FoodBanter.com

FoodBanter.com (https://www.foodbanter.com/)
-   Tea (https://www.foodbanter.com/tea/)
-   -   How can you tell if tea has caffeine? (https://www.foodbanter.com/tea/142520-how-can-you-tell.html)

[email protected] 07-12-2007 08:07 PM

How can you tell if tea has caffeine?
 
How can you determine if tea contains caffeine if the label does not
indicate either way? Are there any ingredients that I can look for to
determine this?

Thanks.

SN 07-12-2007 09:38 PM

How can you tell if tea has caffeine?
 
if they test that batch before packing and put the test result on the
label

which i've never seen. and it would be expensive and time waste for
the tea company.

caffeine is caffeine

usually hope that black tea has more caffeine, but YMMV

Scott Dorsey 07-12-2007 10:27 PM

How can you tell if tea has caffeine?
 
> wrote:
>How can you determine if tea contains caffeine if the label does not
>indicate either way? Are there any ingredients that I can look for to
>determine this?


Tea has one ingredient: tea. If it contains tea, it contains caffeine
unless a process has been used to specifically remove it. If it does
not contain tea, it is not a tea at all but a tisane.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

toci 08-12-2007 09:15 AM

How can you tell if tea has caffeine?
 
On Dec 7, 1:07 pm, wrote:
> How can you determine if tea contains caffeine if the label does not
> indicate either way? Are there any ingredients that I can look for to
> determine this?
>
> Thanks.


I have understood that tea with a lot ot tips has more caffeine.
Toci

Bluesea[_2_] 08-12-2007 01:57 PM

How can you tell if tea has caffeine?
 

> wrote in message
...
> How can you determine if tea contains caffeine if the label does not
> indicate either way? Are there any ingredients that I can look for to
> determine this?
>
> Thanks.


It contains caffeine if there's no indication that it's decaffeinated.


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



[email protected] 08-12-2007 05:52 PM

How can you tell if tea has caffeine?
 
On Dec 7, 2:07 pm, wrote:
> How can you determine if tea contains caffeine if the label does not
> indicate either way? Are there any ingredients that I can look for to
> determine this?
>
> Thanks.


If it's a green, black, oolong, white (or any other kinds of TEA
varieties), it will have caffeine. If it does not have caffeine, it
will say so explicitly on the label (and even then, there are probably
traces of caffeine)

If it's an herbal or rooibos blend, then it is caffeine free. Anything
fruity is generally caffeine free as well. Of course, if it is
combined with a green, black, etc. then it will have some caffeine.

Generally, tea bags will make a big deal if something is caffeine free
(Celestial Seasonings and Tazo I know do this). If they don't mention
it, it probably isn't.

Remember that you can easily "decaffeinate" any tea by steeping it for
a minute and pouring off the contents. The next cup you steep will
have 65-80% less caffeine (the numbers get kinda screwy here, but
that's the general idea). I don't recommend doing this, though, as you
will lose a lot of the flavor if it's a flavored tea.

Bluesea[_2_] 08-12-2007 06:43 PM

How can you tell if tea has caffeine?
 

> wrote in message
...
> On Dec 7, 2:07 pm, wrote:
> > How can you determine if tea contains caffeine if the label does not
> > indicate either way? Are there any ingredients that I can look for to
> > determine this?
> >
> > Thanks.

>
> If it's a green, black, oolong, white (or any other kinds of TEA
> varieties), it will have caffeine. If it does not have caffeine, it
> will say so explicitly on the label (and even then, there are probably
> traces of caffeine)
>
> If it's an herbal or rooibos blend,...


It isn't tea because it didn't come from the Camilla sinensis "tea" plant.

> ...then it is caffeine free.


Unless it's Yerba mate which has caffeine.

> Remember that you can easily "decaffeinate" any tea by steeping it for
> a minute...


After 30 seconds, you lose too much flavor for practically no additional
benefit.

The last time I mentioned DIY decaffeination, I got jumped for propagating a
myth. I still don't understand it because, not only is it fairly common
knowledge by now among tea people, the first time I heard about it, I was
told the name of the man who discovered it and that there was a website.
Since that was about 10 years ago, there's no way I can remember the details
of who discovered it or the URL and the man who told me about it, a former
instructor, has since died so I can't go back to him and ask.

So, now I'm in the position of wondering if the myth about DIY
decaffeinating is a myth since apparently anybody can put up a webpage with
the scientific basis for whatever's being touted.

