I just searched the forums and was surprised to find no discussion of this topic.
The best post I found is reproduced below, so that responses to this one don't re-cover the same old grounds.
My Keurig first produces output 10 seconds after hitting 'Start', and doesn't drip another drop after 35 or 40 seconds. My drip maker takes about 600 seconds for an 8-cup pot. What effect does the high-speed brew have on caffeine content? Surely not 40/600 ths!! (which would be 7%, or 7mg of caffeine for every 100mg in some reference dripmaker cup)
A Wikipedia 'Caffeine' footnote is relevant, but it addresses repeated steepings of tea, and deals in a time granularity of "about 5 minutes".
Lots of folks speculate that steeping time impacts caffeine content. OK, I'll guess that it does too. But how much? Google doesn't seem to know, and I emailed Customer Service at Keurig a week ago and have received no reply at all.
My guess is that single-serve coffee has about half the caffeine of drip.
=================== Best Prior Post, 4.8.2006 ===================
Joined: 07 Nov 2005
PostPosted: Sat Apr 08, 2006 2:39 pm Post subject: Re: Musings on Caffeine Reply with quote
Ingrid these are great questions that I think if we get answered to our satisfaction then the discussion on these forums will be a lot clearer. Also a great weekend discussion. Below is how I think about the points you bring up. Hopefully others will chime in and correct my errors and we can all get on the same page.
In general I believe that a stronger cup of coffee will have more caffiene. To me a stronger cup of coffee is one with a higher amount of the coffee oils and solids extraxted into a given volume. So the more coffee extracted the higher the caffeine. This would be true regardless of the type of bean extracted. To my mind the biggest misconception, and this has now been discussed in a number of topics here, is that many relate strength of the brew and darkness of the roast. To me strength and roast level have no relationship, strength is determined by extraction of coffee oils and solids and roast is a factor that dermines flavor.
There is more caffeiene in green beans than roasted beans and more in a light roast than a dark roast. The heat required for roasting can break down caffeine. I don't know what the difference is as a percentage change through each stage, maybe someone else can help us out there. There are a number of other things that can affect this. How do you grind and measure your coffee? There is more water removed as you continue roasting, so the amount of coffee for a given weight will be different, this will make a pretty small difference for the amount of coffee we prepare at one time. The finer you grind the more coffee you can get into a given volume such as the standard scoop measures that come with coffee machines. I think this would make a bigger difference to the general methods of prpearing coffee. Also how you make your coffee will give different extraction and therfore change caffeine levels. French press will be higher than drip or any of our single serve machines.
The type of beans make a big difference. The main one is that robusta beans (the type in the much cheaper supermarket isles) have more caffeine than arabica beans (the stuff with the great flavor that we all crave). The caffeine levels will vary a little within these two type of beans because of slight varrietal differences and more importantly different growing conditions.
To me the "espresso effect" is all marketing. Espresso is my preferred drink and I think there is less caffeine. In someways it mirrors the Starbuck effect that has happened. Starbucks have very dark roasts and have relied on the darker equals stronger equals more caffeine misconception I mentioned earlier.
We all have different physiology and our own physiology changes. So yes you can develop tolerances to caffeine, and how caffeine affects you now may be different to how it used to affect you and how it may affect you in the future. But it is having an effect. Try giving it up for a week and see how many Advil you go through. Headaches are the most common withdrawal symptom.
I don't choose a particular coffee solely for its caffeine. My guess is that most on these forums are so interested in coffee that they are here for flavor first and caffeine way down the list, probably second. Wink If you were to select for caffeine first I would recommend your favorite commercial, comes in a big can, brand of coffee that is light to medium roast and has a high level of robusta beans. If you brew that up in your French Press you should get a good jolt. Flavoring coffee has no effect on caffeine levels it is all determined by the coffee used. In fact often lighter roasts are used so caffeine may be higher.
Decaf will taste different because of the caffeine extraction process. It uses solvents or water to remove caffeine from the beans. The caffeine is removed from this soup then they try to return the flavor components to the beans. There is no way you can do this without altering the flavor of the bean. than doesn't mean that you won't find some very drinkable decafs, there are many of them. But bottom line is that in general the untreated bean will taste better than the treated bean, so we go back to caffinated beans more often.