Caffeine

10 January 2017

CAFFEINE 2007

 

About ten years ago this discussion appeared on  www.coffeed.com regarding caffeine.  It is still relevant a decade later.  Warning: your head could hurt reading it…(and not from caffeine withdrawl!)

 

 

CONCLUSION:

The short and practical answer to people wanting to know whether a dark roast results in greater caffeine in your cup is: “Yes it does and the darker the roast the more the caffeine”.

 


ostby Instaurator on Thu Aug 09, 2007 11:44 pm

There was an article published recently about caffeine and it perpetuated some urban myths that I have heard one time too many and so Alistair kindly invited me to let off a bit of steam and to hopefully help some people who must be very confused about caffeine at least. 

In this article it said: "Another misconception about the amount of caffeine in coffee and espresso is that the darker the coffee, the more buzz it must have?. 

This is actually not a misconception. It is in fact true that darker roast coffee does have a higher percentage of caffeine. 

As a percentage of 'dry matter? Arabica green has 1.2% whereas roasted it has 1.3%. Robusta green has 2.2% and roasted it has 2.4%. [Ref Dr Illy] 

What happens during roasting is that there is a very small amount of caffeine loss, only a few percent, whereas a medium roast will lose 5-8% organic matter and a dark roast will lose 8-12% organic matter. Very dark roasts will lose more than 12% organic matter. 

So that is why in absolute terms there is actually a loss of caffeine (which is what the article may have been referring to) but in relative or percentage terms there is more caffeine, the darker the roast. This is simply because organic matter and moisture is lost at a greater rate than caffeine. 

So in 10grams of dark roast coffee for an espresso will have more caffeine than 10 grams of lighter roast. It becomes more not less concentrated. 

I hope this makes sense. 

This particular article said: 'Many people " customers and baristas alike " are surprised by this fact [that dark roasts are not meant to give you more 'buzz'] at first...?. These people should be surprised for a very good reason: their bodies are confirming the truth that they are experiencing more caffeine and more 'buzz' and unfortunately if they have been told otherwise it is not a 'fact?. It is another coffee myth or 'DFO' (Data Free Observation) as my agronomist would call it. 

And what is more, caffeine doesn't seem to translate to the cup in a linear fashion, not for espresso anyway. It is often said that robusta has twice as much caffeine than Arabica. 

A pure Arabica blend for an espresso (30mls in 30 seconds) will contain 2.6mg/ml whereas a pure robusta blend will contain 3.8 mg/ml. This is actually not twice as much but just under half as much again. 

Sorry to bore everyone but at least I've got it off my chest now .

Instaurator
http://www.espressoquest.com

Instaurator

 

 

ostby Jeff Givens on Fri Aug 10, 2007 6:21 am

That's interesting stuff. As I understand from your posting, by weight, the relative percentage of caffeine increases with darker roasts; but by volume, the percentage decreases

If my interpretation is correct, wouldn't a darker roast have a greater percentage of caffeine if the barista is dosing into the basket by volume?

Jeff G.
southernskiescoffee.com

Jeff Givens

 

ostby Matthew Brinski on Fri Aug 10, 2007 8:14 am

That is not boring at all ... thanks for sharing. 

(I hope you let off some more steam.)

Matthew Brinski
(non-affiliated)

Matthew Brinski

 

ostby Instaurator on Fri Aug 10, 2007 2:47 pm

"As I understand from your posting, by weight, the relative percentage of caffeine increases with darker roasts; but by volume, the percentage decreases. " 

Yeah that's another way of expressing it - a little more clearly too! So you have less caffeine matter but at a higher percentage or concentration. 

Sure if you dose more, automatically you have more of everything! But I wasn't thinking in terms of dosing or 'updosing' as some people like to call it. By the way I'm not hung up at all on that as being the only way of dosing. For what it is worth there is a whole other theory on dosing that maybe I'll post some time. Actually it's not mine but Scotty Callaghan's the current Aussie Barista Champ.

