Hello all,

Greetings from a tea-lover in the oolong capital of the world, Taiwan!
Great group! I have a strange tea question. I wonder if any of you
might have the answer . . .

I regularly decaffeinate my tea after 7pm by simply discarding the
original 30 seconds of steeped tea water and re-steeping in fresh
water for another minute, two, or three, depending on the tea. This is
quite common here in Taiwan, where for most Oolongs we "wash" the
leaves and remove a bit of the caffeine, and then have three or four
more steepings. Anyone who wishes to avoid excess caffeine simply
abstains from the first round. The flavor of the tea certainly suffers
in the 30-second decaffeinating process, but at the end of the day I
always trade flavor for a good night's rest. Oolong flavor generally
stands up much better to the decaffeinating process than black or
green varieties. Anyway, not to get off track . . .

Up to 75% of the caffeine is eliminated by removing the first 30
seconds of steeped tea water. But what about the L-Theanine? Could I
also be removing the L-theanine (i.e. the de-stressing component of
the tea) and much of the heathful properties of the tea? I drink a lot
of green tea, so I'm concerned I'm missing out on its goodness by
decaffeinating.

If anyone knows the answer or could point me to a source, I would much
appreciate it! Thanks!

--Mark

After my original post, I went back through the archives and
discovered the decaf thread . . . Well, I'd still like to know about L-
theanine . . . thanks!

--Mark

Well as I understand , white tea, green teas due to the fact that the
enzmes are fixed preventing further oxidation seems to yield higher
levels of thenanine than that of fully fermented black teas, so as far
as the oolongs go the less they are fermented the more theanine you
will get out of them. Regarding the release I dont know however for
interests sake I understand that tannin is released after about five
minutes of steeping, this may be that in some teas the longer they
steep the more bitter they become.
...Maurice

"mgford25" > writes:

> After my original post, I went back through the archives and
> discovered the decaf thread . . . Well, I'd still like to know about L-
> theanine . . . thanks!

I don't have any numbers to give you. The best I can do is to not
that theanine is a pretty small molecule, not greatly different in
size from caffeine, and all other things being equal, you'd expect it
to exit the leaf at a similar. Of course, some other things may
be unequal, like the chemical properties of the two molecules! I bet
DogMa could take a far better educated guess than I.

/Lew
---
Lew Perin /
http://www.panix.com/~perin/babelcarp.html

Here I found this article on the web hope it helps
ref http://www.austinchronicle.com/gyrob...d=oid%3A208400


Tea and coffee both contain caffeine, a stimulant, but tea also has
tannin and theanine, which are calming. The presence of these chemical
compounds together in tea allows you to control its effect. When
boiling water is poured onto the tea leaves, in the first two minutes
all the caffeine is drawn out. At this point tea is most stimulating.
During the next few minutes, tannin and theanine are gradually brought
out of the tea leaves. After about five minutes this will tend to
cancel out the effects of the caffeine and will make a more relaxing,
calming tea. If you want only the calming effects from tea, discard
the liquid from the first two minutes of steeping and use only the
liquid from subsequent steeping, containing little caffeine and more
tannin and theanine

Hey guys

To add to the discussion above:

1. The reason green tea and white contain more theanine is because
they tend to be made from young tender shoots. Oolong tea is made from
more mature leaves, which gives them a richer fragrance, but less
theanine.

2. Caffeine is quicker to dissolve in water compared to catechins or
theanine, that is why the first infusion is much richer than caffeine
compared to the other more beneficial chemicals. To answer your
question, later infusion still has the theanine and catechins, but
much less caffeine.

3. Theanine dissolves faster than the other tea tannins. Theanine it
not only calming, it is fresh and sweet tasting. Latter infusion
tastes bitter because there is less theanine in them. So as long as
your tea tastes nice, don't worry, the theanine is there.

The link below contains a discussion on tea chemistry based on
Graham's paper in 1992.

Green Tea Chemical Composition
http://www.amazing-green-tea.com/che...green-tea.html

4. For best type of decaffeinated green tea to drink, check out the
article below:

Decaffeinated Green Tea
http://www.amazing-green-tea.com/caf...green-tea.html

Talking about caffeine and catechins, I had 2.5 grams of dragonwell
yesterday and it keep me wide awake all day! I infuse it four times
and it was still going strong! This stuff is REAL powerful.

Kind regards
Julian

Tea Drinkers,
Thank you everyone for helping me! A very, very cordial group you have
here! I look forward to following the other discussions...

--Mark

Lewis Perin wrote:
> I don't have any numbers to give you. The best I can do is to not
> that theanine is a pretty small molecule, not greatly different in
> size from caffeine, and all other things being equal, you'd expect it
> to exit the leaf at a similar. Of course, some other things may be
> unequal, like the chemical properties of the two molecules! I bet
> DogMa could take a far better educated guess than I.

Julian wrote:
> 2. Caffeine is quicker to dissolve in water compared to catechins or
> theanine, that is why the first infusion is much richer than caffeine
> compared to the other more beneficial chemicals.

I had a quick look in at-hand reference books, but couldn't find good
water-solubility data on both molecules. Perhaps someone with
library access would like to look.

Size matters, but it's not just the molecule itself. Effective
hydrodynamic radius for diffusion depends on the size of the hydration
sphere, which in turn depends on things like dipole moments in various
parts of the molecule, and how it wraps itself up - not a factor for
caffeine, but perhaps important for theanine. If I had to guess, I'd say
that they're probably similar enough in extraction rate that
time-slicing won't allow a useful separation. Perhaps Julian would be
kind enough to provide a research source for his assertion.

