Puerh Storage Anxiety

// Published September 4, 2020 by mgualt

It is one of the ironies of the modern consumption of puerh tea, prized for its relaxing and euphoric effects, that lovers of the tea seem to be quite an anxious bunch. As if the horror show that is 2020 weren’t bad enough, puerh-heads top their basal level of existential dread with such questions as: “Is my tea fake?”, “Does this really have any qi, though?”, “Is my temperature-and-humidity-controlled tea storage hot/cold/humid enough?”, and “Why can noone tell me the ideal atmospheric pressure for puerh?” among many others.

If a puerh cake slips off the shelf of a sealed pumidor, and there are no silverfish to hear it, will it still age?

Even the most laid-back of Seattle hipsters has contacted me, fingernails bitten to the bone, about how to repair a teacake that was unintentionally drenched in about 1ml of water from a stray soaked terracotta shard. It is no surprise, then, that after publishing some posts explaining my approach to puerh storage, I have been on the receiving end of a steady stream of storage sob stories. As usual with tea, problems occur when it isn’t properly protected, either from scents, dryness, humidity, bugs, mold, or acts of God.

After I adjusted my pumidor temperature from 38 to 34.5 degrees Celsius, re-hydrated my 69% Boveda packs, calibrated my Bluetooth hygrometers, checked my Mylar bags for pinpricks and brushed a dozen cakes of boutique Taiwanese sheng with a soft-bristled toothbrush, I asked myself, ‘Why am I doing this, again?’

About a month ago, tiring of the tedium of Zoom conferences, I checked Reddit and was saddened to see this post, by a poor man suffering from, yes, you guessed it, Puerh Storage Anxiety. In fact it’s right in the title of the post. Right off the bat, I must apologize to Arby, the OP: if it’s not already clear, I am not making fun of you. I am making fun of all of us. Back to the PSA Post, we find a “concern too important to keep quiet about” — the complete and utter destruction of an expensive puerh collection through the use of 40 degree Celsius hotbox storage. Arby’s post is a flashback-inducing montage of tea death, with gruesome heat defects so bad that the storage was terminated, and the alarm sounded on the world wide web.

Reading Arby’s post, my reaction was, as usual, skepticism. First, despite the prevalence of Puerh Storage Anxiety, our trusty tea can take a licking and keep on ticking. Also, assuming Arby was correctly reporting his storage conditions (approximately 40C with no added humidity), I find it difficult to believe that he ran into major problems — I have been operating a hotbox at around 40C for more than two years and haven’t ruined anything (yet…). So, I decided to contact him, and offered to taste (and if necessary diagnose) his overheated stash. I have been tasting his teas and today’s post is the result.

Yunnan Sourcing 2018 Impression: room temperature VS 40C

Arby kept the tea on the left at room temperature (21-23C) and the tea on the right at 40C, sealed in Mylar and with no added humidity, for about 5 months. It was clear already from the dry leaf that the unheated tea was pungent, vinegary, green, and roasty, with a tomato vine pungency, whereas the heated tea seemed to have aged out of its vinegary phase. The difference between these two teas was very familiar to me, as a slightly more extreme version of the difference I’ve documented in my previous storage posts.

  1. Right off the bat the colour difference is quite striking, with the heated tea being darker in the cup and less green in the gaiwan.
  2. The unheated tea has a typical green roasty profile with high perfume notes and quite a lot of vegetal notes. The heated tea has a sweeter, more honeyed empty cup aroma in comparison to the more perfumed aroma on the left.
  3. The heated tea is thicker, and the wet leaf has the lemon-esters aroma (more on this below).
  4. Getting some interesting incense notes on the heated tea, lots of pencil shavings. The unheated tea is slightly more astringent than the heated tea, although both have significantly astringency in the later steeps.

