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Oxidation makes tea black

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Re: Oxidation makes tea black

#51

Post by WillPostForFood »

almog wrote: post #40
hinkley wrote: post #23

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…

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).

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: 尔雅), 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...

Re: Oxidation makes tea black

#52

Post by mips_avatar »

hinkley wrote: post #23

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…

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.

Re: Oxidation makes tea black

#53

Post by foo_barrio »

hinkley wrote: post #34
foo_barrio wrote: post #8

Earlier quoted context omitted.

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.

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 expl…

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".

Re: Oxidation makes tea black

#54

Post by WillPostForFood »

prophesi wrote: post #11

"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.

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?

Re: Oxidation makes tea black

#55

Post by R0b0t1 »

hinkley wrote: post #23

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…

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.

Re: Oxidation makes tea black

#56

Post by gwern »

prophesi wrote: post #11

"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.

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.)

Re: Oxidation makes tea black

#57

Post by SamoyedFurFluff »

almog wrote: post #44
hinkley wrote: post #41

Earlier quoted context omitted.

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 probab…

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…

I actually find Sheng more palatable than shou. Shou is too smooth for me. I need a tea with fragrance and brightness.

Re: Oxidation makes tea black

#58

Post by amelius »

throwaway1777 wrote: post #25
amelius wrote: post #21

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.

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.

Maybe I should try a less strong cup.

Re: Oxidation makes tea black

#59

Post by LAC-Tech »

mips_avatar wrote: post #52
hinkley wrote: post #23

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…

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 impor…

I remember in Taiwan I was confused the tea I called "black" they called "red" (紅茶)

But then I google that and there are some seriously red looking teas out there.

Re: Oxidation makes tea black

#60

Post by dgarrett »

odiroot wrote: post #50
timonoko wrote: post #42

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 cheap…

> 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.

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.

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