RFDT needs FRF ( frequently repeated fallacies)

You offering a prize?

/Lew

By no means. When I used to cook roast beef, I used the warm oven/all day method, and got consistently superb results. At the same time, many chemical changes have quite sharp transitions. It makes sense to cook meat to a specified internal temperature because a very long time at just a few degrees less can give the same effective protein denaturation, etc. of seconds at the target value. And some changes just don't occur at all in finite time below a particular temperature - anything involving a phase transition, certain protein foldings, etc. A relevant example is the clarity and non-astringency of refrigerator-brewed iced tea, where quite a few essential oils and other sensory components have nil cold-water solubility and never appear in the mix. So many chemical effects have an exponential rate or equilibrium factor that for practical purposes, even absent a thermodynamic phase transition, there appear to be very sharp thresholds. (Freshman chemthermo students make jokes about things like warming firecrackers in the sun all day, vs. a millisecond with a match.)

I certainly believe that high temperatures often work well. I find that some sheng Pu-erhs and dan cong-type oolongs require hot-and-fast to avoid more astringency than I prefer. But the cooked-vegetable effect (which I only find with un-aged, greenish teas) is, to my taste (and modest relevant knowledge of culinary chemistry) in a different category.

BTW, I consider 140F to be tepid, but that's another personal imprecision.

-DM

To your knowledge, does tea's astringency come from a small set of compounds with known minimum solubility temperatures? I've noticed that the lack of astringency of some green teas brewed at room temperature gives them a creamy texture.

/Lew

Sorry, no prize. Coincidentally, I drank tea with several friends today, and one brought along a Taiwan Oolong, quite green and of high quality, much like the "Day Lily" varietal, whose Chinese name I don't quite recall. The hot and fast method was applied. The tea was delicious: Floral, but with a beautifully balanced bitterness and, aside from that, a pleasing astringency. Balance is the key word here. It was not the best of type I'd ever drunk, being a bit thin, but perfectly delightful nonetheless. There was no hint of vegetal -- read ruined -- flavor to it. While a lower temperature would bring out more floral and less bitter I suspect, I believe you are quite right in your earlier suggestion that no one method can do justice to the entire spectrum of what these teas are capable of. Michael

Jin Xuan.

/Lew

I couldn't get the Biluochun right until I use a small amount. With a small amount, any temperature will do it, even close to boiling point, yielding a sweet, satisfactorily favour. I can imagine the surface drop technique will do nicely for this tea.

Now I have finished the AAA I am moving off to the Jipin grade ... hehehe :)

Julian

Latter: ditto. Former: I defer to someone like Nigel who knows vastly more about tea chemistry than I ever will.

-Alaric

Hello to all who have posted on the temperature of the brewing water for green tea. To my mind, a look at the manufacturing process of green tea may lead to a better understanding on the subject under discussion. The texture of the tea flush after steaming (Japanese Method Of Green tea Manufacture)or after Panning ( chinese method of Green tea manufacture )becomes soft, which is not the case , in the case of black tea manufacture. Further, the flush leaf temperature never reaches the boiling point of water- during the process of steaming or panning. And during the final drying of the green tea, the leaf temperatures are less than boilng point of water. So an interesting query emerges- in hot brewing. is there any relation between the optimum brewing water temperature and the processing temperature achieved by the green tea during its manufacturing process.Thanks in advance to fellow members who will be responding to this query.

I suspect processing temperature is just a long list of factors that influences optimum brewing temperature.

White tea is one example - low processing temperature, higher brewing temperature.

I list below a list of factors affecting brewing, of which water temperature is just one parameter.

Please feel free to add or modify:

type of leaves:

- degree of oxidation

- degree of delicateness

- shape of leaves (degree of rolling)

- quality of tea (higher quality can tolerate larger temp range)

- how broken the leaves are (broken leaves turn bitter more easily)

water to leaf ratio

- higher ratio gives larger tolerance

- higher quality tea gives larger tolerance

brewing vessel

- how much heat is retained

- the shape, which influences heat retention and leaf expansion (for gunpoweder, tieguanyin tea)

brewing technique

- length of time steeping

- ambient temperature

- is the brewing vessel heated beforehand (cold vessel said to reduce water temp by 5 degrees)

- water first or leaves first

- how quicly and slowly water is poured into the cup

- is water pour directly onto the leaves or along the side

- how much movements are created during the pouring process

- how subsequent infusion differs from the first one

water quality (not quite sure the impact but include for completeness)

- type of water (tap, bottled, rain etc)

- water hardness

- addition of other stuff (salt, charcoal etc)

Given the variability, perhaps it is more productive to discuss what "standard" brewing parameters are first.

Julian

This is of course why professional tea tasters throughout the world use a common brewing method and common tasting crockery (as specified in ISO 3103-1980) and a common language of tasting terms (as specified in ISO 6078-1982). This standardization allows them to evaluate teas (black tea at least) on a uniform basis from place to place wirth the minimum of disagreement engendered by variation in preparation technique. Note there are another 25 or so ISO standards that relate to tea quality as internationally traded.

Nigel at Teacraft

I am new to this site but you might like to look at the following site

The tea has been confirmed by a few tea tasters in India as having flavour but not bitterness. I tried to try it at the Canton Fair but the English for boiling water seemed to be translated as boiling water now poured into a porcelain tea pot.

If anybody wants to correspond I am at snipped-for-privacy@iinet.net.au

cheers

Ian

snipped-for-privacy@gmail.com schreef:

What an interesting insight. Although I've enjoyed single-barrel whisky diluted with water from the Aberfeldy burn used in the wort, eaten fried clams and Reuben sandwiches in the restaurant where each was invented, tasted Cassis in Cassis and so forth, I generally don't believe in sympathetic magic. Certainly not stuff about how the shape of a teapot has somehow to mirror the shape of the dried leaf, and so forth.

Having said that, SMC's point makes perfect sense to me, and is helpful. While dry and wet heat don't have quite the same effects, kill-green is (I believe) mostly happening at a pretty high water content. So it stands to reason that drowning the leaf in brewing water hotter than the tea has experienced in processing is likely to cook, volatilize or otherwise do violence to delicate and volatile flavor and aroma components. Yet another reason to start brewing with water far off the boil. It would be very interesting to do the experiment described above

- anyone have access to peak kill-green or final roasting temperatures of some available teas?

-DM