I work with tea both professionally[0] and semi-professionally[1] and will clarify that:
- this is for commercial tea, not specialty or "ceremony" grade tea
- all of the big commodity houses, blending houses, brand buyers, etc have their own modifications on the standard, and this ISO tea prep standard is most definitely not the "standard"
- From elsewhere in the thread: all great tea can be brewed with boiling water. The idea that green tea (or any other type of whole leaf tea) should be brewed with something under ~100C is a technique used by merchants to sell you bad tea.
> From elsewhere in the thread: all great tea can be brewed with boiling water. The idea that green tea (or any other type of whole leaf tea) should be brewed with something under ~100C is a technique used by merchants to sell you bad tea.
Is this "can be brewed" as in you will end up with a beverage that is drinkable, or that you think that in general green tea is fine to be brewed at 100C. The former I can understand (especially with cheap bagged green tea) but I'd be very surprised at the later considering that goes against pretty all modern and traditional guidance I've heard or read.
Tl;dr: yes, use boiling water on very high end Chinese green tea for best results.
Longer Explanation:
In the Chinese tea tradition, water temperature is referred to by the size of bubbles during boiling (crab eyes = small bubbles (cooler) vs fish eyes = large bubbles (hotter)).
In theory, all water at boil is 100°c, but in practice, there is often a temperature gradient within a kettle and only the gas (the bubbles) is at exactly 100°c (assuming you're at sea level), which is why even some culinary recipes will call for a "rolling boil".
In any case, the strength of the stream when pouring will have a greater effect on the resulting flavor profile of very good green tea than the variation in bubble size, as bubble size is a variance of ~2°c while water can lose up to 5°c in a high slow pour.
Thus, boiling water at crab eyes with a thin slow (but not high) pour is the method used for high end Chinese green tea amongst high level Chinese tea practitioners.
Okay, I'm familiar with measuring temperature by the eyes and I get your point (which essentially seems to be the same as traditional guidance i.e. don't steep the tea in boiling water. You're just accounting for the variance in temperature from boiling and pouring) but I'm not sure I follow how this means merchants are trying to sell you bad tea.
Plus there doesn't account for other green teas that aren't poured in accordance with Chinese tea ceremony, such as the Nepalese green I had earlier today.
Yes, the general idea is to adjust your boil and pour method for the type of tea you're brewing, but that is true for all tea. Water will lose the same heat under the same conditions whether you're brewing oolong or green tea.
To summarize the points addressed here:
- High-end Chinese green tea can be brewed with "boiling water" just as oolong or black tea can; the adjustments are within the range used for other classes of tea.
- Merchants recommending cooler water for green tea do so to reduce the astringency and/or grassy flavor found in lower quality tea.
- Nepal does not have a historical tea tradition and the cultivation of Nepalese green tea is a modern development. Nepal inherited its tea habits from India whom had it imposed on them by the British who stole the seeds from China. While Nepal produces good tea on par with Darjeeling, it does not compare to the highest end Chinese green teas, which are an order of magnitude more expensive, if not more.
They are not! Sencha should be brewed with off-boiling water, anywhere from 85 - 95°c (which is still a higher temperature than low end sencha).
What accounts for this difference?
High-end sencha is steam processed at a lower temperature. Steam only gets to ~100°c depending on altitude and that is the highest temperature it is exposed to throughout its production.
High-end Chinese green tea is partially processed in a wok to denature the oxidizing enzymes. The saying for Chinese tea is that "tea remembers the heat of the wok", which is the pan frying process at upwards of ~200°c.
So all wok processed green tea can be brewed with hotter water than steam processed green tea.
I was under the impression that this document exists to have -a- standard such that if followed before performing some sort of experiment whether directly tea related or not, you could more easily exclude preparation differences as a confounder when comparing results with people who'd also followed the document.
Certainly this is how the old coworker who had a paper copy pinned up behind their desk explained it to me, and that understanding was why they found its existence so amusing even if their preferred cuppa's preparation process was substantially different.
