Re: [CH] Botulism
Charles Demas (demas@sunspot.tiac.net)
Thu, 1 Jul 1999 14:55:54 -0400 (EDT)
On Thu, 1 Jul 1999, Tantrika wrote:
> I've always been told that botulism is present in a canned food if the lid
> puffs up, because botulism produce a gas. If that is so, wouldn't the same
> principle apply to home canned jars with the mason lids? Wouldn't that be
> a fairly easy way to tell if a canned jar of salsa went caput? Or is this
> an old wives tale?
The botulism toxin is very potent. A millionth of a gram of botulism
toxin is enough to kill many many people. A toxic dose is measured in
nanograms (billionths of a gram).
There are botulism spores all around us, they live in the soil, waiting
for the right conditions to develop. Fortunately, nature doesn't often
provide those conditions, but we humans tinker with nature, we want to
preserve foods, and indoing that, we sometimes put spores into conditions
that will allow them to develop.
One microscopic bacterial spore in the right conditions is all it takes to
start the process eventually multiplying and producing the toxin. The
toxin kills us, not the spores themselves. The spores don't hurt adults,
we eat them every day. Spores in honey are a common cause of infant
botulism, where the spores develop in the infant's digestive tract. That
doesn't happen after about age 3 or 4, and certainly not (to my knowledge)
in adults.
A swollen can could contain enough toxin to kill a large sized city, but
it didn't get swollen instantly. At some point the swelling was only
barely detectable, but at that point there was still an enormous amount
of toxin. Enough to kill you many many times.
Just before the swelling was detectable, there would still be an enormous
amount of toxin. Still enough to kill you many many times.
With the growth factors of the bacteria controlled by many outside
factors, and because one might eat a canned product anywhere from a day or
two after canning, to months after canning, using the lack of swelling as
a sign that the product is safe is a poor safeguard. You might have
chosen one just before its swelling would be detected.
Certainly, any product showing swelling should be considered unsafe.
Fortunately, boiling water temperatures will destroy the toxin (but not
the spores), so boiling the canned product will destroy the toxin and
allow one to then dispose of the suspect product.
All this worry can be eliminated if you follow the recommended safeguards
and procedures recommended for home canning. Botulism requires specific
conditions to develop. Don't provide those conditions, and it cannot
develop and you're safe.
Further, adding a canned product to a boiling (simmering) sauce would
allow the heat to destroy any toxin in the canned product. I'm not
recommending this as a method to use suspect product, rather, I'm
mentioning it so that people will realize that this cooking method insures
safety when using canned products, even commercially canned products.
Proper cooking techniques will again provide safety.
Unfortunately, boiling water temperatures are not high enough to kill the
spores, but as I've said, not providing the spores an environment in which
to develop will provide safety.
I believe this is covered in the rec.food.preserving FAQ available
on the web, and in URLs provided in previous years posts to this list.
Note that a salsa with a pH below (more acid) than 4.6 will not allow the
growth of botulism. Keeping the pH below 4.3 will provide a margin of
safety. (4.3 is more acid than 4.6) The same goes for hot sauces or
other chile products that might be canned.
Drying and freezing are other alternatives for preserving chiles. I don't
know how well salsa made from frozen chiles would be, perhaps someone on
the list has some experience with this.
Chuck Demas
Needham, Mass.
Eat Healthy | _ _ | Nothing would be done at all,
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