On 04/09/2013 12:34, Nick Maclaren wrote:

The chances of gasless C. botulinum developing may be low, but those
are not typically cooked much after opening, and the risk of death
if the toxin DOES develop are close to 100%. Note the criterion
'gasless' - most C. botulinum produces gases, which is why you should
never eat anything from a bulgy can. But there is also the danger of
a pinhole letting the gas out, which is the reason for testing the
seal before use and never eating from rusty cans.

Regards,
Nick Maclaren.

Is gas production related to whether or not the spoilt food smells? I
had often wondered why those who suffered botulism couldn't detect that
awful smell and so avoid eating the food. I had just assumed that as
only extremely small amounts of toxin were required for poisoning to
take place the smell was present, but in such small amounts as to make
it imperceptible. But I just found this:

"The proteolytic type A, B and F strains produce very heat-resistant
spores which are a major concern in the processing of low-acid foods.
These types digest proteins in foods and produce a foul odor that may
warn consumers of spoilage.

The nonproteolytic B, E and F strains can grow at refrigerated
temperatures, but produce spores of very low heat resistance. These
types cause problems primarily in pasteurized or unheated foods. Because
they are nonproteolytic, no off-odor or evidence of spoilage may be
produced with toxin development."

(from http://www.ext.colostate.edu/pubs/foodnut/09305.html) Some
interesting info there, and for those who doubted your comment about the
effects of altitude, it has a special mention!

I guess that talking about "Clostridium botulinum" as though it is just
one organism is simplifying things too much; I had no idea it was so
complicated.

--

Jeff