Re the reference
http://www.austinchronicle.com/gyrob...d=oid%3A208400
language like "... in the first two minutes all the caffeine is drawn
out. ... During the next few minutes, tannin and theanine are gradually
brought out of the tea leaves" is misleading. Things aren't drawn out;
they fall down a concentration gradient, and not all at once. They tend
to follow a slow induction - quasi-steady state - asymptotic decline
profile influenced by leaf hydration, remaining concentration and even
the local concentration of other ingredients. A mental image of stepwise
effects is not correct. (For an egregious example, see the recent
Illycafe piece in Scientific American, which was so misleading and
self-promoting that I canceled my decades-old subscription.) Until
someone bothers to do real lab work like the caffeine paper cited by
Nigel (unfortunately under conditions not perfectly relevant for most of
us here) on both molecules at once, it's all idle speculation.

-DM

Dear Dogma

You got me there. It is good to hear what a chemist has to say.

I think my assertion comes from two parts: caffeine dissolves in water
faster than catechins, and compared to the theanine, caffeine
solubility in water is more sensitive to temperature - i.e. caffeine
dissolves much faster in hot water.
Sadly, I have a quick scan through my materials and it is not
immediately obvious there is a good relevant study that compares water
solubility of caffeine and theanine.

Another factor is caffeine and theanine reactivity with other
compounds in hot water. There are suggestions that caffeine forms
compounds with tannins and theaflavin. It will be interesting to know
how much of caffeine reacts away and how that compare to theanine -
and in fact how the two interact.

What was interesting during my quick scan is that young leaf (tea
flush) contains more theanine and catechins than older leaves. With
the ratio of theanine (and probably caffeine) to catechins much higher
in younger leaves than older leaves.

Julian
http://www.amazing-green-tea.com

juliantai wrote:
> I think my assertion comes from two parts: caffeine dissolves in water
> faster than catechins, and compared to the theanine, caffeine
> solubility in water is more sensitive to temperature - i.e. caffeine
> dissolves much faster in hot water.

Unfortunately, it's even more complicated than that. Most references
will report equilibrium solubility, which for all materials in question
is far more than the amount of solute available. You're mainly talking
about dissolution kinetics. There again, the model is too simple. A pile
of caffeine powder dissolves in a little hot water with a few swirls.
But the actives in tea are buried in small leaf cells, behind various
membranes and tortuous passageways, all of which change in permeability
(in both directions) as the leaf hydrates; they may also be bound more
or less strongly by electrostatic and hydrophobic interactions, etc.
There's just no substitute for experiment. Too bad no-one with an HPLC
(a very common research tool) has bothered to do the definitive work -
or to report it. Who knows if Lipton and others have done all this work,
and found the results either useful in their business, or deleterious to
same, hence proprietary?

> Another factor is caffeine and theanine reactivity with other
> compounds in hot water. There are suggestions that caffeine forms
> compounds with tannins and theaflavin. It will be interesting to know
> how much of caffeine reacts away and how that compare to theanine -
> and in fact how the two interact.

I don't think that that would affect physiological effects. Those are
weak associations - not "real" covalent chemistry - and probably pop
right apart in the stomach.

> What was interesting during my quick scan is that young leaf (tea
> flush) contains more theanine and catechins than older leaves. With
> the ratio of theanine (and probably caffeine) to catechins much higher
> in younger leaves than older leaves.


It is all interesting. From my perspective, Anyone who's not living
fully organic/macrobiotic, exercising regularly and otherwise living a
healthful life should forget all those alleged tea health benefits and
focus on known, powerful influences. Caffeine certainly has real
sensible effects, and theanine might, but most of the chemical
discussion here seems to me more like self-hypnosis than meaningful
control of self-medication.

-DM

In article >,
DogMa > wrote:
>Lewis Perin wrote:
>> I don't have any numbers to give you. The best I can do is to not
>> that theanine is a pretty small molecule, not greatly different in
>> size from caffeine, and all other things being equal, you'd expect it
>> to exit the leaf at a similar. Of course, some other things may be
>> unequal, like the chemical properties of the two molecules! I bet
>> DogMa could take a far better educated guess than I.
>
>Julian wrote:
>> 2. Caffeine is quicker to dissolve in water compared to catechins or
>> theanine, that is why the first infusion is much richer than caffeine
>> compared to the other more beneficial chemicals.
>
>I had a quick look in at-hand reference books, but couldn't find good
>water-solubility data on both molecules. Perhaps someone with
>library access would like to look.

Catechin is pretty soluble... it just disappears when it hits the
surface. It's still used as a photographic developer and it's one of
the fastest to mix up (unlike developing agents which need to be dissolved
in an alcohol and then added to the water in order to speed the process up).

But, I happen to have a Merck Index in my office and it says that
"Aqueous solutions of caffeine salts disassociate quickly" and that
solubility is one gram to 46 ml water. It also notes that "solubility
in water is increased by alkali benzoates, cinnamates, citrates or
salicylates."

As opposed to catechin which it says is "slightly soluble in cold water,
soluble in hot water."

Tannic acid, by the way, takes 0.35 ml water to dissolve a gram. So it
can be concentrated a lot more than the caffeine though of course this
says nothing about the rate of dissolving.
--scott

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