How to Build a Better Irish Beer

Note: this article also covers difference in Guinness in Ireland and abroad, as well as more information about how the widget works- PGA

Written by John Roach for

A customer drinks a pint of Guinness, in the Gravity bar at the Guinness storehouse, Dublin, in this file photo.

On St. Patrick’s Day, many a pensive imbiber will shake their empty can of Guinness stout and hear the rattle of the widget that gave their beer a foamy head. That idle pleasure could come to an end. Now, a patch of cellulose fibers is all that’s needed to get the magical foam, according to new research.

The makers of Guinness started adding the widget to cans of Guinness Draught in the 1980s. The plastic device sits in the top of the can and when the can is opened, the widget spews nitrogen and beer. This helps give the canned stout the same foamy head and creamy mouth feel as a pint poured in a pub.

Researchers at the University of Limerick previously showed that when champagne and other carbonated drinks are poured in a glass, bubbles form as the liquid hits fibers of cellulose — essentially dirt — on the surface of the glass.

“The cellulose fibers will either have been shed from the cloth used to wipe the glass dry or will have fallen out of the air,” William Lee, a lecturer in mathematics and statistics, who led the research, writes in a Q&A about the findings.

Applied to stout
The team, however, thought this mechanism didn’t apply to stout because when a canned stout without a widget is poured in a glass, bubbles didn’t form. This was thought to be due to the fact that nitrogen is added to stouts to reduce the acidity brought on by carbon dioxide.

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