mao cha vs beeng cha


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Re: mao cha vs beeng cha

Postby TwoDog2 » Apr 9th, '12, 22:39

I think those differences are real hop, I have experienced that too. The problem is, I have never had identical teas, in pressed and loose form side by side. I have had some similar teas though, and there is some difference there. I think it has something to do with the fact that the exposure to air is more uniform in one case than in the other.
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Re: mao cha vs beeng cha

Postby hop_goblin » Apr 10th, '12, 09:37

TwoDog2 wrote:I think those differences are real hop, I have experienced that too. The problem is, I have never had identical teas, in pressed and loose form side by side. I have had some similar teas though, and there is some difference there. I think it has something to do with the fact that the exposure to air is more uniform in one case than in the other.


Yes, very difficult to test in order to come to a definitive conclusion.
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Re: mao cha vs beeng cha

Postby David R. » Apr 10th, '12, 10:01

debunix wrote:
TwoDog2 wrote:I wonder if anyone has done any extensive research on that kind of thing - which chemical reactions occur at which speed, and how they differ in varying 'air'. Interesting ideas that I am not enough of a scientist to dissect


I'm just enough of a scientist to wonder about them, but not enough of a chemist to know how dramatically different the environment is inside a beeng, as all but the most severely compressed bricks don't seem 'airtight'.


Difficult question. I tried to look into that a few months ago. When you have oxygen, there is oxidation. Without oxygen, like in the midle of a cake or brick, there is fermentation, which needs enzymes which are already in the tea leaves. Humidity and temperature play a huge part too.

Problem is oxidation is often called fermentation in the tea business, especially for wulong.

What I understood is that oxidation will help developing in the long run the earthy notes, while fermentation will give more intense fruity notes.

So, mao cha should "age" faster as its leaves have a huge contact surface with oxygen. The heart of a cake will age differently whether it is in a hot and humid atmosphere or a dry one. More earthy in the former case, fruitier in the latter.

This may be too simplified to be exact, but this is want I understood according to my level in chemistry.
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Re: mao cha vs beeng cha

Postby TwoDog2 » Apr 10th, '12, 22:28

[quote="David R."

Problem is oxidation is often called fermentation in the tea business, especially for wulong.
[/quote]

When some people refer to wulong teas as partially fermented, they really mean to say partially oxidized, is that an example of what you mean?
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Re: mao cha vs beeng cha

Postby David R. » Apr 11th, '12, 07:51

Exactly. Fermentation will happen only during the aging/maturation process, not in the actual making of the tea. But somehow the ISO standards word appears to be "fermentation" even if the actual reaction is oxidation.
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Re: mao cha vs beeng cha

Postby wyardley » Apr 11th, '12, 17:41

David R. wrote:Exactly. Fermentation will happen only during the aging/maturation process, not in the actual making of the tea. But somehow the ISO standards word appears to be "fermentation" even if the actual reaction is oxidation.

And similarly, in Chinese, fajiao (which I think is roughly 'fermentation') is the term usually used by farmers and tea merchants for 'oxidation', rather than the technical term for oxidation in Chinese. Maybe this is part of where the confusion comes from.

It does seem like it's commonly accepted that in tea processing, oxidation is sometimes called "fermentation". Maybe someone with more of a chemistry background can enlighten us, but I'm not 100% sure that "fermentation" is such a clear-cut term.

[note mention of tea processing use at:
http://en.wikipedia.org/wiki/Fermentation ]

Also, while I think it's pretty clear that "fermentation" is probably happening during the process of making ripe-tea, it seems like there's a little more dispute about what processes are actually happening in the aging of so-called post-fermented teas, and there is clearly oxidation happening in that process as well as any fermentation that may or may not be happening.

In any event, I try to use "oxidation" when I mean oxidation.
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Re: mao cha vs beeng cha

Postby shah82 » Apr 11th, '12, 18:21

Difference between a hongcha and a heicha is which kind of fermentation (oxidative, anaerobic, mix), and which parts of the leaf is preferably fermented.

Wine ferments sugar to alcohol.

Oolongs and hongcha preferably ferments the nonstructural, soft, parts of the leaf using already present enzymes.

