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I was wondering what process, or processes, would yield the highest caffeine quantity at a fixed drink size (Say 200ml).

Assuming the same variety of bean, same roast, same quantity, same water temperature and same extraction time.

  • So, do you want to know how to extract caffeine from the coffee or how to get more caffeine into the coffee? – Alex Mar 18 '15 at 15:03
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    I want to know which of the common extraction processes gets the most caffeine out of the bean. – Arthur Lobao Mar 18 '15 at 17:00
  • how about time, is it a factor? – Justin C Mar 18 '15 at 17:47
  • Good point. Assume the same time as well. – Arthur Lobao Mar 18 '15 at 17:48
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    You'll also need to assume a same grind consistency to compare, but by normalizing time, you are removing some processes from the running. Drip coffee, AeroPress and espresso will all have different extraction times since the pressures involved are different. Extraction time goes down as pressure goes up with all other things being equal. – Suspended User Mar 19 '15 at 18:31
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EDIT: I thought about this more. In sum, I believe that this question (as asked) is not answerable (but it is interesting!). With just about any selected brewing method, you'll be able to extract almost all of the caffeine from the beans. However, depending on the method chosen, you need to use different parameters to get full extraction (time, pressure, temperature, etc.). For example: Espresso is certainly the fastest to get full caffeine extraction, but you need a fine grind. Filter/drip or French press are slower, but espresso-fine grind just won't work correctly; you need to use a coarser grind. Given the same beans, and the right technique for the given method, you can achieve almost 100% caffeine extraction.

As an example of drip versus espresso, the Wikipedia article on caffeine (and the two cited references that include figures on both espresso and drip caffeine content -- this and this) claim nearly the same caffeine content for drip versus espresso; in fact, they list that drip coffee has slightly more caffeine than espresso. I can't fully accept these, however, because there's no way to know if they're using arabica or robusta, light roast or dark roast, how much ground coffee was used to brew -- there's just too many unknowns that back those figures. Since arabica, for instance, is ~1% caffeine, with 7g of coffee ("standard dose", from INEI) you'll be able to get ~70mg caffeine. Those are pretty consistent with the cited figures -- meaning 100% caffeine extraction.

So, you'd have to ask a different question in a different way (e.g., what's the fastest extraction method? or How to get 100% caffeine extraction with cold brew?) or so.


I agree with most of @Chris in AK's answer (and +1!), but I wanted to add another take on this.

I don't think solubility is a big factor here; caffeine is very soluble in hot water -- approaching 66g/100mL (~150g/cup) in boiling water, and even at room temperature nearly 2g/100mL (~5g/cup) (citation listed at Wikipedia and here). Yes, those are listed as grams, which means that water could dissolve tens to hundreds of times as much caffeine, as compared to the caffeine dose in an average cup/demitasse of strong coffee or espresso (which contain perhaps ~50mg-200mg per cup; see also questions on caffeine content, such as this and this; also keep in mind that the lethal dose of caffeine is somewhere in the 10g-20g range.)

Back to your actual question, I do agree that you've restricted yourself quite a bit; pressure is one of the few variables you didn't eliminate. To that end: a comparison of extraction of pressure-brewed (e.g., espresso) versus filter/drip follows.

In general, caffeine is quickly extracted from coffee beans (and tea leaves); most is extracted within 30 seconds of water contact (though this certainly depends on fineness of grind and other factors). Here's a visualization of extraction of comparison of pressure-brewed and drip versus time, which depicts the quantity of caffeine (and other stuff) extracted over time. I found it amusing that the context of that article is actually advocating for espresso as a way to brew lower caffeine content coffee; the point being that the "other stuff" (aroma, colour, flavour) is extracted even more quickly with pressure-brewed (versus drip) coffee. So, if you extract for only 10 seconds (which is very short indeed) you'll get most of the "other stuff" but less caffeine. On the other hand, a finer grind will permit faster extraction of caffeine and everything else; this article suggests that espresso is higher in caffeine based on the grind factor; I think there are too many other variables for that conclusion.

