Puerh Storage in Low Humidity

One of the intentionally aged teas, Pu-Erh has a loyal following.


User avatar
Oct 20th, '09, 09:21
Posts: 14
Joined: Sep 18th, '09, 21:11
Location: Denver, CO

Puerh Storage in Low Humidity

by xogget » Oct 20th, '09, 09:21

I've read that humidity in the 60-80% range is optimal for puerh storage but I live in Denver where the humidity gets to 30% and often lower during certain times of the year. Is storage in that low of humidity really bad or just kind of bad? I have a few cakes I recently purchased from Yunnan Sourcing and am wondering if it's worth using a humidifier.

Oct 20th, '09, 09:43
Posts: 87
Joined: Jul 22nd, '09, 11:45

Re: Puerh Storage in Low Humidity

by Zanaspus » Oct 20th, '09, 09:43

It's not bad at all. I'm getting frustrated with all the folks saying you MUST have a high humidity environment. High humidity merely speeds the aging process. To anyone who asserts that cycled lower humidity does anything other than slow the process (and perhaps improve the long-term result) I would ask that they show me proof of microbial death in lower humidity environments as this seems to be their only go-to argument against it.

/ranting soapbox moment off :lol:

User avatar
Oct 20th, '09, 11:12
Posts: 467
Joined: Aug 28th, '08, 11:42
Location: The first State (DE)

Re: Puerh Storage in Low Humidity

by nonc_ron » Oct 20th, '09, 11:12

Woe woe woe,Image
You can go too far in either direction.
Too wet and you get mold.
Too dry and the fermentation STOPS!
You will end up with a dried out tasteless tea.
I vote to keep it as close to 70-75% as possible. :D
Last edited by nonc_ron on Oct 21st, '09, 20:59, edited 1 time in total.

User avatar
Oct 20th, '09, 12:43
Posts: 196
Joined: May 1st, '09, 22:28
Location: Malaysia

Re: Puerh Storage in Low Humidity

by oldmanteapot » Oct 20th, '09, 12:43

xogget wrote:I've read that humidity in the 60-80% range is optimal for puerh storage but I live in Denver where the humidity gets to 30% and often lower during certain times of the year. Is storage in that low of humidity really bad or just kind of bad? I have a few cakes I recently purchased from Yunnan Sourcing and am wondering if it's worth using a humidifier.
30% RH or lower isn't bad for your pu. It simply means your Pu will either age slowly or extremely slow, to the extent it almost seems appear to have stopped aging. 60%RH to 80%RH is optimal for aging Pu. Not for storing Pu.

If your preference is young Pu and have no intention of aging your Pu, storing your Pu at 30%RH or below makes no difference to you. Some Pu connoisseurs prefer their Pu aged. So, storing them at a controlled RH of between 60% - 80% is preferred. Exposing your Pu to various levels of humidity will result in a different end result.

Storage at 50% to 65%RH - Pu will generally be strong and astringent. Aftertaste and "huigan" is generally stronger. But it will take at least 8 - 10 years before the tea broth smoothens out. This is considered as Dry Storage commonly found in South East Asia.

Storage 65% - 75% - Pu will generally be moderate but slightly weaker than the above, but the aftertaste and "huigan" are also weaker. The plus point here is, a 4 - 5 year old tea will be rather smooth and ready for consumption. This type of storage is commonly found in colder Asian countries like Hong Kong where humidity is often high. This can also be considered as Dry Storage.

Storage at 75% to 85% RH - Pu will taste very smooth to the tongue but often weak on the aftertaste and "huigan". This is often categorised as Wet Stored.

Humidity Level of 85% and above will introduce a risk of your Pu getting moldy and that will spoil your Pu.

So, at the end of the day, it's entirely up to you. If you're happy with your young Pu staying forever 'youthful', 30%RH won't harm it at all. Just make sure it's stored away from any foreign smell like strong smelling wood, herbs, spices or perfume. Give it plenty of fresh air. Coming back to your question, using a humidifier would be useful if you're thinking of aging your Pu. But don't place it in an enclosure. But, place it in an open space where it will generally bring up the RH level of the entire room or area without compromising fresh air movement.

