Irish scientists create perfect head on Guinness

Posted by Kate Taylor

As everybody recovers from St Patrick's Day, mathematicians from the University of Limerick say they have solved the problem of creating a perfect creamy head on a pint of Guinness poured from a can. 

They say their solution is cleaper than the standard 'widget', which does the job by releasing a jet of gas into the can as it is opened in order to create froth.

Professor Stephen O'Brien and the research team of Dr William Lee say that by examining the equations governing the physics of dissolved gases and fibres they discovered a potentially more cost-effective and green solution to creating the perfect head of stout.

"I was curious about foaming in stouts and sought to understand why the foaming mechanism in carbonated beers and champagnes did not work in stouts," says Lee. 

"Most beers and fizzy drinks are pressurised with carbon dioxide, however stouts also contain nitrogen in order to make them taste less acidic and to create smaller bubbles and a longer-lasting head.  This creates a problem though: stouts containing nitrogen will not foam spontaneously, and so the widget was developed to trigger foaming when the can is opened."

Dr Lee's solution is to coat the inside of the can with cellulose fibres. Pockets of air trapped inside these become seed bubbles, triggering the creation of more.