"I know it's true; I read it on the Internet!"

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



Brent[_4_] 08-12-2007 07:03 PM

How can you tell if tea has caffeine?
 
> So, now I'm in the position of wondering if the myth about DIY
> decaffeinating is a myth since apparently anybody can put up a webpage with
> the scientific basis for whatever's being touted.
>
> "I know it's true; I read it on the Internet!"


The difference is that there are published journal articles in support
of the fact that DIY decaffeination is a myth.

I refer you he http://cat.inist.fr/?aModele=afficheN&cpsidt=2477703

"The overall average caffeine released in the first through third
brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
in the abstract available at the link above, in the full article it is
said that the infusions were 5 minutes each. So... if 5 minutes
removes 69%, how much do you really think 30 seconds will?

-Brent

Bluesea[_2_] 08-12-2007 07:22 PM

How can you tell if tea has caffeine?
 

"Brent" > wrote in message
...
> > So, now I'm in the position of wondering if the myth about DIY
> > decaffeinating is a myth since apparently anybody can put up a webpage

with
> > the scientific basis for whatever's being touted.
> >
> > "I know it's true; I read it on the Internet!"

>
> The difference is that there are published journal articles in support
> of the fact that DIY decaffeination is a myth.
>
> I refer you he http://cat.inist.fr/?aModele=afficheN&cpsidt=2477703
>
> "The overall average caffeine released in the first through third
> brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
> in the abstract available at the link above, in the full article it is
> said that the infusions were 5 minutes each. So... if 5 minutes
> removes 69%, how much do you really think 30 seconds will?


Logically, not enough to matter.

Thanks for the link and the info about the 5-minute steep. Did you notice
the next lines?

"Three cups of tea brewed using three tea bags (Western culture) have
approximately twice the amount of methylxanthines as the same volume
prepared by three successive brews of loose tea leaves (Asian culture). "

Does the full article address the reason for the doubled amount of
methylxanthines? That's a curiosity since the volume and steep time were the
same for both cultural preparations.

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



Brent[_4_] 08-12-2007 07:51 PM

How can you tell if tea has caffeine?
 
The paper doesn't really give a reason, just notes that there is a
difference. They are using bagged teas vs. loose leaf, though, so one
might suspect that the extra surface area to volume ratio of tea bag
fannings would be the culprit.

-Brent

Bluesea[_2_] 08-12-2007 08:10 PM

How can you tell if tea has caffeine?
 
Okay, thanks.

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

"Brent" > wrote in message
...
> The paper doesn't really give a reason, just notes that there is a
> difference. They are using bagged teas vs. loose leaf, though, so one
> might suspect that the extra surface area to volume ratio of tea bag
> fannings would be the culprit.
>
> -Brent




[email protected] 08-12-2007 09:54 PM

How can you tell if tea has caffeine?
 
On Dec 8, 12:43 pm, "Bluesea" > wrote:
> > wrote in message
>
> ...
>
> > On Dec 7, 2:07 pm, wrote:
> > > How can you determine if tea contains caffeine if the label does not
> > > indicate either way? Are there any ingredients that I can look for to
> > > determine this?

>
> > > Thanks.

>
> > If it's a green, black, oolong, white (or any other kinds of TEA
> > varieties), it will have caffeine. If it does not have caffeine, it
> > will say so explicitly on the label (and even then, there are probably
> > traces of caffeine)

>
> > If it's an herbal or rooibos blend,...

>
> It isn't tea because it didn't come from the Camilla sinensis "tea" plant.
>
> > ...then it is caffeine free.

>
> Unless it's Yerba mate which has caffeine.
>
> > Remember that you can easily "decaffeinate" any tea by steeping it for
> > a minute...

>
> After 30 seconds, you lose too much flavor for practically no additional
> benefit.
>
> The last time I mentioned DIY decaffeination, I got jumped for propagating a
> myth. I still don't understand it because, not only is it fairly common
> knowledge by now among tea people, the first time I heard about it, I was
> told the name of the man who discovered it and that there was a website.
> Since that was about 10 years ago, there's no way I can remember the details
> of who discovered it or the URL and the man who told me about it, a former
> instructor, has since died so I can't go back to him and ask.
>
> So, now I'm in the position of wondering if the myth about DIY
> decaffeinating is a myth since apparently anybody can put up a webpage with
> the scientific basis for whatever's being touted.


