[HN Gopher] Oxidation makes tea black
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Oxidation makes tea black
Author : cmogni1
Score : 82 points
Date : 2022-03-15 15:52 UTC (7 hours ago)
(HTM) web link (www.sophiescuppatea.com)
(TXT) w3m dump (www.sophiescuppatea.com)
| hbarka wrote:
| The other dark tea, the fermented tea they mention in this
| article aka _hei cha_ or commonly referred to as pu'er, scares me
| because there are bad quality versions of it containing mold due
| to their fermentation process. Hard to detect since it's also a
| kind of black tea.
| feanaro wrote:
| It's not a black tea, at least in the western sense. Our black
| tea is actually called _hong cha_ in Chinese, which means red
| tea. They 're simply different types of tea.
|
| There are also two different style pf pu'ers which have little
| to do with each other. The style you're talking about is _shu
| pu 'er_, which is deliberately piled and made wet in order to
| trigger a sped up fermentation process. This is opposed to
| _sheng pu 'er_, which is processed into bricks from very young,
| raw leaves called maocha, and is then aged for a number of
| years before it is drank. This results in a much slower and
| subtler fermentation process. The taste of shu and sheng are
| quite different.
|
| I've never personally had an encounter with a bad batch of
| either shu or sheng pu'er, but the shu variant is more prone to
| this due to the process.
|
| It's notable that pu'er is steeped at a (close to) 100 degrees
| celsius and the first one or two short steepings are discarded.
| This is to kill and wash off any microorganisms or dirt that
| may be present.
| hbarka wrote:
| Thank you, that's informative.
| chasil wrote:
| I had always understood that white tea had minimal processing, so
| I don't understand this assertion:
|
| "Without oxidation, tea would taste unbearably bitter."
|
| Perhaps white tea has not reached an adult phase with the
| associated bitterness.
|
| Contast to:
|
| "White tea may refer to... minimally processed leaves of the
| Camellia sinensis plant."
|
| https://en.wikipedia.org/wiki/White_tea
| cmogni1 wrote:
| White tea is oxidized naturally for a while. The article is
| referring to freshly picked leaves.
| foo_barrio wrote:
| That would be green tea no? You pick the green tea, cook it
| to denature the enzymes to arrest the oxidization (called the
| "killgreen" step in Chinese) and voila, green tea! Lots of
| green teas can be quite smooth and even more so with more
| careful brewing.
| yvdriess wrote:
| Yes, green tea needs lower temperature and controlled
| infusion time, but rewards that. The author definitely does
| not seem to be a fan and is not doing it justice.
| cmogni1 wrote:
| Yeah! Green tea gets fried or steamed right away to halt
| oxidation. That kills off some of the undesirable
| bitterness that masks some flavors that are even present in
| fresh leaves. It is not that Green doesn't have any taste;
| it is that there are more guardrails over what flavors can
| appear and how distinct they can be.
| hinkley wrote:
| The Brit I mentioned elsewhere seemed to think it was the
| drying that arrested the chemical processes in the tea.
|
| He was also adamant about storing it in well sealed
| containers out of direct sunlight. I ended up throwing away
| a couple of containers because of this (although I've kept
| a couple that are just too beautiful to part with - I store
| my daily drinker in there since it doesn't need to keep as
| long). Also explains why my dealer uses mylar vacuum packs
| for anything over an ounce. No oxygen, no light.
| foo_barrio wrote:
| White tea does not undergo the "killgreen" step that
| green teas and oolongs teas do IIRC. The drying slows the
| oxidation but does not arrest it. "Aged" white tea is a
| thing. If you let it sit around long enough it turns deep
| red. Green tea just turns into stale tea. They even
| compress white teas into something similar to those
| "Pu'er Cakes".
| chasil wrote:
| The odd thing is that the range (and top end) of antioxidants
| in white tea is larger than in green.
|
| "Total catechin content (TCC) for white teas ranged widely
| from 14.40 to 369.60 mg/g of dry plant material for water
| extracts and 47.16 to 163.94 mg/g for methanol extracts. TCC
| for green teas also ranged more than 10-fold, from 21.38 to
| 228.20 mg/g of dry plant material for water extracts and
| 32.23 to 141.24 mg/g for methanol extracts."
