Regarding long term storage


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

Re: regarding long term storage.

Postby betta » Jan 2nd, '12, 15:55

solitude wrote:The system with the bowl of water in a cupboard doesn’t work very well during the winter. Since the place where I store my puerh is quite cold the water evaporation is limited (17-18°C, around 60% of RH) so, I tried a slightly modified setup

- An old unused bookcase
- One of the shelves is slightly modified (see the pictures below)
- Two bigger plastic flower pots, in one of them a "secret ingredient" - aquarium water heater

Water containers with the heater adjusted to 25°C on the bottom shelf. The upper shelf has holes for air circulation.

The tea is placed on the upper shelf (in paper bags) but can be also on the bottom one.

The front side is covered with a rug which let the tea "breath"

After a few days the temperature is inside 20-21°C and the humidity around 75%.


Solitude, what would be the power consumption of those water heater? 100W?
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Re: regarding long term storage.

Postby tst » Jan 2nd, '12, 21:05

I've been looking into these for a little while now ...

http://www.fishtanksdirect.com/aquarium ... hwodmzMikw

This distributor has them as low as 50W.
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Re: regarding long term storage.

Postby MarshalN » Jan 3rd, '12, 00:20

I think the idea of needing to let the tea "breath" is bogus. They don't really need to breath aside from semi-regular use of the "open the door/close the door" variety. Variations in humidity is definitely a good thing - too wet for too long and you're flirting with disaster.
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Re: regarding long term storage.

Postby solitude » Jan 3rd, '12, 11:13

betta wrote:
solitude wrote:The system with the bowl of water in a cupboard doesn’t work very well during the winter. Since the place where I store my puerh is quite cold the water evaporation is limited (17-18°C, around 60% of RH) so, I tried a slightly modified setup

- An old unused bookcase
- One of the shelves is slightly modified (see the pictures below)
- Two bigger plastic flower pots, in one of them a "secret ingredient" - aquarium water heater

Water containers with the heater adjusted to 25°C on the bottom shelf. The upper shelf has holes for air circulation.

The tea is placed on the upper shelf (in paper bags) but can be also on the bottom one.

The front side is covered with a rug which let the tea "breath"

After a few days the temperature is inside 20-21°C and the humidity around 75%.


Solitude, what would be the power consumption of those water heater? 100W?


The one that I use was the smallest one in the pet shop - 25W. Once the water reach the desired temperature the heater turns off and starts to heat when the temperature drops.
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Re: regarding long term storage.

Postby solitude » Jan 3rd, '12, 11:16

MarshalN wrote:I think the idea of needing to let the tea "breath" is bogus. They don't really need to breath aside from semi-regular use of the "open the door/close the door" variety. Variations in humidity is definitely a good thing - too wet for too long and you're flirting with disaster.


MarshalN, What is the optimal temperature/humidity for puerh ageing in your opinion, and how much is too wet?
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Re: regarding long term storage.

Postby MarshalN » Jan 4th, '12, 01:49

Brief bursts of humidity is ok, but if the cake sits in humidity that's over 75-80% for more than a week or so you can expect to see mold.
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Re: regarding long term storage.

Postby Bryan_drinks_te... » Jan 4th, '12, 10:53

I'm glad to see that this post has evolved somewhat. There's great information in here regarding storage.

This winter, the humidity in the pu cabinet hangs around 60 percent. I haven't done the water bowl thing in a while - i quit doing that, looking at new ways to up the humidity when the time comes. I enjoy shicang pu, but finding good examples of it seems to be difficult sometimes.

take care.

bryan
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Re: regarding long term storage.

Postby tst » Nov 8th, '12, 15:39

MarshalN wrote:Brief bursts of humidity is ok, but if the cake sits in humidity that's over 75-80% for more than a week or so you can expect to see mold.


Little late, but I'm curious. Doesn't it depend on the temperature as well?

If the Rh is 75-80% at 30C (86F), it is very different than 75-80% Rh at 20C (68F), right? My understanding in this scenario, is that there is much more water in the air (which is what matters for storing tea) when the temperature is higher.

So then, my understanding is the answer to the question of "ideal humidity" must be a temperature AND corresponding humidity (i.e. 30C and 75% Rh or 20C and 85%Rh).

