Mold
It's the one thing that can go wrong with pu-erh. Mold is also one of the things responsible for pu-erhs maturation. So, while mold is good, it can also be bad, very bad. Yellow mold on pu-erh is said to be toxic, however, a light frosting of white mold is said to be beneficial. So, in short, mold development must be kept in balance.
Sadly, a few bings in my collection have developed mold. This mold has passed the beneficial point. It journeys into the realm of yellow pu-erh mold. Not only the color, but also the rate at which it has developed is a bad sign (in this case, under a year). Because of the lack of information on pu-erh on the web, especially in the field of mold development, I'm hoping this will be of interest and help to enthusiasts.
The story...
So, here's what happened. I made a storage cabinet for my puerh, with elevated RH levels in the 70-80% range. I got careless in opening it up for air exchange at one point, leaving it closed up for 3-7 days at a time. After a couple months of this, I found mold growing on one of my cakes. I checked most of them out, and about half are affected, this '06 Yongpinhao, for some reason, took the grunt of the burden...
Pu-erh mold starts on stems...
What's very interesting to note, is that the mold is essentially only growing on stems. Is this typical? Does pue-erh mold generally start on stems? Did the stems soak up more water from the air because they're, well, stems, and made to transfer water? Hard to know because of the miniscule amount of data out there. From what I can remember, I haven't seen mold exclusively on stems. Hobbes of the half-dipper posted this photo of moldy puerh (which he drank), which shows mold on the leaf. This seems typical to me. My other bings that have developed a lesser amount of mold, also show it almost exclusively on the stems. Bings from the cabinet that don't have many large stems showing, for example the 01 baoyan, don't have any mold.
So, for now I have opened up the cabinet to ensure good airflow, and removed humidifiers. The area is resting at just over 60%RH on average. For one very stemmy cake ('05 ming-yuan hao), I brushed off the mold from half of it with a toothbrush. The mold on that side hasn't returned, but the mold on the other side hasn't gone away either.
These pictures are all of the '06 Yongpinhao, which I will revisit in this entry. The mold on the other cakes isn't significant enough to photograph, and appears at most as a very light frosting on the cake, with some more significant development on the looser edges of the cake, again, only on the stems. My plan is to brush the mold off all of the affected, except for the ming-yuan, which I will watch closely to observe development. The Yongpinhao is not being subjected to a brushing, but to more air circulation, and light. While these aren't good for the tea, they'll hopefully take care of the mold, and it will be interesting to learn what it takes to get rid of the mold.
So what happened...
Over a few months, in a storage cabinet with no air flow for 3-7 days at a time, and 70-80%RH, raw sheng bings developed significant visible mold. Most with only minimal amounts, occurring mostly on the looser edges, and exclusively on stems. After being opened to free air flow, and resting in an RH just over 60% for a few weeks, the mold has not gone away, but has not increased either.
If you're curious about anything, feel free to shoot me an e-mail (address found at bottom of page).
2006 Yongpinhao Yiwu Zhengshan
I reviewed this tea a while back. My final thoughts were that I was very interested in how the strong lemon/zest and lumber flavors would develop over time. I've been interested in the storage of this cake ever since.
9 Months Later...
Because of the condition of this cake, I had to chip leaf off of the bottom, where there was less mold. I also rinsed it twice, just to be careful. But, to be honest, the mold doesn't scare me too much. Mold is what makes pu-erh better, or so I will tell myself.
So, I'm tasting this 9 months later, and I've noted some new things. First off, the color is much darker, an orange now. Quite amazing really. Compare the orange above to the yellow of this photo, taken 9 months ago:
In addition than the color, the tea has changed in multiple other ways. It now has a very noticeable mouthfeel; it's viscous, and sticks to the tongue and cheeks. I can still smell the lumber on the wet leaf, but I believe that it's a subjective scent. It took a moment for me to recognize the aroma as lumber. It was like it was hidden beneath the other aromas. The taste now is much sweeter. There's still a lot of orange/zest to it. Some smoke, but little bitterness if brewed with very short infusions (except when it has cooled off, then it is very bitter, and can be very bitter with longer infusions). Some astringency sticks to the throat, drying it out.
