It turns out, it’s totally normal.
A little over a month ago, I made this post on Reddit, describing an unpleasant acidic note I encountered in 40 Celsius 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 40C-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 up 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 40C, 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. Of course I want my tea to age out of its youth! 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 32C and 36C.
So, what now? Further testing, of course. I will be storing some more 2018 YS Impression as well as a number of other teas at 40 degrees Celsius to see if the tea can age “through” that note over the long term.
February 2021 Update: I am in the process of determining the root cause of the lemon ester note. For now, it appears that it is simply an early symptom of the awkward stage.