I think this is a more complex issue than just the caffeine, there are
other
stimulants in tea (I believe at least two other ones). Green and white
and
oolong teas can have as much or more caffeine than blacks, but blacks
have a far different 'buzz' (and stronger) than the other teas, as far
as I can tell.
There are a huge number of variables that may affect this. The
difference in
taste itself can have a stimulating effect. The difference in aroma
may have
an effect as well. Various non-stimulating chemicals may have effect
on how
stimulants are absorbed. The ratio of the three stimulants may have an
effect too.

As far as I'm concerned, second, third, etc steeps make tea with
notably
less stimulating effect but also not as tasty, unless you're talking
about
gong-fu method. I usually don't bother. I'm so used to white and green
tea
that I don't get any stimulating effect from 8-9 oz, and the first
steep
tastes much better to me, even for very good teas, although it may be
that I use less leaf than is common..

>
> "I know it's true; I read it on the Internet!"
>
> --
> ~~Bluesea~~
> Spam is great in musubi but not in email.
> Please take out the trash before sending a direct reply.



Slint Flig 08-12-2007 11:21 PM

How can you tell if tea has caffeine?
 
> "The overall average caffeine released in the first through third
> brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
> in the abstract available at the link above, in the full article it is
> said that the infusions were 5 minutes each. So... if 5 minutes
> removes 69%, how much do you really think 30 seconds will?


good point. If they used bagged tea that means that even less will be
released in loose leaf in the same period.



juliantai[_3_] 08-12-2007 11:44 PM

How can you tell if tea has caffeine?
 
On Dec 8, 10:21 pm, "Slint Flig" > wrote:
> > "The overall average caffeine released in the first through third
> > brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
> > in the abstract available at the link above, in the full article it is
> > said that the infusions were 5 minutes each. So... if 5 minutes
> > removes 69%, how much do you really think 30 seconds will?

>
> good point. If they used bagged tea that means that even less will be
> released in loose leaf in the same period.


I am very puzzled about the origin of the "30 second" myth too.

I read about another study which uses hot water decaffeination, but
using semi-processed leaves, which are then pan roasted later. Now
that is real decaffenation that not only removes caffeine but keep the
nutrients intact.

By the way caffeine is good for you so a few cups a day do an awful
good....

Oops! Did I just say that?

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

Lewis Perin 09-12-2007 12:19 AM

How can you tell if tea has caffeine?
 
"Bluesea" > writes:

> "Brent" > wrote in message
> ...
> > [...]
> > I refer you he http://cat.inist.fr/?aModele=afficheN&cpsidt=2477703
> >
> > "The overall average caffeine released in the first through third
> > brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
> > in the abstract available at the link above, in the full article it is
> > said that the infusions were 5 minutes each. So... if 5 minutes
> > removes 69%, how much do you really think 30 seconds will?

>
> Logically, not enough to matter.
>
> Thanks for the link and the info about the 5-minute steep. Did you notice
> the next lines?
>
> "Three cups of tea brewed using three tea bags (Western culture) have
> approximately twice the amount of methylxanthines as the same volume
> prepared by three successive brews of loose tea leaves (Asian culture). "
>
> Does the full article address the reason for the doubled amount of
> methylxanthines? That's a curiosity since the volume and steep time were the
> same for both cultural preparations.


All I have is the same abstract you quote, but I interpret the
language differently. I think they're talking about using a new (I
almost said "fresh") teabag for each steep in the Western trials, but
*resteeping* the loose leaves in the Asian trials. It's no mystery
when you parse it this way.

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

Brent[_4_] 09-12-2007 12:43 AM

How can you tell if tea has caffeine?
 
Thanks for pointing that out Lew, I see how the language in the
abstract is unclear. However, in the full text they make it more
obvious that they are talking about successive steeps with the same
leaf/bag. The full article is available on ScienceDirect (http://
dx.doi.org/10.1016/0963-9969(96)00038-5) if you have a subscription or
university access.

-Brent

Lewis Perin 09-12-2007 01:08 AM

How can you tell if tea has caffeine?
 
Brent > writes:

> Thanks for pointing that out Lew, I see how the language in the
> abstract is unclear. However, in the full text they make it more
> obvious that they are talking about successive steeps with the same
> leaf/bag. The full article is available on ScienceDirect (http://
> dx.doi.org/10.1016/0963-9969(96)00038-5) if you have a subscription or
> university access.


Sorry, I can't get to the original in the near future. But if they
really mean it that way, then what they represent as the Asian (at
least *East* Asian) way of steeping leaves is wrong. Resteeping the
same leaves is the norm in East Asia.

