Beer froth equation to aid perfect pint quest

Updated April 26, 2007 20:30:00

Scientists in the United States say they have devised an equation which could help solve the age-old question: why does the foam on a pint of lager quickly disappear, but the head on a pint of stout linger?

Writing in the British science journal Nature, Robert MacPherson from the Institute for Advanced Study in Princeton, New Jersey, and David Srolovitz from Yeshiva University, New York, say they have devised an equation to describe beer froth.

The breakthrough will not only settle the vexatious lager vs stout debate, it will also help the quest to pour a perfect pint every time.

Beer foam is a microstructure with complex interfaces.

In other words, it is a cellular structure comprising networks of gas-filled bubbles separated by liquid.

The walls of these bubbles move as a result of surface tension and the speed at which they move is related to the curvature of the bubbles.

As a result of this movement, the bubbles merge and the structure "coarsens," meaning that the foam settles and eventually disappears.

Three-dimensional equations to calculate the movement have been made by Professor MacPherson, a mathematician, and Professor Srolovitz, a physicist.

They build on work by a computer pioneer, John von Neumann, who in 1952 devised an equation in two dimensions.

The mathematics of beer-bubble behaviour are similar to the granular structure in metals and ceramics, so the equation also has an outlet in metallurgy and manufacturing as well as in pubs.


Topics: weird-and-wonderful, united-states

First posted April 26, 2007 20:23:00