Cheering 2020 with the perfect beer head

A team of scientists is a step closer to solving the puzzle of how to create the perfect head of beer and make it last all the way to the bottom of the schooner.

Lead researcher Dr Richard Campbell from The University of Manchester said his findings solve a long-standing mystery related to the lifetime of foams.

The scientist, whose study is published in the journal Chemical Communications, turned to the Institut Laue-Langevin in France for one of the world’s most intense neutron sources.

At the research facility, he fired beams of neutrons at the liquids used to make foams.

Dr Campbell said: “For decades scientists have tried to get a handle on how to control reliably the lifetime and stability of foams made from liquids that contain mixed additives.

“While the behaviour of foams made up with just one additive is quite well understood, as soon as mixtures like those used in products were studied the results from research studies failed to paint a consistent picture.”

The team studied mixtures containing surfactant — a compound that lowers surface tension — to come up with a new way of understanding the samples that could help product developers formulate the ideal foam.

In one potential application, beer drinkers might be able to enjoy a pint where the head lasts all the way to the bottom of the glass.

“This is important, as some products benefit from foams that are ultra-stable and others from foams that are very unstable.”

The scientists got to grips with the problem by studying the building blocks of the bubbles themselves, known as foam films.

Through reflecting neutrons off their liquid samples, they devised a new way to relate the stability of foam films to the way in which the additives arrange themselves at the surface of the liquid coating of bubbles to provide the stability needed to prevent them from bursting.

“Foams are used in many products — and product developers have long tried to improve them so they are better equipped for the task they are designed to tackle,” Dr Campbell added.

“But researchers have simply been on a different track, thinking of general surface properties and not about the structures created when different molecules assemble at the surface of bubbles.

“It was only through our use of neutrons at a world-leading facility that it was possible to make this advance because only this measurement technique could tell us how the different additives arrange themselves at the liquid surface to provide foam film stability.

The paper ‘New structural approach to understand the foam film stability of oppositely charged polyelectrolyte/surfactant mixtures’ is published in Chemical Communications.

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