Does dark roast coffee have less caffeine than light roast?

It really depends on how you measure the caffeine. When coffee is roasted the beans lose some water content (somewhere in the 20% range give or take a few percent). At the same time it is losing weight it is gaining size. This leads to a situation that makes answering this question a little interesting.

Assuming all other variables are the same, if you measure by weight you actually have more caffeine in dark roast because the water loss is faster than the minimal caffeine loss during roasting. If you measure by volume you have less caffeine because the beans expand as they roast. This seems to confuse some people so let me restate the above. If you measure your coffee using a scoop you will have less caffeine per cup using dark roast coffee. If you measure your coffee by weight you will have more caffeine per cup using a dark roast. The difference one way or the other is small. If you are buying a cup of coffee and the coffee is measured by weight (common with pre-packed coffee used in many offices and some restaurants) then dark roast will have slightly more caffeine. If you buy a cup and the restaurant measures by volume (common when coffee is fresh ground and measured on the fly) then light roast will be slightly higher in caffeine simply because you will have more coffee grounds. This is really only an issue if you are talking about two identical coffees and even then the differences are small. It is conceivable if you are comparing two available brewed coffees that a difference in varietals between them could make the have as much effect as the roast and the preparation method will almost certainly had a larger effect than the roast level or varietal. If there is a Robusta in one of the coffees it is almost guaranteed to have more caffeine. This is mostly an academic discussion because the differences in caffeine content are relatively small.



Where's the science...

I spend more time trying to fix nonsensical articles about caffeine levels according to roast depth, than almost any other coffee myth...

Here's the cliff notes: Unless you roast the coffee beyond 550F, you're not destroying caffeine. End of the story, nothing more to say about the amount of caffeine available in the bean itself. So the debate about 1st crack vs 2nd crack is a pretty simple answer, they're the same.

Now, brewing method does matter and where time should be spent.

How fine you grind and at what temperature you brew and for how long will determine how much of the total caffeine you extract into the coffee you drink and this can vary widely.

Here are the rules and it's all based on physics:
1. The finer you grind the coffee the more caffeine you have access to
2. The hotter the water you brew with, you guessed it, the more caffeine you can extract
3. The longer you brew for, again, the more caffeine you can extract

Therefor, a Turkish grind brewed to boiling, this usually takes around 5 minutes. Since this is largely a social event and the person preparing the coffee is in social dialog, times vary greatly. If you're fortunate to have a Bekos Turkish coffee maker, then it's done in a thrifty minute or so. Turkish brewed coffee is king of caffeine for these three reasons, finest of grind (less espresso), hottest of water and time is on the longer end of the spectrum for hot brew methods. There's also a twist to Turkish coffee, it is Full-Concoction - meaning the grind is never separated from the drink. Theoretically, if you drank it fast enough and drank a substantial amount of the grinds too, ounce per ounce this is the king of caffeine.

On the other end of the spectrum is Cold Toddy brewing, where temperatures are very cold (floating around 34 degrees) a pretty fine grind, but a substantially longer exposure to water, on the order of 24 hours. Because the temperature is close to freezing, you get some really helpful benefits for the best coffee possible. The cold temperatures slow down the extraction of acid, carbon dioxide, nitrogen, potassium and other roasting bi-products that aren't coffee flavors as well as lower caffeine. Cold Toddy is a Semi-Concotion, meaning the ground coffee is partially removed before serving or consumed.

I'm in the process of sending off a single lot of coffee (from the same harvest, farm and bag), sample of green, 300 Degree, 310 Degree, 320 Degree, 330 Degree, 340 Degree, 350 Degree and a 400 Degree roasted samples to a lab to have the caffeine measured in each sample ground to Espresso and extracted using boiling water for 4 minutes, 200 Degree water for 4 minutes, 180 Degree water for 4 minutes and 34 degrees for 18 hours.

I'll certainly be publishing the results...


RE: Where's the science...

I won't dispute your comments but I will ask that if you are going to make the assertion that that the article is wrong you should be siting your sources instead of making statements without any backing.

If you have articles in peer reviewed scientific journals or respected coffee trade publications please site them so the article can have any inaccuracies corrected. Having said that, at the time this article was written it represented the best understanding of hobbyists and professionals in the field so I will stand by it until better evidence is presented.

