Maths experts zero in on secret to perfect espresso

It's all in the grind, say mathematicians who turned to equations to solve mystery

What's the secret of the perfect espresso? It's a question that has long troubled cafe owners around the world, but now mathematicians say they have worked out the formula for achieving the perfect brew - and it all comes down to the daily grind.

"There is a common experience, particularly for people making coffee in their homes, and baristas as well, that you brew two espressos one after the other, you use the same ground coffee and seemingly you brew it in exactly the same way, yet the two shots can taste quite different to one another," said Dr Jamie Foster at Portsmouth University, a co-author of the research.