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

Bluesea[_2_] 09-12-2007 02:51 AM

How can you tell if tea has caffeine?
 

"juliantai" > wrote in message
...
> On Dec 8, 10:21 pm, "Slint Flig" > wrote:
> > > "The overall average caffeine released in the first through third
> > > brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
> > > in the abstract available at the link above, in the full article it is
> > > said that the infusions were 5 minutes each. So... if 5 minutes
> > > removes 69%, how much do you really think 30 seconds will?

> >
> > good point. If they used bagged tea that means that even less will be
> > released in loose leaf in the same period.

>
> I am very puzzled about the origin of the "30 second" myth too.


I traced it back to a U.S. Department of Nutritional Services report and
quit to go out and get more spring water before it starts sleeting.

Will continue to look.

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



Brent[_4_] 09-12-2007 06:57 PM

How can you tell if tea has caffeine?
 
> Sorry, I can't get to the original in the near future. But if they
> really mean it that way, then what they represent as the Asian (at
> least *East* Asian) way of steeping leaves is wrong. Resteeping the
> same leaves is the norm in East Asia.


That is what I meant to say- they did successive steeps (resteeps, if
you will) of the same leaves or bags. No "fresh" leaves/bags were
used except in the first steeps.

-Brent

[email protected] 10-12-2007 12:08 AM

How can you tell if tea has caffeine?
 
I've heard mixed things about the decaffeinating as well.

Basically, I believe that if you're sensitive to caffeine, drink
tisanes (herbal, rooibos, etc.) Don't bother with this decaf-tea
stuff, because either the flavor was lost, or they used chemicals to
decaffeinate.

But some people still ask, so I tell them what I've always been told.
I never claim to be an expert.

On Dec 8, 5:44 pm, juliantai > wrote:
> On Dec 8, 10:21 pm, "Slint Flig" > wrote:
>
> > > "The overall average caffeine released in the first through third
> > > brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
> > > in the abstract available at the link above, in the full article it is
> > > said that the infusions were 5 minutes each. So... if 5 minutes
> > > removes 69%, how much do you really think 30 seconds will?

>
> > good point. If they used bagged tea that means that even less will be
> > released in loose leaf in the same period.

>
> I am very puzzled about the origin of the "30 second" myth too.
>
> I read about another study which uses hot water decaffeination, but
> using semi-processed leaves, which are then pan roasted later. Now
> that is real decaffenation that not only removes caffeine but keep the
> nutrients intact.
>
> By the way caffeine is good for you so a few cups a day do an awful
> good....
>
> Oops! Did I just say that?
>
> Julianhttp://www.amazing-green-tea.com



Nigel 10-12-2007 04:53 PM

How can you tell if tea has caffeine?
 
On Dec 8, 5:43 pm, "Bluesea" > wrote:

> So, now I'm in the position of wondering if the myth about DIY
> decaffeinating is a myth since apparently anybody can put up a webpage with
> the scientific basis for whatever's being touted.
>


As an antidote to the wishful thinking about the decaffeinating
effectiveness of a 30 second wash I proposed the data presented in
"Tea preparation and its influence on methylxanthine concentration" by
Monique Hicks, Peggy Hsieh and Leonard Bell which was published in
1996 in Food Research International. Vol 29, Nos 3-4, pp. 325-330.
Hicks et al measured the caffeine and theobromine (total
methylxanthine) content of six different teas (three bagged and three
loose leaf, including black, oolong and green types). They measured
caffeine extraction in boiling water at 5 minutes (69%), 10 minutes
(92%) and 15 minutes (100%). They replicated all their extractions
three times to eliminate error.
I extrapolated their data below 5 minutes which gave the following
caffeine extraction percentages (averaged over all their tea types and
formats; note while loose tea extracted marginally more slowly than
teabag tea it made only a couple of % points difference):

30 seconds 9%
1 minute 18%
2 minutes 34%
3 minutes 48%
4 minutes 60%
5 minutes 69%
10 minutes 92%
15 minutes 100%

This was very much at odds with the mythical "30 or 45 second hot
wash
to remove 80% of the caffeine " advice - as a 30 second initial wash
of
the tea will actually leave in place 91% of the original caffeine!

