Wednesday TeaDay 9/10/08 Craving Pu-erh?

[olivierco]

Wikipedia lists these figures, near meaningless to me:

• Solubility in water
  22 mg·mL−1 (25 °C)
  180 mg·mL−1 (80 °C)
  670 mg·mL−1 (100 °C)

[/i]
I take it to mean that caffeine is extracted much more slowly in cold water, but still extracted. The fact that you are infusing for such a long period, however, may mean that you are getting a full dose of caffeine.

In fact it isn't a matter of how slowly caffeine is extracted but more of how much caffeine can be dissolved in your tea.

If you brew your tea at 25°C, you never get more than 22mg/ml of caffeine in your tea, even if you wait for a very long period of time.

If you want a basis of comparison, regular Coca Cola contains 100mg/l caffeine

Darjeeling Phuguri FTGFOP1 right now.

edit typo (thanks Pentox!)

[Pentox]

At the same time though you have to consider the chemical properties of the tea being able to hold more in solution vs. pure water. If your tea was pure water you wouldn't have more than 22mg/mL of caffeine, but coke is served at lower than 25C, but you don't see the caffeine precipitate out of a cooled coke. The solubility of the caffeine in the coke is probably higher due to the composition of coke vs pure water.

Btw Oliver, you labeled your numbers as mg / L where the wiki article numbers are mg/mL. You'd never get any caffeine in your blood at that rate

[olivierco]

At the same time though you have to consider the chemical properties of the tea being able to hold more in solution vs. pure water. If your tea was pure water you wouldn't have more than 22mg/mL of caffeine, but coke is served at lower than 25C, but you don't see the caffeine precipitate out of a cooled coke. The solubility of the caffeine in the coke is probably higher due to the composition of coke vs pure water.

Btw Oliver, you labeled your numbers as mg / L where the wiki article numbers are mg/mL. You'd never get any caffeine in your blood at that rate

Sorry for the typo.
100mg/l for Coca Cola is 0.1mg per ml so well below the max solubility of caffeine in water which explains you won't see it, even at cold temperatures.

[Pentox]

100mg/l for Coca Cola is 0.1g per ml so well below the max solubility of caffeine in water which explains you won't see it, even at cold temperatures.

Ah yeah that does sound about right.

[Victoria]

In my cup at work -

Enjoying some nice Li Shan from Floating Leaves Tea.

A nice everyday oolong.

[horsencl]

I'm not one to crave the pu either. That being said, the only one I have tried is Rose Pu-erh Tuocha from Mighty Leaf. It was a ok but nothing to rave about. Pu-erh is just too expensive for me.

[Salsero]

Ah yeah that does sound about right.

So does that mean we don't get much caffeine in cold brewed? Does it mean cold brewed has more caffeine than Coke? I am lost. Give me some hints! Drop some bread crumbs on the forest floor.

[Chip]

no no no no no no no. if I crave pu erh, I can just have a cigarette or eat my ashtray

having some fantastic Ali Shan oolong....we'll be getting it soon on the site! It's my new favorite!

Ohhhh cruel torture!!! I can't wait to try!

Actually, ALI SHAN is now on the Adagio site! I placed it on my wish list. Looks tasty.

I voted 5, but this changes constantly as I go from wanting no pu-erh to wanting all the pu-erh I see. I am quite daunted by the task of trying to find simplicity in just enjoying pu-erh. It seems to call for a certain level of dedication and commitment. Therefore, I said 5 in the poll. But there are times when it approaches 8, but never as high as greens.

Adagio Golden Monkey to start the day. Currently finishing a 4th steep of shincha Yutaka Midori from you guessed it, O-Cha. I was so distracted earlier, that I drank the first steep without realizing I had taken a single sip. I missed all the flavor and aroma of the first steep.

[Chip]

100mg/l for Coca Cola is 0.1g per ml so well below the max solubility of caffeine in water which explains you won't see it, even at cold temperatures.

Ah yeah that does sound about right.

However, Coke is not simply water. Thus the solubility could be quite different anyway. And since it is already dissolved in solution, it may not precipitate at any temp even in super saturation???