That's my 2cents.

Cheers! :mrgreen:

User avatar
Oct 20th, '09, 13:13
Posts: 803
Joined: Sep 3rd, '08, 11:01
Location: Claremont,CA
Contact: Maitre_Tea

Re: Puerh Storage in Low Humidity

by Maitre_Tea » Oct 20th, '09, 13:13

Faced with a similar problem, since I live in a such a dry climate (Southern California). Since my collection is still small, I'm just letting it sit there; however, what would happen if in the future I move my cakes to a more humid environment? Will they just adjust to the new environment and start to age faster or will spending a few years in the desert (literally) screw them up in aging forever?

User avatar
Oct 20th, '09, 13:18
Posts: 455
Joined: Jun 15th, '06, 13:04
Location: Lawrenceville, GA

Re: Puerh Storage in Low Humidity

by bearsbearsbears » Oct 20th, '09, 13:18

Zanaspus wrote:It's not bad at all. I'm getting frustrated with all the folks saying you MUST have a high humidity environment. High humidity merely speeds the aging process. To anyone who asserts that cycled lower humidity does anything other than slow the process (and perhaps improve the long-term result) I would ask that they show me proof of microbial death in lower humidity environments as this seems to be their only go-to argument against it.

/ranting soapbox moment off :lol:
No, it's not going to *harm* your tea to age it in 30% RH, but the chances are you won't be drinking anything aged in 30 years. You'd be better off leaving that tea to your grandkids.

Anyone who ever tried 1990s tea stored in Kunming, or 1990s tuos stored in Los Angeles Chinatown, would never be so misguided about the importance of humidity in aging: low humidity (<60-65%) means no aged taste and leaves still mostly green after 15 years.

The only very dry stored aged pu'er I've had, a 1950s cake stored in 50% humidity in the upper floors of an apartment building in Guangdong, took some 50 years to reach a 20-year aged taste. It was very good, but do you want to wait that long?

Microbes are only one small part of the aging process. Humidity aids in oxidation aging process of pu'er (consider how water rusts iron much faster than had the iron stayed completely dry).

All it takes is $150 for a good humidifier for you to guarantee your collection ages. If you don't want to spend this, save your money to buy properly aged tea in the future. With high interest in pu'er now, there's likely to be a huge amount of aged tea available in the next 20-30 years.

User avatar
Oct 20th, '09, 19:08
Posts: 153
Joined: Sep 11th, '08, 17:15
Scrolling: scrolling
Location: PA, USA

Re: Puerh Storage in Low Humidity

by pb2q » Oct 20th, '09, 19:08

You may find this series of Cha Dao articles useful: Perspectives on Storing and Aging Pu'er Teas (this is the last article which links to the previous ones).

This subject comes up here pretty often. See here for instance.

Oct 20th, '09, 19:27

Re: Puerh Storage in Low Humidity

by aKnightWhoSaysNi » Oct 20th, '09, 19:27

Ah, the average annual RH in my part of Alabama is in the 60s, but it can get into the upper 80s/low 90s during the dog days of summer. So I guess I don't need to build a pumidor :D

Oct 20th, '09, 21:40
Posts: 969
Joined: Dec 17th, '08, 15:13
Scrolling: fixed

Re: Puerh Storage in Low Humidity

by Intuit » Oct 20th, '09, 21:40

Here is from my perspective as an applied microbial ecology and civil engineering professional.

First, indoor weather and outdoor weather are two different situations. I've lived in the moderately humid Midwest, exceptionally humid Southeast and Western drylands. You can have pert near close to 100% humidity outside, and have moderate humidity indoors, regardless of the season, if you got drying heat or air conditioning removing water from the air. Similarly, you can have 10-15% humidity outside in early and late summer, and have 50-60% relative humidity indoors, if you have inadequate air turnover resulting from lack of ventilation and daily showering, laundry and kitchen cooking activity going on.

