On Sat, 6 May 2006, Dave Fawthrop wrote:
On Sat, 6 May 2006 13:25:22 +0100, Tom Anderson
wrote:
|On Sat, 6 May 2006, David P wrote:
|
| On 06 May 2006, Dave
| wrote:
|
| On Sat, 06 May 2006 00:34:13 +0100, The Natural Philosopher
| wrote:
|
| |Raising the water to 60 C kills about 95% of the bugs in seconds.
|
| That temperature is actually *82* deg C to kill food poisoning bugs
| Some food poisoning bugs breed nicely below 64 deg C
|
| I think amino-acids/proteins get denatured (and becoma deformed beyond
| use) at about 62 degrees.
|
|Depends on the protein - there's quite a variation in denaturation
|temperature, and it depends on the chemical environment etc. 60-odd
|degrees is in the right area, though.
|
| I thought that was the basis for saying that food (eggs, meat, etc) must
| be cooked over approx 62 C.
|
|That's because that's the sort of temperature where collagen denatures,
|becoming gelatin, which is how cooking softens meat. I believe collagens
|from different kinds of animals have different conversion temperatures - i
|ISTR 58 C for fish and 65 C for mammal meat.
I am not disputing your protein denaturing figures, it is just that
bacteria are not just protein, but a lot tougher. Some will withstand
greater than 100 deg C and even breed at that temp.
Oh, absolutely. I wasn't disputing that at all - just commenting on the
denaturation of protein and its relation to cooking (trying to hold up the
uk.food+drink.misc end here!). As you say, there are certainly
thermophilic bacteria that will survive elevated temperatures, even above
100 C. None are pathogenic,
AFAIK - indeed, body temperature is probably
too low for them (as for the examples you gave).
What's more of a concern is bacterial spores; i'm hazy on the details, but
i believe there are spore forms of some pathogenic bacteria that will
survive 100 C temperatures; that's why medical autoclaves go to 100 C -
15 mins at 121 C is the traditional gold standard for autoclaves, although
the one in my old lab went up to 140 C (and it looked like R2D2 - bonus!).
Okay, have looked it up - pathogenic spore-forming bacteria (and the
diseases they case) include _Clostridium tetani_ (tetanus), _Bacillus
anthracis_ (anthrax), _Clostridium perfringens_ and _Bacillus cereus_
(food poisoining), and _Clostridium botulinum_ (botulism).
So, if you've got any of those in your hot tank, well, you're buggered
either way, basically.
tom
--
Know who said that? ****ing Terrorvision, that's who. -- D