Re: Caffiene in tea - Long brew vs. Short brew

A 2001 paper by a Unilever Research team from Bedford, England, found
that anything from growing conditions to the age of leaves, plant
cultivars and methods of cultivation affects tea's caffeine content.
All these things remaining equal, the temperature of water, leaves to
water ratio and steeping times also have a big impact on caffeine in
the end brew.

When it comes to steeping times specifically, it is true that a lot of
the caffeine content is extracted in the first thirty seconds. As the
brew time increases, the rate at which caffeine is extracted from the
leaves slows down-but that's doesn't mean that the longer leaves are
steeped, the less caffeine content the brew will have. In fact, it's
quite the opposite.

According to this study, 34.6% of caffeine is extracted from the
average teabag in the first 30 seconds of infusion. This figure will go
up to just over 50% after a minute. After 5 minutes, the total caffeine
extracted from the leaves will have gone up to more than 90%. By
contrast, polyphenols are extracted more slowly, with just 19.9%
extracted in the first 30 seconds. So the longer you steep your tea,
the lower you push the rate of caffeine extraction per second and the
ratio of caffeine to polyphenols--but the overall amount of caffeine
will go up. Of course, if you are discarding the first infusion, the
subsequent brews will have less caffeine and comparatively more
polyphenols. Although the study looked specifically at teabags, I
believe they said its results could be extended to loose leaves too.

The Linus Pauling Institute
(http://lpi.oregonstate.edu/infocenter/phytochemicals/tea/) has a quick
overview of caffeine in tea with links to the abstracts of a number of
studies, if anyone is interested.

.

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