Using words like “vapour” and “soluble,” the BBC digs tenaciously into the science of brewing. Yeast consistency, carbonation levels, lights exposure, and fun facts like this:
Cans of Guinness and a number of other brands have a “widget”, which is simply a ball with a small bit of beer inside. When the can is opened, the contents depressurise which forces the widget’s payload out through a pinhole.
“It’s like a bullet of Guinness passing through Guinness, if that makes sense,” says [Guinness brewer Gearoid Cahill]. “And that physical disruption to the beer actually triggers the nitrogen to come out of solution and form this swarm of bubbles. They will then rise very slowly to the top.”
A bullet of Guinness? That’s the kind of thing that makes science fun. Educate yourself and read the whole thing here.