Kind of a strange question...
Suppose you brew your coffee to your liking, a v60 filter or an espresso. The ingredients are water and coffee grounds. But how much 'coffee' is there actually in the end cup? That is, if you would be able to extract the water from the cup; what percentage of the original cup of coffee would be left?
Has anyone ever read anything about this?
What I'm trying to get at is; the strength of a cup of coffee. Everyone uses the saying a strong cup of coffee when they quite often refer to the roasting. This could also be a reference to how diluted coffee is; e.g. an americano. But what percentage of that americano would then be 'real coffee'.