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For example;

1) 100mL water + 4 tablespoons of green tea leaves 2) 100mL water + 12 tablespoons of green tea leaves

Will the second one result with higher EGCG and caffeine content? Or is there a upper limit for the absorbable amount? If not, how much difference can occur? 3x content of the first one?

  • Hello Leloux, and welcome to the site! Note that we do not take questions about health and the effects of food on the body, so I had to remove the last sentence. But the rest is a nice first question, even though I suspect the answer is not the one you hoped for. – rumtscho Jun 26 '16 at 10:42
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3x tea would not mean 3x extract

But it is going to be close to 3x for small amount

Water is a good solvent for those chemicals but there is a limit

The solubility of caffeine is 2 g/100 mL at room temperature (by weight about 1 : 50). 66 gram / 100 mL at boiling.

A coke is 20 mg (milli 1/1000) 12 oz.
The caffeine we drink is not even close to saturation.

In extraction you equalize the mole fraction with a fudge factor. I don't know where to find fudge factor for tea. But it would favor the water.

A dry tea leaf is about 3% caffeine. Getting the caffeine out with boiling water you can pretty easily get up to saturation at room temperature. But you would need quite a bit of tea. 2 g caffiene would be 66 g of tea. A tea bag is about 2 grams.

In a commercial extraction they would use a solvent like ethanol.

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There are two factors here, both of which will limit you.

The first is the solubility of caffeine in water. Paparazzi found it for room temperature, it is going to be higher for a hot beverage, but whatever it is, it is a hard upper limit. So, if you were to drop a tablet of 1 g pure caffeine into 100 ml water, and a tablet of 6 g into another glass of 100 ml, you would only get 2 g of caffeine from drinking the second water, not 6 g. But that's unlikely to matter in real tea making.

The second one is the extractability of caffeine from tea leaves. I am not going to do any back-of-the-envelope calculation for that, but basically, the amount of caffeine you can extract into the tea depends on the concentration of caffeine in the tea and the concentration of caffeine remaining in the leaf. The less concentration you have outside the leaf, the more can you get from inside the leaf to the outside. In practical scenarios, this is going to limit you much earlier than you hit the caffeine solubility problem.

It is impossible to predict how much the difference in extraction will be. Somebody with a scientific computing background and access to the right formula and hardware could make a model for a given tea making recipe and a given leaf, but a recipe which uses different time, temperature, and a different plant will end up with a different factor. The best we can say is, there will be a difference (it won't be the same amount extracted), but it will be noticeably less than 3x the same amount.

This goes for basically anything you extract from the tea, so also EGCG.

  • You do not need a computing background. You need a chemist or chemical engineer. The are formula for extraction. I just could not find to coefficients to plug in. – paparazzo Jun 26 '16 at 12:50
  • OK, I don't know enough about chemical education to know if the average chemist or chemical engineer has access to something (formula, software, whatever) to easily calculate it. It probably depends on how much precision you want - I was considering a case where you take into account the cooling of the liquid during the extraction process. Anyway, such calculations are of limited usefulness, because as far as I remember they depend on the initial concentration of caffeine in the leaf, and that's highly variable (or can you assume "unlimited" supply of caffeine on first extraction)? – rumtscho Jun 26 '16 at 13:13
  • Extraction is a very common process. Any chemist or chemical engineering would receive training. You can only extract what is there. As the water get closer to saturation then it will only get part of caffeine out. The precision is you can get to saturation at room temp pretty easy and don't need and advanced model for that. – paparazzo Jun 26 '16 at 13:42
  • Ok, that's great to know! Is the background information on that formula available somewhere freely on the Internet? Also, how does it account for different forms of tea (shredded vs. whole leaf vs. matcha-like powder etc.)? – rumtscho Jun 26 '16 at 13:43
  • Read my answer I don't even need the formula for this one. – paparazzo Jun 26 '16 at 13:45

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