Anyone studied the chemistry of Tea?


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

Anyone studied the chemistry of Tea?

Postby vibrantdragon » Dec 28th, '08, 21:04

Here is some of the latest info I have collected, and some of it I and others have posted in other locations. This is for cooked tea, but raw tea will have many of the same chemical reactions just slower and along a different path. The change in path does make a different tea, but both offers great health benefits.

Like other traditional fermented foods and drinks, Puer tea is made by empirical procedures. The manufacturing process can be outlined as follows: fresh tea leaves collected from farmland are heat-treated to inactivate the enzymes contained in the tea leaves and dried thereafter. This heat treatment allows tea leaves to be stored for longer periods. Then they are combined with an adequate amount of water and piled into a windrow shape in the fermentation room. Microorganisms inhabiting the straw mat covering the pile and/or in the room infect the tea leaves. Changes in the color and flavor of the leaves are checked during the fermentation process, and the endpoint of fermentation is decided by an experienced manufacturer. Puer tea is distinctive among various processed teas such as black tea since microorganisms contribute to the fermentation process.

1. Pu’er starts as normal Green Tea
a. Heat treated to stop the enzymes.
b. If the raw leaves are not heat treated quickly they will covert to a black tea.
2. The leaves are stored and mixed in the proper formula.
a. Large leaf mixed with small and medium size leaves to give the desired mixture and taste.
b. At this point leaves can be shipped to tea factory.
3. Water is added to the tea leaf mixture until the water content is about 30%.
4. Small piles are made and a bamboo mat or straw mat is placed over the tea to keep the water from evaporating.
5. The mats might be the key to each tea factory. These mats contain the wild yeast or microorganisms that cause the secondary fermentation too occur. This is the way that each factory produces their own unique mix of cultures that give the tea their own unique taste.
6. The fermentation is very different than the normal enzyme driven fermentation of tea that produces oolong and black teas. As a result the chemicals in the tea are different. You will get different benefits from each tea.
7. Now we can really see why everyone compares Pu’er tea to wine. A type of yeast driven fermentation of the raw tea leaves into their new chemicals. Since these are much more complex chemicals than just simple sugars, you do not get alcohol but new tannins and polyphenols.
Pu’er is a very potent antioxidant blend.

This process really depends upon the quality of the tea leaf. Leaves that have the wrong chemical structure will not develop or make the correct final product.

I keep trying to talk about fake and using leaves brought in from other provinces. Look at this process and many things must be done correctly to get the best tea and it all starts with the right dirt, trees, bushes air and water. Yunnan has a unique place in the world and we must wonder if any other area can make the right blend of tea.
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Postby vibrantdragon » Dec 28th, '08, 21:07

I hope to finalize some data on making the raw cakes, but I need to finish checking some of my data. I try to only include data from refereed or well check sources. If anyone has a good source for the raw cakes let me know.
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Postby PolyhymnianMuse » Dec 28th, '08, 21:57

First I would like to acknowledge all of the really "hardcore" information seeking and researching of tea that I have seen increasingly across the forum here. Personally I am the kind of person that is really OCD about understanding things much like the way that you said in your post, when it comes down to it good tea starts at the very chemical structure of the leaves being used to begin with, or even further you could say that its the very earth and weather that ultimately dictate it, but I digress....

Something I have brought up in a few other threads regarding subjects like this with pu'erh draws interest to the very organisms that that create the "ageing" of pu. It would be nice to see exactly what micro organisms are growing on certain cakes, and deeper into that what can individual and certain combinations of them do in regard to flavors. Of course there are also so many aspects including humidity of the environment and the amount of fresh air it is getting...

So many questions, which will only create more questions....
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Postby Proinsias » Dec 28th, '08, 22:21

PolyhymnianMuse wrote:So many questions, which will only create more questions....


I'm comfortable with it all being down to magic.
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Postby PolyhymnianMuse » Dec 28th, '08, 23:16

Proinsias wrote:
PolyhymnianMuse wrote:So many questions, which will only create more questions....


I'm comfortable with it all being down to magic.


Haha indeed, I really don't have much of a problem leaving it up to the forces :lol:
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Postby tenuki » Dec 28th, '08, 23:49

"Tiger gotta hunt. Bird gotta fly.
Man gotta sit and wonder why, why, why.
Tiger gotta sleep. Bird gotta land.
Man gotta tell himself he understand."

