Oolong Tea Roasting

"winston" ha scritto nel messaggio news:7vfIc.83367$ snipped-for-privacy@bgtnsc05-news.ops.worldnet.att.net...

Oxidation and roasting are two complitely separate phases of oolong tea processing. After picking and withering, tea leaves are left to oxidize to the wanted degree of oxidation and then fixated by a first firing. The indication on roasting you found are related to the final process which is done in the rifining of oolong teas in order to add a "roasty" taste and in some case also to decrease astringency. So oxidation and roasting are unrelated and you can find teas with combination of different degrees of these two precesses. L

Livio is very much right about "oxidation and roasting are unrelated". I will start from this point-

Oxidation process can also make some Oolong more roast and flowery fragrant. Oolong tea can undergo 20-60% oxidation. When they pan-fry some oolong teas- timing can vary. That gives Oolong more roast or more flowery flavor. Some Oolong teas pan-fried longer then others. When they talk about "medium or dark roast"- they mean the timing of pan frying. But again oxidation level has an big impact on Oolong taste. Darjeeling Oolong, Bai Hao and some other Oolong undergo through less oxidation. Miang Xiang Oolong undergo through higher oxidation and also pan fried longer time. So the straight answer of your question is- yes you Ti Guan Yin can be medium and dark roasted.

Ti Guan Yin can be many types. I have tried more then 15 types. If you try different kinds of TGY, you will see they can be also marked as- Ti Guan Yin, Monkey picked Ti Guan Yin, TGY 1st grade, TGY K100, superior, tei baoota, top confou etc. etc. Ti Guan Yin can have different taste- some has more roast flavor and aroma, some are more floral, some can be very aromatic or even can be mild aromatic. All this happened for the processing- Oxidation or roasting timing.

High grade Oolong processing is still considered as one of the Chinese tea master's secret. Oolong can be processed in two different ways- one is the traditional method, another is ancient China method. You can tell this if you carefully take your infused oolong tea leaves under magnifying glasses(That's another topic).

Their is no straight forward answer about Oolong processing. Hope I have answered your question, Thanks.

Ripon Vienna,VA

I would like to add only a few remarks on roasting.

I personally do not know which can be considered the differences between traditional and ancient oolong production methods. What I will try to describe are the main phases of the process used for yan tea, TGY and phoenix mountain dancong teas, which I could see in China. The biggest difference is in the rolling process, but other phases are basically the same and differ only in their degree and in the way they are performed.

Since my English is terrible and I do not make a consistent use of terms, I want first to fix some concepts on these processes.

I will refer to "pan-roasting" (I used the term "pan-firing") in order to translate the Chinese term "chao". I do not like too much the term "frying" since there is no oil used in this process.

With the English term "baking" I will translate the Chinese word "bei" (In my previous message I used the term "roasting").

Pan-roasting is a process common to all green and oolong teas. It is so called since it was performed in an pan. Many green teas are still roasted in wok-like pans today, but most of oolongs are "pan-roasted" in a rotating heated iron barrel.

Pan-roasting process has these main purposes.

1) Fixation ("Shaqing", killing the green): stop all enzymatic oxidation activities in the tea leaves at the wanted degree (nominally 0% for greens, or 20-60 for oolongs). 2) Cook the leaves in order to decrease water content and make them soft and suitable for the subseguent "rolling process". After pan-roasting, tea leaves must not be dry, but soft and pliable and the more or less time you roast is adjusted in order to abtain this result. Being still rich in water content, in this phase tea leaves change and improve their taste and fragrance but get little "roasty" taste.

After rolling (that in the case of TGY can be quite complicate), rolled (and so shaped) tea leaves undergo a first "baking" which has only the purpose of drying complitely them. This process might be performed using some special "baking baskets" (beilong) made with a frame of bamboo with a metal net in the middle and posed on hot charcoal, or, in a more modern fashoned way, with a multi-layers hot air dryer.

