As any bartender will tell you, getting a nice, frothy head on a pint of beer is an art form. There’s also plenty of science involved, too, and new research sheds light on exactly how that tasty foam appears on top of your beer.
In a new study, published in the journal Chemical Communications, researchers at the University of Manchester in the U.K. made a big step toward understanding how the additives in a liquid arrange themselves to create and stabilize foams—including those found in a pint glass.
To be clear, scientists already have a good understanding of how foam is made from relatively pure liquids. But the way foam forms in liquids with many additives—like beer, for example—is more of a mystery.
“For decades scientists have tried to get a handle on how to control reliably the lifetime and stability of foams,” lead researcher Richard Campbell said in a University of Manchester news release.
To explore what’s happening in these complex liquids, Campbell and his team headed to the Institut Laue-Langevin in France, which has one of the world’s most powerful neutron beams. By firing beams of neutrons at liquids, the researchers could study the way the neutrons reflected off the surface of the liquid. With that data, they could draw conclusions about the way molecules in the liquid were behaving.
To assess how foam behaves in real-world situations, the researchers created a liquid with a similar chemical composition to foaming products like beer and shampoo. By firing neutrons at this sudsy test liquid, they learned more about how the molecules behave within the foam. Most importantly for beer drinkers, they found that the way additives—such as the ingredients in an ale or lager—link up on the individual bubbles of the foam has a big affect on how long the foam lasts.
“It was only through our use of neutrons at a world-leading facility that it was possible to make this advance,” Campell said. “Only this measurement technique could tell us how the different additives arrange themselves at the liquid surface to provide foam film stability.”
The new discovery could help brewers formulate beers that have a head that lasts all the way to the last drop. Of course, the research has big implications beyond beer, too: It could help make more effective shampoos and laundry detergents, and improve firefighting foams and the substances that are used to soak up oil spills.
We’ll drink to that.
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