It’s harvest time, and if you’re lucky, you have plenty of produce from your garden to go around. Canning it is a great way to preserve it and share it with family and friends, but it can be risky if it’s not done correctly. Before you get started, it’s important to be knowledgeable about proper canning techniques so you can make sure your home-canned vegetables aren’t contaminated by the germ that causes botulism.

What is botulism?

Botulism is a rare but serious illness caused by a bacteria that produces powerful toxins that can lead to serious illness, including paralysis, and even death. The bacteria produce hardy spores that can survive in soil. Fruits, meats, fish, and vegetables could be contaminated with the bacterial spores before they are canned. The spores can survive, grow as bacteria, and produce toxins in improperly canned jars of food. It can be deadly to take even a small taste of food that has this toxin in it. 

How do people get botulism?

Botulism infections generally fall into three categories; foodborne botulism, which we are talking about today, infant botulism, and wound botulism. Home-canned vegetables are the most common cause of foodborne botulism outbreaks in the United States. They also have caused outbreaks in Idaho.

What are the symptoms of botulism?

Symptoms may include double or blurred vision, drooping eyelids, slurred speech, difficulty breathing or swallowing, dry mouth and muscle weakness with paralysis. They generally start anywhere from 8-36 hours after eating contaminated food. Call 911 or get to an emergency room as soon as possible if you see signs of this disease. Prompt treatment drastically reduces the risk of death and long-term health problems.

Are there ways to tell if a jar of food might be contaminated?

If the container is leaking, bulging or swollen, or it looks damaged or cracked or abnormal in any way, don’t eat the contents. If it squirts liquid or foam when you open it, throw it away, and then wipe up the spill using a solution of a quarter cup bleach for each 2 cups of water.

Jars of improperly canned vegetables and meats can contain the deadly botulism toxin without showing signs of spoilage. You can’t taste it or smell it, so you don’t even know it’s there, and it can kill you. The toxin can be absorbed through the skin, so always wear waterproof gloves to avoid exposure to the toxin if you must touch potentially contaminated contents. Finally, if the food is a funny color or is moldy or smells bad, don’t eat it. When in doubt, throw it out!

What’s the best way to be sure you haven’t contaminated your canned foods?

You can use modern preservation techniques and the right equipment for the kinds of foods you are canning. You should use a pressure canner or boiling water canner and be sure the gauge on it is working properly. Pay special attention to the processing times for low-acid vegetables like green beans, carrots, and corn. The USDA, Centers for Disease Control and Prevention, and county extension offices all have useful, step-by-step information about canning on their websites.

Resources

• Home canning and botulism from the CDC
• USDA Complete Guide to Home Canning
• FAQ from U of I Extension