In article ,
Jeff Layman wrote:
On 04/09/2013 01:20, Christina Websell wrote:
"Gary Woods" wrote in message
...
Baz wrote:

I am going to do some beetroot, onions, tomatoes and some cucumbers
(gerkins?).

I may have missed mention of botulism; surely everybody knows that
non-acid
foods need the temperature of a pressure canner to be sure?
I had to dig out my EnglishAmerican reference to find out that we call
them "Mason jars," after the dominant (but surely not only) manufacturer.
What are use are similar to the pictures of Kilner jars, with a separate
ring (usually removed after the contents cool) and lid with rubber seal,
which is not to be re-used.

My grandfather managed to not kill us all with his kidney beans storage but
IIRC he used rock salt. It came in loaf shape and had be sawed by a knife.

Bit puzzled by that comment. Kidney beans contain a mild toxin
(although if you have eaten them when they haven't been cooked hot and
long enough, it doesn't seem /that/ mild. I speak from experience). It
is in a different league (or different galaxy...) from botulism. I'm
not sure, but I would guess that if you cooked kidney beans long enough
to inactivate their toxin - basically 30 minutes at a rolling boil - you
would also kill any C.botulinum or its spores,as well as inactivating
any botulinum toxin, but I am happy to be corrected.

If you get enough of the bean toxin, it can kill - there were a number
of such cases when slow cookers first became popular. But you need
nothing like 30 minutes for that toxin - 10 is plenty - though you
probably need 30 minutes if there was significant botulinus toxin.

I would also guess that high concentrations of salt prolong spore
survival time. The less water a spore is exposed to, the longer it can
survive. Excess salt, even in solution, would keep a spore partially
dehydrated and more viable. But then salt isn't used to control botulism
- what is needed is potassium nitrate (saltpetre).

No, it's not like that. Clostridium is effectly not infectious, so
it's only when the spores germinate and have time to grow that the
toxin builds up. Common salt discourages that in several ways, as
does saltpetre. So do acids and allowing aeration.

If I were Baz, I would use a pressure cooker for those vegetables.
Fruit isn't a problem.

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.

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