[Pentox]

Ah yeah that does sound about right.

So does that mean we don't get much caffeine in cold brewed? Does it mean cold brewed has more caffeine than Coke? I am lost. Give me some hints! Drop some bread crumbs on the forest floor.

It doesn't really mean much at all. The saturation level of caffeine in water/tea/coke is much higher than any level that you're drinking it at. To put it in perspective, the wikiquoted solubility at 25C is 22 mg/mL. That means that at around room temp you could fit as much caffeine in 1mL as there is in half a can of coke. (12oz can is approx 50 mg caffeine).

So basically all that these numbers are saying is that the maximum caffeine solubility amounts are incredibly high. If you had a cup of tea at maximum caffeine solubility you would be dead. The LD50 for caffeine (medial lethal dose) is 193 mg/kg in a rat. So if you were an average 200lb rat it would take 17.5 g of caffeine to kill you. Although I have read elsewhere that lethal dosages occur at around 10g in humans. The trigger for caffeine overdosing i've heard range from 700mg to 2g. So the short story is if you were drinking room temp maximum solubility caffinated water, you would be dead at about a 20oz bottle. If you were drinking maximum solubility caffinated water at 100C, you'd be dead from a small cup.

But the fact of the matter is that while it is nearly impossible to say what the caffeine level is going to be for a given tea, the levels are WAY below maximum solubility. They are more along the lines of 30-100mg / 8 oz. So the amount of caffeine that you will pull from cold brewing vs hot brewing won't be affected at all by the caffeine maximum solubility. Nor will it be that close to lethal unless you're drinking it by huge huge amounts. In which case I think you would die by kidney failure first.

Extraction rates of caffeine into water from tea are a whole different subject matter though.

Also all these numbers are incredibly varying. I've heard numbers that swing massively from either side.

[Victoria]

having some fantastic Ali Shan oolong....we'll be getting it soon on the site! It's my new favorite!

Ohhhh cruel torture!!! I can't wait to try!

Actually, ALI SHAN is now on the Adagio site! I placed it on my wish list. Looks tasty.

Yes, but Xine and Cyn drank it all!! I guess the big shipment will be here mid month. I wonder if we will have an un-crating event with pictures, like for the Spring Darjeeling???? I HOPE SO!!! Ilya - make it so!!!

[kongni]

Ok, now I'm completely lost on this caffeine extraction thing.

So far I'm hearing that cold brewing extracts less caffeine.

But if I let it brew, say overnight, will I get more caffeine without astringency?

[olivierco]

Ah yeah that does sound about right.

So does that mean we don't get much caffeine in cold brewed? Does it mean cold brewed has more caffeine than Coke? I am lost. Give me some hints! Drop some bread crumbs on the forest floor.

The solubility values give only the maximum amount of caffeine that can be dissolved in water.
22mg/ml are 22g per liter, enough to kill someone with only half a liter.

There are about 2.5g caffeine in 100g of sencha.
So 4g of sencha yield about 100mg of caffeine.
With 120ml of water you get a maximum of 83 mg/l concentration ie 0.083mg/ml, way under the maximum solubility of caffeine in water, even at low temperature.

What is really important is how fast the caffeine is extracted from the tealeaves to the water (which can't be determined with the solubility values).
If you put sugar cubes in water, they don't dissolve themselves instantaneously that is the same with caffeine in tea leaves.
The extraction process is faster at higher temperatures but as cold brewing means longer steeping times caffeine has more time to get extracted from the tealeaves.

Caffeine has a bitter taste, so if your cold brewed sencha is as bitter as your regular sencha, their caffeine levels should be quite the same. For more accuracy, you should have access to a chemistry lab.

[Salsero]

If you had a cup of tea at maximum caffeine solubility you would be dead.

I guess I extracted the wrong data from the Wikipedia article. The conversation has taken a definite mobid turn. I think Kongni and I are more interested in staying awake than in being dead. Will we?

[olivierco]

[If you were drinking maximum solubility caffinated water at 100C, you'd be dead from a small cup.

and severely burnt