Caffeine by the Numbers

Like a lot of you, I have a love affair with coffee.  By monitoring my withdrawal symptoms, I know I was a caffeine addict as early as 19.   But it took about 10 years before I figured this out.

I have done cursory studies on the caffeine amount in coffee/tea/soda over the years, but was frustrated because the presented facts were always incomplete, and often contrary.  Does espresso have more caffeine, or less?  The studies said yes.  

 The coffee/tea comparison was always muddled.  How much coffee, how much tea?  It turns out that the standard cup of coffee is 5 oz, or maybe 7oz.   I don’t know about you, but my smallest coffee mug is 14oz.  Dark roast vs light?  It turns out that dark is actually lower in caffeine.

I heard an article on the subject the other day, on a “WhatYou Should Know” podcast, that did a pretty good job of explaining things, and brought to light a few things I wasn’t aware of, and has made me think on this again.  So here is Caffeine, by the Numbers.

There are a number of factors that will affect the caffeine content of coffee.   

They are:

     Bean type, Arabica or Robusta.

     Grind, from coarse to Turkish

     Extraction, perc, drip, press Turkish or espresso.

     Roast, from dark to light.

With four vectors it is almost impossible to actually make a statement of how much caffeine is in a cup, aside from actually testing that specific cup.  So all you can do is imply, less or more.

Beans Type:  There are two types of beans, Arabica and Robusta.  Arabica beans are smaller, more flavorful, but have half the caffeine as the Robusta bean.  Arabica is more expensive, Robusta beans tends to be in the discount store brands.  Most coffee shops use exclusively Arabica beans.

The Grind:  Coarser grinds yield less caffeine for a process.  All other vectors being even, Turkish will yield double the caffeine over a coarse grind.

The Extraction Process:  French press has the least.  Drip the next, followed by percolated, espresso then Turkish.

The Roast:  Dark roasts are, slightly lighter on caffeine then lighter roasts.  The roasting process changes the caffeine per weight ratio.  The net effect is if you measure your coffee grounds by volume, there is less caffeine, but if you measure by your grounds by weight, there is more caffeine.  Mostly we measure by volume so there as small drop in the caffeine content.