The 5 factors that affect the caffeine content of coffee

Caffeine is a bit more complex than just a beverage that “keeps us awake”, and so are the interactions through which we effectively consume it. Let’s take a look at the factors that affect it.

Caffè Lab Editors
Caffè Lab Editors
caffè e miscele

We’ll start with one of our trusty old friends, Wikipedia:

“1,3,7-trimethylxanthine, IUPAC name 1,3,7-trimethylpurine-2,6-dione, better known as caffeine or theine, is a natural alkaloid present in the coffee, cocoa, tea, cola, guaranà, and yerba-mate plants and in the beverages obtained from them. At times it is referred to by its synonyms, guaranine and mateine, which are chemically identifiable in the same molecule.”

So caffeine is a bit more complex than just a beverage that “keeps us awake”, and so are the interactions through which we effectively consume it.

Even if we consider just the coffee itself, there are many stages during its processing in which it’s possible to reduce (or maintain or increase) the quantity of caffeine present in the individual coffee plant (yes, plant, caffeine isn’t only in the beans) that we effectively consume. But let’s try to understand this better…


Even in the worst bars in Caracas, if you ask about the type of coffee used, they’ll tell you that the blend is made up of two botanical species: Arabica and Robusta (or Canephora). 

The best bartenders in Caracas (but also in Viterbo or Treviso) will tell you that, on average, Canephora contains two times as much caffeine as Arabica. This explains why the first type of blends have a much higher caffeine content than 100% Arabica. To get scientific, we can say that caffeine accounts for 1-2% of the weight of an Arabica bean and 2-4% of a Robusta.

If we get down to the level of variety, rather than type (and in the bars of Caracas its pitch black down here), we see that some botanical varieties of Arabica have an extremely low caffeine content: in Laurina, for example, it’s as low as 0.4%, while a very rare and recently discovered type from Madagascar, that isn’t readily available for purchase, Coffea Charreriana, has no caffeine at all.


This might sound strange, but something else that influences the amount of caffeine in coffee is the altitude at which the beans were cultivated. Caffeine is, in and of itself, a poison which the plant develops in order to defend itself from insects and from various “diseases”. The higher the altitude, the less risk there is of mold and parasites. Therefore, a plant doesn’t need to defend itself against these and will have a lower caffeine content.

It seems that we’re all tamer in the mountains.

caffè e montagna


The first phase of a coffee bean’s stressful life is the roasting process. But how much does this affect the caffeine content?

Only minimally. In terms of the bean’s final weight, after roasting the percentage of caffeine will have increased, but only because, with evaporation, the total weight of the bean itself has decreased. 

Interestingly, if the caffeine is dark roasted, the final phase of the roasting process involves a phenomenon known as “pyrolysis”, in which the coffee begins to “burn itself”. In this phase there is a slight reduction in caffeine content, however a cup of this “super roasted” espresso will be perceived as fuller bodied and more bitter, and therefore “stronger”!


The time has come (finally, we dare say, since reading without a cup in hand makes us sleepy…) to make some coffee, but does the method with which we prepare it alter the amount of caffeine that we consume? 

Let’s start with the idea that the percentage of dissolved caffeine depends on:

  • how long the coffee (solute) was in contact with the water (solvent);
  • the relationship between the amount of water and the amount of coffee.

It’s easy to understand that the more coffee we’ve used and the longer it was in contact with the water, the more caffeine will be in the cup.

If, for example, we use 8gr to prepare Espresso, but 12-15gr for a cup of filtered coffee, then obviously the cup of filtered coffee will have more caffeine as compared to the Espresso. But the quantity of caffeine will also vary if the filtered coffee was made using a french press (a potentially longer contact time) or a V60 (shorter contact time). To complicate matters further, there’s the temperature of the water: the hotter it is, the more it extracts. Too complicated? Oh, come on! Try making a cup of tea with cold water…


We mentioned that a coffee which we perceive to be “strong” has usually been very dark roasted, to exalt its body and bitterness. If it were decaffeinated, we wouldn’t even notice!

So can we smell the aroma of caffeine in a cup of Espresso? Actually, no. The percentages are minimal and only a taste expert can discern between one that’s decaffeinated and one that isn’t, and this only by tasting the same coffee, prepared in the same way, and through comparison. In this case, we’ll notice a slightly higher acidity in the decaffeinated one.

So it’s hard to taste the difference, even though pure caffeine is very characteristic. It is, in fact, quite bitter. So much so that it’s used in tasting courses to help students understand what “pure” bitterness is. In moderation of course. Remember that caffeine is a poison and that 4gr of it is lethal!

caffè amaro