I meant no disrespect, just trying to get the truth out there


Accept my apology if I offended you, that is not my intent. I think it's great that people write about coffee with passion. This happens to be one of those hot topics for me that I spend so much of my time dispelling that sometimes I have a hard time being completely objective.

I have other citings for this, I just am not able to locate them at the moment. This is the most recent citing, the rest of them date back into the 60's, 70's and 80's. If I'm not mistaking, the first such studies were conducted by Scott Laboratories in the 1930's and 1940's as they were creating hybrids for disease resistance and more robust production of Arabica beans. Again, I can't find those articles - I swear I'll scan all of this written documentation so it's searchable...


Citing for Temperature that caffeine is destroyed

Melting Point 238.00 °C (about 460 °F - so my memory was off but still in range)
Boiling Point 416.8±37.0 °C Press: 760 Torr
Enthalpy of Vaporization 67.01±3.0 kJ/mol Press: 760 Torr
No mention of decomposition when it boils.
Thermal decomposition of methylxanthines.
Authors: Wesolowski, M.1 [email protected] Szynkaruk, P.1
Journal of Thermal Analysis & Calorimetry; Sep2008, Vol. 93 Issue 3, p739-746, 8p, 3 charts, 3 diagrams, 3 graphs
The thermal decompn. of theophylline, theobromine, caffeine, diprophylline and aminophylline were evaluated by calorimetrical, thermoanal. and computational methods. Calorimetrical studies have been performed with aid of a heat flux Mettler Toledo DSC system. Ten mg samples were encapsulated in a 40 μL flat-bottomed aluminum pans. Measurements at form 20 to 400° were carried out at a heating rate of 10 and 20° min-1 under an air stream. It has been established that the values of, heat of transitions and enthalpy for methylxanthines under study varied with the increasing of heating ra...

1 more tidbit

I need to add that 2nd crack coffee, while not containing more caffeine, does make it easier to harvest the caffeine because the event of 2nd crack is the destruction of cellular walls and burning of sugars. What this means is that the caffeine already present in the bean is far easier to extract in a coarser grind than a 1st crack coffee.

The finer you grind the less effect this has, but it is something to understand and consider.


I enjoyed the post, thank

I enjoyed the post, thank you. For the readers who are still unclear; The truth is that caffeine is extremely stable during the roasting process. You will not lose caffeine in the roasting process. The only things that change are the acidity("bite" or "flavor") and weight of the bean. The amount of caffeine in your cup depends on the density of the bean (weight determines your caffeine intake) lighter doses are the only way to lessen the buzz.


here guys, something to help u out. a good memory tool for ya. light for light roast and light on the caffeine please. yaw holla now if I can help out anymore with this BULLSHIT!!!!!!

I like this very much

My husband and I have been having this very same conversation for over the last year. He's been telling me that the lighter roast has more caffeine in it. While other people have either agreed or disagreed. And I have a really good friend who has worked at Starbucks for a long time and been to many training seminars involving such topics. And when I asked him, I honestly can't remember what it was that he actually said. But I do know that whatever it was it still did not really answer my question. So when I was in a debate with a roommate this morning (my husband is out of town for work so he was not involved) I decided to get back online and try do some research on it and see what I could find. I will say that your article is the best one that I have read. It explains everything so clearly and it make it much easier to understand. I was finding it very hard to understand how one or the other would have more caffeine than the other either way. So thank you for your article. It was very helpful and I'm actually going to send the link to my husband so he can read it. I think he will like how you explained it as well. Thanks. 2013-07-21

not liking the blond veranda

not liking the blond veranda roast from starbucks. some people still believe that caffeine response is all in a persons head. I got the blond k-cup with expectation of less caffeine response not more. didn't know anything about the length of roasting time having anything to do with it. I just thought it would be a lighter brew. mega heart palp reaction and not in my head. I have less reaction to the expresso brews and dark brews.

dark coffee is easy for the stomach

If not anything else, recent research shows that roasting the coffee seeds more results in a chemical that reduces the formation of acid in the stomach. This means less heartburn with dark coffee.

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