Bluesea wrote:
I don't understand how a kettle can superheat water since it turns to steam
when boiled and evaporates unlike a microwave which can heat water above 212
degrees F with no loss of liquid or even boiling as we see it on the stove.

Same reason that water can be supercooled by tens of degrees when very
clean: boiling and freezing are both nucleation phenomena. That's why
microwaved water can geyser when agitated, and why some chefs use
boiling stones in a large kettle. The superheating isn't much, but
enough to have a large effect on expulsion of dissolved gases. There's
also a significant effect (absent in pre-boil microwaving) due to
"sweeping" of the bulk liquid by rising bubbles, a standard industrial
technique for removing gas from water, organics and even molten glass. I
speak as one who has had to degas all sorts of liquids with methods
ranging from simple boiling and helium sparging to freeze-pump-thaw to
ultrasound and other mechanical approaches.

-DM

On Dec 8, 9:19 am, DogMa wrote:
Fran wrote:


The reasons could be important if one has reason to use a microwave -
e.g., no alternative, as in many office situations - and can easily make
better tea by taking better care. That's why I mentioned food odors,
commonly present in microwave oven as they are fiddly to clean well. The
step-drop in temperature I mentioned is simple to demonstrate. One
might surmise that you don't like microwaved tea because the brew
temperature is hotter than suits you. It's easy enough to check.

Good point about the food odors -- the main reason I avoid using the
microwave in the office for any reason. But even a microwave that
hasn't been contaminated with other foods does not make a great cup of
tea. I've never gotten any tea from the microwave that wasn't
undrinkably harsh. The microwave is the only thing available in my
office, so I've brought in my own electric kettle so I can get a
decent cup of tea a few times a day.

As for the temperature drop -- another good point. I think that is
the main reason why brewing tea in a teapot makes better tea than
brewing it directly in the mug. I only brew in the mug at work due to
the lack of facilities, but always preheat the mug and cover it while
the tea is brewing. This helps maintain the heat longer and makes a
huge difference in the taste of the tea.

I'm also a "milk in first" person because adding milk last tends to
scald it and just doesn't taste the same. Obviously when brewing in
the mug, "milk in first" is not an option, so when I'm at work, I
always wait a minute or two after brewing my tea to let it cool
slightly before I add any milk.



Some of us here may appear as rigid fundamentalists, didactic,
intolerant or otherwise inhibiting of tea art. A closer listening might
reveal that we're trying to prevent the propagation of silly, untested
or (in many cases) demonstrably erroneous "received wisdom" that
actually gets in the way of beginners' experimentation to find their own
best preferences.

Have a cup of tea, and speak to personal experience.

-DM

Fran wrote:
I've never gotten any tea from the microwave that wasn't
undrinkably harsh.

Not inconsistent with the overheating proposition, ne?

-DM

"Fran" wrote in message
...
On Dec 8, 8:18 am, "Bluesea" wrote:
wrote in message

...

1.) Is it a bad idea to microwave a cup of tea with the tea bag
already inside it?

From a safety standpoint, no, it's a good idea because doing so keeps
the
water from exploding.

Huh??

With a microwave, if conditions are right, it's possible to heat water above
the boiling point with no water movement as we'd see on a stove. Having a
microwave-safe object in the vessel, like a plastic or wood stirrer or
instant coffee or sugar or (ick) teabag, keeps the water from exploding.

It's a dangerous possibility and it happened to me in 2003 when I was
microwaving 24 oz of water in a 32 oz Pyrex glass measuring cup (wide
opening) on a turntable (moving, not still). Maybe the water remained too
stable despite the movement of the turntable, a manual wind-up model that I
had used without incident many times before under similar conditions to
"boil" water for tea. Anyway, the water went from stillness straight to
BLAM! and nearly all the water was blown out of the cup.

Thank God(!) it exploded in the microwave before I opened the door or I
could have been severely burned. It surely did stun the heck out of me and I
switched immediately to using a kettle on the stove.

I did some research and learned that water typically explodes *after* being
removed from the microwave. For more info:
http://www.snopes.com/science/microwave.asp.

For an MPG or Quicktime movie, and more info, please see:
http://www.phys.unsw.edu.au/~jw/superheating.html.

