Don’t let food poisoning spoil your next meal.

Botulism is one of the deadliest forms of food poisoning. It’s often caused by eating food that hasn’t been processed properly, especially home-canned food.

Although commercial canners are extremely cautious about their canning procedures, they’ve occasionally had to recall foods because of a safety risk.

Symptoms include blurred or double vision, slurred speech, difficulty swallowing, muscle weakness, nausea, vomiting, stomachache and diarrhea. The symptoms usually start to appear 18 to 36 hours after eating food containing the toxin.

Botulism is treatable if the victim receives prompt medical care. Without treatment, the illness causes paralysis that starts with the head and moves to the arms and legs and can cause death, according to the Centers for Disease Control and Prevention.

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Vegetables and meats are low-acid foods, which means that they do not contain enough acid naturally to prevent bacteria from surviving and growing. The bacteria can produce a deadly toxin in an airtight environment, such as a sealed jar, unless the food is acidic or has been heated under pressure for a specified time.

For example, home-canned tomatoes need to be acidified with lemon juice or citric acid and properly processed to be safe.

Boiling food will not kill the bacteria. If you want to can low-acid foods such as vegetables and meat safely, you need to use a pressure canner and standard canning jars with new two-piece lids.

Foods such as salsa, which is a mix of acid and low-acid ingredients, need to be acidified properly with lemon juice or vinegar using a tested formula and processed according to current recommendations.

Unfortunately, you can’t tell whether a canned food has been contaminated with botulism. It generally doesn’t taste or look unusual, although the cans may provide a clue that the food is contaminated.

Throw away any cans that are swollen or bulging and food from glass jars with bulging lids. Don’t taste food from swollen containers or food that is foamy or smells bad. Get rid of recalled canned products without opening the cans.

However, even properly processed canned foods won’t last forever. Cans and metal lids on glass jars can rust. The acid in foods such as tomatoes and fruit juices can cause cans to corrode. Light may cause food in glass jars to change color and lose nutrients. Temperatures above 100 F can cause food to spoil.

Here are some tips for storing canned foods:

  • Store them in a cool, clean, dry place where temperatures are below 85 degrees. Temperatures in the 60- to 70-degree range are ideal.
  • Store commercially canned low-acid foods (such as green beans and peas) in a cupboard for up to five years, but for best quality, use them within a year.
  • Use high-acid foods (such as commercially canned tomato-based products) within 12 to 18 months. Foods stored longer will be safe to eat if they show no signs of spoilage and the cans don’t appear to be damaged, but the food’s color, flavor and nutritive value may have deteriorated.

For more information on home canning, contact Christina Rittenbach, Stutsman County Extension agent, at (701) 252-9030 or christina.rittenbach@ndsu.edu.