Mold contamination in homes is widespread, a significant problem in many regions throughout the world, where modern residential construction, slack ventilation building code and enforcement, and careless residents contribute to chronically excessive in-home RH.

So the last thing you wanna do is keep your pu in a mold-prone environment, the attic, basement or god forbid, your mildewy bathroom.

Next, you want to completely segregate shu and sheng. Different containers, not close by, if that's possible.

You shouldn't even be thinking about keeping pu, other than for immediate consumption, 'til you've been heavily sampling and learning it for 1-2 years, minimum. No way in sam hell are you gonna have the palate for it, no matter how much black or oolong tea you've been drinking over the years.

Plus, you need to figure out how to keep your starter sample libraries of shu and sheng in decent shape, because the game plan should be to systematically revisit some of these pu's to fine-tune evaluation skills as your palate recognition gets more sophisticated.

Pu's got chemicals you ain't never gonna see in other teas.

When you have a finally begun to sort out the many factors that contribute to pu qualities you love AND hate, from various starting materials, certain sellers, and infusion intuition, and sharpening evaluation skills..then you start to think about keeping a FEW beengs, bricks and tuos.

The next big learning curve is storage.

Interestingly, some of the big flavor producers of the microbial communities found in aged sheng aren't molds. They're bacteria.

http://twistedbacteria.blogspot.com/200 ... -jade.html
http://pubs.acs.org/doi/abs/10.1021/jf071629p
Full paper: edoc.ypu.edu.tw:8080/paper/biotech/Pu%20Erh%20tea.pdf

This 2007 paper suggests that will some clever microbial culturing techniques, it should be possible to produce the effects of 20+ yr old aged sheng in much shorter time period, sans wet process method, meaning less mold pathogen risk.

The very cool part is that microbial isolates were able to boost GABA content of freshly innoculate young leaf by 4-5-fold, compared to non-innoculated fresh young leaf. GABA is a central component of the neurochemical soup that constitutes 'cha-qi', a topic that is frequently babbled about on pu blogs.

Humidifiers should probably be a last resort; they're meant to humidify entire rooms, not small enclosures. Humidity control can be achieved with wetted florist foam blocks, built-in ventilation (fans/screened openings), a rack storage system for allowing air flow around your cakes, and cheap but effective temperature and humidity monitoring.

WallyWorld carries an inexpensive weather monitoring device that will allow you to keep track of temp and humidity high/low reading. Runs on batteries. If you have problems keep the humidity low enough, there are inexpensive dryrite beads in plastic enclosures, meant to dry small spaces, with rechargable or replaceable cartridges.

Oct 21st, '09, 08:17
Posts: 87
Joined: Jul 22nd, '09, 11:45

Re: Puerh Storage in Low Humidity

by Zanaspus » Oct 21st, '09, 08:17

Bears^3 wrote
A dissertation on low humidity pu. :P

Jason; I wasn't suggesting 30% forever. The OP wrote that it "sometimes" dips to 30%. I was merely suggesting that this would do no harm in and of itself.

I actually seem to remember Mike Petro writing somewhere that a pu guru had told him cycled humidity was actually optimal for fine pu aging. Please don't ask me to cite as I'm old and feeble minded.

But listen to Bears^3, you don't get to write THE wikipedia article by knowing too little. :lol:

User avatar
Oct 21st, '09, 11:34
Posts: 14
Joined: Sep 18th, '09, 21:11
Location: Denver, CO

Re: Puerh Storage in Low Humidity

by xogget » Oct 21st, '09, 11:34

Thanks for all the helpful info! I'll be purchasing an RH meter to see what it's actually at inside. It's actually probably fairly high in the summer because of my swamp cooler.
bearsbearsbears wrote:
Zanaspus wrote:With high interest in pu'er now, there's likely to be a huge amount of aged tea available in the next 20-30 years.
Never thought about that. in 20 years I can buy a 20 year cake for less than $500!

