Caffeine in Beverages

http://www.straightdope.com/mailbag/mcaffeine.html

I know this one is old, but I had to comment…

In the report, SDSTAFF Dex explains that the reason a cup of coffee has more caffeine than a cup of tea, even though teal leaves contain more caffiene than coffee beans is that caffeine is “more readily extracted” from the coffee beans

While I’m not sure if this is true of not, I do know that to brew an 8Oz cup of coffee, you use about four times the amount of ground beans (10g or so) than you use tea leaves for a cup of tea. (2.5 g )

The higher caffeine content of coffee is obviously due to tha fact that so much more product is used to make the same size serving.

Welcome to the Straight Dope Message Boards, Dozer05, glad to have you with us.

I don’t pretend to have knowledge of the subject, I got all the info from my son (then a biochemist.) While you could be correct, I don’t see that there’s necessarily a correlation between volume of product and amount of caffeine. The question is the concentration of caffeine in the product. If the concentration is the same, then your argument would be valid. The Report mentions that some beans are more “loaded” than others.

By analogy: I start with a quart of seawater, I evaporate the water and have some salt left, which I sprinkle on my scrambled eggs. Then I take sixteen gallons of milk, from which I extract the salt content and sprinkle that on another batch of eggs. Which eggs are saltier? You’re trying to argue that the second set is saltier because there was more product, but that ignores the concentration of salt being different in the two substances. Get it?

Well, no, the concentrations don’t have to be the same.

Googling around, several sites list the caffeine percentage in tea leaves as 3.5 to 4 percent, and the percentage in coffee beans as 1 to 2 percent. See here, here, and here. So tea leaves have two to four times the caffeine as coffee beans. If, as Dozer05 says, you use about 4 times the weight of tea leaves as coffee beans per cup, you’d expect the caffeine level in coffee to be somewhere in the range of equal to about twice as much as in tea. In the Staff Report, Dex says the average cup of coffee has about 1 1/2 times the caffeine as the average cup of tea, right in the middle of that range. I’m not seeing any justification for saying that caffeine is more readily extracted from coffee than from tea.

Dozer05’s statement that “The higher caffeine content of coffee is obviously due to tha fact that so much more product is used to make the same size serving.” seems justified.

That should be “…you use about 4 times the weight of coffee beans as tea leaves per cup…”