|
| https://pubmed.ncbi.nlm.nih.gov/20722909/
| hinkley wrote:
| Is it odd or is it thermal breakdown of chemicals?
| hinkley wrote:
| Traditionally white tea was created from tea buds. If you've
| ever gardened, you know how dicey those first few days are
| because the plants that have defenses against caterpillars and
| slugs are vulnerable until the leaves are fully formed.
| Caffeine is a pesticide, and the young shoots don't contain
| much of it. Last I remembered looking, white tea has about the
| same caffeine as decaffeinated coffee (which I use both as a
| sales pitch for getting people to try white tea and a warning
| against people complaining about having trouble sleeping -
| there's still caffeine in your decaf, buddy).
|
| Since you pick the leaves before they are grown, you're pruning
| the tree and potentially reducing your crop. Which is why it
| was a drink of the nobility. Basically you're so rich you can
| afford to reduce your crop by (conjecture) 10% for a taste
| sensation, or pay someone else for the privilege.
|
| I suspect we have so much of it now because 1) Republic of Tea
| basically went through every tea fad in the history of tea in a
| 15 year period, presumably to keep sales numbers up with
| novelty, and 2) it's likely that there is oversupply in the tea
| market, so white tea gives you another shot at a sale.
|
| Unlike coffee, which gets one harvest per year (although some
| people are trying to bring coffee leaf tea into the group
| consciousness), it's typical to get at least 2 harvests of tea
| per year, 3 or more in a great year. Which I discovered when I
| noticed my dealer putting numbers and/or seasons on her tea. If
| they are regrowing that fast then white tea might not be that
| big of a burden.
| [deleted]
| amelius wrote:
| Tangential. Has anyone tried Tulsi tea? I recently did and got a
| bad experience from it. I think it has some psychoactive
| substance in it.
| throwaway1777 wrote:
| Tulsi, aka holy basil, has a lot of effects, but not really
| psychoactive ones. It's generally thought to have a wide range
| of beneficial properties on stress, the immune system, etc but
| it does disagree with some people too.
| amelius wrote:
| Maybe I should try a less strong cup.
| mbg721 wrote:
| It's basically basil-like in flavor, right?
| hinkley wrote:
| I stumbled into a presentation on tea at a tea festival a number
| of years ago. I keep meaning to figure out which notebook my
| notes are in and make copies because it was so good. The
| presenter was this elderly British gent with a background in
| operations who got sent out to figure out how to boost tea
| output.
|
| There were a bunch of charts about time and temperature and
| humidity for various types of tea but the biggest fact was
| slightly buried. 'fermentation' with respect to tea is a bit of a
| euphemism. It's actually autolysis. The big epiphany moment for
| me was connecting the dots and seeing why that was the case.
| Caffeine is an insecticide. It's stored in little crystals in the
| tissue. With oxalic acid, the crystals are the point. They're
| sharp and they damage the attacker.
|
| With caffeine it's metabolic disruption. Within other organelles
| in the tea leaf are enzymes that can decompose the caffeine
| crystals into a solluble form. These chemicals only mix when the
| leaf is bruised, or masticated. They are booby trapped.
|
| When you process _camellia sinensis_ into tea, the oldest process
| is matcha, which started in China and is now mostly preserved in
| Japan, is drying the leaves and then powdering them, which I
| presume frees up some of the caffeine simply by mechanical
| decomposition. For the others the leaves are processed by
| bruising, heating and drying the leaves, and the order and
| duration dictates which kind of tea you get, and how much of the
| caffeine has been converted to a form that is water soluble.
| Black tea is aged longer, and has more available caffeine.
|
| Almost none of them are actually fermented as in beer (puehr is
| the most notable, and the common reaction upon smelling it is,
| "This reminds me of my grandmother's garden." It is an acquired
| taste.) Edit: and kombucha, which is fermented after being
| steeped, rather than before. Also by many accounts an acquired
| taste.
