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Roast and caffeine
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Discussions > Coffee > Q and A > Roast and...  
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jpender
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Posted Thu Jul 18, 2013, 4:31pm
Subject: Roast and caffeine
 

For a given type of coffee....

How does the degree of roast, light to dark, affect the amount of caffeine in the coffee on a per weight basis?

How does the degree of roast, light to dark, affect the extractability of caffeine from the coffee?
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NobbyR
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Posted Thu Jul 18, 2013, 11:03pm
Subject: Re: Roast and caffeine
 

As a general rule, roasting reduces the amount of caffeine contained by the beans. Depending on the variety, green beans contain about 0,92,6% of caffeine and roasted about 1,32,0 %. However, the roasting level only affects that by permille. The amount of coffee extracted largely depends on the brewing method. A single shot of espresso has less caffeine than a cup of drip coffee, when made of 7 g of ground coffee, because extraction happens a lot faster.

 
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CoffeeLoversMag
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Posted Fri Jul 19, 2013, 4:13am
Subject: Re: Roast and caffeine
 

Caffeine content is affected by the roasting level. As you increase the roasting level, caffeine diminishes. The different roast levels contain respectively different caffeine levels when measured by volume or mass because the density of coffee changes but the bean has still the same caffeine level.

Degree of roasting also affects the extract-ability of caffeine. It is observed that the higher the roasting level, the bitter the taste. Meaning, more caffeine is extracted when it is high roasted.

 
Did you know...? Dark roast coffees actually have less caffeine than lighter roasts due to the fact that the process of roasting burns off caffeine.
www.coffeeloversmag.com/theMagazine
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jpender
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Posted Fri Jul 19, 2013, 11:38am
Subject: Re: Roast and caffeine
 

NobbyR Said:

As a general rule, roasting reduces the amount of caffeine contained by the beans. Depending on the variety, green beans contain about 0,92,6% of caffeine and roasted about 1,32,0 %. However, the roasting level only affects that by permille. The amount of coffee extracted largely depends on the brewing method. A single shot of espresso has less caffeine than a cup of drip coffee, when made of 7 g of ground coffee, because extraction happens a lot faster.

Posted July 18, 2013 link

Nobby, it seems weird that the range for roasted coffee would be narrower. Was that a typo? Also are these values a percentage by total mass or by dry mass?
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Flori
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Posted Sun Jul 21, 2013, 11:33pm
Subject: Re: Roast and caffeine
 

they are correct. the longer you roast, the lower the caffeine level would be.

flori
blogger, coffeeloversofworld.com
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Netphilosopher
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Posted Mon Jul 22, 2013, 5:37am
Subject: ...
 

...
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jpender
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Posted Mon Jul 22, 2013, 8:47am
Subject: Re: Roast and caffeine
 

Question: "For a given type of coffee....How does the degree of roast, light to dark, affect the amount of caffeine in the coffee on a per weight basis?"

So far we have one person who says the amount of caffeine per mass of coffee diminishes by a very small amount, one who says it increases by a very small amount, two who say it decreases but shy away from estimating by how much, and zero who offer any credible source for their claim.
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Netphilosopher
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Posted Mon Jul 22, 2013, 9:30am
Subject: ...
 

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jpender
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Posted Mon Jul 22, 2013, 10:45am
Subject: Re: Roast and caffeine
 

Netphilosopher Said:

Caffeine that's present in the green coffee remains intact throughout the roasting process.

So, if you have 1200mg of caffeine in a sample of green coffee (that maybe weighs 117.5g) and has about 1.02% caffeine by mass,

after roasting the sample will weigh around 100g if roasted darkly (and be about 1.2% caffeine), or it will weigh about 105g if it contains 5% moisture and is roasted lightly with same amount of caffeine (and contain about 1.15% caffeine by mass.

Most high-grade coffees will be 3% or less moisture by mass.

Posted July 22, 2013 link

Caffeine sublimation occurs to some extent and that would tend to decrease caffeine per mass of coffee as the roast progresses. But there are other mass losses during roasting which would increase the caffeine per mass of coffee. It's not obvious to me what the balance is.

Moisture is of course one of the things that is lost from green coffee during roasting. But do darker roasts really have a lower moisture content than lighter roasts? The half a dozen or so times I've oven dried freshly ground coffee I didn't see that correlation. Even if it were true for coffee straight out of the roaster certainly age and storage conditions matter a lot.

Anyway, I have seen the claim that darker roasts have less caffeine a number of times (twice recently here on CG) and was curious if it was true and, if so, if it was significant.
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Netphilosopher
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Posted Mon Jul 22, 2013, 12:11pm
Subject: ...
 

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