Learn About Canned Food Safety and How to Know When to Dispose of Canned Goods

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Dangers of Botulism

Improper home canning can encourage the growth of the botulinum bacteria. This is a potentially fatal form of food poisoning, called botulism. Botulinum bacteria spores are normally present on your fresh food, however they only grow when oxygen is removed. This means that improperly canned food is the ideal environment for this deadly bacteria.

Canning Your Food Safely

To prevent botulinum bacteria from growing, follow these canned food safety guidelines. Process all food items to be canned in a temperature range between 240 to 250 degrees Fahrenheit. This is especially important for foods with a low acidity. Foods with a high acidity present a less nurturing environment for botulinum. These items may be processed in a boiling-water canner.

Ensure that all food to be canned is processed for the correct amount of time. After achieving a high enough temperature, low acidity foods must maintain this temperature for 20 to 100 minutes. High acidity foods may be processed in a boiling-water canner for five to 85 minutes. If you attempt to process low acid foods in a boiling-water canner, it will take at least seven to 11 hours, however this method is not recommended.

High Altitudes

These food canning safety guidelines are geared toward people who live at about sea level. If you live at a higher altitude, however, your canned food will have a greater tendency toward spoilage. This is because water will boil at a lower temperature. To ensure your safety, contact your local Extension agent or local district conservationist. They can tell you the exact recommended guidelines for your altitude.

Storage Guidelines

After you safely can your food, label the cans with the date. A general rule of thumb for canned food safety is to discard unused canned food after one year. Canned seafood and meats should always be used within one year. If the cans contain low acid food, it may be kept for eight to 12 months. High acidity foods keep a little longer, about 12 to 18 months. If you can fruit juices, these may be stored for as long as three years.

Avoid storing canned foods in extreme temperatures. An ideal temperature range is between 50 to 70 degrees. Avoid storing them at freezing temperatures or above 85 degrees. This not only increases the risk of spoilage, it also encourages the loss of nutrients.

When Not to Use Canned Foods

Inspect your canned foods before opening and eating them. Discard cans that are rusted or have rusted lids. Over time, the rust can penetrate the metal and create tiny holes.

Discard any cans that are dented or bulging. This includes dented or bulging lids. Misshapen cans indicates potentially dangerous spoilage. Give your cans a sniff before eating them. If the food smells foul, it is spoiled.


University of Minnesota

USDA: Complete Guide to Home Canning