Sure, some old canned foods might get a little weird in the flavor department, but these 9 foods can become dangerous if you eat them past their expiration date listed on the lid.
Canned pumpkin puree
Pureed pumpkin is extremely dense. This makes it difficult for heat to fully penetrate the can during processing and becomes an issue as your can continues to age.
As pumpkin ages past its “best by” date, moisture can get trapped in the thick puree, inviting thermophilic bacteria to grow.
The ideal conditions for these microbes are found in a comfortably warm pantry, and they can multiply without the can ever visibly changing. You’ll still vomit violently, however, and become severely dehydrated if you ingest them.
Experts generally advise against consuming canned pumpkin puree that’s past its prime, given its low acidity.
Canned sardines in tomato sauce
Plain sardines have a pretty good shelf life, but their acidic tomato sauce eats through the can at an accelerated rate compared to normal tin.
This process, called “hydrogen swelling,” produces flammable gas that can eventually explode the seal and allow harmful bacteria such as Staph aureus inside.
Furthermore, once the inner lining of the can is punctured by tomato acid, the fish absorbs excessive amounts of tin and lead which causes neurologic defects when consumed.
If the sauce inside has turned a metallic grey color or if the can has a springy texture, the chemicals have already spoiled and made the sardines toxic.
Condensed milk
The high sugar content in condensed milk typically keeps it shelf-stable for a long time, though after the expiration date, the “Maillard reaction” kicks in.
This process transforms the milk into a potential source of harmful molds. When left in a warm place, condensed milk can ferment internally and burst open with dangerous spores.
Even baking with expired milk won’t kill the mycotoxins, because they can withstand heat. Eating it will put your liver or kidneys at risk, potentially causing permanent harm.
Should you open a can of condensed milk and find it darker than usual, or with a clumpy texture, it’s best to discard it.
Clams and chopped seafood
Seafood spoils fast, but canned seafood seems to be the worst because it breaks down itself from enzymes that literally chew through its own proteins until you eat it.
Past the expiry date, these proteins morph into deadly biogenic amines such as histamines. They trigger Scombroid poisoning, essentially tricking your body into thinking you’re experiencing fatal seafood allergies.
Your face will swell, your heart will pound, and your airways will close up.
Because these nasty chemicals aren’t bacteria, heat won’t neutralize them.
Canned potatoes in brine
Potatoes are dense, starchy, and covered in bacteria from the soil that survives most methods of high-heat canning. However, any surviving spores will slowly start to reproduce in the potato brine if the can sits around for too long.
The waterlogged, oxygen-poor environment frequently results in “flat sour” spoilage of the potatoes. The can might seem fine from the outside, but those potatoes have become a dangerous mix of lactic acid and bad bacteria.
Eating these contaminated potatoes will trigger an instant and drastic blood pressure plunge, along with irreversible internal inflammation.
Low-acid asparagus
Spoiled asparagus can be particularly hazardous, especially if it has been canned or stored for a long time.
Low acid vegetables like asparagus provide ideal conditions for botulism to grow without any noticeable changes in smell or taste. Botulism causes paralysis and can kill you.
Home-canned or older low-acid veggies have unfortunately been the source of most botulism outbreaks lately.
Corned beef hash
Corned beef hash can spoil more easily than you would expect. Once the “use by” date passes, the meat can start tasting different.
Some people say it tastes like metal since it’s stored in a can. Even small, microscopic pinhole leaks can occur. Bacteria can fester on the inside of the compact block where you can’t see it.
If a can has gone bad or is bulging, you’re in for a bad time if you eat it.
Spinach
Spinach goes bad in a can too, eventually.
The nitrate in the leaves slowly converts to nitrites when they react with the metal container. Consuming large amounts of nitrites is bad for you because it prevents your blood from carrying oxygen.
Adults won’t typically become extremely ill from spoiled spinach, but for your health, you should stay away from eating large quantities. For babies, too much of it can lead to “blue baby syndrome.”
When spinach gets a slimy coating or the liquid turns dark and greasy, toss it.
Chicken or turkey broth
Broth is essentially a thin protein soup.
When the can’s seal fails, it creates the perfect conditions for anaerobic bacteria to flourish. Tiny punctures that occur naturally through friction will allow Bacillus cereus to grow in your chicken broth.
The bacteria itself isn’t dangerous, but the toxins they release into the broth will make you violently ill with stomach cramps and vomiting.
The clarity of most broth makes it difficult to visually detect the changes caused by bacteria.
Most food safety authorities agree that broth is one of the most dangerous foods to keep in your pantry past the printed expiration date.
Sources: Please see here for a complete listing of all sources that were consulted in the preparation of this article.
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