Clear signs of oxidation on the heated (right) side

First, both are recognizably the same tea, a spring+autumn taidi blend of decent quality especially considering the price. The roughness does come but there is plenty of sweetness and thickness to be pleasant enough. The unheated tea might as well be a brand new production, ultra green, roasty and vegetal, whereas the heated tea is believable as a 2016-2018 sheng with natural storage in Taiwan or Malaysia. There is a clear modification of profile: first, the green roasty notes are much reduced, and the ultra high floral pungency is truncated. Second, the colour deepens and the liquor thickens in the heated tea. Third, the type of sweetness is more honeyed and rich in the heated tea, and last the bitterness and astringency is slightly reduced. There is no question that I prefer the heated tea, in every respect. You haven’t ruined this tea, or your others, Arby!

Where are the defects?

So, wherefore art thou, defects? I hope I can say something useful in this direction. The heated tea, and some other of Arby’s heated teas (the 2015 BYH Lishan Gongcha and 2013 BYH Mahei), have a certain recognizable note, one which I have smelled and tasted many times before and even commented on. It is what I call a roasty lemon ester aroma. I imagine it is like the smell of a burning lemon beeswax candle. I’ve speculated that it is the source of the Yangqing Hao house aroma, and I have noticed it on some of my cakes if the humidity and heat reach higher levels. Cakes with small amounts of mold (Aspergillus) have a very strong version of this aroma. My guess is that with higher temperatures and humidity levels (a sealed cake brought to higher temperature will release more humidity and raise the humidity level, as I have documented) a small amount of mold begins to grow on the cake — this would normally be invisible until it is quite a lot of mold or releases spores, which it may not do for months, or ever. I can hear the objections already: “but the humidity is not high enough!” — When it comes to mold growth, parameters are never hard cut-offs. And local conditions may be difficult to measure absolutely precisely, anyway.

Supposing that I am right and Arby managed to grow a small amount of mold – does this mean his tea is ruined? Absolutely not — his tea tastes the way young sheng should! In fact, the unheated tea is the one which rings a warning bell as too green, roasty and vegetal. And I must stress, there is no visible mold at all, I am only guessing that there might be mold based on an aroma and taste — and this taste is not in any way “moldy” or “musty” — it is a lemony ester note as I described above.

About the other teas that I tested out: The 2015 BYH Lishan Gongcha was kept in 40C storage for 50 days, and when I first received this tea, it tasted and smelled good, with a faint but noticeable lemon ester note. The aroma and taste persisted in the wash but not in the first steep. This tea is a very strong tea in my opinion, and could do with a great deal of heated storage over the next few years. The 2013 BYH Mahei was also kept at 40C for 50 days, and I did notice a lemon ester note here which I was not a fan of on the first tasting, as it gave a slight sourness in the first steeps. After a few weeks I tried it again and found it difficult to detect the note. Again, this is a quite strong tea and still has a long road of aging ahead of it. I think the 40C is just moving it along quicker, and I would advise a long resting period after a major temperature swing. When taking cakes out of heated storage, they are essentially experiencing jetlag — give them a few weeks before jumping to any conclusions.

Why are we doing this, again?

This brings up a question: why should Arby continue heated storage, whether it be 36C or 40C, if he prefers his tea in its original state? The answer is: he shouldn’t. I expose different teas to different storage conditions – some mellow, aged teas are kept at room temperature, while more aggressive young ones are kept at 32C or 38C. The decision about how to store your teas should be based on what you want your teas to become, and to know this you must taste mid-aged and aged teas with warmer storage conditions (e.g. Taiwan, Malaysia, Guangdong etc.). New-make sheng transforms a lot in the first two years. It looses many aroma and flavour notes, and can even be comparatively bland for a while before aging begins to transform it into a different, potentially more interesting profile.

If you don’t know what is supposed to happen to young sheng, you might panic when it ages out of its childhood due to proper aging. In my opinion, let your roasty green astringent sheng grow up. You might even enjoy its personality when it matures.


  1. "Heat Defects" - The lemon ester note. - Empirical Tea
  2. Stephan
    September 5, 2020 @ 2:02 pm

    Your posts only get better with more opinion.


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