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