Subsequent to that posting I rediscovered a paper by Professor Michael
Spiro whose group did some ground breaking physical chemistry on tea.
In "Tea and the rate of its infusion" Chemistry in New Zealand, 1981,
pp172-174, they disclose caffeine concentration diffusing into water
(4g loose leaf - it will have been CTC small fannings type - in 200 ml
water held at constant 80 deg C, and stirred with a magnetic
stirrer). First data point is at 90 seconds and shows 49% caffeine
removed from leaf (i.e. into water). Extrapolating from Spiro's plot
gives:
30 seconds 20%
1 minute 33%
2 minutes 34%
3 minutes 76%
4 minutes 85%
5 minutes 88%
10 minutes 99%
15 minutes 100%
Thus while a 30 second "wash" under Spiro's rather extreme laboratory
conditions (small leaf, loose in the "pot" rather than teabag, at
constant temperature and stirred vigorously) leached 20% caffeine
rather than just 9% under Hick's more normal steeping, neither of
these findings anywhere near match the 80% decaffeination claims of
the wishful thinkers perpetuated as an Internet Myth.

Nigel at Teacraft

Nigel 10-12-2007 05:51 PM

How can you tell if tea has caffeine?
 


ADDENDUM

Should read "Two minutes . . .64%"

>
> Subsequent to that posting I rediscovered a paper by Professor Michael
> Spiro whose group did some ground breaking physical chemistry on tea.
> In "Tea and the rate of its infusion" Chemistry in New Zealand, 1981,
> pp172-174, they disclose caffeine concentration diffusing into water
> (4g loose leaf - it will have been CTC small fannings type - in 200 ml
> water held at constant 80 deg C, and stirred with a magnetic
> stirrer). First data point is at 90 seconds and shows 49% caffeine
> removed from leaf (i.e. into water). Extrapolating from Spiro's plot
> gives:
> 30 seconds 20%
> 1 minute 33%
> 2 minutes 34%
> 3 minutes 76%
> 4 minutes 85%
> 5 minutes 88%
> 10 minutes 99%
> 15 minutes 100%
> Thus while a 30 second "wash" under Spiro's rather extreme laboratory
> conditions (small leaf, loose in the "pot" rather than teabag, at
> constant temperature and stirred vigorously) leached 20% caffeine
> rather than just 9% under Hick's more normal steeping, neither of
> these findings anywhere near match the 80% decaffeination claims of
> the wishful thinkers perpetuated as an Internet Myth.
>
> Nigel at Teacraft



Scott Dorsey 10-12-2007 07:01 PM

How can you tell if tea has caffeine?
 
In article >,
Slint Flig > wrote:
>> "The overall average caffeine released in the first through third
>> brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
>> in the abstract available at the link above, in the full article it is
>> said that the infusions were 5 minutes each. So... if 5 minutes
>> removes 69%, how much do you really think 30 seconds will?

>
>good point. If they used bagged tea that means that even less will be
>released in loose leaf in the same period.


I don't know how much 30 seconds will.

That's why I'd like to see a plot of residual caffeine given steeps of
varying lengths, as well as a plot of residual tannins. So we know just
how nonlinear the dissolving is for each.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Bluesea[_2_] 11-12-2007 02:17 AM

How can you tell if tea has caffeine?
 

"Brent" > wrote in message
...
> > So, now I'm in the position of wondering if the myth about DIY
> > decaffeinating is a myth since apparently anybody can put up a webpage

with
> > the scientific basis for whatever's being touted.
> >
> > "I know it's true; I read it on the Internet!"

>
> The difference is that there are published journal articles in support
> of the fact that DIY decaffeination is a myth.
>
> I refer you he http://cat.inist.fr/?aModele=afficheN&cpsidt=2477703
>
> "The overall average caffeine released in the first through third
> brews were 69%, 23%, and 8%, respectively." Though it doesn't say so
> in the abstract available at the link above, in the full article it is
> said that the infusions were 5 minutes each. So... if 5 minutes
> removes 69%, how much do you really think 30 seconds will?


Thinking it over makes me question:

Did Hicks et al measure and report the amount of caffeine released in the
first 30 seconds, 45 seconds, 1 minute, or at any other point before the
first 5-minute steep was over?

What if the "myth" is correct - that up to 80% of tea's caffeine is released
in the first 30 seconds and there's no point to a longer DIY decaffeinating
steep because the rate of caffeine is greatly slowed and the amount of
caffeine released after 30 seconds isn't enough to warrant sacrificing
flavor?

If Hicks et al didn't measure the amount of caffeine released before 5
minutes had passed and if caffeine is as highly water-soluble as purported,
there's no evidence to support that a 30-second steep is significantly less
effective at releasing caffeine than a 5-minute steep.