Now, I don't think this cake is of good quality. In fact, I find it to be pretty low. So, why do I like it? I enjoy the flavors it presents, especially the lumber and orange/zest, and am real interested in how these will change over the years. Puerhshop still has them in stock, for $17/400g, which is worth it to me. So, I think I'll buy another, and keep it mold free, but I'll keep this moldy one around to see what happens to it.
11 comments:
Are you sure about all the "good mold / bad mold" stuff? Ive always heard that any mold is bad mold. One of the articles in Art Of Tea magazine discusses Puerh storage and it states that one of the danger signs of improper storage is mold. And that if any is present that the tea should be discarded. I don't know, drink it if you want but I,d be kinda put off by it.
I agree with Bret, any mold is toxic and carcinogenic - I would never drink a molded pu-erh.
Myself had a similar mold accident - see http://tuochatea.blogspot.com/2008/09/experiment-went-terribly-wrong.html - and after opening the beengs I found out, that mold is not growing just on the surface of the beengs but also, in lesser extent, inside the beengs.
Thanks Tuocha, I was actually looking for that entry while I was writing this, but couldn't find it.
Concerning mold, all puerh has mold on it. Check out the "In Science" section of AoT No.1, p.142. You can see that all 30 types of puerh tested have mold. Cfu/g levels even reach a height of 470,000(this is dispersal in cold water). You'll also notice that when water was used (in a machine-controlled steeping) that was 80°c(176°f), no mold was present. This suggests that moldy pu-erh infused at 100°c (212°f) poses no health risk.
But were these molds studied the same as the visible molds seen in my entry? We can't know for certain, but the article states, "They also represented a vast spectrum of storage methods, including wet and dry storage, *moldy*, sprayed with water and forged, etc." Which suggests that there was puerh with similar visible mold included in the experiment.
Stems are definitely where they start.
It's simply not true that any mould is bad. If you believe any mould is bad, then I am sure you don't eat any cheese, since most of them contain some mould.
I have friends who have been drinking this stuff for decades. Brush it off and drink it. The whole "if there is any mould you should throw it away" is simply false. Almost all teas that are over 15 years old have at least some mould on it. Should you throw them ALL away? We wouldn't have any old puerh to drink then.
Also, historically puerh has been stored quite carelessly -- and that's just how things have always been. The whole "you must keep mould off at all cost" is a VERY VERY new trend -- something which has absolutely no historical precedent to support whatsoever.
I don't know, your probably correct that all Puerh has mold to some degree. But if it,s gotten to the point where it,s covered the surface of the cake with fuzzy, hairy looking stuff WHY would you drink it? Is it really that good? For me NO it,s not.
Yes, MarshalN, I don't eat molded cheese :-) - OK, I don't like it's taste. And I don't eat any mold-surfaced food, like salami or so.
i like "fresh puerh" too ,. it seems so wild with that mold ,. and brush it and drink sounds so stupid ,.because if you have mold on surface ,. whole cake is covered by mold ,. but if you like it ,donthesitateand drank ,. have anice day ,
You should read this article on mold and mycotoxin in tea by Terry Mabbett in Tea & Coffee Trade Journal Friday, August 1 2008. It seems clear that the toxins some molds produce are damaging to organs at their least and deadly at their worst in very small trace amounts. There are some molds specific to tea that produce harmful mycotoxin. Probably best not to ingest contaminated tea.
Anonymous: RE; DR Terry Mabbett's paper - Not to cause too much abrasive resistance and the possibility of libel action - but don't you think it is fairly suspicious that there is only one paper on the internet about the harms of carcinogenic mould in green teas and the author of this paper is also author of 'soluble sophistication for coffee'? I wonder how much he was paid for writing the paper? And who paid him the money for writing it? If it was a research paper - which university? And if it was a tea and coffee company which commissioned the paper... the answer to the validity of the research is a no brainer.
I have just spoken to relatives in China who say that the very finest green tea has white mould that grows off it very rapidly. This is normal. Chinese drink the tea and the mould is completely harmless.
Just thought you should know.
If you are afraid of mold don't drink Pu'er or wine or eat cheese or antibiotics. Look out because you are breathing in a variety of wild yeasts and penicillium right now. I've been to many tea markets in Guangdong, China and learned that there is little care for mold. Unless blue green mold has consumed your cake brush it off wash it twice and enjoy.
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