Still the chemistry of oxidation doesn't add or subtract. I understand oxidation can change the taste but you don't end up with more caffeine or polyphenols. I still assert it is more varietal than oxidation that determines the taste of tea. What we call tannins are concentrations of polyphenols and catechins which are easier leached after oxidation. I've give your assertion there is some bonding from enzymes but nothing that adds up to much. You saturate a cup of green tea long enough it'll taste just like any black made from the same leaf. Your taste buds can detect changes that essentially aren't measureable in a laboratory. That's all you're doing with oxidation or any form of cooking.
There's a red/black tea made from the same Zhenghe varietal normally used for white tea. It's delicious, but radically different in taste from the white.
You are equating "polyphenols" with "catechin"; there are others in tea, and in oolong/black tea, they are mostly formed by oxidizing catechins.
Rolling/tossing allows the polyphenol oxidase and the catechins to mix; the catechins are oxidized and combine to form thearubigins and theaflavins until the enzyme is stopped by steaming/firing. The catechin oxidation can happen in your cup, too, when you (accidentally ) leave a cup of green tea sitting till it turns dark. That isn't extra catechins leaching out till they look dark; it's the catechins' turning into different polyphenols with different chemical and optical properties.
Nigel's talked about this before:
And there's a blurb with reference on the LPI's tea page:
Shou mei and bai mu dan white teas are pretty bold, so it's hard to use 3g per cup. Add to that leaf size, varietal differences, terroir, infusion time, water temperature.... While it's plausible that a serving of (suitably prepared) white tea could have less caffeine than a serving of a (suitably prepared) black tea, it's pretty meaningless unless what is being said is tied down a lot better.
E.g., for the pot of New Vithanakande (Ceylon black) I made yesterday, i used 3.8g tea for 48oz water (with a long infusion; very pleasant). Let's say it has 2.8% caffeine by mass (Holy Mountain's old number for Kenilworth OP) and assume all of it extracts. The whole pot had just
106mg of caffeine. So each 8 oz of that had 18mg caffeine, comparable to what is claimed for white tea (by Stash, say). :-P
Analyzing the brew chemically you probably couldn't tell one from the other ie both will fall into a standard deviation. The chemical analysis of a cooked(oxidation) versus raw vegetable would be the same. When I speak of tastebuds it is not a specious argument. They're more sensitive than almost any laboratory equipment. Your taste buds can taste anything a dog can smell and things a dog can't smell. I knew watching the Food Network isn't a waste of time. The difference in taste is minutia and not quantitative. Oxidation simply breaks down the cells for easier leaching of the nutrients which is what you taste as the difference.
The chemical analysis of any leaf green, oolong, black is still the cultivar. Oxidation won't change any measureable chemical footprint. Statements like green tea contains the highest amount of catechins and EGCG, black tea contains the highest amount of theaflavin, oolong tea highest amount of polyphenol from oxidation is misleading. Any leaf will possess all three and all you can say is the proportions of any given cultivar and not the processing type. And the only way you would know any difference at all is applied differential chemisty using only given test samples. If you found a drop of tea at a crime scene you probably couldn't tell what it was because the water signature itself would interfere with the analysis. I don't know of any study that relates chemical analysis to tea taste. The only one mentioned is the taste of tannins or what we call astringency which is simply a function of brewing time, leaf grade and type. Leaf grade and leaching of nutrients is more reflective of tea taste than any chemcial change through oxidation which at best is statistically insignificant in the laboratory but not the tastebuds. I argue oxidation does change the taste of tea but nothing we can account for chemically except the taste of tannins which is typical of any vegetable when it is overcooked. You can't make a decent cup of tea using chemistry.
No, both the cultivar and the processing influence what ends up in the cup.
There is a scholarly literature on this, actually. I don't pretend to mastery of this field, but there is published scientific work on the chemistry of tea components influencing perceived taste and aroma.
I've drunk a lot of Yunnan white tea in the last several months. The tea has been from two different vendors, and both teas are bud-only. I've had beautiful results from both teas treating them more or less like oolongs, with temperatures higher than I'd use on greens, getting many steeps of gradually increasing length. These teas are mild, in that they're neither bitter nor astringent, but they're also rich, with a soft mouth feel and a sweetness that persists for as many six steeps or more, sometimes reminding me of caramel or butterscotch.
Maybe the white-tea-panacea fad is distorting prices. Maybe, if you develop a taste for white tea, you should try to get it from China.
It took me twenty years to finish my first box of 100g SowMee. I was so impressed I recently bought another. Boy have the prices changed from $2 to $6 Just a couple of months ago I also bought my first BaiMudan and spent some time comparing the two tastes. I couldn't tell the difference to justify the much more expensive price of the latter but developed an appreciation of the SowMee perse. I agree it has a pleasant aftertaste but I describe it as scotch or bottom of barrel like a bock. I can load up my pot with about 25% leaf and drink it all day with refills. The last few pots become slushy and clog any filters. Since my filters have been retrofited near the lid of my teapress I just rinse with tap water before pouring. I don't drink Yinzhen regularly but I keep it on hand to impress friends or myself when I get tired of all the hoopla about the pu. I can't think of a more honest tea in the sense the taste is more primal because processing hasn't changed it very much. If I'm a monk this is my tea because the taste is complexly simple. I brew a pot of white tea and a pot of the pu and imagine all the teas in between and realized Darwin could have stayed at home and came to the same conclusions. I think my late appreciation for white tea are like some others that have escaped my attention over the decades because I thought it was an intellectual exercise in acquiring knowledge. Drinking tea is discovery of yourself given enough time and I'm just starting to get the hang of it till another revelation that I've been blowing smoke up my own ... and have to change course again.
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