Instaurator
http://www.espressoquest.com

 

Re: Caffeine

ostby barry on Fri Aug 10, 2007 8:06 pm

Instaurator wrote:So that is why in absolute terms there is actually a loss of caffeine (which is what the article may have been referring to) but in relative or percentage terms there is more caffeine, the darker the roast. This is simply because organic matter and moisture is lost at a greater rate than caffeine.




I usually describe this as "bean for bean, less caffeine; pound for pound, more caffeine". 

I distinctly recall answering this question correctly during a trivia-for-tshirts interlude during the barista competition at the san francisco convention (standing next to jeff taylor). I was promptly chastised by the "expert" and several members of the audience who, quite obviously, hadn't read their illy. ) I did not get the t-shirt, which is okay, because we dropped Torani shortly thereafter.

barry

 

 

ostby barry on Fri Aug 10, 2007 8:09 pm

Instaurator wrote:"As I understand from your posting, by weight, the relative percentage of caffeine increases with darker roasts; but by volume, the percentage decreases. "

Yeah that's another way of expressing it - a little more clearly too! So you have less caffeine matter but at a higher percentage or concentration.




I'm not sure that's accurate, because relative volumes depend upon bean density, not just bean mass. bean for bean, the amount of caffeine decreases.

barry 

http://www.rileys-coffee.com/

 

ostby Instaurator on Sat Aug 11, 2007 3:57 am

Barry said: 
"I'm not sure that's accurate, because relative volumes depend upon bean density, not just bean mass. bean for bean, the amount of caffeine decreases." 

I'm not sure I understand what you mean. I missed out on a whole lot of physics at high school by spending way too much time at the beach surfing. But as I understand it, density is mass divided by volume. Whereas weight is mass multiplied by gravity. So 1 pound of coffee on planet earth will weigh 1/6 of a pound on the moon but it will have the same mass. Density doesn't change unless the volume of the same 1 pound changes. But this is all very abstract. The fact remains when we drink a cup of coffee made from the same mass of coffee, a dark roast will have a higher percentage of caffeine in comparison to a light roast of the same coffee. This is of course assuming we are not weighing and brewing our coffee on the moon....or some other planet. I'm not saying you are doing this Barry but sometimes I fear some people must be.

Instaurator
http://www.espressoquest.com

 

Re: Caffeine

ostby Jim Saborio on Sat Aug 11, 2007 6:43 am

Instaurator wrote:As a percentage of 'dry matter? Arabica green has 1.2% whereas roasted it has 1.3%.[Ref Dr Illy].



With this in mind, I'd imagine the difference between a light and dark roast would be even smaller. Would this small increase be significant to the consumer? 

At my first barista gig, our roaster gave us a sheet detailing varying caffeine contents between origins. People really latched on to the "fact" that our Tanzanian peaberry had the most caffeine of our offerings. Some would avoid the Tanzanian like the plague... "Whoah, I don't want to be bouncing off the walls!" 

I suspected the difference was largely in their heads. 

Should we be telling folks "Yes, dark roasts generally DO contain more caffeine than lighter roasts BUT the difference is negligible"? 

I'm confused.

-JIm

...aaannndd the Starbucks down the street just got a Clover

Jim Saborio

 

ostby barry on Sat Aug 11, 2007 1:05 pm

Instaurator wrote:Density doesn't change unless the volume of the same 1 pound changes.



Exactly. The volume of a pound of dark roast coffee is different than the volume of a pound of light roast coffee. What the difference is depends upon bean, relative degree of roast, and roasting method, so making a statement on caffeine in a given volume of beans (which is {perhaps incorrectly?} how I read the initial volume comment) is difficult, at best.

 

The fact remains when we drink a cup of coffee made from the same mass of coffee, a dark roast will have a higher percentage of caffeine in comparison to a light roast of the same coffee.



Agreed wholeheartedly.

barry

 

 

Re: Caffeine

ostby barry on Sat Aug 11, 2007 1:47 pm

Jim Saborio wrote:Should we be telling folks "Yes, dark roasts generally DO contain more caffeine than lighter roasts BUT the difference is negligible"?



This one. 


The difference depends entirely upon the relative percentage of caffeine at any given roast level. The "1.3% roasted" value is not exact, and ought to vary with roast level... in fact, it must vary with roast level for there to be a difference at all based on mass (I'll show the math if you want). In other words, 1.3% caffeine in a dark roast and 1.3% caffeine in a light roast result in the same 1.3g per 100g sample. 

