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!…