  • So I guess my response to this is that espresso (or pressure brewing) is more efficient and you can can confirm this by looking at concentrations of final product. Espresso caffeine concentrations are generally thought to be around 25 to 50 mg of caffeine per ounce. So with 20 gm of coffee and 2 ounces of water, you end up with 50 to 100 mgs of caffeine. Drip coffee concentrations are much lower 8 to 15 mg caffeine per ounce. So with 20 gm of coffee (enough for a 12 oz drip cup) and 2 ounces water, you'd probably only end up with 30mg (or just over) of caffeine. Less efficient. – Suspended User Mar 20 '15 at 16:46
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    @ChrisinAK - You and OP were correct in the comments above -- this question is fascinating and unanswerable. :) Given equal amounts of the same coffee to begin with, I still maintain that you're going to end up with nearly 100% extraction if you want to -- just need to use different techniques (varying the parameters, like you said) depending on the method chosen. Additional info in edit above. – hoc_age Mar 21 '15 at 20:55
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    I agree on both less than fully answerable and very interesting. Coffee brewing is such a large equation with so many variables that "optimal" is hard to define. The variety of brewing methods available is to some extent proof that coffee is all taste. Different methods support different flavor profiles. Espresso may not even answer this question since a longer brew/extraction time would not be available with this method. – Suspended User Mar 23 '15 at 15:51
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I think the answer to your question is generally going to be espresso.

Brewing process all comes down to pressure, temperature, extraction time (water contact time), possibly agitation and filtering. I may be missing a variable, but all the methods of brewing are just mixing of those variables. If you fix all but one variable, you'd have an answer for any given equation.

All of these things are ultimately affecting the solubility of the caffeine in the coffee. Since espresso is one of the few brewing methods to affect pressure (and generally uses the greatest pressure) it's going to be the winner. Increased pressure means increased caffeine solubility.

From wikipedia you'll note the two major factors affecting solubility are temperature and pressure. You'll also note that dissolution doesn't always happen instantly; rates may vary based on conditions. By increasing pressure during brewing my guess is that the rate of caffeine dissolution is increased. making it more efficient for short brewing times.

  • By holding constant so many of the major variables, one is basically restricted to a single brewing method! +1 insightful. But I don't agree about pressure and solubility; can you clarify or do you have a reference? See also analysis in my answer. – hoc_age Mar 20 '15 at 1:54
  • @hoc_age I've added some citations. Pressure most certainly affects solubility as well as probably affecting the rate of dissolution. – Suspended User Mar 20 '15 at 16:56
  • First, I'll note that I prefer this as the accepted answer (but that's up to OP @Arthur). I agree that pressure affects solubility and rate of dissolution. But what I meant was that since caffeine is so very soluble in hot water, the temporary pressure used in espresso isn't a big factor in this case; I do believe that pressure will make the process more efficient in time (but that wasn't precisely OP's question). If the question was about then quickest brewing/extraction method, espresso wins without question. Espresso takes seconds; drip takes longer; both are caffeine--delicious. :) – hoc_age Mar 21 '15 at 20:59
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    @hoc_age I found it very interesting that there wasn't any published research (that I could find) on caffeine dissolution rates based on pressure (and or temperature). It seems like something the cold brew crowd would be interested in if nothing else. Maybe there is a market out there for a "fast" cold brew method using pressure. – Suspended User Mar 23 '15 at 15:53
  • Agreed; the research seems to be focused on improving decaffeination -- such as your link about supercritical CO2. "Fast cold brew" -- I like it! Sounds like a question and/or experiment... :) – hoc_age Mar 23 '15 at 18:47
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This study on the caffeine concentration of Turkish Coffee, shows that it can have concentrations of up to 300 mg per 40ml cup (table 6). This method of preparation has much stronger concentrations than the espresso or the drip coffee, since you end up drinking a lot more of the grinded coffee beans.

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    Ahah, this is the obvious but maybe unpopular answer: if you drink the dregs of your Turkish coffee (yuck!) you will certainly have consumed 100% of the caffeine. – Nathan Sep 19 '17 at 23:17

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