Being new to espresso, I am still getting my technique down and pulling several shots in a row in order to analyze taste and play with variables. Without thinking about it this morning, I drank four shots in a row. I didn't feel any different than if I had had my regular french press coffee, which got me to wondering about caffeine. In order to make the four shots, it didn't take a lot more whole beans than I would have used to make a 16oz travel mug with the french press. Thus, is the caffeine content similar? Or, because of the finer grind of espresso does that method extract more caffeine than brewing? Is it the other way around for some reason?

I have looked around and found different answers on websites ranging from espresso has far less than drip coffee, about the same, and even up to three times as much. I know that anything relating to caffeine has a lot to do with type of bean, roast, and preparation method, but I am wondering what people here think or if anyone knows of research done in this area that would have some hard answers.

Zach

Zach, a) there is no simple answer; and b) I am no expert.

Of the two major types of coffee plants, arabica and robusta, robusta beans contain a higher caffeine content than do arabica. (Source: http://www.coffeeresearch.org/agriculture/coffeeplant.htm) Some roasters include robusta beans; some do not. Robusta has about twice as much caffeine as arabica therefore a coffee blend starting with a large amount of robusta will have more caffeine regardless of prep method. Many (but not all) supermarket brands of coffee have a fair amount of robusta mixed into the blend to keep production costs low.

In addition, some sources say that the darker the roast, the less caffeine it contains. Also, some sources say that the higher in altitude the coffee is grown, the less caffeine it contains. (Who knows?)

If you look at this table, you'll get a VERY rough idea of how widely the caffeine content can vary in coffee/espresso. For that very reason, no one can do absolutely definitive scientific research of the kind that will result in "x" -- a single number applicable to all. It, obviously, isn't a one-size-fits-all thing . . .

Are you pulling a single or a double shot of espresso? Are you using 14 grams for your double? 15 grams? 18? All arabica, or does your blend contain some robusta? Are you using a blend, or a single-origin coffee? Is it a dark roast of a type favored in Southern Italy, or a lighter, Northern Italian roast?

And on and on and on . . .

I know: I've been of no help whatsoever.

Cheers,
Jason

I think I remember reading somewhere that caffeine content was largely dictated by the length of time the water was in contact with the coffee grounds. French Press has four minutes or so to leach caffeine from the grounds, whereas only 25 or 30 seconds for espresso. People have the misconception that espresso is high in caffeine because it is strong. That is probably true in percentage terms, but not per serving, eg one shot of espresso vs one mug of french press.

Thats my recall of it, but I have nothing to back it up with!

Here's what I do to get a rough estimate:

1) assume that on average, arrabica has 1% caffeine content by weight.

2) assume that the espresso process does not wring 100% of the caffeine into your cup. Let's guess 75% (based on no knowledge of caffeine's extraction rate.)

Now just use the weight (dose) of coffee you prefer for your espresso. For example, a 16gm dose should render a total possible caffeine content of 160mg. However, we assumed that only 75% of that gets extracted, so .75 x 160 = 120mg.

So, assuming you use arrabica beans, a 16gm dose probably gets you somewhere around 120mg of caffeine. At least you know that the upper bound is somewhere around 160mg for a 16gm dose.

I used 75% extraction as a rate for espresso solely because I read about how much caffeine is in a 10oz $bux drip coffee (200-250mg). This would suggest that drip extracts more caffeine from the coffee than does espresso.

I can see why the range given for espresso beverages varies so much. A 7gm dose could have as little as 50mg of caffeine, whereas a 22mg triple could pack 200mg of caffeine.

Can anyone provide some information to improve this guesstimate?

Mark

I figured that there weren't going to be any solid answers, but they have made for some interesting and informative reading. I am pulling 14-16g doubles using a fairly dark, all-arabica blend from a local roaster, though I don't know what is in the blend. I keep forgetting to ask the owner when I go in. I will have to ask and see what his thoughts are on the subject. Most of these answers make sense and back up what I have been able to find: espresso has much more caffeine by volume (mg/ml), but less than drip coffee per serving. So I guess I am safe having several shots in the morning, I am sure many people here drink much more coffee than I do and they seem to be okay.

One 17g double of the last batch of Black Cat I tried packed a serious caffeine punch whereas I can drink 2-3 17g doubles of Atomic's Daterra Reserve without feeling as buzzed. Both are all arabica & the roast level looked similar.

gyro wrote:I think I remember reading somewhere that caffeine content was largely dictated by the length of time the water was in contact with the coffee grounds.

Caffeine extraction rates are also highly dependent upon water temperature. Darker espresso roasts, combined with short extraction times, reduce the amount of caffeine in the cup. But this is partially offset by the higher temperatures used in espresso brew water. (I have no idea whether brewing under pressure also increases caffeine extraction rates, but it probably doesn't decrease them.)

EDIT: Wikipedia reports that the solubility of caffeine in water increases from 22 mg/ml at 25°C to 180 mg/ml at 80°C to
670 mg/ml at 100°C (look under Properties in the right-hand sidebar). For US readers, that's a four-fold increase in solubility of caffeine as the brew temperature increases from 175F to boiling. So if you want to reduce caffeine in your coffee: avoid robusta beans, use less coffee per cup, and brew at lower temperatures.

Robusta = higher caffeine content
Arabica = lower caffeine content (but may vary depending on varietal)

Roast level influences caffeine content in all coffees. I am under the impression that caffeine is not destroyed by the roasting process but more overall wight (from water content etc.) is lost when roasting darker. Therefore it stands to reason that comparable doses of a light roasted coffee will have less caffeine than the same weight doses of a darker roasted coffee.

I don't know about the influence of temperature relative to caffeine extraction but is a critical function. A typical French press or drip brew time is four minutes whereas the typical espresso extraction is done in 22 - 30 seconds. Shorter extraction = less caffeine.

I can confirm from personal experience that one 16 oz cup of press or drip coffee gets me a lot more jazzed than two double ristretto shots.

By volume, dark roasts have less caffeine, assuming the beans get bigger as they burn.

Here's a Roast Magazine article on Caffeine Control

Some additional industry-supported research and anecdotal information:
European Coffee Science Information Centre
http://www.cosic.org

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