This could of course be entirely wrong but seeing the paper copy pinned to the wall always did make me smile.
This is not used for tea sourcing. The document explicitly states its purpose as being for the preparation of tea for sensory tests. It has nothing to do with brewing tea for enjoyment.
Sensory testing (which is what is what I and my company specialize in) is a large component of tea sourcing and absolutely part of the process.
To illustrate this:
Just as coffee has "cupping", a method of preparation used for sourcing and evaluation but which no consumer would ever use to prepare coffee for enjoyment....
Commodity tea has this ISO standard (also called cupping).
The reason that this method, over a method that results in a better tasting cup is used, is because commodity tea is selected via flaw minimization and consistency testing.
I'm unsure why you presented the entire point of the conversation as if it was a gotcha, but assuming it was a genuine mistake I can only suggest that you read my comment again.
I made the other comment about not using boiling water. I've also run a tea shop and have imported very high quality tea. I've tried green and white teas with boiling water and they definitely did not taste as good as with 70-80 C water. At boiling temperatures they taste somewhat burnt and astringent.
I'm a math and tea geek and since it's so very rare when the two worlds overlap I'll take the opportunity to mention it here. The British argument of tea-or-milk-first helped lead to a formalization of random experimentation and the null hypothesis: https://en.wikipedia.org/wiki/Lady_tasting_tea
The method consists in extracting of soluble substances in dried tea leaf, containing in a porcelain or earthenware pot, by means of freshly boiling water, pouring of the liquor into a white porcelain or earthenware bowl, examination of the organoleptic properties of the infused leaf, and of the liquor with or without milk or both.
The student came to the Zen master and ask 'Would you like your tea with or without milk?' to which the Zen master replied 'I will take my tea with milk, without milk, and both.'
That would make a bitter cup of green tea. Green tea infuses best at 80 degrees and the time is dependent on the tea.
Green tea taste follows a bell shaped curve, there is a small window of about 10 seconds when the brew is best, you got to stop it precisely at the top. You can use a thermometer and a watch, but the easiest is to just take a sip of the brew every 30 seconds.
Black teas, oolong and puerh can handle 100 degree water and are not as fussy about timing.
I've read in one of previous threads about it that it's for the purpose of comparing different teas accurately. It's not supposed to result in the best possible tea. Instead it's supposed to make the tea's aroma and taste as clear as possible and it's supposed to be used uniformly across different varieties of tea, so that they can be compared accurately without much error margin introduced by the preparation itself. This may be entirely wrong though. After all, it's just something someone wrote on the Internet...
It's just odd that one would not make green tea at anywhere near the right temperature. Green tea is simply not comparable with black; they are fundamentally different. It is as if there were an ISO standard on the quality of fruits and they are "compared" by assessing color (deviation from yellow is a fault, increasing by reflected wavelength difference).
It's not about comparing quality, it's about comparing consistency. Brands want their blends to be consistent from year to year. So every year they might create hundreds or thousands of different combinations of the specific teas they've acquired, until they find one that tastes as similar as possible to the blend they had last year.
Also, green tea is just fine at boiling, if it isn't of poor quality :)
It means something, which in this case means "taste is individual". I prefer to take the advice of my green tea supplier, who tells me to use 75°C water for brewing my tea. Using other advice is up to the user. Not my monkeys, not my circus.
It was part of the quality control at the tea blending / packaging factory. It ensures repeatable consistency. It's not supposed to be the best taste, or follow some tradition or style.
It is the tea equivalent of checking the strength of cement, or measuring the brightness of a light bulb.
For most kinds of tea, boiling is fine or even preferred if the tea is of good quality. I would never steep any of the white teas I own below 90°C, and most days I prefer boiling. Likewise with green (and yellow) tea, unless Japanese. Oolongs and blacks I always steep at boiling.
If you've had high quality loose leaf tea, you'll know that that's not true. It's like saying you need to grind coffee very finely to extract all the flavor when in reality, different grind levels are for different types of procedures like espresso, filter, pour over etc. If you try to use super fine coffee grounds for a pour over, you're gonna have a bad time.
