Density of extraction water vs kettle water?

"Ian Rawlings" <news05@tarcus.org.uk> wrote in message
news:slrndsldmn.79b.news05@desktop.tarcus.org.uk.. .
> Tea certainly doesn't need boiling water, you'll wreck it like that,
> I'm British, trust me ;-)
>
What then does the STAA (Brit branch) recommend as the corect brew temp
range for tea?

My idea is related to Andy's, but in a slightly different form. Since
tea has oils, I'm guessing that when you add normal water, even boiling
water, to it, that some air remains entrained on the surface of the
leaf, causing it to float. You could test this by shining a light up at
the floating leaves in your press. When water comes out of the boiler,
it's superheated and flashing into steam a bit, hence the sputtering.
My guess is that this, hitting the tea, either aggregates microbubbles
and allows them to float up off the leaf, or affects the surface of the
leaf in some similar way so that it doesn't hold the air.

Best,
David

Ian Rawlings notes:
> For black tea, it's recommend that you use a "rolling boil"
> [...]

A surprising consensus, because black tea varies quite a bit from
region to region. Also, Chinese people often use boiling water to
prepare green tea on a per-cup basis, whereas Upton recommends lower
temperatures. More than one way to ...


Felix