-- Kurt Vonnegut Jr. (RIP)
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Postby heavydoom » Dec 28th, '08, 23:55

it's deja vu all over again.
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Postby Proinsias » Dec 29th, '08, 00:03

heavydoom wrote:it's deja vu all over again.


My brain hurts
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Postby vibrantdragon » Dec 29th, '08, 02:02

PolyhymnianMuse wrote:Something I have brought up in a few other threads regarding subjects like this with pu'erh draws interest to the very organisms that that create the "ageing" of pu. It would be nice to see exactly what micro organisms are growing on certain cakes, and deeper into that what can individual and certain combinations of them do in regard to flavors. Of course there are also so many aspects including humidity of the environment and the amount of fresh air it is getting...

So many questions, which will only create more questions....


The fungi are known, the most common is the A.Niger strain and it cousins. Of course what does that mean is the hard part. There are several others and it is very important to make sure that the correct micro organisms are used. The ultimate flavor is determined by these fungi. The organisms break down the organic matter just like the making of Miso and soy sauce. The flavor is determine by this mixture. I suspect that each tea factory has their own little starter fungi like the straw mats that that make sure the fungi that infect the leaves are correct and produce the best flavor. The papers indicate that several types of fungi related to A. Niger and B. adeninivorans are found in the leaves and help the transformation of the leaves. The smell, taste, color and chemical breakdown of the tea is due to these components.

We can all hope for some one else's magic, but i like to make the magic. I want to meet the people and learn how they make this happen. If i can understand the best way to make the tea,than i know that the tea i drink and sell is the best. I would not trust some one that did not understand and know how to make and keep this tea.
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Postby Wesli » Dec 29th, '08, 03:58

vibrantdragon wrote:I want to meet the people and learn how they make this happen.

You want to meet A.Niger? :shock:


BTW, thanks for the research, keep it up.
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Postby tenuki » Dec 29th, '08, 05:02

If you saw the pictures of barefoot men raking the tea at the factory that were posted a while back you can see my vote for where the fungus is coming from... ;P
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Postby vibrantdragon » Dec 29th, '08, 11:30

It is good that the process seems to be pretty robust. In one of the papers they tried to find some toxins produced by the fungi, but could not. It seems like the tea is self regulating. The fungi related to the A. Nigri ( a better spelling i hope, I have seen different spelling in different papers), can produce some toxins. The strains in the tea seem to be very clean in that manner.
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Re: Anyone studied the chemistry of Tea?

Postby augie » Dec 29th, '08, 14:14

vibrantdragon wrote:Microorganisms inhabiting the straw mat covering the pile and/or in the room infect the tea leaves.


I would prefer the word "infuse" in lieu of "infect". :wink: Just try not to think about it and drink & enjoy!

1. I haven't had a migraine in 2+ years.
2. I have (several times) rid myself of a cold or stomach flu in a few short hours.
3. Cha qi.

Barefoot, naked toe jam from the tearoom processing floor can't be all that bad???
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Postby silverneedles » Dec 29th, '08, 14:22

Aspergillus species (MPT1 a relative of Aspergillus Niger) [A. Niger & Foetidus are part of A. Nigri "series"]
& Blastobotrys adeninivorans
were found as the major ones, in 1 study in 1 puerh manufacturing room.

"Only 3–10% of the strains examined for ochratoxin A production have tested positive under favourable conditions. New and unknown isolates should be checked for ochratoxin A production before they are developed as production organisms. It is concluded, with these restrictions, that A. niger is a safe production organism. " linky

aka very likely that most strains do not produce mycotoxins

"Ochratoxin A is one of the most abundant food-contaminating mycotoxins in the world.," found in grapes, coffee, pork

and ochratoxin doesnt seem to be as famous for cancerigen effects as aflatoxin (produced by the "bad" Aspergillus Flavus & Parasiticus)

think i saw on the Discovery channel that the cheese fungus that makes those French stinky cheeses are the same species as the smelly athletes foot toes
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Postby expatCanuck » Dec 29th, '08, 15:51

silverneedles wrote:...think i saw on the Discovery channel that the cheese fungus that makes those French stinky cheeses are the same species as the smelly athletes foot toes
Some things are best left unknown.
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