If you want to make up numbers for demonstration purposes, perhaps assume 1.29% for medium roast and 1.31% for dark roast, and there will be a .02% difference based on mass. I'll see if there are any references which show %caffeine based on roast degree. 

BTW, it's easy to demonstrate that bean for bean, there is less caffeine. I'll show the math for that, too, if you want.

barry

 

 

ostby Jim Saborio on Sat Aug 11, 2007 9:29 pm

barry wrote:

The fact remains when we drink a cup of coffee made from the same mass of coffee, a dark roast will have a higher percentage of caffeine in comparison to a light roast of the same coffee.



Agreed wholeheartedly.



As someone who might have 10 seconds to clear-up a consumer's caffeine misnomer, I'm more concerned about the results in the cup. That's what people care about. Pound for pound, bean for bean, or content by volume is just fun trivia that may or may not help you win a t-shirt. 

Supposedly a 12oz can of Coke has 3.5mg more caffeine than a 12oz can of Pepsi. 

Is this the kind of difference we're dealing with here? 

I doubt there are many consumers who choose Coke because the extra .291 mg/ounce gives them the edge they need in today's hectic world. At the same time I wouldn't expect many to choose Pepsi because their delicate hearts can't handle Coke. 

Even if there's a 25mg difference between two 16 oz. cups of coffee, is this something a consumer should concern themselves with? 

Will they physiologically notice the difference or is it just fun trivia? 

That's what I was attempting to ask.

-JIm

...aaannndd the Starbucks down the street just got a Clover

Jim Saborio

 

 

Re: Caffeine

ostby barry on Sat Aug 11, 2007 10:38 pm

Jim Saborio wrote:Should we be telling folks "Yes, dark roasts generally DO contain more caffeine than lighter roasts BUT the difference is negligible"?




Again, the above is the correct response (imho). 

You're not going to get hard numbers, because caffeine is a natural component in coffee, and final content in the cup depends upon way more variables than you'd be able to account for precisely. It's easier with soda, because caffeine is an additive, and the manufacturers know just how much they put in, and lab tests on one can of Coke pretty reliably reflect the content in other cans of Coke. Not so with coffee. So, don't look for hard numbers, just look for general relationships of contributing factors. If you use 8 grams to brew a cup of coffee, and the bean has 1.3% caffeine, then the cup will have 104 milligrams of caffeine in it provided 100% of the caffeine is extracted. Not all brew methods achieve 100% extraction of caffeine, caffeine content in the bean varies somewhat, and dose values vary somewhat, so I would be reluctant to start throwing hard numbers at customers w/o some lab analysis.

barry

 

 

Re: Caffeine

ostby Brent on Sun Aug 12, 2007 5:23 pm

Jim Saborio wrote:I suspected the difference was largely in their heads.

I'm confused.



In a recent (last 2 years?) issue of National Geographic, they covered caffeine, and one of the points that came out was that caffeine does not affect the system immediately, rather about an hour later, hence that "instant kick" IS all in your mind...

Brent

Brent

 

 

Re: Caffeine

ostby Andy Schecter on Sun Aug 12, 2007 6:11 pm

Brent wrote:In a recent (last 2 years?) issue of National Geographic, they covered caffeine, and one of the points that came out was that caffeine does not affect the system immediately, rather about an hour later, hence that "instant kick" IS all in your mind...



The article claims the effects don't PEAK for an hour. 

Even if true, that's very different from saying there's NO effect for an hour.

-AndyS
Schectermatic(tm), the oldest, most trusted brand of espresso grinder shnozzola
http://www.flickr.com/photos/andy_s/sets/

Andy Schecter

 

 

Re: Caffeine

ostby Brent on Sun Aug 12, 2007 9:02 pm

Andy Schecter wrote:The article claims the effects don't PEAK for an hour. 

Even if true, that's very different from saying there's NO effect for an hour.