From that evening until February 2005 when a friend saw a TV program that
said that inserting a microwave-safe object like a wooden stick or plastic
stirrer would make it okay, I heated water solely in my kettle. Even now, I
use the microwave to heat water only for green or white teas which need
water below the boiling point. I always have a wooden stick in the cup and
zap it for no more than 2 minutes.

May a word to the wise be sufficient. Two online acquaintances said it's
happened to them, too. My real life friends said, "Didn't you know?"


--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.

"Bluesea" wrote in message
...

My real life friends...

Sorry, I meant real world as compared to cyberspace. We're all really alive,
aren't we?

--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.

Bluesea wrote:
"DogMa" wrote in message
...
Beyond that, heating water to boiling in a kettle
is like to degas it much more effectively than a microwave, since the
kettle superheats the water locally - a good way to ensure efficient
removal of dissolved gases.

I don't understand how a kettle can superheat water since it turns to steam
when boiled and evaporates unlike a microwave which can heat water above 212
degrees F with no loss of liquid or even boiling as we see it on the stove.

It's the same thing.

The only reason you see water superheating in a microwave is because the
heating is very rapid and you're using a vessel with smooth walls and few
nucleation points for the bubbles to start.

The only reason you don't see water superheating in a kettle is because
the sides aren't completely smooth, so there are plenty of places for
the bubbles to begin, and the heating is comparatively slow because there
are fewer watts going directly into the water, so there is more time for
it to start.

Scientific American had an article in the eighties on the subject that
is really worth looking up. I believe it was one of Jearl Walker's
Amateur Scientist columns.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Fran wrote:
I'm guessing that you've never made tea from water boiled in a
microwave. It's not a subtle difference and it's not psychological.
The resulting brew is undrinkable. I don't need scientific evidence
to tell me when something tastes bad. And the reasons why microwaved
water makes poor tea isn't all that important. It just does.

No, the reasons are _very_ important. Once we know the reasons, we can
prevent it from happening.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Fran wrote:
On Dec 8, 8:18 am, "Bluesea" wrote:
wrote in message

...

1.) Is it a bad idea to microwave a cup of tea with the tea bag
already inside it?

From a safety standpoint, no, it's a good idea because doing so keeps the
water from exploding.

Huh??

Water won't superheat if the tea bag is in there.

If you're worried about superheating, a better solution is to get an
earthenware mug with a rough glazed surface.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Bluesea wrote:
It's a dangerous possibility and it happened to me in 2003 when I was
microwaving 24 oz of water in a 32 oz Pyrex glass measuring cup (wide
opening) on a turntable (moving, not still). Maybe the water remained too
stable despite the movement of the turntable, a manual wind-up model that I
had used without incident many times before under similar conditions to
"boil" water for tea. Anyway, the water went from stillness straight to
BLAM! and nearly all the water was blown out of the cup.

If you do this regularly, get a diamond engraver and put a couple lines
down the side of the cup on the inside. This will provide nucleation
points to start boiling.

You can also buy a "boil over preventer" or "pot watcher" made of
acid-etched glass. They used to be free handouts at the Corning museum.
Problem is that you can't leave one in a measuring cup all the time because
it's displacing some of whatever you're measuring.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"DogMa" wrote in message
...
Bluesea wrote:
I don't understand how a kettle can superheat water since it turns to
steam
when boiled and evaporates unlike a microwave which can heat water above
212
degrees F with no loss of liquid or even boiling as we see it on the
stove.

Same reason that water can be supercooled by tens of degrees when very
clean: boiling and freezing are both nucleation phenomena. That's why
microwaved water can geyser when agitated, and why some chefs use
boiling stones in a large kettle. The superheating isn't much, but
enough to have a large effect on expulsion of dissolved gases. There's
also a significant effect (absent in pre-boil microwaving) due to
"sweeping" of the bulk liquid by rising bubbles, a standard industrial
technique for removing gas from water, organics and even molten glass. I
speak as one who has had to degas all sorts of liquids with methods
ranging from simple boiling and helium sparging to freeze-pump-thaw to
ultrasound and other mechanical approaches.

