>
> Everytime I read steeping recommandations for green teas, they don't make
> sense. They seem highly illogical to me. Here's how I understand it : >
> Tannins, astringent substances present in tea leaves, are disolved into
> water. The quantity released depends on steeping time, water temperature,
> and the variety of tea.
>
> If you brew a green tea for too long, in a too hot water, it will taste bad
> because to much tannins are released, in proportion to other desired
> subtances. The desired substance are released much faster than the unwanted
> tannins. Therefore, most green teas acheive a peak in "good tasting"
> chemicals, without releasing too much "bad tasting" tannins, in less than > 120 seconds.
>
> [...diagram...]
>
> Where it gets illogical is where I read "a green tea can be steeped several
> times". Multiple infusions seem to have a magical reset effect on relative
> concentrations. I would have taught that eventually all the "tasty"
> subtances will be extracted and overpowered with remaining tannins. For me,
> the last of three 2 minutes infusions should be at least as bad as a single
> 4 minutes infusion.
>
> Why am I wrong?
1) Even granting your assumption that all components are either good or bad, why assume *all* the bad ones are slower to dissolve than *all* the good ones?
2) I know you've mentioned that temperature is important, but by focusing on time you've pretty much abstracted away temperature. I think it's fair to say that for those of us who tend to brew greens fairly cool (say 140F) astringency is rarely much of a concern. Bitterness, maybe, but not astringency with a decent green.
3) I don't have measurements to back this up, but I think there are lots of cases where greens yield up their goodness - and badness? - along curves that are more complicated than you assume. That's why for lots of greens, especially Japanese ones, the first steep will take longer than either of the next two. Unsupported by plant physiology, I suspect that this has to do with the cell walls getting damaged enough during the first steep that the loss of the mechanical barrier to solubility dominates the decline in the sheer amount of potential solutes.
That said, I'm confused too. It would be so nice to have a universal formula or rule of thumb rather than having to try lots of possibilities each time I encounter a new type of green!
/Lew