I was remembering the article, not quoting oops:

Brent

Brent

 

 

ostby Instaurator on Mon Aug 13, 2007 10:58 pm

As someone who might have 10 seconds to clear-up a consumer's caffeine misnomer, I'm more concerned about the results in the cup. That's what people care about.



 

Jim said 
'Yes, dark roasts generally DO contain more caffeine than lighter roasts BUT the difference is negligible"? 

I'm confused.?


The aim here was to hopefully try and dispel some confusion. Jim's point about whether it is noticeable in the cup is great! That is what counts. If something doesn't make a difference in the cup than the debate becomes as practical as a medieval discussion about how many angels there are on the point of a needle. 

For what it is worth, a roast at Agtron whole-bean 60 (say light/medium drip-filter roast) will equate to about 80 beans per 10 grams versus a roast at Agtron whole-bean 13 (say Italian or French very dark roast, depending what part of the country you are in) will equate to 90 beans per 10 grams. This is 12% more per cup on top of the greater percentage that has already been agreed to. 

Given that most of us either weigh the same amount of coffee for each brew of drip-filter or dose it to our own recommended level in a porta-filter, regardless of roast variations (Again assuming we are on planet earth, with who knows how many angels around!) I would suggest this is a substantial increase in caffeine not a 'negligible? increase, without wanting to get into semantics. 

And given that everyone's caffeine tolerance varies much like alcohol tolerance, it is hard to say how it affects individuals physiologically, but I would venture to say it is noticeable by most people. No data here, but certainly if you have an empty stomach because you've missed breakfast and you don't have milk with your first coffee of the day it is pretty easy to feel that caffeine hit. 

What Barry said is true in regard to quantifying the amount of caffeine. It is very difficult to quantify this in real-time due to the variability of how it is extracted; type of beans; how much the internal of the beans has been roasted; etc but in 10 seconds you can say to your customers: yeah in general a dark roast has more caffeine but also recommend they find their own enjoyment and tolerance level. At the very least they should definitely not be told there is less caffeine in a darker roast cup of coffee!


http://www.espressoquest.com

Instaurator

 

ostby Sean Starke on Tue Aug 14, 2007 3:36 am

Would it help to explain in terms of the serving size? It seems to me that's what the consumer cares about: how much caffeine is in my shot of espresso as compared to my 12 oz regular cup?

Sean Starke 
Coffee America (USA) Corp.

 

ostby Ric Rhinehart on Tue Aug 14, 2007 7:44 am

How many angels will fit on the head of a pin? This conversation is interesting but operating out of the realm of the real world. Please read this thread Starbucks vs Caffeinefor an interesting background discussion. 

Consider the enormously broad standards we apply to coffee. A shot of espresso needs 7-9 grams of coffee, a range in excess of 20%. A gold cup brew requires 3.25 - 4.25 ounces of coffee for 1.9 liters of water, a range of more than 20%. Green arabica coffee has caffeine content by mass of 1.0 - 1.4%, again a range in excess of 20%. A shot of espresso ranges from 1 -1.5oz in volume, a range in excess of 30%. Roasted coffee is 28 - 35% soluble...you get the picture. 

Caffeine is moderately soluble in water and is increasingly soluble with higher temperature. I would be willing to bet that solubility increases with pressure and with contact time as well, so throw in some more variables. All this without accounting for any operator errors. Complex question without an answer.

Ric Rhinehart

 

 

ostby Edwin Martinez on Tue Aug 14, 2007 8:38 am

Ric Rhinehart wrote:This conversation is interesting but operating out of the realm of the real world.



What does the real world have to do with anything? (i'm teasing, ric) 

I can appreciate the big picture and understand how context can turn a 180 on just about any hard fact statistic. But am glad to see coffeed is a place for the real world as well as the methodical mad scientist that continues to push the envelope. 

I learned something new this morning.

Edwin D. Martinez

 

ostby barry on Tue Aug 14, 2007 12:07 pm

Instaurator wrote:For what it is worth, a roast at Agtron whole-bean 60 (say light/medium drip-filter roast) will equate to about 80 beans per 10 grams versus a roast at Agtron whole-bean 13 (say Italian or French very dark roast, depending what part of the country you are in) will equate to 90 beans per 10 grams. This is 12% more per cup on top of the greater percentage that has already been agreed to.