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



Bluesea[_2_] 11-12-2007 03:42 AM

How can you tell if tea has caffeine?
 

"Nigel" > wrote in message
...
> On Dec 8, 5:43 pm, "Bluesea" > wrote:
>
> > So, now I'm in the position of wondering if the myth about DIY
> > decaffeinating is a myth since apparently anybody can put up a webpage

with
> > the scientific basis for whatever's being touted.
> >

>
> As an antidote to the wishful thinking about the decaffeinating
> effectiveness of a 30 second wash I proposed the data presented in
> "Tea preparation and its influence on methylxanthine concentration" by
> Monique Hicks, Peggy Hsieh and Leonard Bell which was published in
> 1996 in Food Research International. Vol 29, Nos 3-4, pp. 325-330.
> Hicks et al measured the caffeine and theobromine (total
> methylxanthine) content of six different teas (three bagged and three
> loose leaf, including black, oolong and green types). They measured
> caffeine extraction in boiling water at 5 minutes (69%), 10 minutes
> (92%) and 15 minutes (100%). They replicated all their extractions
> three times to eliminate error.
> I extrapolated their data below 5 minutes which gave the following
> caffeine extraction percentages (averaged over all their tea types and
> formats; note while loose tea extracted marginally more slowly than
> teabag tea it made only a couple of % points difference):
>
> 30 seconds 9%
> 1 minute 18%
> 2 minutes 34%
> 3 minutes 48%
> 4 minutes 60%
> 5 minutes 69%
> 10 minutes 92%
> 15 minutes 100%
>
> This was very much at odds with the mythical "30 or 45 second hot
> wash
> to remove 80% of the caffeine " advice - as a 30 second initial wash
> of
> the tea will actually leave in place 91% of the original caffeine!


It's "up to 80%" and extrapolation doesn't work if caffeine is so highly
water-soluble that the rate of release decreases dramatically after 30
seconds. We need the actual measurements at the precise points of time.

> Subsequent to that posting I rediscovered a paper by Professor Michael
> Spiro whose group did some ground breaking physical chemistry on tea.
> In "Tea and the rate of its infusion" Chemistry in New Zealand, 1981,
> pp172-174, they disclose caffeine concentration diffusing into water
> (4g loose leaf - it will have been CTC small fannings type - in 200 ml
> water held at constant 80 deg C, and stirred with a magnetic
> stirrer). First data point is at 90 seconds and shows 49% caffeine
> removed from leaf (i.e. into water). Extrapolating from Spiro's plot
> gives:
> 30 seconds 20%
> 1 minute 33%
> 2 minutes 34%
> 3 minutes 76%
> 4 minutes 85%
> 5 minutes 88%
> 10 minutes 99%
> 15 minutes 100%
> Thus while a 30 second "wash" under Spiro's rather extreme laboratory
> conditions (small leaf, loose in the "pot" rather than teabag, at
> constant temperature and stirred vigorously) leached 20% caffeine
> rather than just 9% under Hick's more normal steeping, neither of
> these findings anywhere near match the 80% decaffeination claims of
> the wishful thinkers perpetuated as an Internet Myth.


Caffeine is water-soluble above 175 deg F. Since Spiro's using 80 deg C is
right at 176 degrees, I question if a higher temperature, such as the
boiling water recommended for the 30-second DIY decaffeinating steep,
releases more caffeine than was released at 176 F.

See, it would be easier to accept your Hicks and Spiro defenses if their
experiments were conducted using actual measurements at the time and
temperature points pertinent to the "myth" because the rate of release at
the different temperatures preclude the use of your extrapolations.


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



Bluesea[_2_] 11-12-2007 03:53 AM

How can you tell if tea has caffeine?
 

"Brent" > wrote in message
...
> > Sorry, I can't get to the original in the near future. But if they
> > really mean it that way, then what they represent as the Asian (at
> > least *East* Asian) way of steeping leaves is wrong. Resteeping the
> > same leaves is the norm in East Asia.

>
> That is what I meant to say- they did successive steeps (resteeps, if
> you will) of the same leaves or bags. No "fresh" leaves/bags were
> used except in the first steeps.


That raises another point. Does the report say that they used boiling water
for black tea and cooler water for green and oolong teas? If so, that might
account for the lower amounts of methylxanthines released for the green and
oolong teas.