I had to look up boiling stones
(http://en.wikipedia.org/wiki/Boiling_stones) and, I'm sorry, but I still
don't understand. Are we using different definitions? Please see:
http://www.m-w.com/dictionary/superheat
http://www.m-w.com/dictionary/supercool
http://en.wikipedia.org/wiki/Supercooling.

By your reply, I'm thinking that you mean heating/cooling faster, not to a
higher/lower temperature to boil/freeze. Is that right? My understanding of
superheating matches the following from
http://en.wikipedia.org/wiki/Superheating:

"Liquid would not be superheated if the liquid is heated via heated
container (e.g. water in a pot on top of a stove) because the heated
container surface that heats up the liquid provides nucleation sites for the
liquid to boil off and cool down. This is in contrast to a microwave, where
the water is directly heated via microwaves and not by the container."

Is it possible that we're saying the same thing and I don't recognize that
we are?

--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.

Here's my take from a tea-novice (but no longer just a tea-newbie).

When I first started with this "loose tea" business, I always
microwaved my water. And it was sufficient. And as I became more into
tea, I invested in an electric kettle (and an automatic tea maker-
because I'm still lazy). I could taste a difference from the
microwaved water. Maybe it was just psychological, but I did notice it
- especially with flavored teas. It may also be the "food odors" and
such, too. I don't clean out my microwave as much as I should :-x

Now, when I brew tea, I always try to use loose leaf, kettle boiled
water. Of course, I don't always have that convenience, usually at
work or when I'm traveling. While I think loose leaf teas are a better
investment, I'm not "above" using a bag or microwaved water if I have
to. It tastes good enough. And if I want tea, I'd rather go for
something than nothing. Even if it's bigelow, although I really REALLY
have to want tea to use bigelow.

Also, I always boil my milk in the microwave when I'm making chai
(with the chai in the microwave, as well). It tastes fine to me.

And as for the tea bag issue, I wouldn't use them more than twice. The
first time they can be good, the second time they're all right. The
third time, there's really not much flavor left and you'll just get
"kinda-tea flavored water".

On Dec 8, 9:19 am, DogMa wrote:
Fran wrote:
I'm guessing that you've never made tea from water boiled in a
microwave. It's not a subtle difference and it's not psychological.
The resulting brew is undrinkable. I don't need scientific evidence
to tell me when something tastes bad. And the reasons why microwaved
water makes poor tea isn't all that important. It just does.

Bad guess - please read the rest of the post. In any event, I'm not
arguing that there's no difference, only that the imputation of same to
heating methods is generally vague pseudo-science. I'm a firm pragmatist
when it comes to cuisine, and believe "de gustibus non est disputandum."
It's only when people insist on invoking the authority of science
without bothering to do a little homework that I would affirm that "ars
sine scientia nihil est."

The reasons could be important if one has reason to use a microwave -
e.g., no alternative, as in many office situations - and can easily make
better tea by taking better care. That's why I mentioned food odors,
commonly present in microwave oven as they are fiddly to clean well. The
step-drop in temperature I mentioned is simple to demonstrate. One
might surmise that you don't like microwaved tea because the brew
temperature is hotter than suits you. It's easy enough to check.

Some of us here may appear as rigid fundamentalists, didactic,
intolerant or otherwise inhibiting of tea art. A closer listening might
reveal that we're trying to prevent the propagation of silly, untested
or (in many cases) demonstrably erroneous "received wisdom" that
actually gets in the way of beginners' experimentation to find their own
best preferences.

Have a cup of tea, and speak to personal experience.

-DM

i did a double blind test on myself - heating water itself in the mw,
without any nucleation enablers,
and the microwaved water tasted different, and the tea infused tasted
different,
not major
but distinctly different and to me somewhat un-enjoyable

http://tgfop.wordpress.com/2007/03/0...ling-electric/.

"Scott Dorsey" wrote in message
...
Bluesea wrote:
"DogMa" wrote in message
...
Beyond that, heating water to boiling in a kettle
is like to degas it much more effectively than a microwave, since the
kettle superheats the water locally - a good way to ensure efficient
removal of dissolved gases.

I don't understand how a kettle can superheat water since it turns to
steam
when boiled and evaporates unlike a microwave which can heat water above
212
degrees F with no loss of liquid or even boiling as we see it on the
stove.

It's the same thing.

