za-hi said

my theory about caffeine content in tea (please read.. interesting stuff)

i keep reading that processing determines the caffeine content in a tea leaf. i think that’s wrong. * this is just a guess. i know that there are other factors that determines caffeine content, but this guess is based on ideal conditions.*

let’s say we have identical tea leaves. one is a white tea leaf, the other is green, oolong, and black. i think that the caffeine content is the same with in each leaf; however, the amount of caffeine that’s extracted is different.

the amount of caffeine extracted is correlated with its processing (drying, firing, oxidation). i say correlated, because there are obviously other factors that determines caffeine content. however, this is under ideal conditions.

back on topic, a white is just left to dry out, so that allows its cell structure to remain intact, which means that not a lot of caffeine is able to be extracted. black tea, on the other hand, is bruised/twisted (etc). this also means that its cellular structure is damaged, allowing more caffeine to be extracted.

let’s say we have two identical balloons filled with equal volumes of air. one of the balloons isn’t damaged (white tea). the air in the undamaged balloon will stay in the balloon for a long time. one of the other balloons is damaged (black tea). the air in the damaged balloon is going to escape.

green tea is a different story, because it’s either steamed or pan fired. if you’re into science, keep reading. because green tea is pan fired or steamed, this alters the proteins that allow the cell walls to be selectively permeable, because non optimum temperatures destroys the proteins structure. as a result, caffeine is able to freely move out of the cells and end up in the water.

7 Replies
Uniquity said

The problem with this is that many good quality white teas release more caffeine than black teas.

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Kittenna said

I would say that processing does actually determine the content of caffeine in a tea leaf… if you take two identical leaves, and subject them to different processing conditions, one likely results in greater destruction of caffeine. Then, as you described above, extraction is different, which may also relate to processing.

But here’s another problem – white teas are not made from the same part of the plant as black, green, oolong… caffeine is produced as a plant defense, and therefore is likely present in different concentrations in different tissues. For example, meristematic tissue, which is the growth point of the plant, likely contains higher concentrations, and that’s the bud, whereas older leaves and stems contain less. And then, of course, other factors are the amount of leaf used, water temperature, infusion time, and how intact the leaf structure is.

za-hi said

i know there are other factors… i stated that in bold. this is dealing with identical leaves in ideal conditions. the only thing that changes is the category of tea. (i.e. white, green, oolong, black)

TeaLady441 said

I didn’t realize white tea was made from a different part of the plant than the other types of tea! That’s pretty interesting.

I guess with that in mind we can’t really compare the white teas for this theory, but could with a green vs black vs oolong test.

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alice said

For me tea is a bit like coffee, you never quite know how much caffeine you are going to get until you drink it.

The genetics of the individual plant (or plantation, since I think most plantations clone plants rather than grow from seed), the growing conditions, and the time of picking all could potentially alter the caffeine levels prior to harvest. Then the processing has an influence, probably storage too, and finally brewing.

Caffeine in tea also works on the brain together with theanine so the amount of theanine extracted into your cup will also most likely impact how you perceive the caffeine. I’ve heard that theanine is the reason many people don’t get jitters from drinking a lot of tea as they might coffee.

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sansnipple said

some Actual Science here: http://chadao.blogspot.ca/2008/02/caffeine-and-tea-myth-and-reality.html
skip to section 2, processing has a small effect but not nearly as much as genetics and picking standard and growing conditions.

Different types of tea aren’t usually made from the same exact leaves though, nor picked at the same time, or in the same way, they aren’t identical at all pre-processing. Different types of tea are generally made from different cultivars (thus genetic variation) specific to the style of tea you want, you’re not going to pick tieguanyin or long jing #43 leaves and then process it into a black tea.

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Brewing also plays a part. Caffeine is very soluble at high temperatures, but not so at low temperature. If you use boiling water you’ll extract more caffeine.
Also, if the tea is powdered (like matcha) you get 100% of the caffeine content of the leaf.

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