This graph below shows nicely how the amount of water in the air changes as temperature changes.

Am I way off here? (still trying to get a grasp on it). It would be nice to see a graph that represented Cloud's recommended 20-30C and 70-80%Rh. I figure they are inversely related ... 20C and 80%Rh and 30C and 70%Rh are good numbers to aim for.

http://upload.wikimedia.org/wikipedia/c ... midity.png
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Re: regarding long term storage.

Postby apache » Nov 9th, '12, 13:52

Me is no physicist, so don't blame me if I got it all wrong. Also I didn't read all the posts of the thread from the beginning, I'm too lazy to bother with that, but I can't resist to chip in!

I heard a lot of people saying, higher temperature will hold more moisture in the air with same RH. I won't dispute this. However, I think we are interested in the moisture content in the 'dry' leaves here.

Say if you keep your tea in a box or cupboard i.e. not hermetically sealed. There should be unlimited supply of moisture from the air to the leaves or unlimited supply of air to carry off the water from the leaves until moisture content inside the leaves reaches an equilibrium.

I doubt I could find any information about tea leave moisture content equilibrium on the web, however, I find some information about wood:
http://en.wikipedia.org/wiki/Equilibrium_moisture_content
I hope the piece of wood model would be good enough for tea leaves. If we look at the graph we could see there isn't much different between 0C and 30C, what more, there is in fact slightly more moisture content inside a piece of wood at lower temperatures for almost any RH.

However, chemical reaction including biochemical reaction rate is higher at high temperature. Hence we keep foods inside fridges and freezers to lower the rate of rotting.
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Re: regarding long term storage.

Postby tst » Nov 9th, '12, 19:01

Interesting points apache.

With more moisture available in the air, I just assumed more would be available to be absorbed into the leaves, resulting in a higher moisture content in the leaves (which seems like it could very well have been a false assumption).

This line from your link is interesting ... "This equation does not account for the slight variations with wood species". Would less dense wood species follow the graph more or less (I would expect tea leaves to act more like a less dense wood than a more dense wood)? Or, is the variation in species not dependent on wood density ... maybe instead something like chemical makeup of the wood cells, aromatic compounds, sap content, etc. ... ?

The point you make about temperature and biochemical reactions I think is very important here. We aren't just concerned with pumping humidity into tea leaves. I believe the consensus is that the main factor driving aging is the biochemical reactions taking place on a cellular/microscopic level. Temperature is important beyond the humidity factor, since enzymes all work at optimal temperatures. Too hot or too cold results in less than optimal enzymatic function (which I would think is what would slow down the aging process). It would be interesting to figure out which enzymes are mostly used by the microbes in puerh (or another way of figuring out the same thing would be to find out the optimal living temperature range for the microorganisms suspected to have the most impact on aging).

Love this topic though. I know I've seen studies/research papers on aging puerh ... maybe I'll see what I can dig up.
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Re: regarding long term storage.

Postby theredbaron » Nov 9th, '12, 23:43

I am neither a biochemist, nor a physicist, or anything related. But i have to say that some of the humidity cabinets shown in this discussion here do scare me.
I live in a wooden house in hot and high humidity climate where mold, especially in the rain season is a constant worry. In days of strong monsoon rains the humidity jumps to insane levels, and wood and leather is quickly covered in a thin layer of mold. It's especially bad in enclosed spaces, such as in closed cupboards, boxes, etc., where trapped moisture can't escape easily. That can happen within a day or so.
I have once discovered a few cakes of Pu Erh that i have forgotten in a wooden box for about ten years, most were OK, after airing them out for a while, but one in particular was completely off, and had a very musty smell/taste.

Open water and heat in an enclosed space without airflow, creating a tropical micro climate, can be a recipe for disaster. I think the numbers game here is a bit misleading, looking at exact levels of humidity, or temperature. Pu Erh's are aged successfully in many different climates. Hongkong, KL, or Singapore have quite different climates, but each has a history of excellent aged teas. But especially in KL and Singapore, being hotter and more humid, care has to be taken regarding mold (i have seen and drunken quite a bit of Pu Erh from there that was a bit too musty for my taste).