Given that most of us either weigh the same amount of coffee for each brew of drip-filter or dose it to our own recommended level in a porta-filter, regardless of roast variations (Again assuming we are on planet earth, with who knows how many angels around!) I would suggest this is a substantial increase in caffeine not a 'negligible� increase, without wanting to get into semantics.




Except the data on caffeine content is based on mass of beans, so 1.3% caffeine, by weight, is 1.3% no matter what the density of the coffee. Bean count is irrelevant when dealing with mass. Sort of like the old joke, "which weighs more, a pound of feathers or a pound of gold?" D 

If you use 65g/l for drip brewing, then, ceteris paribus, the difference in caffeine content between two brews would be whatever difference in caffeine content there is between the two roasts, ie, most likely not significant, even though the light batch used 520 beans and the dark batch used 585 beans. In other words, the two brews made with 65g/l would each yield 845mg caffeine, even though the dark brew was made with 12.5% more beans, if the caffeine content is 1.3% by weight. 

So, what we need to know is what the relative caffeine content is based upon roast color. IIRC, the first edition of Illy had a table with this data in it. Unfortunately, that copy of mine is out on loan and I can't seem to find the equivalent data in the new edition. 

I don't think Sivetz addresses this, either, but I'll double-check to make sure. It's probably in Clarke, but I haven't that one.

barry

 

company: Coffee Projects Inc.

 

 

ostby barry on Tue Aug 14, 2007 3:33 pm

Okay, another way to look at it which might make things clearer (I hope). 

Browsing through Coffee Technology finds the assertion, "Hardly any caffeine is lost in the roasting." (Sivetz, pg 562) The following example is also provided, "...if caffeine is 1.0 percent in green coffee and there is a 16 percent roast loss, then 1.2 percent caffeine will result in the roast coffee." (Sivetz, pg 562). 

1% = 1g/100g sample. A 16% roast would yield 84g of coffee, with essentially that same 1g of caffeine. 1/84 = 1.19% 

So, let's spread this out a bit further. The assumption is that the absolute value of caffeine remains the same regardless of roast loss (note it's the absolute value, not any percentage value). 

1% = 1g/100g sample. A 15% roast yields 85g, for a final caffeine content of 1/85, or 1.17%. 

A dark roast, of 20% weight loss, yields 80g with that same 1g of caffeine, or a final content of 1/80, or 1.25%. 

So, there you go, a darker roast has more caffeine, by weight, than a lighter roast. In a 65g/l brew, ceteris paribus and assuming 100% extraction of caffeine, the medium roast would have 760.5mg of caffeine and the dark roast would have 812.5mg caffeine (or only 6.8% more caffeine). 

In a 300ml cup, that would be 228mg for medium and 243mg for dark. 

Much clearer that way.

barry

 

 

 

ostby Instaurator on Tue Aug 14, 2007 9:55 pm

Except the data on caffeine content is based on mass of beans, so 1.3% caffeine, by weight, is 1.3% no matter what the density of the coffee. Bean count is irrelevant when dealing with mass. Sort of like the old joke, "which weighs more, a pound of feathers or a pound of gold?" 



Yeah but a pound of caffeine is going to have more caffeine than a pound of feathers or a pound of gold. And that was the point I was trying to make in regard to the darker the roast, the more concentrated the caffeine. It won't stay at 1.3% if you go darker still. This is supported by the 6.8% Barry came up with. If the 1.3% Illy figure came from a 'Normale' roast that would be about 47-50 wholebean Agtron. If you go right down to a Agton 13 you have to make up your target weight for your brewer with more beans. This results in more caffeine per cup.

Instaurator
http://www.espressoquest.com

Instaurator

 

 

 

ostby zak on Mon Aug 20, 2007 10:04 am

Let me pose this, which may be rather moot. Let's say you roast a pound of bean A to a let's say a city roast but there are far more beans in a pound because as a green bean A weighs less than bean B and lets say you take bean B to a city plus. If bean A at this point is now lighter but after weight loss during roast is equal to bean B so will now take an equal amount of beans to obtain it's respective brew parameter say 7-9 grams for an espresso. Wouldn't it now be true that the lighter roast now contains more caffeine. 

