This article is from the Food Preserving FAQ, by Eric Decker firstname.lastname@example.org with numerous contributions by others.
EXAMINE ALL HOME-CANNED FOODS BEFORE USING THEM.
1. Inspect the can before opening: Glass jars: metal lids should be
firm and flat or curved slightly inward. There should be no sign of
leakage around the rubber sealing compound. If there is mold growth
around the exterior neck of the jar--there may be mold growth inside.
Check for signs of "gassiness"--floating food, bubbles rising in the
food, swollen lid.
2. As the jar is opened, notice whether there is an inrush or an
outrush of air. Air rushing out or liquid spurting out indicates
3. Smell the contents at once. The odor should be characteristic of
the food. An "off" odor probably means spoilage (acid, acrid, sour,
4. Check the food carefully to see that it appears to have a
characteristic texture and color. Liquids in all foods should be
clear. Any change from the natural texture and/or color indicates
spoilage. DO NOT TASTE ANY QUESTIONABLE FOOD.
5. Discard canned food with signs of spoilage.
a. High acid foods (fruit) may be discarded in the garbage or
b. Low acid food (vegetables, meat, fish, poultry) must be dis-
carded more carefully because it could contain botulinal toxin.
Discard the spoiled food carefully using one of the following
methods. Be careful not to contaminate your work area by spilling
the food. Wear rubber gloves before handling food or containers.
c. Boil meat, fish and poultry for 15 minutes.
1. Boil at full rolling boil for 20 minutes. Discard.
3. Mix with 1-2 Tbsp household lye *or* 1 cup chlorine
bleach in non-metal container and let stand over- night.
Flush down the toilet, discard in garbage or garbage
disposal. Note: any containers or utensils that come in
contact with spoiled canned foods should be carefully
washed. Use soap and water to wash containers used for high
acid foods. Containers that come into contact with low acid
foods should be sterilized with chlorine bleach or boiled
for 20 minutes. Discard all lids, screw bands, wash cloths,
sponges and rubber gloves used during detoxifying low acid
6. As a safety precaution, boil all low acid foods (meats, fish,
poultry, vegetables) BEFORE TASTING. Boiling destroys the botulinal
toxin should it be present. a. Boil most vegetables for 10 minutes
(full rolling boil). b. Boil thick vegetables (spinach) for 20
minutes. [Louis Nagel, professional canner from Embarcadaro Canning,
suggests that thick vegetables like spinach and chard should *not* be
home canned in the first place.
Prepared by Susan Brewer/Foods and Nutrition Specialist/July, 1990 EHE-682