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