Scientists find trick for longer-lasting foam

Tired of beer heads vanishing? Zurich researchers have found a method for producing more stable foam, with possible implications for both the food and construction industries.

The research, done at the federal technology institute ETH Zurich, aimed to tackle what’s known as “Ostwald ripening”: the classic process whereby foam disintegrates as large bubbles become larger and smaller ones shrink.

A solution to this, the scientists found, is to use special stabilisers. Adding specific particles to the mix can create an “irregular network structure at the bubble interface”, which can withstand pressure and help protect smaller bubbles from shrinkage.

Simulating the Ostwald ripening process in a mini pressure chamber allowed the researchers to pinpoint “precisely the pressure at which the bubble begins to shrink and finally collapse”, said Peter Beltrano, a member of the team.

Thus, having determined that surface stress was the prime parameter that needed to be controlled to prevent shrinkage, the researchers experimented with the volume ofparticles required to stabilise the bubbles. Their conclusions were recently published in the scientific journal PNAS.

Stable walls

So far, so scientific. But what about the applications? The findings are “universally valid for all materials with large surfaces or for applications in which surfaces play an important role”, said research group leader Jan Vermant.

And, though general, the results could have specific uses in the food industry. If edible stabilisers are isolated, they could be used to make foods like ice cream or bread dough last longer.

Even concrete, which is better able to resist the weakening effects of harsh freeze-thaw weather cycles when small stable bubbles are incorporated in its design, could benefit.

And beer? It might take a while before centuries-old brewing traditions come around to adding more ingredients to the mix, but if they do, your head might just last all the way to the bottom.