Josh Longsdorf 
Ugly Mug Cafe

zak

 

www.Gaslightcoffee.com

:www.uglymugcafeandroastery.com

 

 

ostby barry on Mon Aug 20, 2007 11:00 am

zak wrote:Let me pose this, which may be rather moot. Let's say you roast a pound of bean A to a let's say a city roast but there are far more beans in a pound because as a green bean A weighs less than bean B and lets say you take bean B to a city plus. If bean A at this point is now lighter but after weight loss during roast is equal to bean B so will now take an equal amount of beans to obtain it's respective brew parameter say 7-9 grams for an espresso. Wouldn't it now be true that the lighter roast now contains more caffeine.



That depends upon the initial caffeine content in the green, and the roast weight loss of each particular roast. You've posed a problem w/o sufficient data to support your conclusion. 

Or, as I used to say in symbolic logic class, "If you're going to assume all that stuff in the beginning, why not just assume the answer and we can all go home early?" 

D

barry

 

 

 

ostby zak on Mon Aug 20, 2007 11:23 am

barry wrote:
Or, as I used to say in symbolic logic class, "If you're going to assume all that stuff in the beginning, why not just assume the answer and we can all go home early?"

D



I think you've kind of gotten to the point I was trying to make in that it will always depend on more variables than a barista may know. Therefore we cannot conclusively state one or the other. Every coffee is going to be different. The only thing we can actually state is that if a coffee is roasted to two varying degrees, the darker will have more caffeine. There are many baristas out there and I would venture to say most, even of the most well trained cafes, that do not have the background knowledge to the extent they need to answer a question about two or three or however many coffees they may have available. So if we are looking at the question "which has more caffeine?" from the perspective of some one serving the customer, how now do we answer it? 

Josh Longsdorf 
Ugly Mug Cafe

 

 

 

ostby barry on Mon Aug 20, 2007 11:37 am

Therefore we cannot conclusively state one or the other. Every coffee is going to be different.



The original hypothesis dealt with two roasts of the same coffee. Your's was two roasts of different coffees. With the former, it's clear that there is more caffeine, by weight, in a darker roast. With the latter, it all depends.

 

So if we are looking at the question "which has more caffeine?" from the perspective of some one serving the customer, how now do we answer it?



Again:

 

Jim Saborio wrote:
Should we be telling folks "Yes, dark roasts generally DO contain more caffeine than lighter roasts BUT the difference is negligible"?




This one.




In the above calculations, it was shown that the difference in caffeine between a 15% roast and a 20% roast was only about 6.8%. Some might feel that 6.8% is more than "negligible", but I'm not sure many folks would consider it "significant". 

So, perhaps you could say that the difference is "not significant"?

barry

 

 

 

ostby phaelon56 on Mon Aug 20, 2007 11:48 am

Am I missing anything here or can this be distilled down to a relatively simple description? 

Can we assume that caffeine is an inherent component in two identical weight samples (A and B) of identical green beans and that it's present in the same percentage by weight in each? And can we assume that loss of water weight, certain aromatics and other volatile components of the beans are responsible for the loss of weight when roasted? But that the actual weight of the caffeine remaining in each sample stays the same after roasting? 

I think the answer is yes to all these questions. 

Based on those assumptions and a further assumption that there is a greater weight loss experienced when roasting to darker levels than there is to lighter levels.... it seems very simple. 

If samples A and B have the same percentage of caffeine by weight prior to roasting but sample B is roasted darker and we then brew coffee using identical throw weights of both A and B - dark roast sample B should have more extracted caffeine in the cup. It just doesn't seem complicated to me even though the math and chemistry discussions have gotten very dense. 

I'd love to read the Starbucks vs. Caffeine discussion thread Roaster's Guild that Ric linked to but it's on the private rather than public side of that forum and you need to be a Guild member to read it. 

But the mention of Starbucks brings to mind the common public misperception of "dark roast = strong = lots-o-caffeine". I recall Consumer Reports doing a review of national coffee chains a few years back - Starbucks, Dunkin', Caribou et al. 

