I was spring cleaning my pantry last week when I spotted a dusty can of soup pushed way back on the shelf. No idea how long it had been there! When I picked it up, the can had a small dent and the lid was slightly bulging. Into the trash it went – no hesitation. Many of us stock our pantries with canned goods as affordable kitchen staples, but do you know when those seemingly indestructible cans need to go? Those mysterious codes printed on the bottom don’t always tell the whole story, and sometimes your eyes and common sense are better guides than any date stamp.
Bulging or swollen cans mean serious trouble
When you see a can with a bulging or swollen lid, don’t think twice – toss it immediately. That bulge isn’t just a minor defect; it’s a serious warning sign that dangerous bacteria are growing inside. When bacteria multiply in canned food, they produce gases that cause pressure to build up, making the can swell. This is particularly worrisome because it could indicate the presence of Clostridium botulinum, the bacteria that produces the deadly botulinum toxin. Botulism is rare but extremely dangerous, and you should never take chances with food that shows these signs.
The thing about bulging cans is that the food inside might look and smell perfectly normal, which makes it even trickier. That’s why food safety experts are so firm about this rule – never taste food from swollen cans to check if it’s good. The bacteria that cause botulism can’t be detected by taste or smell. If you find a bulging can in your pantry, carefully place it in a sealed bag before disposing of it to prevent anyone from accidentally using it. This isn’t being wasteful – it’s protecting your family from a serious risk.
Rust and deep dents are not just cosmetic issues
While a tiny bit of surface rust on the outside of a can might seem harmless, extensive rust is another story altogether. Rust can eat through metal over time, potentially creating microscopic holes that allow bacteria to enter the can. If you spot a can with severe rust, especially along the seams or near the lid, it’s time to say goodbye to it. These seemingly small imperfections can compromise the airtight seal that keeps the food safe. The same goes for deeply dented cans – particularly those with dents along the seams or that affect the lid or the sealing surfaces.
Those small dings from dropping a can in your grocery bag? Usually not a problem. But deep dents that distort the shape of the can or affect the seam are different. These deeper dents can break the seal of the can, allowing bacteria to contaminate the food inside. Food safety experts recommend being particularly cautious with dents that are sharp enough to rest your finger in, or dents on the top or bottom seams where the can is sealed. The money you might save by keeping questionable canned goods isn’t worth the potential risk to your health or your family’s wellbeing.
Watch out for spurting liquid when opening
Ever opened a can of food and had liquid spray out unexpectedly? That’s not normal, and it’s definitely not a sign to ignore. When liquid spurts out of a can as you’re opening it, it typically means that gas has built up inside, creating pressure – and that’s a red flag for spoilage. This happens because bacteria inside the can have been busy producing gases as they multiply. Even if the can looks perfectly normal from the outside with no bulging or damage, this pressurized release of liquid is telling you something important about what’s happening inside.
If you notice liquid squirting out when you open a can, stop right there. Don’t smell it, don’t taste it – just carefully dispose of the entire can and its contents. And don’t forget to wash your can opener, countertop, and hands thoroughly afterward to prevent cross-contamination. This kind of spoilage can happen even in cans that otherwise look perfect, which is why it’s important to pay attention to all warning signs, not just the obvious visual ones.
Strange smells, colors, or textures are deal breakers
Trust your senses when it comes to canned food safety. If you open a can and notice an off smell – one that’s sour, fermented, or just plain weird – that’s your cue to toss it. Our noses are actually pretty good at detecting when food has gone bad. The same goes for unusual colors – if the food has darkened significantly, developed strange discolorations, or has an unnatural-looking tinge to it, that’s another warning sign. Food shouldn’t change color dramatically when it’s properly canned and stored, so these visual clues are important indicators that something has gone wrong.
Texture changes can be just as telling. Canned foods that have become slimy, mushy (when they shouldn’t be), or have separated in unusual ways deserve your suspicion. And if you see any sign of mold growing on the food – even if it’s just a small spot – the entire can needs to go. Mold visible to the eye means there are likely invisible spores throughout the food. Some molds produce toxins that can make you sick, and it’s simply not worth the risk. When in doubt, remember the old saying: “When in doubt, throw it out.” It’s a cliché for a reason – it’s good advice!
