Keeping a stash of canned goods is very convenient. Beans provide a quick and easy protein option, and canned vegetables are a solid backup choice when you realize that the fresh bag of green beans in your fridge that you were saving for dinner actually smells a little funky. After all, some canned foods are just as good as fresh, both in taste and nutritional value. When stored in proper conditions — that is, in a cool, dry place — most canned goods can last for up to five years. Foods with high acidity, like tomatoes or fruit, are best used within 18 months.
However, there are some markers to look out for that tell you that the food inside the can is no longer safe to eat and that you should toss it in the trash. A huge red flag that a canned good isn’t edible anymore is if it spurts liquid or foam out while you’re opening it. Other warning signs to keep an eye out for are cans that are dented, leaking, bulging, or smell bad once opened. These issues can be indicators of a toxin that causes botulism, which is a rare but potentially deadly illness that attacks the body’s nerves, resulting in breathing issues and paralysis.
Risks of eating canned goods that have gone bad
Botulism is caused by a toxin that is produced by a bacteria called Clostridium botulinum. The bacteria thrives in environments that have low oxygen levels, hence why a tightly sealed can or jar can house spores that lead to its production. However, the bacteria also requires an environment that is low salt, low acid, and low sugar. Because of these very specific conditions and the rigorous safety standards in commercial food canning, foodborne botulism is extremely rare in food purchased from a store. Home-canned vegetables are the most common cause of botulism in the United States, so if you’re someone who cans their own food, be sure you are carefully following the USDA’s Guide to Home Canning.
You often won’t be able to see, smell, or taste the presence of the toxin that causes botulism. Since ingesting only a tiny amount of food that contains it can be deadly, it’s important to keep an eye out for those telltale signs that your canned food has gone bad. If the can clearly looks like it’s in bad shape or sprays liquid once you’ve broken its seal, throw it away and absolutely do not consume any of it. If you’re unsure, it’s always better to err on the side of caution and toss out the can in question.