My recollection is that they measured caffeine content per ounce of brewed coffee and found Starbucks with its "signature dark roast profile" to have significantly higher caffeine levels than the others. But the higher percentage caffeine content was attributed to Starbucks using markedly higher throw weights of coffee per ounce of brewing water than the other chains.Thus if we brew two pots of coffee with our dark roasted Sample B and one of them is brewed with the Starbucks coffee/water ratio it should have a higher caffeine content - correct? 

Is it conceivable that this fact (assuming that it is a fact - can any Starbucks alumni confirm that for us?) is the primary reason for the misperception about dark roasted coffee having more caffeine? We can easily see from the specific percentages discussed it this thread that although there is "technically" a difference in caffeine content it is not statistically significant enough for any but the most highly sensitive to actually feel the difference.

Owen O'Neill
Syracuse NY

Phaelon Coffee
and
New York Central Coffee Roasters

phaelon56

 

I apologize, I was aware that yes when dealing with the same coffee a darker would have more caffeine. I had just put the question raelating to the customer into the realm which I have most frequently heard the question which is to find out which of the coffees we are offering has the highest caffeine.

zak

 

www.Gaslightcoffee.com

:www.uglymugcafeandroastery.com

 

 

ostby Brent on Mon Aug 20, 2007 2:34 pm

phaelon56 wrote:it seems very simple. 

If samples A and B have the same percentage of caffeine by weight prior to roasting but sample B is roasted darker and we then brew coffee using identical throw weights of both A and B - dark roast sample B should have more extracted caffeine in the cup. It just doesn't seem complicated to me even though the math and chemistry discussions have gotten very dense.



in simple terms, yes I think thats it...

Brent

Brent

 

: .

 

 

ostby Jack Hanna on Wed Sep 05, 2007 6:51 am

for last month or so i have been working on the caffeine subject.. 
its quite interesting certain aspects of caffeine. 

I have done some research at the Sydney University and have spoken to some people are certain independent research labs regarding the content of caffeine in cup, in different brewing technics vs roast vs species etc. 

One thing i have found is that Caffeine DOES reduce due to the colour of the roast, but not a large amount only 4% (at 45 agtron) 

My understanding of the module is that it has a very high melting point of 237degrees Celcius, (phys. chem lab Oxford), Its boiling point is however at 178Degrees Celcius.. 
However having said this, the caffeine molecule is fairly solvent in water, and the standarad rate of solubility is 
22 mg-mL'1 25 C 
180 mg-mL'1 80 C 
670 mg-mL'1 100 C 
There is also a standard loss on drying is based at 0.0005%,mg with Caffeine. 

Having said all of this, during the roasting process the caffeine within the coffee technically should not burn off in the process unless that the roast is taken above 237C. As Inny said that the organic matter is burnt off the darker the roast is completely true (Obviously due to the lower melting point in many oils etc) 

However the highly solubility of the caffeine molecule under high heat allows it self to be attatched to some of the water molecules in the organic matter, as we know during the roasting process a lot of the moisture content is lost due to heat, thus creating a "drying" process on the caffeine. Take into consideration that once the molecule is solvent and the boiling point is at 173 (which is easily reached in a roaster) thus the molecule starts to also evaporate due to its attatchment to water. It does not lose a great deal but it does lose content. once the drying process begins also after roast the caffeine again loses a slight content. 
The longer the roast means the more loss of moisture and thus the continuation loss of caffeine. This will only mean a higher % loss. 

based on my testing of the several espressos(ONLY) and its caffeine content via HPLC (high performance liquid chromatography)it averages out roughly to be 120mg per 30ml. @ 45 agtron

so by working backwards, we have lost already (without accounting for burning off) 0.06% caffeine purely from drying. the rest is accountable via roasting. 

