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Oxidation makes tea black

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21–30 of 79 posts

Re: Oxidation makes tea black

#22

"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.

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.

Re: Oxidation makes tea black

#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 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.

Re: Oxidation makes tea black

#25
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.

Re: Oxidation makes tea black

#26

"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.

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.

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).

Re: Oxidation makes tea black

#27
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.

Re: Oxidation makes tea black

#28

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.

“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...

Re: Oxidation makes tea black

#29
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.

It's basically basil-like in flavor, right?

Re: Oxidation makes tea black

#30
post #14

"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.

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).

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.
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