"Dog Ma 1" (reply w/o spam)> writes:
> [...caffeine and steeping...]
>
> I'm going to hazard a guess that for most teas, a few minutes in tepid water
> will take out most of the alkaloids and not much else. That five seconds in
> hot water will take out 90% from anything. And that in fannings/dust and
> even small broken-leaf blacks, with most of the taste in dried surface
> exudates, only cold water will remove buzz w/o taking away too much flavor.
I've just been trying to find some data on caffeine's extraction from
tea leaves as a function of steep temperature and time. (Using the
lazy man's research tool: Google.) Regarding temperature, there's
lots of talk about how lower steep temperatures slow down the
extraction, but not numbers.
A Canadian university student health pamphlet
http://www-health.concordia.ca/healt.../caffeine.html
cites these caffeine concentrations:
Tea (5 oz)
Brewed for 3 minutes--------------------------- 20-46
Brewed for 1 minute -----------------------------9-33
That is to say, after steeping 1 minute at an unspecified temperature
(but most people would assume near boiling) at least 11 to 13 mg of
caffeine is yet to emerge from the leaves.
A British government study
http://archive.food.gov.uk/maff/arch...144/annexc.htm
found that a 1-minute infusion from a teabag had 30% less caffeine
than a 5-minute infusion. They're talking about finely chopped leaves
here, and presumably very hot water, and still 30% remains after a
minute.
> That's an informed guess, because it's what I do. Too much caffeine just
> keeps me awake at night; I only have a cup every month or two,
Are you referring to coffee here? Or late-night tea?
> and have a low tolerance. Theophylline OD makes me quite ill. So if
> I'm having more than one mug of strong Assam or one pot of sencha,
> I'll wash out most of the theophylline per above. Cold water seems
> to work pretty well, though I have yet to try it on expensive
> oolongs.
I'm a little dubious about cold water, because I actually use tepid
water a lot to brew tea in the summer. (I don't really like iced
tea.) I find that a 15-minute steep of a green yields a delicious cup
with no astringency at all, which gives a kind of creamy mouth feel.
I've no idea how much caffeine there is in the cup, but clearly a lot
of the good stuff in the leaves comes out in 15 minutes, so I'm not
sure I'd want to toss the liquor from a 5-minute steep in tepid water.
/Lew
---
Lew Perin /
http://www.panix.com/~perin/babelcarp.html