The only reason you see water superheating in a microwave is because the
heating is very rapid and you're using a vessel with smooth walls and few
nucleation points for the bubbles to start.

The only reason you don't see water superheating in a kettle is because
the sides aren't completely smooth, so there are plenty of places for
the bubbles to begin, and the heating is comparatively slow because there
are fewer watts going directly into the water, so there is more time for
it to start.

Scientific American had an article in the eighties on the subject that
is really worth looking up. I believe it was one of Jearl Walker's
Amateur Scientist columns.

Thanks, Scott.

--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.

"SN" wrote in message
...
i did a double blind test on myself - heating water itself in the mw,
without any nucleation enablers,
and the microwaved water tasted different, and the tea infused tasted
different,
not major
but distinctly different and to me somewhat un-enjoyable


http://tgfop.wordpress.com/2007/03/0...ling-electric/.

"Flat" is a good description and I agree.

(Nice glasses, BTW.)


--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.

Responding (for some reason) to several posts:

Scott Dorsey wrote:
The only reason you see water superheating in a microwave is because the
heating is very rapid and you're using a vessel with smooth walls and few
nucleation points for the bubbles to start.

The only reason you don't see water superheating in a kettle is because
the sides aren't completely smooth, so there are plenty of places for
the bubbles to begin, and the heating is comparatively slow because there
are fewer watts going directly into the water, so there is more time for
it to start.

Sort of. Nucleation requires addition of enough energy to overcome the
newly created bubble's surface energy. In a microwave, heat is added
over a large volume at low energy density, so local thermal gradients
are low, there is nil turbulence (as distinct from laminar convection)
and superheating only when the bulk is quite warm. With a heating
element, energy is deposited in a turbulent and unstable boundary layer,
guaranteeing local superheating and boiling while the bulk is still
cool. We all know what that sounds and looks like: large bubbles formed
at the element or bottom surface disappear before surfacing as they are
cooled by the bulk. The issue is not rate of energy deposition (power),
but spatial density of same.

wrote:
Also, I always boil my milk in the microwave when I'm making chai
(with the chai in the microwave, as well). It tastes fine to me.

And as for the tea bag issue, I wouldn't use them more than twice. The
first time they can be good, the second time they're all right. The
third time, there's really not much flavor left and you'll just get
"kinda-tea flavored water".

Microwaving milk (vs. heating in a pot) can limit caramelization, for
those who prefer the more raw taste. As to bags, I presume we're staying
with black/red tea. Most greens and oolongs are far from their best at
boiling. At more modest temperatures, they may well deliver several good
steeps. When I started drinking bagged Japanese green tea many years
ago, I quickly learned to use coolish water. First steep bitter, second
and third perfect, fourth OK but weak. I was pleased on my first
business trip to Japan to find my colleagues and customer doing exactly
the same thing.

Bluesea wrote:
Having a microwave-safe object in the vessel, like a plastic or wood
stirrer or instant coffee or sugar or (ick) teabag, keeps the water
from exploding. being removed from the microwave.

From that evening until February 2005 when a friend saw a TV program
that said that inserting a microwave-safe object like a wooden stick
or plastic stirrer would make it okay, I heated water solely in my
kettle.

Scott Dorsey wrote:
If you do this regularly, get a diamond engraver and put a couple
lines down the side of the cup on the inside. This will provide
nucleation points to start boiling.

You can also buy a "boil over preventer" or "pot watcher" made of
acid-etched glass.

These things can all work, but not reliably or repeatedly. Any dry
powder like salt or sugar will work well until it's dissolved due to
both rough surfaces and adsorbed gas. Dry wooden spoons, ditto. A fresh
teabag will work, but typically not a wet used one. Almost anything
else, even roughened glass, will eventually passivate for a wide range
of reasons. Chemists have a bunch of tricks like active stirring that
aren't practical or aesthetic at home. A bit of clean gravel will work
(we call them "boiling stones") as long as it's dried completely between
uses. A cute reusable device is glass beads - like tiny marbles - called
boiling beads. These work by bouncing around and making a fresh burst of
small bubbles at each bounce. But the liquid can still superheat unless
the container is shaken to start the process. A toothpick or single dry
tealeaf (can be used) would work.

-DM