As gardens begin to produce tomatoes, green beans, peppers and other summer favorites, many home cooks are preparing to preserve their harvest through canning.
Home canning can be a safe and rewarding way to store food for months or years. But food safety experts warn that improper canning techniques can create conditions for the growth of dangerous bacteria, including Clostridium botulinum, which produces the toxin that causes botulism.
Botulism is rare but can cause paralysis, respiratory failure, and death. Botulinum toxin cannot be seen, smelled or tasted.
“Home canning is one method of food preservation in which it is important to follow tested procedures,” according to guidelines from the Centers for Disease Control and Prevention (CDC) and the U.S. Department of Agriculture.
Why botulism is still a concern
Botulism occurs when Clostridium botulinum grows in an oxygen-free environment and produces a powerful neurotoxin. Improperly canned food can provide ideal conditions for bacteria to grow.
Symptoms of foodborne botulism include:
- Double or blurred vision
- drooping eyelids
- slurred speech
- difficulty swallowing
- dry mouth
- muscle weakness
- shortness of breath
Symptoms may begin hours or days after eating contaminated food. Anyone who experiences these symptoms after eating home-preserved food should seek medical attention immediately.
Pressure canning vs. water bath canning
One of the most common mistakes made when home canning is using the wrong canning method.
Highly acidic foods, such as many fruits, jams and jellies, can generally be processed using boiling water canning.
Low-acid foods require pressure canning to reach temperatures high enough to destroy botulism spores.
Low-acid foods include:
- green gram
- corner
- sugar beet
- potato
- asparagus
- carrots
- meat
- poultry
- seafood
Many vegetables produced in backyard gardens fall into the low-acid category.
According to the USDA, pressure canning is the only recommended method for canning these foods safely.
Safe Home Canning Tips
Food preservation experts recommend some basic precautions.
Use tested recipes. Follow recipes and processing instructions from trusted sources such as: The Complete Guide to USDA Home Canning, National Center for Home Food PreservationUniversity Extension Program.
Use appropriate equipment — Ensure that the pressure vessel is operating properly and follow the manufacturer’s instructions for maintenance and calibration.
Inspect the bottle and lid — Discard bottles with cracks, chips, or other damage that may prevent a proper seal.
Please follow processing times carefully — Turnaround times are based on extensive research and should not be shortened.
Adjust altitude if necessary — Higher altitudes often result in different processing times or pressures.
Store Canned Foods Properly — Store jars in a cool, dry place and label with canning date.
When in doubt, throw it away.
Food safety experts emphasize that consumers should never taste food to determine if it is safe.
Throw away home-canned food if:
- If the container is leaking, swollen, or swollen
- The seal is broken.
- The jar is broken or damaged.
- When you open the container, liquid comes out.
- Food becomes moldy, discolored, or has a strange odor.
Even small amounts of microscopic botulinum toxin can cause serious illness.
Your trusted resource for home canning
Consumers looking for canning guidance should rely on science-based resources rather than social media trends or untested family recipes.
Some of the most widely recommended resources include:
Many extension services offer free classes, online tutorials, and updated instructions tailored to local growing conditions.
As harvest season gets into full swing across the country, food safety officials say spending just a few extra minutes following tested procedures can help keep home-preserved foods tasty and safe.
