neděle 29. září 2013

The origin of microorganisms in pchu-er.

With a little delay I respond to one of my reader. He wrote comment on my article about oxidation, fermentation and maturing of tea. The reader said that, according to his opinion, during fermentation of shu pchu-er the mao cha is artificially inoculated by microorganisms. On the other hand in my article I claim that the microorganisms, which are needed for fermentation, are presented on the leaves from the nature. The reader quotes English article from Wikipedia. Exactly these sentences about shu:
"The bacterial and fungal cultures found in the fermenting piles were found to vary widely from factory to factory throughout Yunnan, consisting of multiple strains of Aspergillus spp., Penicillium spp., yeasts, and a wide range of other microflora. Control over the multiple variables in the ripening process, particularly humidity and the growth of Aspergillus spp., is key in producing ripened pu'er of high quality."
However in these sentences there isnt any mention about inoculation of tea with anything and, according to my opinion, artificial inoculation even doesnt ensue from these sentences. We could just found that microorganisms vary from factory to factory. According to me, the author wanted to highlight geographical differences rather than manufacturing differences. Yunnan is a very large area and therefore we can presume that composition of microflora in different part of this province will be different. Microorganisms of the tea leaves can vary based on the altitude of plantation, orientation of the slope of the tea garden, quantity of precipitation, already mentioned geographical location and surely on others variables. I admit, that the sentences have not been written clearly and both interpretations are possible. Authors of the article on Wikipedia quote as a source scientifical study: Isolation and Identification of Aspergillus Species from the Post Fermentative Process of Pu-Er Ripe Tea.
It wasnt easy to find out this study. It is not available on the Web of Knowledge. After some time I had a bit of luck. I found the study but it is written in Chinese and i dont speak this language. Only the abstract is written in English and it consists of four sentences. From these sentences the number three is important: It is noticed that the compositions of fungus flora in the post fermentative process of different Pu-Er ripe tea produced from different places were different. I suppose that only this one sentence was the main source for the author of the article on the Wikipedia. I tried to translate this study with a help by Google Translator. But after translation of the first sentence, I found out that this programme is not capable of translation from Chinese to Czech or English properly. The Translation was very bad but I got rough summary what the study is all about. And then another problem appeared. The second page of the study was inserted as a picture so I wasnt able to copy its text for translation. The introduction of the study describes manufacture of pchu-er and results of some previous studies. Then the founded microorganisms, mainly fungi (molds), are described. At the end there is a description of what fungi (molds) were found in concrete teas from different regions. I think that authors connected the presence of different fungi with environment (f. e. tropics and so on) not with processing. They didnt mention artificially inoculation. Because of bad translation, it is all I can say about the study.
Can someone help me with translation? 
Source: Isolation and Identification of Aspergillus Species from the Post Fermentative Process of Pu-Er Ripe Tea,  Chen Keke, et al., Acta Botanica Yunannica. (28)2, 2006.

Robert J. Heiss is the author of the article Oxidation and Fermentation in Tea Manufacture. This article was published in The Leaf Magazine and it is also about origin of microorganisms in pchu-er. The author says that bacteria (but i think that word microorganisms is more accurate) which are needed for the process of fermantation can be found:
  1. on the surface of the leaves of old tea trees that grow in the original forests in Xishuangbanna. Here I suppose that microorganisms can be found also on the leaves of plantation tea trees, not only on old trees in forests.
  2. in controlled area, where the ma ocha is temporarly stored before compression to sheng pchu-er,
  3. in the piles of mao cha during fermantation of shu pchu-er,
  4. in the humid environment, where the mao cha is steamed before compression to sheng pchu-er,
  5. in smaller scale in the rooms that are devoted to maturing of pchu-er.
We can deduce that, to the places marked 2 till 5, the microorganisms were transfered on the surface of the leaves. The author also wrote: During the fermentation phase of Puerh manufacture, several important factors must coalesce. Following the harvest of the appropriate leaf, there should be ´wild´ bacteria available on the leaf itself; this will range from ´very little´ to ´an abundance´. The author used directly the word wild, that mean the natural origin. And I think again that the word microorganisms is better than bacteria.
The same author says in his book The Story of Tea: A Cultural History and Drinking Guide: The goal in making sheng pu-erh is to create an environment that will encourage the micro-organisms present on the leaf to remain alive. In the broader context of whole chapter about pchu-er in this book I understand the term "on the leaf" as an expression of natural origin of microorganisms. But I admit that this interpretation can be subjective.
Especially from the first article is obvious, that this author (or authors in a case of the book The Story of Tea) supports the natural origin theory. He claims this statement several times and he puts emphasis on it. There is no mention about artificial inoculations in his articles.

I thanks to one tea lover (maybe better pchu-er lover) for posting me the study: Characteristic fungi observed in the fermentation process for Puer tea. There are two important sentences in this study:
  1. Microorganisms inhabiting the strawmat covering the pile and/or in the room infect the tea leaves.
  2. Microorganisms are thought to infect the leaves from the mats and/or the ambient atmosphere.
This facts overlap information from Robert J. Heiss, specifically with points 2 and 3 that are written some paragraphs above. From this sentences it ensues, that required microorganisms comes from nature (or from places, to where they were transfered from nature).

I know at least four people, that (according me) have very good tea knowledge and therefore I asked them for their opinions. Independently each of them agreed on natural origin. At the same time they all added that artificial inoculation can‘t be entirely excluded. There are so many producers and also tea research centers and therefore inoculations can be somewhere practised.
I have found much more references about the natural origin and nothing about artificial inoculation. This references support my original opinion which I published in this aticle. The origin of microorganisms needed for pchu-er fermentation is natural, not artificial. I suppose that there is much more sources about pchu-er fermentation and if you have some article about artifitial inoculation I would be glad to see it – maybe we will learn something new.

It is interesting, that there are many articles about pchu-er, but only a few of them describes the origin of microorganisms and usually in a very briefly way.

Finally I thank all people for sharing their knowledge or sending information.

1) The Leaf - Tea and Tao Magazine, Issue 2, Oxidation and Fermentation in Tea Manufacture, Robert J. Heiss (,
2) the reader, who stimulated creation of this article, refers to English article from Wikipedia,
3) Tea: history, terroirs, varieties, Kevin Gascoyne, Francoise Marchand, Jasmin Desharnais, Hugo Americi, 2011 Firefly Books Ltd., ISBN: 978-1-55407-937-7,
4) The tea drinker´s handbook - Francois-Xavier Delmas, Mathias Minet, Christine Barbaste, Abbevillw Press 2008, ISBN: 978-0-7892-0988-7,
5) The Story of Tea: A Cultural History and Drinking Guide, Mary Lou Heiss and Robert J. Heiss, Ten Speed Press 2007, ISBN: 978-1-58008-745-2,
6) Isolation and Identification of Aspergillus Species from the Post Fermentative Process of Pu-Er Ripe Tea, Chen Keke, et al., Acta Botanica Yunannica. (28)2, 2006,
7) Characteristic fungi observed in the fermentation process for Puer tea, Michiharu Abe, Naohiro Takaoka, Yoshito Idemoto, Chihiro Takagi, Takuji Imai, Kiyohiko Nakasaki, International Journal of Food Microbiology 124, 2008,
8) opinions of me or my friends, that were surely influenced by what have we heard or read somewhere, but we have already forgotten where.

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