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I see all over the Internet that botulism is a threat in food from dented cans. The problem seems to be if the dent falls on a seam on top, bottom, or side, the seam might be compromised.  However, one food expert says if the seam is compromised, air would enter, and perhaps other harmful problems might develop, but not botulism, because it needs anaerobic circumstances. This sounds logical to me, but I can't find it substantiated anywhere. What do you think, and why?
I don't know what to do about food from a can with a dent along the top edge that we put in the pan and then had second thoughts and didn't heat it or eat it..would I have to boil the whole pan in a bigger pan, since food touched the side, the lip, and even the outside a little?

Hi Kat
The bacteria in question here is Clostridium botulinum. It is a gram positive anaerobe that grows in the absense of oxygen. It requires an acidic environment so grows best in canned vegetables like green beans and tomatoes. It will not grow in alkaline conditions. It is found in swollen cans not in dented cans due to the build up of gasses. As long as a dented can has no breaks there no danger. Of course, if when opening a can there is a bad smell it should be disgarded. If in doubt it is best to disgard the can. Boiling dented cans will not kill bacteria. Many bacteria are spore formers and are not destroyed at 212 degrees F.. Boiling cans could cause them to explode.
 In summary: Swollen cans could contain botulina toxins
         Dented cans without a puncture are not dangerous
         Do not boil any cans
         When in doubt discard


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Walter Hintz


Science teacher for over 50 years. MSc. in biology. I can answer questions in general biology, zoology, botany, anatomy and physiology and biochemistry.


I have a MSc in biology and have been a science teacher for over 50 years. At present I am a faculty member at a college and a science consultant at seven catholic schools.

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