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Do you know the signs to watch for to avoid eating canned food that might be deadly?  There are several ways harmful bacteria can contaminate canned food.  “In the United States, about 110 cases of botulism are reported each year“.  A person can’t see or smell if a can is contaminated with botulism spores, however, there are other contaminates that can be seen and smelled.  The good news is that most of the signs that canned food has spoiled are fairly easy to recognize once you know what to look for.  Below is a quick review of what to keep an eye out for.  See if you know all the signs to watch out for.

1. A Lid that Bulges Moving Up & Down

This unsafe can of whole potatoes had been exposed to extremely cold temperatures and relatively hot temperatures in my garage, over a 6 month period.

2. Food Projecting or Exploding When Opened

This YouTube video was made by TheModernSurvivalist. Check out some of their other informative videos here and don’t forget to subscribe!

3. Rusting / Corrosion of Can

This was pulled out of a house fire and it was covered with soot.  Soot and moisture corrodes metal.  Corrosion will eventually create holes that let in air and bacteria.

4. Leaking

This YouTube video was made by Mrs. Crosby. Check out some of their her informative videos here and don’t forget to subscribe!

5. Dents

Dents compromise the integrity of the air tight seal which can expose the food to harmful bacteria.

6. Acrid Smell


If it smells pungent, acidic, chemical, or has a unnatural smell don’t eat it!

7. Rising Bubbles or Unnatural Looking Colors



The picture above is of a well shook can of safe bubbles.  I didn’t have an example of unsafe bubbles so I thought I’d show you safe bubbles.  The bubbles to be watchful of are small rising gas bubbles.

8. Hisses Loudly When Opened

A soft quite hiss when the air rushes into a can you are opening is normal but a can that hiss loudly when opened is a warning sign.

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So if a can is bulging, projecting, rusting, leaking, is dented, has a weird smell, looks funky, or hisses loudly DON’T taste it and handle it carefully!  “Contact with botulinum toxin can be fatal whether it is ingested or enters through the skin. Take care to avoid contact with suspect foods or liquids.”  Carefully dispose of the contaminated food.

  • How do I safety clean up and dispose of spoiled canned food?  Find the answer at the National Center for Home Food Preservation
  • Do you have food safety questions?  Find answers at USDA Shelf-Stable Food Safety
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