All the phases above are usually performed directly by the producers (farmer) in they own, or collective, premises. The result (fermented, rolled and dryed leaves) is called "mao cha", semi-processed tea. Tasting this tea you can apreciate very well the quality of the plants and the way all the above processes have been carried out, but tea leaves have no "baky" or "roasty" taste.

Mao cha is not intended for direct consumption and needs a finishing process. This might be performed by the producer (in the case of middle or big scale producers) or more often by a whole-sale dealer who collect mao-cha from many different small producers (a widespread practise in Anxi area).

Finishng process includes the phases of removal of stems, sieving, final baking.

Final baking is tipically performed in baking-baskets. It is a very delicate and important phase, the one that brings tea leaves to the wanted final "roast degree". As Ripon has already explained, this degree which might vary a lot, but it is with the final baking that, varying the process timing, an oolong tea can become a light, medium or heavy roasted one, and not during the pan-roasting process.

Sorry for being so verbose. Livio

"Ripon" ha scritto nel messaggio news: snipped-for-privacy@posting.google.com...

*snip*

Not all all, *thank you* for being so verbose.

Thank you Livio! This really helps me understand why there are so many tastes for oolong teas. If I understand correctly, then it is possible to have a light oxidized oolong (i.e 20%) that is a heavy roast?

I am wondering if the oolong processing in Taiwan is similar to China ? In my experience, the oolongs from Taiwan such as Tung Ting, Bao Zhong, Gao Shan all have much more flowery notes than some that I've tried from mainland China. Is this because they are less roasted? I'm making the assumption (incorrectly perhaps?) that more flowery means less roasting and vice versa?

Winston

*snip*

Thanks, Ripon. Could you tell us more about the difference between traditional method and ancient China method? Sounds intriguing. Also, what are the names of the teas using the ancient China method and are they available for mere mortals to buy?

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Winston, you and I both could use some more clarification here. It appears to me that if a tea is more heavily roasted, but not very highly oxidized, it will appear quite dark as dry leaf, but become much greener in the water. The taste will also be different. Oxidation and roasting are totally different processes, in some sense diametrically opposed, I think, since roasting should stop oxidation, and lead to taste differences. *Exactly* what they are eludes me sometimes. That's why I too need a bit of clarification.

Michael

Hi Michael,

Me too. I have problems with English. So far, I thought the term "roast" for tea was reserved to the roasting done to certain teas (mostly green or oolong) after the whole first process is done, after they are completely oxided/stopped/dried/fermented. The operation to stop the oxidation is called anything but roasting (pan-firing, steaming, heating, cooking....). My understanding is the packages allude to that second-process roasting.

Not all oolongs are roasted. You can roast your tea yourself at home (it's a good way to recycle greens that are getting a bit old) to see the effect.

No, in my experience, they appear very dark brown/orange in the water, they get closer to coffee. In taste too.

About the health point of view. I don't have the reference here, but roasting tea make it lose some exciting substances like cafeine/theine, so roasted teas can be better for children or to drink in the evening if you fear to have problems to sleep. They also have properties for Chinese medicine, and are given to people that are sick and recovering. But they lose vitamins or I don't remember what.

Kuri

Kuri,

Problems with English put us all on an equal footing. Many words are used in a very sloppy way. Two of my favorites among these words are "fermentation" and "roasting." We use the word fermentation when it would be more accurate to say "oxidation." We use the words "roast," "fire," and "fry" to mean the same thing. These are undoubtedly translations from a single Chinese word. I've heard the words "uncooked," "raw," "green," and "unoxidized" to refer to one type of Pu-erh, each word meaning the same. So, the question of language is a problem for us all.

Recently I bought a hand held, hemispheric, handled, unglazed ceramic "roaster" which I use to roast a half ounce of tea at a time by holding the roaster over a flame and turning constantly. I've been enjoying this since there are indeed changes that occur with my additional roast.

More interspersed comments and questions below

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Wouldn't nearly all Oolongs be at least a bit roasted as part of the complex Oolong production process? Unless "roasting" refers to that final roast.

