Kuri and Michael wrote:
Recently I bought a hand held, hemispheric, handled, unglazed ceramic
"roaster" which I use to roast a half ounce of tea at a time by holding
the
roaster over a flame and turning constantly. I've been enjoying this since
there are indeed changes that occur with my additional roast.
Not all oolongs are roasted. You can roast your tea yourself at home
(it's a
good way to recycle greens that are getting a bit old) to see the
effect.
....
About the health point of view. I don't have the reference here, but
roasting tea make it lose some exciting substances like cafeine/theine,
so
roasted teas can be better for children or to drink in the evening if
you
fear to have problems to sleep. They also have properties for Chinese
medicine, and are given to people that are sick and recovering. But they
lose vitamins or I don't remember what.

Are you quite sure the roast lowers the caffeine (teine) level? That
would
be good news for people, like me, who are supposed to cut down.


Well, I'm not a chemist, but - oh, wait a minute, I am one after all!
Caffeine has a listed sublimation point of 178 C. That's not a precise
number like a boiling point; it's where a heated sample of the pure compound
starts to evaporate (without melting) very quickly. As folks in northern
climes know, snow disappears even at -20 C, so the real question is one of
vapor pressure at more moderate temperatures. Another point to recognize is
that a substantially dry material like tea can be heated to way over 100 C;
it's probably reaching at least 250 C in the roaster. Hence the destruction
of delicate, health-giving organics - and the creation of new flavors. So
given free air exchange, the tea might be almost completely decaffeinated in
a minute or so.

I've thought of roasting tea at home, especially as I've got half a pound of
stale gunpowder green that wasn't very good in the first place. Anyone other
equipment/procedure recommendations? I was going to use either a
toaster-oven or a heavy frying pan, as some use for home-roasting green
coffee beans.

-DM