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
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