Nigel wrote:
> While this reply has to be guesswork based on first principles rather
> than experience I would not advise freeze sterilizing pu-erh to kill
> insects or mites unless it was for immediate consumption (in which
> case boiling water will suffice). Maturation of pu erh depends on a
> healthy component of living organisms (good bacteria and fungi) which
> freezing would kill.

Interesting - while not any kind of microbiologist, it's my impression
from a couple of dozen food/drink projects (plus random reading) that
pathogenic bacteria and fungi are not usually killed by freezing.
Rather, their metabolism and reproduction are suspended for the
duration. Is there evidence that the living elements in Pu-erh that (are
alleged to) cause beneficial aging could be harmed by freezing?

> Carbon dioxide ... requires the tea to be
> infused with the gas in an hermeticly sealed vessel (taping up a
> closet would not contain it or would need an excess of CO2 - which
> also kills higher life).

Perhaps you could amplify here, Nigel. My empirical observation is that
this worked fine both times I tried it, without even bothering with tape
- I only mentioned that in case someone has a very loose-fitting closet
or cabinet door. The evaporating lumps of dry ice quickly fill whatever
space is needed, then continue to emit CO2 until they have sublimated
completely. Even then, I suspect that lethal concentration for bugs
isn't that much higher than the 10% or so that's fatal to larger
life-forms. Leaks and breezes in the average home would probably leave a
normal closet or cabinet at that level for a few days, once it was fully
"charged" with CO2.

> CO2 does not ruin coffee - it's oxygen that stales it and quickly.

I passed along the comment as cited by senior engineers (not scientists)
at what I think was then Europe's largest coffee company, during a 1990s
engagement to invent novel packaging and presentation designs. I didn't
believe it at the time, and am happy to correct the belief. Perhaps
their point was that absent a valve, the (two-way) leak required to
avoid bag explosion would allow in too much oxygen.


-DM