Happy St. Patrick’s Day – Enjoy your Guinness.
Stout is my favourite type of beer. One of the things that are fascinating about stouts, such as Guinness, are the bubbles. Firstly, beers are carbonated by carbon dioxide, but stouts use a mixture of nitrogen and carbon dioxide – this makes a creamier as well as less acidic taste and for a longer lasting foam head. Another thing is that the bubbles sink. Here’s the science and mathematics of sinking bubbles in Guinness, with the academic paper here.
On tap the bubbles are created by forcing the beer at high pressure through tiny holes as it is dispensed, the turbulence does the rest. This method obviously doesn’t work for canned beer and this is where the widget comes in. Apparently recent research suggests that bubbles in stout can be nucleated without the widget by potentially coating part of the can’s interior with cellulose fibres. Here’s the link to the research, with the submitted academic paper here.