Coffee: Unevenly packed grounds to blame for weak espresso, say mathematicians

Grinding coffee beans too finely makes espressos weaker and now mathematics can explain why.

Inside of an espresso machine, boiling water moves through a bed of ground coffee under high pressure. One factor used to rate the resulting espresso is called extraction yield, which is a measure of how much of the coffee dissolves in boiling water during the brewing.

In 2020, William Lee at the University of Huddersfield in the UK and …