Heicha and lucha has a denaturing step that stops the leaf from digesting itself + whatever anaerobic fermentation resulting from rot (why do you think fresh shu smells of swamps?). The first merely denatures enzymes, sometimes the leaves are rolled to expose more material to the elements. Lucha is practically sterilized, with the leaf parts that would have slowly fermented being slightly carbonized and dried into a tight matrix that does not allow much in the way of access to either oxygen or bacteria, so most volatiles merely escape from lucha as time goes gone, rather than be captured in new aromatic complexes.

Sooo, what do you think of *this* explanation. I think also it works well, in thinking about the reroasting of aged oolongs, too.
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Re: mao cha vs beeng cha

Postby David R. » Apr 12th, '12, 08:18

I am sorry to say that I am not very knowledgeable about red tea I am afraid... :roll:

About puerh, one other thing I gathered, is that the pan frying and the sun drying phases do not deactivate totally the enzymes responsible for oxidation. Therefore oxidation will occur while the tea is aging, more than with another kind of tea where enzymes would have been totally inhibited.

But the precise chemistry involved with puerh maturation is far beyond my knowledge...
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Re: mao cha vs beeng cha

Postby Saayuq » Apr 12th, '12, 18:09

I think I understand chemistry a little bit better than I do tea, nevertheless here are some musings. If the agents responsible for converting a young sheng into an old sheng are microbial, I would predict that the steaming of the leaves prior to pressing and the subsequent warmth of drying the beeng should kickstart the microbial process. Since there would be significant period of time during which the beeng would be moister than the mao cha. Then assuming the storage conditions are equal, the beeng would age faster, having a denser initial population of microbes.

If the presence of oxygen as an oxidizer is more important, the mao cha should have more uniform access to it and age faster. I'll let somebody else try this: raise the oxygen level in your left cupboard by putting a tbsp of yeast in a cup of hydrogen peroxide every day (this generates diatomic oxygen) and let everything else be equal in your right cupboard except for the additional oxygen.
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Re: mao cha vs beeng cha

Postby Drax » Apr 12th, '12, 20:08

Ugh, I've been trying to stay out of this conversation because there's so much "sounds like science" versus any actual real science.

One of the first things to consider is that when you are talking about "oxidation" you are likely referring to the reaction of oxygen with chemicals in the tea. These reactions probably don't need any enzymes, because oxygen is pretty reactive.

As Saayuq says, the agents responsible for the aging are likely microbial, that is, not the innate tea machinery itself -- by that, I mean the tea leaf itself is pretty dry, and enzymes really need to be in an aqueous environment to have the right shape and function properly. However, living microbes will have their own contained environments to properly live (and feed) off of the tea. They are the ones likely doing the aging, or composting. And again, oxidation will just happen with oxygen in the atmosphere. No extra machinery required... though the microbes might also appreciate the oxygen. :D
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Re: mao cha vs beeng cha

Postby wyardley » Apr 12th, '12, 20:21

Drax wrote:One of the first things to consider is that when you are talking about "oxidation" you are likely referring to the reaction of oxygen with chemicals in the tea. These reactions probably don't need any enzymes, because oxygen is pretty reactive.

But to achieve "oxidation" in tea production with oolongs and red teas, there is usually some kind of process that happens besides just exposure to air.

http://en.wikipedia.org/wiki/Tea_processing says:
This is accompanied by agitation in some cases.[1] In this process the chlorophyll in the leaves is enzymatically broken down, and its tannins are released or transformed. This process is sometimes referred to as "fermentation" in the tea industry. The tea producer may choose when the oxidation should be stopped, which depends on the desired qualities in the final tea as well as the weather conditions (heat and humidity).


With oolong tea, this is achieved by bruising the tea and letting it oxidize somewhat before kill-green; with red (black) tea, I'm not sure how it's accomplished technically. So I guess the point is, the steps taken to oxidize the tea may also create some other chemical reactions. Whether those are actually "fermentation" or not, I am not at all qualified to speak on.

With green tea and pu'er, the idea is to do kill-green before the tea changes color, but obviously with exposure to air, the tea will continue to oxidize -- just at a much slower rate.
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Re: mao cha vs beeng cha

Postby Drax » Apr 12th, '12, 21:35

I believe that the physical process is well-explained, but I still have a feeling that people are just making up what they think is chemically happening (note which pieces of information the citations usually follow) -- especially when it comes to the oxidizing part.