I don't know a whole lot about coffee, but I stand by that good tea can be brewed well using boiling hot water. I run a direct to consumer tea business and much of my family is involved in the farming and production of tea, specifically Wuyi oolongs. Very rarely do I intentionally reduce the temperature more than a few degrees - and that is usually by boiling the water and then waiting a minute before starting.
It's different for Wuyi oolongs, they're much closer to black tea so they can withstand boiling water. If I did the same for a green dragonwell or white silver needle, it tastes terrible. I also ran a direct to consumer tea business so I've also tasted quite a lot of teas as I'm sure you have as well.
Around 70-80 C, you'll have to play around with it as it's a little different for each tisane.
Fun fact, tea is technically only the leaves of the camellia sinensis plant, all the permutations of black, green, white etc teas are how the leaves are processed by humans after cultivation, they're not different species of the plant. Any "teas" that are not of the camellia sinensis plant are technically called tisanes, although in colloquial usage no one says tisane.
As an example, I use a glass teapot with 1 liter of water.
I preheat the water 4 minutes (@ 1000 W), I add the tea bags, then I heat again for 2 minutes 10 seconds.
Obviously the precise times will be different for other microwave ovens and teapots, but the point is that with a microwave oven you can experiment with fine adjustments of the time until you get what you deem to be the best taste.
Once optimal times are found, the process will be perfectly reproducible, so you will obtain the best taste every time.
I have transitioned a couple of years ago from making the tea on a traditional gas stove to using the microwave oven and the result was much better tea tastes that are always the same.
Controlling the time in this case controls the temperature, but it is more convenient than attempting to control directly the temperature when using other cooking devices.
Smart, reproducible technique! I do hope you are being careful with that: heating liquids past their boiling point can potentially create a superheated state. Very clean containers in a microwave are said to be especially good at causing this.
If the starting temperature is 20C then to get to boiling you need to add 80 kelvin * 1000 gram * 4.2 joule/gram = 336 kJ to get to 100C. At 1000 W that takes 336 seconds, or 5 minutes 36 seconds. In practice my 850 W microwave takes nine minutes to raise a litre of milk to 85C from fridge temperature so I don't think there is too much risk of boiling.
I'm not (just) being facetious - I don't think it can be well answered, because you're obviously thinking of something specific, and someone's going to answer with their own probably different specific 'herbal' tea in mind.
I don't know about the biological definition of "herbal" but in practice herbal is used as a catch-all for tisanes, teas that are made without the Camellia sinensis (tea) plant. It's not a hard rule, e.g. rooibos teas are generally listed separately from herbals.
In any case, there are a lot of different herbals and the perfect water temperature might be different for all of them. When I drink herbals (rarely) I just use boiling water.
Fun! Another hidden trap when English is not your native tongue, I guess. Today I learnt that "herbal" does NOT mean "with herbs", but instead means "with PLANTS". All of them! Thanks, English.
In Swedish, the word for non-tea tea is "örtte", where "ört" means "herb". Very confusing.
It depends.
In America at least people generally mean Herbal tea to mean any beverage steeped with plants that is not made with the actual tea plant. They also may or may not be including Yerba Mate in this, which is a South American beverage made with a different plant, but still caffeinated.
In other cooking context Herbs pretty much mean fresh (not dried) plants that are used to add an aromatic flavor, such as Basil or Rosemary. A chef would not refer to a carrot as an herb.
- this is for commercial tea, not specialty or "ceremony" grade tea
- all of the big commodity houses, blending houses, brand buyers, etc have their own modifications on the standard, and this ISO tea prep standard is most definitely not the "standard"
- From elsewhere in the thread: all great tea can be brewed with boiling water. The idea that green tea (or any other type of whole leaf tea) should be brewed with something under ~100C is a technique used by merchants to sell you bad tea.
[0] www.gastrograph.com
[1] teatechnique.org/