So basically, the caffeine content IS affected by the colour of the roast but not a dramatic difference but still there is loss. 
However due to the loss of organic matter, the ratio of caffeine to organic matter is reduced infavour of caffeine, thus when brewing a darker roast you technically have SLIGHTLY more 

Hope this helps, please this is only meant to be submitted as a discussion point through my research.. 
and open for further discussion

Jack Hanna
World Latte Art Champion

Jack and the Bean
Artisan Espresso Coffee

http://www.jackandthebean.com
jack@jackandthebean.com

Jack Hanna

 

 

 

ostby Instaurator on Wed Sep 05, 2007 7:38 pm

Nice work Jack. I am doing some further research next week so we should compare notes.

Instaurator
http://www.espressoquest.com

ostby Andi Trindle on Sat Sep 08, 2007 8:01 pm

This is a good thread even though my head hurts a bit. I still had some confusion around this apparently and the last time I was asked the question (granted probably a good five years ago or so) I gave the wrong answer. Thanks for the info. 

It would be nice still to have it explained in a way that can be communicated quickly by a barista-- or any other coffee professional--who gets random questions, without pulling out the calculators. 

Did I miss it or can someone give the elevator pitch version? 

Best wishes, 
Andi 

Please forgive any small typos caused by a voice dictation.

Andi Trindle

 

 

 

ostby phaelon56 on Mon Sep 10, 2007 7:26 am

I'll take a stab at the elevator pitch... 

"If an identical coffee is available in both light/medium roast and a dark roast version then the dark roast version - from a strictly technical standpoint - has a higher percentage of caffeine per ounce of brewed coffee. But the difference is so minute that it's not noticeable to the coffee drinker." 

I'd also reserve this comment for those remaining doubtful: 

"If you've had a dark roasted 'strong tasting' coffee that seemed to have a distinctly more noticeable effect on you from the caffeine jitters standpoint it's almost certain that it was simply brewed stronger - i.e. more grounds were used per ounce of water and therefore it yielded a stronger tasting more highly caffeinated cup of coffee".

Owen O'Neill
Syracuse NY

Phaelon Coffee
and
New York Central Coffee Roasters

 

 

ostby Jack Hanna on Mon Sep 24, 2007 5:47 pm

after some more research the caffeine content in different roasts varies different beans... 
certain denser beans have a higher capacity to resist the drying off process and retain more caffeine in darker roasts, so the levels are similar however 
on a whole scale, averaging around 20 different coffees 

the average result between the coffees are around about 0.18% difference in favour toward the dark roast... 
so therefore as i mentioned previously that darker roasts do have a slight higher content due to the moisture organic loss. 

hope this helps, I’m off to drink some tea now. 

I am awaiting for some more results from Swiss Water for different ranges of caffeine levels in different coffees from different countries to compare.

Jack Hanna
World Latte Art Champion
http://www.jackandthebean.com/

 

 

ostby tonx on Tue Sep 25, 2007 9:43 am

Jack Hanna wrote:the average result between the coffees are around about 0.18% difference in favour toward the dark roast... 
so therefore as i mentioned previously that darker roasts do have a slight higher content due to the moisure organic loss.



just to clarify - is this difference based on measurements from equivalent green weight or equivalent roasted weight?

t o n x
http://www.tonx.org

 

 

ostby Instaurator on Tue Sep 25, 2007 2:30 pm

just to clarify - is this difference based on measurements from equivalent green weight or equivalent roasted weight?

This is with the different roast weights. I.e. 100g green bean roasted to agtron 47 will equate to 83g roasted and this roasted weight will have a higher percentage. 

"In relative terms it increases in absolute terms it decreases. " 

In some testing I have done with Swiss Water Decaf in Vancouver the prelinary results are quite astounding if you evaluate equivalent weights of dark and light roasts in terms of the overall caffeine differences. Once I have the full lab results and protocols I will post them.

Instaurator
http://www.espressoquest.com

 

 

For what is worth, the trial conducted at Swiss Water Decaf laboratory Vancouver utilising High Performance Liquid Chromatography (HPLC) analysis, resulted in  35% greater quantity of caffeine per espresso shot.   This was comparing a roast of approximately Agtron WB 47 and WB 60.  Obviously this is a significant increase in caffeine per cup between a dark and lighter roast. 

 

CONCLUSION:

The short and practical answer to people wanting to know whether a dark roast results in greater caffeine in your cup is: “Yes it does and the darker the roast the more the caffeine”.