User avatar
Oct 21st, '09, 11:49
Posts: 14
Joined: Sep 18th, '09, 21:11
Location: Denver, CO

Re: Puerh Storage in Low Humidity

by xogget » Oct 21st, '09, 11:49

Intuit wrote: Interestingly, some of the big flavor producers of the microbial communities found in aged sheng aren't molds. They're bacteria.
.
I wonder how comparable this is to sourdough bread, which gets much of its flavor from local bacteria. Beyond storage conditions, could each puerh also taste different because of local bacteria? Bread made in different areas each have a unique flavor because of the local bacteria in the air, which is why San Francisco sourdough tastes like San Francisco sourdough only when it's made in San Francisco. Could there be "San Francisco Menghai 7542?"

hmm, except for the bacteria that comes with the cake from the factory

Oct 21st, '09, 12:03
Posts: 969
Joined: Dec 17th, '08, 15:13
Scrolling: fixed

Re: Puerh Storage in Low Humidity

by Intuit » Oct 21st, '09, 12:03

"With high interest in pu'er now, there's likely to be a huge amount of aged tea available in the next 20-30 years."

The human global population will nearly in that time, because poor nations encourage mass migration and rich nations see cheap labor opportunity in these immigrants. As a result, formerly flatlined population growth in the West has once again started to grow.

More humans, less land for agriculture, but greater demand for basic food crops. Where tea is grown at lower elevations, these lands will have to be converted to basic food production.

User avatar
Oct 21st, '09, 12:42
Posts: 455
Joined: Jun 15th, '06, 13:04
Location: Lawrenceville, GA

Re: Puerh Storage in Low Humidity

by bearsbearsbears » Oct 21st, '09, 12:42

xogget wrote:Thanks for all the helpful info! I'll be purchasing an RH meter to see what it's actually at inside. It's actually probably fairly high in the summer because of my swamp cooler.
LOL. Chances are you won't have much problem with a swamp cooler!
intuit wrote:More humans, less land for agriculture, but greater demand for basic food crops. Where tea is grown at lower elevations, these lands will have to be converted to basic food production.
I don't see your concerns effecting pu'er supply in the short term and aged tea supply in the long term. For one, thousands upon thousands of kilos of pu'er was produced in the past 10 years, most of it traded like a commodity and sold wholesale to large collectors. This is already sitting around aging and will probably mean lots of aged tea in 20-30 years. [In fact, there's a lot more aged tea now than consumers are lead to believe. The five or ten big collectors in HK, TW, and Malaysia drip it into the market to keep prices artificially inflated.]

Secondly, pu'er is highly profitable; there's no economic sense to swapping an expensive crop for a cheap one. Last, China (and other overpopulated Asian countries) are already outsourcing their farming to less developed and unfarmed areas of Southeast Asia, and purchasing and cultivating land in Madagascar and other African nations for this purpose as well. That should cushion their food supply for a while.

Yeesh, that was off topic. :oops:

Oct 21st, '09, 13:43
Posts: 969
Joined: Dec 17th, '08, 15:13
Scrolling: fixed

Re: Puerh Storage in Low Humidity

by Intuit » Oct 21st, '09, 13:43

Xogget, factory cakes have different leaves on the outside, right?

The working assumption has been that they're windowdressing, to pretty up the cake.

My assertion is that they're also inoculant, older leaves with established microbial community cultures; factory tea masters have their signature cultures used in annual recipe batches, probably matched more recently to leaf harvest origin, as a refinement. Thus, the large, exclusive contracting (mentioned in Nadas blog, for instance) of entire growing areas to a certain factory to ensure product consistency.

In commercial fermentation, this is how you add 'starter culture', like your trademark SF Sourdough bread is made with starter using proprietary wild yeast strains that when mixed with a particular dough recipe, yield the familiar baked bread:

http://www.exploratorium.edu/cooking/br ... dough.html

This company has maintained it's unique starter cultures for decades.

Bread, cheese, beer and wine all have proprietary microbial fermentation culture management practices, from secret strains, to bioengineered mixtures that prevent spoilage during product aging.

For example:
http://www.foodnavigator-usa.com/Produc ... en-sulfide

+ Post Reply