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



Brent[_4_] 11-12-2007 04:04 AM

How can you tell if tea has caffeine?
 
> See, it would be easier to accept your Hicks and Spiro defenses if their
> experiments were conducted using actual measurements at the time and
> temperature points pertinent to the "myth" because the rate of release at
> the different temperatures preclude the use of your extrapolations.


I agree that these studies weren't meant to prove what we are using
them for, but until you present plausible data of similar credibility,
I will continue considering it a myth.

-Brent

Bluesea[_2_] 11-12-2007 04:45 AM

How can you tell if tea has caffeine?
 

"Nigel" > wrote in message
...
> On Dec 8, 5:43 pm, "Bluesea" > wrote:
>
> > So, now I'm in the position of wondering if the myth about DIY
> > decaffeinating is a myth since apparently anybody can put up a webpage

with
> > the scientific basis for whatever's being touted.
> >

>
> As an antidote to the wishful thinking about the decaffeinating
> effectiveness of a 30 second wash I proposed the data presented in
> "Tea preparation and its influence on methylxanthine concentration" by
> Monique Hicks, Peggy Hsieh and Leonard Bell which was published in
> 1996 in Food Research International. Vol 29, Nos 3-4, pp. 325-330.
> Hicks et al measured the caffeine and theobromine (total
> methylxanthine) content of six different teas (three bagged and three
> loose leaf, including black, oolong and green types). They measured
> caffeine extraction in boiling water at 5 minutes (69%), 10 minutes
> (92%) and 15 minutes (100%). They replicated all their extractions
> three times to eliminate error.


Another thing is that the 69% at 5 minutes is artificially low because they
included herbal tisanes in the overall average. From the abstract at
http://cat.inist.fr/?aModele=afficheN&cpsidt=2477703:

"In this study, methylxanthine (caffeine, theobromine, and theophylline)
contents in three brews of four types of tea (black, oolong, green, and
herbal) in both bags and loose leaf forms were investigated to determine the
actual amount of methylxanthines present in tea as a function of different
brewing methods...Caffeine and theobromine were not detected in either
herbal tea samples, and theophylline was not detected in any tea tested. The
overall average caffeine released in the first through third brews were 69%,
23%, and 8%, respectively."

Why in the world they included herbals, I have no idea, but if they are
tossed out as they should be simply because they're not from any Camillia si
nensis, the overall average percentages go up for the amount of caffeine
released.


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



Bluesea[_2_] 11-12-2007 04:53 AM

How can you tell if tea has caffeine?
 

"Brent" > wrote in message
...
> > See, it would be easier to accept your Hicks and Spiro defenses if their
> > experiments were conducted using actual measurements at the time and
> > temperature points pertinent to the "myth" because the rate of release

at
> > the different temperatures preclude the use of your extrapolations.

>
> I agree that these studies weren't meant to prove what we are using
> them for, but until you present plausible data of similar credibility,
> I will continue considering it a myth.


I don't mind your considering it a myth in the absence of a quoted study
(right now, I'm thinking a 1986 report of a study done by Kaiser Permanente
MIGHT be the source), but I surely don't appreciate getting jumped for what
is supposedly common knowledge by now by people who use studies that haven't
in any way whatsoever supported as yet their stance that it's a myth.

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



Brent[_4_] 11-12-2007 04:54 AM

How can you tell if tea has caffeine?
 
> Another thing is that the 69% at 5 minutes is artificially low because they
> included herbal tisanes in the overall average. From the abstract athttp://cat.inist.fr/?aModele=afficheN&cpsidt=2477703:
>
> "In this study, methylxanthine (caffeine, theobromine, and theophylline)
> contents in three brews of four types of tea (black, oolong, green, and
> herbal) in both bags and loose leaf forms were investigated to determine the
> actual amount of methylxanthines present in tea as a function of different
> brewing methods...Caffeine and theobromine were not detected in either
> herbal tea samples, and theophylline was not detected in any tea tested. The
> overall average caffeine released in the first through third brews were 69%,
> 23%, and 8%, respectively."


Actually, they did not include herbals in those percentages. The teas
used to calculate those averages are Lipton black tea bag, loose black
leaves, two loose Formosa oolongs, Lipton green tea bag, and loose
green leaves.

-Brent

Bluesea[_2_] 11-12-2007 04:55 AM

How can you tell if tea has caffeine?
 