| almog wrote:
| That's a very good description of the enzymatic process in tea.
|
| Regarding "oldest process" though, I'm not sure which is the
| earliest processing method for tea but compressed tea / tea
| bricks as Pu-erh (although compressed tea [?] Pu-erh) is
| attributed to Tang dynasty (AD 618-907) and it precedes Matcha
| which is attributed to the Song dynasty period (960-1279).
| WillPostForFood wrote:
| The way they drank tea in the Han dynasty is interesting;
| centuries before before a real processing method came about.
|
| _Guo Pu noted in the book Er Ya (Chinese: Er Ya ), the
| earliest Chinese dictionary, tea can be boiled to consume
| like thick soup. More precisely, to make a cup of tea at that
| time you need to mix millet and other condiments with tea
| leaves first them boil them together till mushy state_
|
| https://www.teavivre.com/info/ways-of-drinking-tea-in-
| ancien...
| hinkley wrote:
| The problem with summarizing complex things for people is
| that you leave out the bits that you don't think will stick,
| and even what is left over becomes a game of telephone.
|
| At the time, puehr was about to have a little resurgence but
| was pretty obscure in the west. I'm not sure which of us
| redacted that from the brief timeline.
|
| I like a little puehr once in a while. It tastes like leaf
| mould smells, which is probably not far off from reality.
|
| Edit: some imported tea is still delivered in compressed
| bricks, green, black and oolong. Among those are teas that
| are treated like scotch. and I have seen but not tasted a 25
| year old tea brick (which I think she kept in part for
| bragging rights. IIRC it was not for sale.) I already have a
| Scotch habit, I don't need to be buying 18 year old tea on
| top of it, so as curious as I was I made no attempts to get
| involved in any private tea tastings.
| almog wrote:
| Agreed. AFAIK it was created as a method to transport tea
| efficiently all across the Tang empire (and as a mean to
| keep the peace within it) while not crushing the leaves. I
| have no idea about what kind of tea made it to the west
| back then. Even today most western people aren't aware of
| the variety of teas there are out there or how wildly
| different the final product is depending on the processing
| methods, let alone bush cultivar, age, flush stage,
| altitude etc.
|
| Pu-erh really can be weird, Hei-Cha even weirder I think.
| It took my quite a while to like pu-erh and if it wasn't
| for its aesthetics I'm not sure I'd have bothered to try
| that much. For my palate, Shou pu-erh teas were an easier
| taste to acquire. It took me a lot of trial and error to
| get my palate around Shengs but now I like it well enough
| to get the same kind of craving I get for a good coffee.
| SamoyedFurFluff wrote:
| I actually find Sheng more palatable than shou. Shou is
| too smooth for me. I need a tea with fragrance and
| brightness.
| mips_avatar wrote:
| The term black tea is ambiguous because it refers to different
| things depending on where you are/who you are talking to. In
| the west, black tea generally refers to a fully oxidized
| (autolysis) red tea that has not been fermented. However, in
| other parts of the world black tea refers to fermented puerh.
| How the puerh is fermented depends on whether it is wet or dry
| processed (shu vs sheng) but fermentation is an important part
| of both processes.
| LAC-Tech wrote:
| I remember in Taiwan I was confused the tea I called "black"
| they called "red" (Hong Cha )
|
| But then I google that and there are some seriously red
| looking teas out there.
| R0b0t1 wrote:
| You sure on the oxalic acid aspect? I could see it maybe for
| bugs, but I figured the crystals would be too tiny. Oxalic acid
| causes kidney problems in larger organisms because it is hard
| to process. I suppose its crystal formation and poor solubility
| are linked here.
| blacksmith_tb wrote:
| This is a pretty thorough intro to (mostly) Chinese tea, which
| seems fair to me since tea originated in China. Though I can see
| a few details to quibble over (e.g., some Taiwanese oolongs are
| barely oxidized, ~5% for Baozhongs sometimes[1]). Personally as
| much as I like white, green, and black teas, I think oolongs have
| the most variation, since they can have a mix of the
| characteristics of the other types. But I drink plenty of them
| all.
