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New chicken stock preservation issue
- Thread starter Kunmui
- Start date
Re: [email protected]
zxcvbob wrote:
You are both correct, except for the disassembly part. Denaturing (which
actually is not molecular disassembly but more a rearranging IIRC) is
specific to the toxic protein and each requires a specific combination of
time and temp.
I kinda like the term "thermal death time."
MartyB
zxcvbob wrote:
You are both correct, except for the disassembly part. Denaturing (which
actually is not molecular disassembly but more a rearranging IIRC) is
specific to the toxic protein and each requires a specific combination of
time and temp.
I kinda like the term "thermal death time."
MartyB
oldteacher
New member
Re: [email protected]
Landon wrote:
Reposting this link:
http://aggie-horticulture.tamu.edu/extension/poison.html
Landon wrote:
Reposting this link:
http://aggie-horticulture.tamu.edu/extension/poison.html
Re: [email protected]
Landon wrote:
In the specific case of C. Botulinum at least, it seems Bob's statement that
all toxins can withstand boiling may not be correct. However it's more
complicated than that.
The way I understand it, some pathogens and their byproducts are more heat
resistant than others. The same is true with pathogens, and the spores they
produce are usually more heat resistant. Toxins, which are protein related
substances, can be denatured under sufficient heat, but that is different
than what is required to kill live pathogens. In the text portion of the
cited page of the Texas A&M Extension website, under Clostridium Botulinum,
they cite boiling at 10 minutes at a presumed 212F rather than 5 minutes at
a stated 85C (=185F, CDC Emergency Preparedness site) to denature the toxin.
I would be more inclined to trust an FDA or university food safety
recommendation or this CDC site
http://www.cdc.gov/nczved/divisions/dfbmd/diseases/botulism/#prevent where
they also call for 10 minutes boiling.
Each pathogen is a different case. It's noteworthy that at the
oft-recommended 165F for reheating, the organism may be reduced to a safe
level or eliminated but toxins would remain. (Noting that the primary object
is to kill the botulinum bacteria in the first place rather than the toxin
so most food safety information concentrates on this aspect)
It's also true that boiling is not sufficient to destroy C. Boltulinum
spores in a reasonable time, which is why canning must be done under
pressure which can raise temp above 212F. If you look at figure 6.4 on this
page http://www.nzifst.org.nz/unitoperations/httrapps2.htm it shows that as
temp goes up, kill time for the spores goes down.
The point I hope people take away from this is that there are both organisms
and toxins which can remain viable even when cooked, and which can become
harmful unless proper procedures are followed for cooking, serving, and
storage.
Food is rarely sterile (canning process is one exception) nor is the
environment. From the tamu.edu page, "Therefore, illness can be prevented by
(1) controlling the initial number of bacteria present, (2) preventing the
small number from growing, (3) destroying the bacteria by proper cooking and
(4) avoiding re-contamination." Cooking serves to reduce pathogens to a
safe level, not to sterility. Food can be held heated or refrigerated for a
period of time provided the guidelines are followed, for example, that which
states which limit the amount of time food should be held in the "danger
zone" between 40F and 140F which is usually cited as 2 hours.
http://www.fsis.usda.gov/factsheets/Danger_Zone/index.asp However extended
storage, sometimes even under refrigeration, can allow some pathogens to
propagate, again per the tamu.edu page. You only need to find that "science
project" in the back of your fridge to know this is true.
That's probably more than you asked for but there it is. Hope that helps.
MartyB
Landon wrote:
In the specific case of C. Botulinum at least, it seems Bob's statement that
all toxins can withstand boiling may not be correct. However it's more
complicated than that.
The way I understand it, some pathogens and their byproducts are more heat
resistant than others. The same is true with pathogens, and the spores they
produce are usually more heat resistant. Toxins, which are protein related
substances, can be denatured under sufficient heat, but that is different
than what is required to kill live pathogens. In the text portion of the
cited page of the Texas A&M Extension website, under Clostridium Botulinum,
they cite boiling at 10 minutes at a presumed 212F rather than 5 minutes at
a stated 85C (=185F, CDC Emergency Preparedness site) to denature the toxin.
I would be more inclined to trust an FDA or university food safety
recommendation or this CDC site
http://www.cdc.gov/nczved/divisions/dfbmd/diseases/botulism/#prevent where
they also call for 10 minutes boiling.
Each pathogen is a different case. It's noteworthy that at the
oft-recommended 165F for reheating, the organism may be reduced to a safe
level or eliminated but toxins would remain. (Noting that the primary object
is to kill the botulinum bacteria in the first place rather than the toxin
so most food safety information concentrates on this aspect)
It's also true that boiling is not sufficient to destroy C. Boltulinum
spores in a reasonable time, which is why canning must be done under
pressure which can raise temp above 212F. If you look at figure 6.4 on this
page http://www.nzifst.org.nz/unitoperations/httrapps2.htm it shows that as
temp goes up, kill time for the spores goes down.
The point I hope people take away from this is that there are both organisms
and toxins which can remain viable even when cooked, and which can become
harmful unless proper procedures are followed for cooking, serving, and
storage.
Food is rarely sterile (canning process is one exception) nor is the
environment. From the tamu.edu page, "Therefore, illness can be prevented by
(1) controlling the initial number of bacteria present, (2) preventing the
small number from growing, (3) destroying the bacteria by proper cooking and
(4) avoiding re-contamination." Cooking serves to reduce pathogens to a
safe level, not to sterility. Food can be held heated or refrigerated for a
period of time provided the guidelines are followed, for example, that which
states which limit the amount of time food should be held in the "danger
zone" between 40F and 140F which is usually cited as 2 hours.
http://www.fsis.usda.gov/factsheets/Danger_Zone/index.asp However extended
storage, sometimes even under refrigeration, can allow some pathogens to
propagate, again per the tamu.edu page. You only need to find that "science
project" in the back of your fridge to know this is true.
That's probably more than you asked for but there it is. Hope that helps.
MartyB
On Wed, 13 Apr 2011 20:58:58 -0500, "Nunya Bidnits"
wrote:
Sorry I couldn't trim this last post. Everything in it has something
to do with what you've said or what I've asked.
Thanks for all the information. One thing that I might suggest you
refrain from using as a guideline is the term "boiling". Its too
vague. Boiling happens at a wide span of temperatures and doesn't
necessarily mean much. Instead, I would refer to actual temperatures.
A persons own immune system has a lot to do with it also. Some people
can withstand much more contamination in their systems before it makes
them sick. Others, get sick at the slightest presence of toxins.
Thanks again for the information.
wrote:
Sorry I couldn't trim this last post. Everything in it has something
to do with what you've said or what I've asked.
Thanks for all the information. One thing that I might suggest you
refrain from using as a guideline is the term "boiling". Its too
vague. Boiling happens at a wide span of temperatures and doesn't
necessarily mean much. Instead, I would refer to actual temperatures.
A persons own immune system has a lot to do with it also. Some people
can withstand much more contamination in their systems before it makes
them sick. Others, get sick at the slightest presence of toxins.
Thanks again for the information.
Re: [email protected]
Landon wrote:
True enough. If it were technically necessary I would. In the case of Usenet
I say it's close enough for government work. ;-)
That's a fact. A lot of the safety rules and regs are written with that in
mind... best practices are designed to avoid worst case scenarios.
You're welcome!
MartyB
Landon wrote:
True enough. If it were technically necessary I would. In the case of Usenet
I say it's close enough for government work. ;-)
That's a fact. A lot of the safety rules and regs are written with that in
mind... best practices are designed to avoid worst case scenarios.
You're welcome!
MartyB