Here are some questions that pop into mind from that description:

What is enzymatically breaking down the chlorophyll? By that, I mean what enzyme? And why does it act upon bruising? That is, what doesn't it break down the chlorophyll while the leaf is whole?

Tannins are released or transformed. Well, which one is it? What does "transformed" mean? And by what? Oxygen? Enzymes? Microbes?

Please don't mis-understand my intent here. I had to throw a red flag on a description on the matcha page that claimed that chlorophyll slowly transformed into tannin over time -- which was absolute horse-cocky. These descriptions have a high tendency to "sound good" but actually not mean anything.
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Re: mao cha vs beeng cha

Postby shah82 » Apr 12th, '12, 21:51

Wikipedia is your friend, or at least the first stop.

http://en.wikipedia.org/wiki/Tannins

As for enzymes..., think of them as running construction equipment, and BOOM, a leaf is bruised and the equipment escapes the construction site! OH NOs, the equipment is tearing chunks out of cars and buildings! A growing leaf using many enzymes to modify and place proteins where they are supposed to be. A few more specialized enzymes build chromatic complexes, aromatic chemicals, and stores carbohydrates created from the chlorophyl complexes. Lots of things happening, with many different enzymes doing different things. When we make hongcha or oolong, we're taking advantage of the destructive potential of various enzymes that are now out of place to create a certain mix of chemicals that pleases our noses and mouths when prepared properly.
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Re: mao cha vs beeng cha

Postby gingkoseto » Apr 12th, '12, 22:15

Saayuq wrote:I think I understand chemistry a little bit better than I do tea, nevertheless here are some musings. If the agents responsible for converting a young sheng into an old sheng are microbial, I would predict that the steaming of the leaves prior to pressing and the subsequent warmth of drying the beeng should kickstart the microbial process. Since there would be significant period of time during which the beeng would be moister than the mao cha. Then assuming the storage conditions are equal, the beeng would age faster, having a denser initial population of microbes.

If the presence of oxygen as an oxidizer is more important, the mao cha should have more uniform access to it and age faster. I'll let somebody else try this: raise the oxygen level in your left cupboard by putting a tbsp of yeast in a cup of hydrogen peroxide every day (this generates diatomic oxygen) and let everything else be equal in your right cupboard except for the additional oxygen.


I like your analysis, especially the underlined part! :D
A few years ago, a puerh manufacturer gave me two aged loose sheng (mao cha) in his personal collection to taste. All people involved in the tasting thought it tasted "younger" than tea cakes from same region (Menghai) going through similar storage (dry storage in Yunnan). His hypothesis is, the steaming process kicks start aging. He couldn't explain why but said once he tasted a loose sheng that tasted well aged, and the owner said the tea was once steamed.
After he told me his "hypothesis", I was still puzzled what steaming could do to the long-term fermentation of the tea. But now I think what you said could be a reasonable explanation for his hypothesis.

On the other hand, probably oxygen does make an impact on the aging of loose sheng. I have a Jing Mai cake that was pressed in 2009 but stayed in loose tea form from 2002 to 2009. I think the liquor is redder than liquor of tea of similar age going through similar dry storage. But since I don't know the background of this tea, I don't know if the red liquor color is a loose tea effect or due to the tea's own characters.
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Re: mao cha vs beeng cha

Postby shah82 » Apr 12th, '12, 22:32

gingkoseto, the example of that jingmai (although poor fermentation is a serious hazard for all smaller-leaf puerh--good leaf and good process is even more important) is why I don't do puerh made with aged maocha. Virtually all of them have a stereotypically "dark" and simplified taste.

Puerh is made from a variety of decay processes. If steaming was all that, at the very least, the japanese greens would age. They don't.

However...

http://mattchasblog.blogspot.com/2010/0 ... k-cha.html

This green tea does age after steaming. Therefore, as the post illustrates, caking allows for a higher quality kind of aging, and different shapes, with different processed leaf, ages differently.

The key thing about not having leaves in loose form is that no one fermentation process dominates. You'll have straight up oxidation. You'll have whatever enzymatic processes (especially from dead microbials), you'll have different kinds of microbes munching different parts of the leaf, more or less on an even pace. You'll have anaerobic fermentation of other parts, generating sourness and other interesting tastes. So forth and on, creating an ubercomplex tapestry of aromas, tastes, textures, and chaqi...
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