|
| 1: https://teadb.org/baozhong/
| timonoko wrote:
| I was sort of suffering from colored tooths (teeth?) problem.
| Meaning every time I took selfie I suffered about 5 seconds. The
| bloody dentist suggested monthly visits to the bloody dental
| hygienists.
|
| Strange thing happened: I was flying my kite for kite aerial
| photography and a chinese ((or taiwanese) or japanese) tourist
| noted my blackened teeth an told that green tea does not color.
| And it worked ok. Even the cheapest Lidl tea works ok. I bit of
| acquired taste, but you will learn to love it.
| mgkimsal wrote:
| pfft.... what do the Chinese know about tea? ;)
| timonoko wrote:
| Shudup son. There is a very special connection between China
| Tea and Finland: https://www.youtube.com/watch?v=hlMYrblsZp4
|
| I have tasted genuine Silver Needles but was not impressed.
| odiroot wrote:
| > I was flying my kite for kite aerial photography and a
| chinese ((or taiwanese) or japanese) tourist noted my blackened
| teeth an told that green tea does not color. And it worked ok.
|
| I think black (red) tea is very much worth it. I just couldn't
| do without at least a single cup a day. I do brush my teeth
| afterwards though.
| dgarrett wrote:
| I've been told by a dentist specifically not to brush your
| teeth after tea. Instead, swish your mouth with water and
| brush your teeth later.
|
| The claim is that the acidity of the tea will soften your
| teeth and lead to damage from the brushing.
| aradox66 wrote:
| The website is new, but this business also runs one of my
| favorite brick and mortar tea shops! It's in the Oakland hills.
|
| They pile up the steaming leaves from every cup they brew and the
| shop fills with the earthy caramel aroma of good tea.
| dijondreams wrote:
| ditto, one of the best stores i know of
| jeffbee wrote:
| It's going to be even better with the new plaza on Antioch.
| andjd wrote:
| May just be the prices on their website, but they strike me as
| being quite expensive. They also use anglicized names with very
| little information about the tea, so it's hard to know what
| you're buying.
| dijondreams wrote:
| yeah it's definitely expensive but that's mainly because they
| go to China every year to each farm to find the best teas.
| they will go into depth on each and every one if you inquire
| [deleted]
| hammock wrote:
| Most things that are black are oxidized
| lambic wrote:
| Can anyone explain this sentence: "Because tannins weigh more
| than catechins, they do not taste bitter."
| cmogni1 wrote:
| Higher weight polyphenols tend to taste less bitter than lower
| weight ones. Its more correlation than causation because I
| don't think we precisely know why this is.
| hinkley wrote:
| I wonder if they're talking about the blurred lines between
| taste and smell. Most of what we 'taste' is happening in our
| nose.
|
| Turns out the French and Italians with all of their fancy
| wine glasses for different kinds of wine are not insane.
| Glass shape effects the timing of scent versus taste, and so
| lighter wines have a narrower glass to shorten the time. The
| heavier the red the wider the glass.
| prophesi wrote:
| "Contrary to popular belief, Red teas like Darjeeling actually
| have less caffeine than White or Green teas because they are so
| highly processed."
|
| Is this actually true? I've never heard of green tea having more
| caffeine than red tea, besides maybe gunpowder green tea, which
| retains more caffeine due to less breakage from being rolled up.
| Bayart wrote:
| I think lighter teas does have more caffeine per weight, but
| they're have much shorter infusion times (with the exception of
| Pu'er, which can go through15 infusions).
| hinkley wrote:
| I think it's some of both. I emulate my dealer (Taiwanese
| direct importer), who intimated that she skips the strainer
| with her green tea and just puts here whole leaf green tea
| straight into the cup (you can only do this with whole leaf,
| as your lip becomes the strainer and broken tea ends up in
| your teeth). She reuses the same cup all day, topping it off
| when it's half full. When I space and drain it (often in the
| middle of a coding session), it still tastes and acts like
| tea for at least the first three cups, after that it gets
| pretty weak, until I abandon it for a good long while and
| then discover it's gone from weak to bitter.
