On Mon, 7 Mar 2005 07:36:27 -0800, "Curt Nelson" <[email hidden]>
Quoted message said:Peter Aitken said:"Siobhan Perricone" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:The OP posted:
>> Is there something about the steaming process that accelerates
>> cooking of meats like this? Should I go an extra ten minutes just
>> to make sure it's cooked thoroughly?
Just a note, steam is hotter than boiling water (that's why it's
steam).
Not actually. Steam and water will be at the same temperature.
Wrong. Go recheck your physics regarding phase transitions and the heat
content of water.
Ok, I asked my resident Science Man(tm) and this is the reply I got.
Me: ok, I'm right about this aren't I? Steam is hotter than boiling water,
isn't it? I mean, that's why it's STEAM right?
Him:
Well, technically it's the same temperature, but technically boiling water
isn't what you're thinking of when you say "boiling water". Steam *can* be
hotter of course.
What happens is... you heat up water, which means you keep adding heat to
it. Imagine dropping chunks of heat into water. Each chunk converts into a
temperature increase until the water reaches the boiling point. Then you
have to add a few more chunks of heat during which the water does NOT
change temperature. The amount of chunks of heat you have to add is called
the energy of evaporation. Once enough has been added, the water turns into
steam.
Now in a cookpot it immediately leaves the pot, so you can't keep heating
it. If you keep it in a sealed chamber though you can keep heating it and
it *will* end up hotter. In fact, again you add chunks until you reach the
plasma point, then a few more chunks to get through the transition to
plasma. And the same happens when you heat ice, only that's called the
energy of fusion.
So essentially a bunch of H20 at temperature 100C could be boiling water or
steam, depending on whether the energy of evaporation has been added or
not. But water sitting in a pot on the stove at a rolling boil is probably
not quite at 100C. *Some* of it is but most of it isn't, and each bit that
is convects, and when it hits the energy of evaporation, it turns to
steam, which becomes a bubble, which bubbles up to the top and escapes and
that's what makes it a rolling boil, but the water around the bubble is
probably still 99C or so.
[end Science Man's explanation]
So, that's what makes pressure cookers work. You hold the steam in and that
increases the heat. 🙂 Anyway, I stand mostly corrected. 🙂
--
Siobhan Perricone
"I ain't afraid of your Yahweh
I ain't afraid of your Allah
I ain't afraid of your Jesus
I'm afraid of what ya do in the name of your god"
- Holly Near