Frozen and thawed cans can be risky
Did you know that freezing canned foods in the can is a bad idea? Whether it happens accidentally (like storing cans in an unheated garage during winter) or on purpose, freezing can cause serious problems. When liquid inside a can freezes, it expands – this can break the seal of the can, create tiny cracks, or cause seams to burst, even if the damage isn’t immediately visible to your eye. Once that seal is compromised, bacteria can enter and contaminate the food, even after it thaws back to normal temperature.
If you find cans in your freezer or know they’ve been frozen and thawed, it’s safest to discard them. Even if the can looks normal after thawing, the integrity of the seal may have been compromised during the freezing process. This is especially important with low-acid canned foods like vegetables, soups, and meats, which provide perfect environments for bacteria growth if the seal has been broken. The temperature change can also affect the texture and quality of the food inside, making it less enjoyable even if it remains safe.
Homemade canned goods require extra caution
Store-bought canned goods go through rigorous commercial processing to ensure safety, but homemade canned goods need extra scrutiny. If you’ve been gifted home-canned vegetables, fruits, or other preserves, pay special attention to the seal and condition of the jar. Check for any signs of seal failure – a popped button on the lid, leakage, or cloudiness in the jar. Improperly canned foods, especially low-acid vegetables and meats, can harbor dangerous bacteria without showing obvious signs of spoilage. This is why following proper canning procedures is crucial for home canners.
For safety’s sake, experts recommend that you boil home-canned, low-acid foods for 10-20 minutes before eating them, even if they show no signs of spoilage. This extra step can destroy the botulinum toxin if it’s present. If you’re at all uncertain about the safety of home-canned goods – perhaps you’re not sure how old they are or if proper canning methods were used – err on the side of caution and discard them. As wonderful and economical as home canning can be, it requires strict adherence to safety guidelines to prevent foodborne illness.
Storage conditions matter more than dates
Here’s something that might surprise you – those dates on canned goods aren’t actually expiration dates in most cases. They’re usually “best by” dates that indicate peak quality, not safety. Properly processed and stored canned foods can remain safe to eat for years beyond these dates. The key phrase here is “properly stored” – because how you store your canned goods affects their lifespan significantly. Cans stored in a hot garage or damp basement won’t last nearly as long as those kept in ideal conditions. And what are those ideal conditions? A cool, dry place with consistent temperatures.
The sweet spot for storing canned foods is between 50-70°F, according to food preservation experts. Temperatures above 85°F can accelerate deterioration and increase the risk of spoilage. Always store cans off the floor, away from furnaces, pipes, and other heat sources. High humidity is also an enemy of canned goods, as it can accelerate rusting and potentially compromise can integrity. Generally, high-acid foods like tomatoes and fruits can be safely stored for 12-18 months, while low-acid foods like vegetables and meats can last 2-5 years under proper storage conditions.
Once opened, use it or lose it within days
After you’ve opened a can, the clock starts ticking on its freshness and safety. That shelf-stable food is now perishable and needs to be treated accordingly. The general rule is to refrigerate any unused portion in a clean, covered container – not the original can – and use it within 3-7 days, depending on the food type. Leaving opened canned food at room temperature for more than two hours creates an opportunity for bacteria to multiply rapidly. And if you’ve transferred the food to another container but can’t remember when you opened it? Better safe than sorry – toss it if you’re unsure.
Also worth noting: different types of canned foods have different refrigerator lifespans once opened. High-acid foods like pineapple or tomatoes will generally last 5-7 days, while low-acid foods like beans or corn should be used within 3-4 days. For unused portions of canned seafood or meats, the window is even shorter – about 1-2 days maximum in the refrigerator. If you know you won’t use the remainder within these timeframes, consider freezing it instead. Just remember to label containers with the date so you’re not guessing later about when you opened that can of crushed tomatoes.
Your pantry is probably full of perfectly good canned foods that will last for years. But knowing when to toss the bad ones is just as important as knowing how to use the good ones. Food safety isn’t about being wasteful – it’s about protecting yourself and your family from unnecessary risks. Trust your eyes, nose, and common sense. When a can shows any of these warning signs, remember that the small cost of replacing it is nothing compared to the potential cost of foodborne illness. Better to waste food occasionally than to waste your health even once.
