This document discusses the process of making espresso coffee. It begins with an introduction to espresso coffee consumption and caffeine content. The main concepts covered include percolation, which is the extraction of coffee solids and flavors from ground coffee beans using hot water under pressure. The key parameters for percolation in an espresso machine are water temperature of 90 degrees Celsius, an inlet pressure of 9 atmospheres, and a percolation time of 30 seconds. In conclusion, making a good espresso requires understanding percolation as the essential extraction stage.
