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. Dry tea is not generally attractive to mites;
chances are it's the fungi that the mites are eating. In standard tea
reducing the moisture would deter any alien insect growth, but again
pu erh needs some moisture for its maturation to continue. Carbon
dioxide for 72 hours is a standard insect kill method that would not
upset the fungi and bacteria too badly but 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).

CO2 does not ruin coffee - it's oxygen that stales it and quickly.
Freshly roasted coffee actually gives off carbon dioxide - the valves
are there to stop the pouches from exploding. Before valves the roast
coffee was left in the open to give off its gas (degas) for a week
before packing but this allowed a week for oxygen to wreak havoc with
the quality.

Nigel at Teacraft

On 29 Dec, Dogma wrote:
> > If I ever find creepy-crawlies in my Pu-erh, I'll probably do the same
> > thing. I'd stack all the boxes in a small closet, put in a few pounds of
> > dry ice, and tape the door shut for a week or two. Dry ice is readily
> > available in most urban areas, cheap, leaves no residue, and (IMO) is
> > very unlikely to induce any changes in the tea itself. On the other
> > hand, CO2 ruins coffee (why European bags have a vent), so I'd probably
> > test it first.