite common. Because
the filled jars are not pasteurized or sterilized by heating after the lids are
put on, molds, yeasts and bacteria survive and can cause food to spoil. The lids
may seal at first, but later on become unsealed, indicating that food is
spoiling. Do not use this method for any home-canned food. When foods canned in a pressure canner spoil, it is usually due to one of the
- An inaccurate dial gauge
- Failure to vent steam from the canner for 10 minutes before closing the
petcock or placing the weighted pressure control on the canner. This allows air
to remain in the canner and temperatures will be lower than needed.
- Fluctuating heat under the canner
- Processing for too short a time
If you used a boiling water bath canner and canned food spoils, the cause
could be failure to have water hot when you placed the jars in the canner, not
having enough water to cover the tops of the jars by at least an inch,
processing for too short a time, or processing low-acid foods with this
It is possible for canned foods to spoil, either due to improper heat
processing or damage to the container. Examine the container of food before you
open it. Cans with bulging ends or leaks or bulging, or unsealed jar lids
indicate the possibility of spoilage. When you open a can, spurting or frothy
liquid, mold or off-odors indicate possible spoilage. Do not use canned foods
that show any of these signs of spoilage. Dispose of the food without tasting
it, and do it in a way that will prevent consumption by other people or by
Canned low-acid foods can contain the deadly toxin caused by growth of
Clostridium botulinum bacteria, without showing any visible signs of
spoilage. The risk of botulism is greater with home-canned foods than it is with
commercially-canned products. There is no danger of botulism if you can low acid
foods at the correct pressure, and for a sufficient time in a pressure-canner.
But, if you are uncertain that you followed such procedures, it is best to boil
home-canned vegetables and meats for 10 minutes before tasting. If the lids on
jars of these low-acid foods are not sealed, or if you know that such foods were
canned in a boiling water bath canner, do not use them under any conditions.
Dispose of improperly processed home-canned foods in away that will prevent
consumption by humans or animals.
Tightly sealed, cooled jars are ready to be stored. Wash the
lid and jar to remove food residue; rinse and dry jars. Label and
date jars, and store them in a cool, dark, dry place (50-70 degrees
F is ideal). Do not store jars above 95 degrees F or near hot pipes,
a range, a furnace, in an uninsulated attic, or in direct sunlight.
Under conditions such as these, food will lose quality rapidly and
may spoil. Dampness may corrode metal lids, break seals, and allow
contamination and spoilage. Plan to use home-canned food within
one year for optimum quality and nutritional value.
Canned foods, whether in tins or glass jars, won't keep forever. Commercial
canners work under tightly controlled conditions with careful sanitation and
just the right heat and timing periods, but there are still limits to how long
food quality can be preserved. Home-canned foods, processed under less carefully
controlled conditions, may have even shorter storage lives.
There are several factors that limit the shelf-life of canned foods. First,
cans or metal lids on glass jars can rust. When rust is deep enough, tiny holes
open in the can or lid that may let spoilage agents in. Shipping accidents that
dent or crush cans also cause container problems.
Then there is can corrosion. In all foods, especially high-acid foods like
canned tomatoes and fruit juices, the food continually reacts chemically with
the metal container. Over several years, this can cause taste and texture
changes, and eventually lower the nutritional value of the food.
High temperature over 100 degrees F are harmful to canned foods, too. The
risk of spoilage jumps sharply as storage temperatures rise. In fact, canned
goods designed for use in the tropics are specially processed. Even at prolonged
storage temperatures above 75 degrees F, the rate of nutrient loss in canned
foods increases. Light can cause color changes and nutrient losses in foods
canned in glass jars.
Never use foods from containers with these spoilage warning signs--loose or
bulging lids on jars; bulging, leaking or badly dented cans, or foods with a
foul odor. To store canned food wisely, follow these guidelines:
- Store them in a cool, clean dry place where temperatures are below 85
degrees. A range of 60-70 degrees is even better.
- Store canned hams in the refrigerator for use within six to nine months.
- Low-acid canned foods may be stored in a cupboard for as long as two to five
years. For top quality use before one year.
- Use high-acid foods within 12 to 18 months. Foods stored longer will still
be safe to eat if the cans show no signs of spoilage or damage,but the foods may
have deteriorated in color, flavor and nutritive value.