"Brent" > wrote in message
...
> > Another thing is that the 69% at 5 minutes is artificially low because

they
> > included herbal tisanes in the overall average. From the abstract

athttp://cat.inist.fr/?aModele=afficheN&cpsidt=2477703:
> >
> > "In this study, methylxanthine (caffeine, theobromine, and theophylline)
> > contents in three brews of four types of tea (black, oolong, green, and
> > herbal) in both bags and loose leaf forms were investigated to determine

the
> > actual amount of methylxanthines present in tea as a function of

different
> > brewing methods...Caffeine and theobromine were not detected in either
> > herbal tea samples, and theophylline was not detected in any tea tested.

The
> > overall average caffeine released in the first through third brews were

69%,
> > 23%, and 8%, respectively."

>
> Actually, they did not include herbals in those percentages. The teas
> used to calculate those averages are Lipton black tea bag, loose black
> leaves, two loose Formosa oolongs, Lipton green tea bag, and loose
> green leaves.


Ok. I was misled by the abstract.

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



Brent[_4_] 11-12-2007 05:05 AM

How can you tell if tea has caffeine?
 
> I don't mind your considering it a myth in the absence of a quoted study
> (right now, I'm thinking a 1986 report of a study done by Kaiser Permanente
> MIGHT be the source), but I surely don't appreciate getting jumped for what
> is supposedly common knowledge by now by people who use studies that haven't
> in any way whatsoever supported as yet their stance that it's a myth.


You're not getting jumped- it's just that referring to "common
knowledge" isn't a valid counter-argument to (at least) plausible
scientific data, despite a lack of detail. You say that our data has
not supported our conclusions "in any way whatsoever" (a point I would
disagree with), yet you do not provide *any* data whatsoever, not even
incomplete data, supporting your assumptions. I can think of plenty
of times over the course of human history when the common knowledge
was blatantly wrong, so it is only reasonable to question it.

-Brent

Nigel 11-12-2007 10:47 AM

How can you tell if tea has caffeine?
 
On Dec 11, 2:42 am, "Bluesea" > wrote:


> Caffeine is water-soluble above 175 deg F. Since Spiro's using 80 deg C is
> right at 176 degrees, I question if a higher temperature, such as the
> boiling water recommended for the 30-second DIY decaffeinating steep,
> releases more caffeine than was released at 176 F.
>
> See, it would be easier to accept your Hicks and Spiro defenses if their
> experiments were conducted using actual measurements at the time and
> temperature points pertinent to the "myth" because the rate of release at
> the different temperatures preclude the use of your extrapolations.
>
> --
> ~~Bluesea~~
> Spam is great in musubi but not in email.
> Please take out the trash before sending a direct reply.- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -


I disagree, both sets of data look like a classic second order
quadratic response to me - and caffeine does not not suddenly become
100% soluble at 176 deg F, neither (in the real world) does a "wash"
with water at boiling point take place at 212 F. But, as Professor
Ingolfsson remarked (about polar bear ancestry): "This is just how I
interpret it. This is science - when you have little data, you have
lots of freedom."

However I am mildly surprised that the long term supporters and
advocates of this unnatural practice have never actually undertaken
(or caused to be undertaken) the key measurements at 0, 15, 30, 45 and
60 seconds.

Nigel at Teacraft

Alan 11-12-2007 08:38 PM

How can you tell if tea has caffeine?
 
On Dec 11, 2:47 am, Nigel > wrote:
> I disagree, both sets of data look like a classic second order
> quadratic response to me - and caffeine does not not suddenly become
> 100% soluble at 176 deg F, neither (in the real world) does a "wash"
> with water at boiling point take place at 212 F.


Does this mean that cold-brewed iced-tea would have less caffeine than
hot-brewed? Or does the extended steeping time (hours) allow the
caffeine to eventually dissolve in the water even though it is cold?

Alan

Nigel 12-12-2007 11:38 AM

How can you tell if tea has caffeine?
 
On Dec 11, 7:38 pm, Alan > wrote:

> Does this mean that cold-brewed iced-tea would have less caffeine than
> hot-brewed? Or does the extended steeping time (hours) allow the
> caffeine to eventually dissolve in the water even though it is cold?


Assuming you cold steep at 1 gram leaf per 100 ml water and that
avearge leaf contains 3% caffeine I would say yes it will eventually
all leach out. I
base this on placing 0.3 grams pure caffeine into 1 liter of water at
room temperature - it dissolved completely within 2 hours.

Nigel at Teacraft


All times are GMT +1. The time now is 06:55 AM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
FoodBanter