Today, in a discussion with some friend I found out that there is a lot of confusion about how coffee is prepared and what is its caffeine content. Let’s look at it a bit more closely.
First of all, the coffee preparation is a process that technically is called solid-liquid extraction. The water (liquid) goes through the coffee, and in the meanwhile extracts the substances that will give it the taste and the consistence. In other words, it is water that acts as a solvent for certain substances contained in the coffee powder. The preparation of a coffee does not involve steam, and surely is not an extraction with steam! Two considerations make this clear: there’s nothing in a coffee machine that would condense the steam (the coffee comes out liquid), and the water does not actually boil in a good coffee machine, because the right temperature to obtain a good coffee is 92-93°C according to experts.
About the caffeine content, there is the widely spread idea that espresso is more concentrated and so it contains more caffeine than an American coffee. Actually, even if the caffeine content strongly depends on the type of coffee used (robusta quality has about 2.5 the caffeine content of the arabic one), one espresso contains from 30 to 90mg (average 40mg) of caffeine, while a generic brewed coffee contains from 102 to 200mg (average 133mg) of caffeine. You can read more data here.
Enjoy your coffee! 🙂