| radicaldreamer wrote:
| Same thing with coffee, light roasts have more extractable
| caffeine than dark roasts.
| prophesi wrote:
| Ah that would make sense. And water temperature likely plays
| a vital role as well. But for properly brewed green tea, it
| will still result in less caffeine than red tea as expected.
| x3iv130f wrote:
| We really shouldn't be judging caffeine content by color.
|
| Certain tea varietals like Assamica have more caffeine than
| others.
|
| Black teas are seen as high caffeine because they use Assamica
| varietals more than other types of tea.
|
| Processing tea does remove caffeine. However I wouldn't be
| surprised if it also removed some of the neurochemicals that
| modulate caffeines effects.
|
| So your results may vary.
| hinkley wrote:
| I'm not sure it's so much removing as bioavailability. As I
| just stated up thread, black and green tea rely on autolysis
| - enzymes in the leaf decompose insoluble caffeine crystals
| into a water soluble form.
|
| L theanine I think may be some of both. The heating and
| drying processes also help define what kind of tea you get,
| and we know that some vitamins don't survive cooking all that
| well (famously, sailors and scurvy).
| hackernewds wrote:
| Red tea from Darjeeling is in a category called CTC tea, which
| is distinct from what you'd expect from black tea. Easy mixup
| since they look similar, besides the packaging
| prophesi wrote:
| You can have loose leaf Darjeeling red tea as well. CTC is
| typically for bagged tea, which is unfortunately what's most
| popular in the USA/UK.
| gwern wrote:
| A while back I looked at a few chemistry papers on measuring
| caffeine content in a variety of tea leaves, in the hopes of
| finding some low-caffeine green/oolong I could drink late at
| night. The impression I got was that there is so much variation
| batch to batch or year to year (not to mention preparation)
| that it largely swamps any attempt to say 'Darjeeling has less
| caffeine than Gunpowder Green'. There may be average
| differences but it's not too useful to know. Whether Red or
| Green, that tea could still easily be one that will keep you up
| if you drink it at 10PM. Ah well. (And decaffeinated teas are
| uniformly garbage-tasting, so that's no, ahem, solution.)
| WillPostForFood wrote:
| Generalizations like this are always dicey, especially when the
| statements are so imprecise. Is he talking about green tea vs
| black tea leafs, or prepared green vs black tea? When he says
| green tea, what variety?
| andjd wrote:
| My suspicion here is that black tea, especially when prepared
| in the British style, has more caffeine per cup because it's
| brewed to be much stronger than green teas typically are. So
| both can be true, black tea typically has more caffeine per
| cup, but black tea leaves have less caffeine than green tea
| leaves when compared by weight or volume.
| [deleted]
| noufalibrahim wrote:
| An interesting colour change I've noticed it when you squeeze
| lemon into dark (almost black) tea. It lightens up a lot and
| becomes a pale brown. I'm not sure what but there is some
| chemical change going on there.
| skibob1027 wrote:
| "The thearubigins in brewed tea are highly coloured (red-brown)
| molecules that change according to the acidity of the liquid
| used.
|
| If the water used for the tea infusion is relatively alkaline
| (for example, due to limescale found in "hard" water), the
| colour of the tea will be darker and deeper.
|
| However, once an acid such as a slice of lemon or lemon juice
| is added, tea changes colour because of an increase in acidity
| (reduction in pH) of the beverage itself. Lemon juice is quite
| strong as a food acid - a few drops are enough to alter the
| theaurbigins, resulting in a dramatic change in colour.
| Interestingly, theaflavins are not that affected by the change
| in acidity, and still retain their normal dark red colour."
|
| Source: https://theconversation.com/ive-always-wondered-why-
| does-lem...
| Teracotage wrote:
| How about manipulating Oxidation of your tea cup? I add a squeeze
| of lemon and the tea lightens up in color, and it lasts longer
| before it tastes stale. In addition to lemon, I would add either
| cardamom,or cinnamon, or event mint leaves, and the over-
| oxidation that would make my cup of tea go stale will be delayed.
| I am that lazy tea drinker who is OD'ing on tea/j.
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