# Long steeps and caffeine levels



## urbanbumpkin (Jan 30, 2013)

In the last year I've really gotten into longer brew times using Sowdens, CCD and even the Aeropress and I really like the sweeter tastier brews they produce.

However does the longer brew times greatly increase the caffeine levels?

The reason I ask is because this was raised on Beans Not Machines by someone who couldn't get their head round the longer brew time concept. They thought it would produce strong stewed coffee with tonnes of caffeine in it.

I've never felt it significantly did raise caffeine levels but wondered if anyone knew the actual answer.


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## garydyke1 (Mar 9, 2011)

Anecdotally - I feel caffeine more off under-extracted espresso than well extracted shots . Brewed I've not really noted much of a difference


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## MWJB (Feb 28, 2012)

In immersion brew tests performed by MIT in the 50's they found that caffeine extracted pretty much in proportion to the total extraction yield, so no reason to expect that, unless you are severely overextracting (very unlikely with a declining temperature steep), you should have a higher than normal dose of caffeine.

My long steeps are often at fairly low brew ratios (52-52g/l in a Sowden, up to 58/59g/l in a big French press), so it's possibly more related to brew ratio & dose size as much as anything else. E.g. two brews with the same amount of water 67g/l for 4 min could have slightly more caffeine than a 52.5g/l brew that takes an hour.

Coffee doesn't typically taste "stewed" like tea can, though some very soluble coffees (Kenyans) might be pushing it?

It's best to think about long steeps as hitting a desirable extraction, rather than thinking about the time specifically...as the temp drops, they naturally need more time to do this. A long steep, kept at a constant high temp, would be another matter.


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## MWJB (Feb 28, 2012)

Overlapping with the caffeine thread - roasted Arabica might typically be ~1.2% caffeine, pretty much all of that is extracted in a well extracted immersion brew, so whether you steep for 10 minutes or 10 days, with a declining temp brew, the caffeine content of the beverage (same brew ratio & dose) won't be greatly different.


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## urbanbumpkin (Jan 30, 2013)

Cheers MWJB. So do robusta beans release more caffeine (as well as tasting like burnt rubber).


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## MWJB (Feb 28, 2012)

urbanbumpkin said:


> Cheers MWJB. So do robusta beans release more caffeine (as well as tasting like burnt rubber).


They are though to typically contain twice the caffeine of Arabica.


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