Tannins in tea is a topic worthy of discussion simply because understanding how they work is crucial to creating a tasty and a healthy
cup of tea.
Tannins are
molecules that get released from the tea leaves as these are brewed in hot
water. The taste of your black tea (*only black tea will be discussed in this node) is directly related to the length of the brewing process and how many of these tannin molecules make it into your cup.
It is the tannins that are responsible for the bitter sensation in the mouth that you get after drinking tea since they reduce the
lubrication in the mouth and force its tissues to contract. Hence "that dry puckery constriction sensation that follows on a sip of a strong tea." (1)
Now, people who aren't aware of tannins make serious mistakes in their tea preparation. A lot of people who want to drink a strong
black tea whose
caffeine power rivals that of
coffee erroneously believe that they can produce that hearty, full-bodied
brew simply by brewing for a long time, five minutes or so.
However, brewing a tea for five minutes does not a tasty brew make. First of all, most of the tea's caffeine is released within the first two minutes of brewing. After that, the caffeine content of the tea does not increase significantly. Only the the level of tannins does. But, I am talking about
full leaf tea here! In the case of tea bags with grinded leaves, the caffeine is released with the first 40 seconds or so. It's not only the caffeine that gets released quicker: the tannins do as well... Whereas with loose leaf black teas, it's possible to end up with a moderately acerbic tea after 5 minutes of brewing, a 3 or a 3 1/2 minute brew from a
tea bag of grinded leaves is impossibly bitter! A 2 minute long brew is bearable but far from pleasant.
So, for those of you seeking to brew a great tea using tea bags, here's what you should do. If you want a great
taste that's moderately bitter and packs a jolt of caffeine, let your tea bag steep for about 30 - 45 seconds and take it out. The tannins won't have enough time to make your tea bitter. Now, if you want to end up with a super caffeinated tea that packs a punch, no need to let your tea bag brew longer. That would only make it more
bitter. You'd be best off simply brewing your tea with two bags for no longer than 30 to 45 seconds. That way you get tons of caffeine without the bitterness-producing tannins turning your tea into a
poison.
(Loose leaf tea brews slower, so brewing it for 2 minutes still produces a tea that's not too bitter. In some cases, where the leaves are huge and take a long time to unfold, even a 5 minute brew is permissible.)
When I say poison, I am not only referring to the bitterness. You see, tannins also interfere with the absorption of non-heme
iron from vegetable sources, inhibit the absorption of
starches, and some studies have related their unpleasant way of constricting the mouth tissues and reducing its lubrication with esophagus cancer. So, to
power up your tea, add a second tea bag, but never ever let the first one brew longer than a minute! For the sake of both taste and health.
Sources:
1. http://www.ochef.com/197.htm
2.http://findarticles.com/p/articles/mi_m0876/is_n56/ai_9164614
3. http://www.austinchronicle.com/gyrobase/Issue/column?oid=oid%3A208400
4. http://www.veetea.com/site/articles/Tea-and-Iron/
P.S: I am no expert in science, so if my scientific reasoning has failed me in leading me to some unjustified conclusions, please let me know.
Shaogo's interesting comment:
"All of this (but for brewing) applies to the tannins in
wine, too. I've seen people make themselves sick drinking
Medoc or a super-dry
Sangiovese. This is not because of the alcohol but because of the tannins' tendency to linger in the
esophagus, especially on an empty stomach. A great Medoc or a very dry Pauillac must be drunk with
food else the tannins go to work."