It turns out, it’s not a defect.
A little over a month ago, I made this post on Reddit, describing an unpleasant acidic note I encountered in 40°C storage. Please read that post for context before continuing. Since making that post, there have been some interesting developments.
- Every tea listed in that post with “heat defects” has recovered (meaning that the sharp acidity I noticed disappeared) except for the 2019 Farmerleaf Ao Ne Me cake and the 145 day 40°C-stored 2018 Yunnan Sourcing Impression sample. The latter of which was much more heavily affected, and that would be explained by the longer heated storage period. Anyway, the fact that a lot of these teas lost the acidic unpleasantness after this period of rest should be a pretty convincing clue that raw puer can suffer jet-lag after major temperature swings. I was under the impression that jet-lag could only be caused by changes in air pressure (like during airplane transport). In the future, I’ll need to wait a month for evaluation after removing samples from heated storage.
- I sent some samples for Marco to taste, and he wrote a post about it on his site. He described the unpleasant acidity I encountered as a “lemon ester” note and said that it could be mold, but that my tea was not ruined either way.
Personally, for the specific use case of near-future drinking, I would still not store any of my youngest raw puer at 40°C, simply because I find the lemon ester note to be highly intrusive and unpleasant. This doesn’t mean that I want my tea to stay young forever, as Marco implied near the end of his post. I’m just highly sensitive to the lemon ester note, which so far I have been able to avoid by using lower temperatures such as 32°C and 36°C.
So, what now? Further testing, of course. I will be storing some teas at 40°C to see if they can age “through” that note over the long term.
Update: August 30, 2021
The lemon ester note occurs only with sufficient humidity. Heating a dry sample does not form the lemon ester note, or any storage note for that matter.