I believe that in a more dry climate it would be more important, and much safer, to find ways to raise humidity in the entire room the tea is stored in, than just in a small enclosed space, to enable more airflow and ventilation (that doesn't mean a heavy fan, just natural air circulation). That means in a tea storage room not to have aircondition, have a humidifier, and regularly air the room (as one should anyhow do).

Open bowls of water combined with heat, all in closed proximity to tea and hardly any air circulation might turn into a breeding ground for mold. I think that a healthy amount of air circulation is more important than desperately keeping humidity levels up to a specific number (and 70% is rather high humidity, and dangerous), especially when that number is reached only by having not enough air circulation in an enclosed space.
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Re: regarding long term storage.

Postby Tead Off » Nov 10th, '12, 03:00

Redbaron, your place sounds quite sticky to me the way you are describing it. I'm wondering if you have enough air flow since you are developing so much moisture in your place. Airflow is what helps evaporate moisture build-up. Do you use fans or aircon at all?
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Re: regarding long term storage.

Postby theredbaron » Nov 10th, '12, 04:45

Tead Off wrote:Redbaron, your place sounds quite sticky to me the way you are describing it. I'm wondering if you have enough air flow since you are developing so much moisture in your place. Airflow is what helps evaporate moisture build-up. Do you use fans or aircon at all?


It is much less sticky than when i lived at the Khlongs in Nonthaburi in the mid 90's ;)

I don't like aircon at home, i only use fans. On my shelves the tea is fine, ages very well. I got enough airflow there.
The advantage and disadvantage of living in a wooden house is that the climate outside is more or less the same as inside. I guess it also depends how high up you live, on the ground it often is far more sticky than a few floors up (i don't like living in a high rise).

But especially because at times it gets really sticky in my place, i would want to warn people of being very careful with high humidity and especially lack of airflow as will be the condition in the micro climate created in such artificial storage spaces. The line between a climate conductive to aging, and to a breeding ground for mold can be thin.
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Re: Regarding long term storage

Postby gasninja » Nov 10th, '12, 10:05

[
theredbaron wrote:I am neither a biochemist, nor a physicist, or anything related. But i have to say that some of the humidity cabinets shown in this discussion here do scare me.

Open water and heat in an enclosed space without airflow, creating a tropical micro climate, can be a recipe for disaster. I think the numbers game here is a bit misleading, looking at exact levels of humidity, or temperature. Pu Erh's are aged successfully in many different climates. Hongkong, KL, or Singapore have quite different climates, but each has a history of excellent aged teas.

When you give honk kong Singapore and Kowloon as exaples of " many different environments.
I think that you are viewing thing through the lens of where you live . To me those places all sEem to have similar environments hot and humid.

You live in an environment is one where it is hot and humid all the time . So you are worried about mold . Ours is an environment where cakes will not age (see any tea from David lee Hoffman). I don't think there are many pumidors in hot humid environments. For many it is the only option in order to age tea.
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Re: Regarding long term storage

Postby theredbaron » Nov 10th, '12, 10:42

gasninja wrote:[
theredbaron wrote:When you give honk kong Singapore and Kowloon as exaples of " many different environments.
I think that you are viewing thing through the lens of where you live . To me those places all sEem to have similar environments hot and humid.

You live in an environment is one where it is hot and humid all the time . So you are worried about mold . Ours is an environment where cakes will not age (see any tea from David lee Hoffman). I don't think there are many pumidors in hot humid environments. For many it is the only option in order to age tea.


Kowloon is a part of Hong Kong, KL is Kuala Lumpur, the capital of Malaysia. The climate in KL and Singapore is similar, but very different from Bangkok, which is also very different from Hong Kong.
Here in Bangkok we have a very humid wet season, a very hot hot season which can get stuffy towards the end, and also a cool season which has quite normal humidity levels, and very pleasant temperatures. Hong Kong can get quite cold in winter, and never as hot as Bangkok in the hot season.

What i am saying is that, being used to such climate, and knowing how conductive this can be for mold and rot, that in some of the cabinets i have seen pictures from here, similar tropical micro climates can be created within these cabinets, yet not with sufficient airflow to ensure that the teas stay mold free.
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