A more efficient way of making an espresso could reduce the amount of coffee wasted per cup, potentially saving billions of dollars every year.
Coffee baristas must decide how finely to grind their beans and then set their machines in a way to exploit the flavours of the coffee compounds. Jamie Foster at the University of Portsmouth, UK, and his colleagues decided to investigate the best way to maximise yield from the smallest possible amount of coffee.
They created a mathematical model of the “basket” of an espresso machine, the cylindrical container that contains the ground coffee. “We had to capture how the water is flowing through this bed of packed grounds, and how various coffee chemicals move around and dissolve,” says Foster.