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Lumifer comments on Open thread, August 4 - 10, 2014 - Less Wrong Discussion

5 Post author: polymathwannabe 04 August 2014 12:20PM

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Comment author: Lumifer 04 August 2014 03:48:43PM 1 point [-]

it seems that kinds of tea vary too much in caffeine content for classifying by preparation method to be a meaningful indication of caffeine content

Here is some data on tea caffeine content.

Anecdotally, I know a person who drinks a lot of "regular" black tea (Ceylon/Assam), but doesn't drink Darjeeling tea because it gets her jittery and too-much-caffeine-shaky.

Comment author: gwern 04 August 2014 03:51:28PM 3 points [-]

Yeah, that was one of the studies I read on the topic. (The key part is "Caffeine concentrations in white, green, and black teas ranged from 14 to 61 mg per serving (6 or 8 oz) with no observable trend in caffeine concentration due to the variety of tea.", although they bought mostly black teas and not many white/green or any oolongs; but the other studies don't show a clear trend either.)

Comment author: Lumifer 04 August 2014 04:03:00PM 0 points [-]

Did you see any data on natural variability -- that is, compare the caffeine content in tea from two different bushes on the same planation; from different plantations (on different soils, different altitude, etc.)?

What makes tea white/green/oolong/black is just post-harvest thermal processing and it seems likely that the caffeine content is determined at the plant level.

Comment author: gwern 04 August 2014 04:37:23PM *  1 point [-]

Did you see any data on natural variability -- that is, compare the caffeine content in tea from two different bushes on the same planation; from different plantations (on different soils, different altitude, etc.)?

Don't think so. It'd be a good study to run, but a bit challenging: even if you buy from a specific plantation, I think they tend to blend or mix leaves from various bushes, so getting the leaves would be more of a challenge than normal.

What makes tea white/green/oolong/black is just post-harvest thermal processing and it seems likely that the caffeine content is determined at the plant level.

I thought that they were also usually harvested at different times through the year?

Comment author: Lumifer 04 August 2014 04:50:16PM 2 points [-]

I thought that they were also usually harvested at different times through the year?

You mean that tea intended to become, say, white, is harvested at different time than tea intended to become black? I don't think that's the case. As far as I know the major difference is what you harvest, but that expresses itself as quality of the tea, not whether it is white or oolong or black. For the top teas you harvest the bud at the tip of the branch and one or two immature leaves next to it (which often look silverish because of fine hairs on these leaves), such teas are known as "tippy". Cheaper teas harvest full-grown leaves. There might well be the difference in caffeine content between the two, but it's not a green/black difference, it's a good tea vs lousy tea difference.

Darjeeling is unusual in that it has two specific harvesting seasons (called "first flush" and "second flush") but both are used to make black (well, kinda-black) tea.

Comment author: Douglas_Knight 05 August 2014 05:31:44PM 1 point [-]

White tea is harvested early and immature. Black/oolong/green is a matter of post-processing.

White tea has huge variance in caffeine across varieties. Both tails of the distribution are white.

Comment author: Lumifer 05 August 2014 05:48:22PM 0 points [-]

White tea is harvested early and immature. Black/oolong/green is a matter of post-processing.

Can you provide a link for that assertion? The post-harvesting processing of white tea is quite different from that of green, not to mention black. Also, I believe that while white tea requires top-quality leaves (the bud + 1-2 young leaves) and other teas don't, the top quality greens, oolongs, and blacks use the same "immature" leaves as white.