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Science and making a cup of tea

From (a rather battered) New Scientist
I was delighted to discover that a letter written to New Scientist described how a reader responded to the NS review of Inflight Science by doing an experiment with tea making.

In the letter, Joan Mascaró points out that the review had said 'that airline tea tastes so appalling because water boils at too low a temperature to make a decent brew.' The writer then goes on to test tea at different temperatures and concludes that too low a temperature is a real problem, but 92 °C doesn't seem to make much difference.

While I could dispute minor details - cabin pressure varies, and can drop boiling point as low as 90 °C - it's unfortunate in a way that the whole thing was based on the review rather than what I said in the book. My actual words were:

Tea enthusiasts like their tea made with boiling water – which means getting the water up to 100 degrees Celsius. That is never going to happen on a plane. Not because the cabin crew can’t be bothered to do it properly, but because it’s impossible get water up to 100 degrees on board the aircraft.

Definitely not tea
Now I ought to make clear that I am not a tea enthusiast. In fact I can't stand the stuff (except green tea). However, time and again tea lovers have hammered into me that the water has to be actually boiling (100 degrees) when it hits the leaves. They want to see bubbles. Leave the kettle five seconds before pouring and they start to twitch and get uncomfortable. 'The water isn't hot enough!' they cry. And they insist you switch the kettle on again.

So taking this assertion (it doesn't have to be true, but it's a nice touch if it is) as a starting point I went on to discuss cabin pressures and its impact on making tea. It was really just what they call in the trade a 'hook' to discuss pressure onboard the aircraft. It seems to have been quite a good hook from the number of times it has got picked up in reviews and interviews... and now in an experiment.

So while I am delighted that the experiments were carried out, I'm not too worried that they change things substantially.


  1. Interesting. If the water is still boiling when it hits the tea it scalds the tea resulting in a horrible brew. The best tea is made when the water HAS boiled, but has been left to go off the boil before making the tea. Hence the advice - make tea with freshly BOILED water, not boiling water.

  2. The confusion comes when people realise that water boiled on a plane does indeed boil - there are bubbles and steam and stuff - but just at a temperature lower than 100C. So what's more important - the temperature, or the fact of boiling?

  3. After reading your book, Brian, I watched the cabin staff very carefully when they made tea. I have to report they didn't even try to boil the water, but just poured it from an insulated jug onto the tea bag in a beaker - quite disappointing. But then it was BMI Baby...and I have to say it tasted perfectly fine to me!

    The insulated beaker was a wondrous thing, though. We had a fine time dissecting it.

  4. Interesting Dave - but totally disagreeing with some tea lovers' view.

    Henry - it's temperature. The fact that it's boiling & bubbling isn't the point, merely the indicator.

    Clare - I'm the last one to judge since I can't stand the stuff. I can only go on what I've been told! If we are to believe the NS experimenter, 72 C does produce bad tasting tea...


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