N.B This post was written in February 2018. Much has happened since, so expect to see updates shortly.
This is my failure. There are many like it, but this one is mine.
Different people add value to a community in different ways. Sometimes that means demonstrating how something can be improved, sometimes it means cocking up and serving as a warning. Today I have my tent pitched decisively in the latter camp.
I’ve only been into pu’er for a year and a half, but the idea of experimenting with controllable storage is something I’m already keen to pursue. As a fan of humid storage and a poster-child for impatience, my goal is to emulate Malaysian-style storage at home. For the last couple of months, my pumidor has maintained a steady 30.5°C and 70% with an equilibrium-state variation of 0.1°C and 2% between the top and bottom of the mini-fridge. Fresh air exchange occurs a few times per day when I open the door to grab tea.
For the most part, this has resulted in fantastic fragrance and a sense that the tea is “thriving”. At various times, I put poor (and already-well-rested) samples in there along with a friend’s cake which he found unpalatable, and after a few weeks they became completely different animals. Whether that difference is due to hydration or something else I can’t say.
I’ve been keeping a very close eye on my tea – ambition, laziness and triumph are a “pick two” sort of deal here. I wasn’t too concerned when I noticed a tiny speck of white mold on a tuocha I’d stored in the door, since it wasn’t bad and I hadn’t noticed any problems with my other teas.
A week later I realised I wasn’t so lucky – two $15 cakes I rarely drink had copped it and smelled pretty nasty. A close inspection turned up another few cakes with rice-grain-sized growth spots, nothing major. $30 isn’t a huge loss, but the threat of losing other cakes has forced me to back off and re-evaluate my approach.
First, a couple of observations: The two worst cakes were stored in brown paper bags, were the only cakes stored in such, and were significantly worse than any of the other affected cakes. All affected cakes were on the bottom of a stack. The dew point at setpoint-conditions is 25°C, which is higher than ambient temperature much of the time. I suspect that the root cause is condensation formation when the door is opened, causing cooler air to displace air inside the fridge. It seems reasonable to suggest that the cotton wrappers and paper bags would allow transfer of heat away from the cakes, without allowing the air between wrapper and cake to be displaced, resulting in condensation forming on the cake. The paper bags, being less permeable, would slow evaporation of condensate more than the cotton-paper wrappers, which might explain why the brown-bagged cakes were heavily affected.
I’ve tried to keep observations factual, so you can form your own conclusions, but here are my personal takeaways:
- Elevation of temperature was probably the biggest factor here – I have had a cooler of pu sitting at 75% for the last year and a half with zero issues. Pumidor temperature should not be elevated to the extent that the dew-point rises above worst-case ambient temperature.
- Wrapping material may be important (there’s a reason they’ve been wrapped in open-“weave” mulberry-paper for hundreds of years? Who knew?)
- One warning sign may be the texture of wrappers. Wrappers can be bone-dry, nearing dampness, or in an almost “limp” state, somewhere between the two. My wrappers were often in that limp state, at least between stacked cakes, and this may be a useful sign that you’re getting undesirable moisture formation.
- Smell will confirm the presence of mold. Lack of smell (from a wrapped cake) does not preclude the presence of mold
- A wrapped cake may give no indication that it’s moldy until it’s far too late. If you’re not unwrapping your cakes regularly, you aren’t actually monitoring your stash for mold.
- If you see mold on one cake, I’d suggest checking EVERY cake, removing the wrapper.
I’ll continue to experiment and share what I find, and with any luck you can learn from my mistakes instead of your own. I’m convinced that the US (and LA in particular) need not be the red-headed-stepchild of the storage world, but clearly there’s a lot to consider before trying to democratise good storage.