Science of perfect espresso uncovered

The formula for the perfect cup of espresso has been unveiled by scientists and contrary to popular belief the secret is fewer beans, ground more coarsely.

According to mathematicians at the University of Portsmouth and the University of Oregon, the problem lies in the fact that grounds are often packed so tightly that they form clumps which water cannot pass through.

The scientists concluded that using 15 grams of coffee rather than 20, at a coarser grind, and letting the water run for just seven to 14 seconds, instead of the usual 25, gives the best flavour, and prevents any bitterness from occurring, the Telegraph reported.

Baristas normally say that the finer the coffee grinds, the more efficient the resulting brew due to an increased surface area of the coffee beans. But Jamie Foster at the University of Portsmouth and his colleagues found that their mathematical model showed that using slightly coarser ground coffee resulted in better mixing.