(Of course, if you prefer a latte, cappuccino or flat white, the milk is a whole other story.)
Here is a little graphic of my own that I will use to describe what happens when we change our four variables.
On the horizontal axis we have relative time, on the vertical axis the numbers represent amount. The curves are extraction profiles.
Caffeine is very water soluble and the vast majority of the caffeine is extracted early. The volatile oils, which give coffee its complex flavour and aroma, extract more slowly. The organic acids, which make coffee taste bitter, are extracted the most slowly of all.
So let’s go through each of our four variables in turn.