Botulism and cans

Botulism has a few requirements before it can grow. It requires a moist, low acid environment with low oxygen. Dry beans are safe as are all dried foods. Canned foods, because of being moist and low oxygen could be ideal environments. That's why the foods are either acidified by adding citric acid, ascorbic acid (vitamin c) or some other food acid, or are canned at high enough heat (pressure canning for soups, meats, etc) that the botulism spores are killed.

Botulism produces pressure, so if a can is bulged, avoid it. Also, heat breaks down the botulism toxin. Cooking canned foods for 10-15 minutes would break down the toxins, but it's better to avoid any suspected foods and not take the risk.

BJJ_Grappler said:

Are you sure that heat will denature botulism toxins? Any sources for that?

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The botulism spores are heat tolerant, that's why the higher heat of pressure canning is needed for low acid foods. But the toxin breaks down readily when heated to normal cooking temperatures. Here's a few links, google found many.

Journal of the American Medical Association:
http://jama.ama-assn.org/cgi/content/full/285/8/1059
The toxin is readily inactivated by heat (85°C for 5 minutes).

http://edis.ifas.ufl.edu/FS104
While the botulinum spores are heat stable, the toxin itself is heat-labile, so heating a food to 176°F for 10 minutes before consumption can greatly reduce the risk of illness.

http://www.medterms.com/script/main/art.asp?articlekey=25769
The toxin is heat labile and can be destroyed if heated at 80°C for 10 minutes or longer.

bulrush said:

Nope, the bacteria is destroyed by heat but the toxins are not. Can't remember where I read it. But if it smells or tastes "twangy", spit it out immediately.

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Poke around google a bit and you'll find out a lot about botulism. From reading this thread, it's apparent that a lot of folks aren't very knowledgeable about it, yet we all need to be. It's one of the most toxic substances known, yet easily avoided with a little knowledge and caution.

gkmiami said:

I know I've read from several sources that when opening home pressure canned foods that it is recommended to always simmer them for 10 - 15 minutes before consuming. Reading that never gave me supreme confidence in the home canning methods but I look at it as perhaps another layer of cya. I also believe that as others have posted most of the time the signs are evident whether a jar has been compromised. Be observant.

gk

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I see that recommendation a lot too. It's just an additional safety net and a good one in my opinion. The problem with recognizing a jar (or metal can) that has been compromised is that by the time you can see it, it's been compromised for some time. It's in the early stages, when you can't see it, that worries me. It's just as deadly, but no blown seal (or bulging can) yet.