I've noticed that in TGY's; however, what about Dan Congs from Phoenix Mountain and Yan teas from Wuyi Mountain? These appear quite dark in the leaf, but turn greener in the water to varying degrees. I was thinking of these two when I made my statement.

Are you quite sure the roast lowers the caffeine (teine) level? That would be good news for people, like me, who are supposed to cut down.

Thanks, Kuri.

Michael

For fermentation the mistake comes from a former misundertsanding of the phenomemon.

I have one too, and I'm looking for a second one (the handle is too short, I need to wear gloves to use it and well it's unpleasant in this season).

I mean the final one. Let's say post-roast.

Well, certainly the way to "heat" them during the process causes that effect (the length of heating also produces different color effects in Japanese senchas).

Yes, for the Japanese roasted or post-roasted Bancha (older leaves picked later) and post-roasted Sencha. Less cafeine and less tanin. They are considered OK for children. They are darked roasted. I've drunk them in the evening for years. Maybe it's psychological but they don't prevent me from sleeping.

No about post-roasted oolongs and other teas, no information. But why wouldn't that not produce the same effect ?

Kuri

...

Well, I'm not a chemist, but - oh, wait a minute, I am one after all! Caffeine has a listed sublimation point of 178 C. That's not a precise number like a boiling point; it's where a heated sample of the pure compound starts to evaporate (without melting) very quickly. As folks in northern climes know, snow disappears even at -20 C, so the real question is one of vapor pressure at more moderate temperatures. Another point to recognize is that a substantially dry material like tea can be heated to way over 100 C; it's probably reaching at least 250 C in the roaster. Hence the destruction of delicate, health-giving organics - and the creation of new flavors. So given free air exchange, the tea might be almost completely decaffeinated in a minute or so.

I've thought of roasting tea at home, especially as I've got half a pound of stale gunpowder green that wasn't very good in the first place. Anyone other equipment/procedure recommendations? I was going to use either a toaster-oven or a heavy frying pan, as some use for home-roasting green coffee beans.

-DM

.....

That was not that hot I think. I have measured and....sorry I don't remember, . Well, I'll do it again.

I have recipe that says 40 minutes to 1 hour at 100 degree C in a oven. Maybe the length has the same effect as the higher temp. I didn't try. I guess the taste is different than with a shorter skillet roast.

A light one is better. I also roast green coffee, and the problem is the same : you need to agitate the thing you roast to avoid scorching, with coffee that can be done in a wok or a pan if you stir very quickly. But I don't imagine stirring the tea leaves without crashing them. Agitating a little pop-corn skillet (with a net-cover) is easier. There are people that use a net basket and agitate it over the fire.

Maybe about 40 g is a good quantity.

Kuri

FWIW, it's not easy to get an accurate temperature measurement with this kind of arrangement, unless one uses a low-mass sensor or an off-contact infrared emissivity thermometer.

By coincidence, I did part of my doctoral work on flash vacuum pyrolysis. I was making delicate, unstable molecules that would be destroyed in a few seconds of warming in solution. But with contact times of around a millisecond, "cooking" at over 1000 C gave excellent yields.

Some reactions increase in rate exponentially with temperature, while others increase more gradually or even slow down. Some reactions won't occur at all below a threshold temperature. So just as with brewing parameters, roasting at different time/temperature combinations to the same overall degree will doubtless change the balance of flavors and aromas. I'll try the slow-roast next. I had no problems with sticking, burning or breaking, but of course gunpowder tea is already in neat pellets. A bold-leaf tea might be a little more challenging, and better suited for the toaster-oven.

-DM

Michael & Kuri:

Sorry I mixed up your question, can you please tell me- what kind of clarification you guyes are talking about? Thanks.

Ripon Vienna,VA

Fun! At last, something to do with my stale greens to (hopefully) make them usable, instead of throwing them out.

I remember home-roasting green coffee beans back in the day. Nothing better (within the coffee world, that is).

Joe

Ripon,

I think I had the question: Could you tell us more about the difference between traditional method and ancient China method? Also, what are the names of the teas using the ancient China method and where can they be purchased?

Sorry if I've mixed up the thread.

Winston