Irish mathematicians have discovered tiny plant fibers can make nitrogen bubbles out of stout beer and form a creamy head of foam. The find could mean an end to more expensive and less-eco-friendly technology currently used to create fizz.

Nitrogen-infused stouts are known for their long-lasting and creamy heads, a feature that carbonated beers can’t emulate. But nitrogen doesn’t froth up on its own, so to get foam on a canned stout, brewers insert a widget — a small plastic ball with a hole in it. When a can is opened, the widget releases pressurized nitrogen into the beer, which then t...