Good beer foam is an indicator of the quality and freshness of a beer. A typical head is 1.5 cm thick and consists of 1.5 million bubbles. Ideally, it stays stable, but most of the time the bubbles merge or burst and the head collapses. This behaviour is typical of all types of foam, be it in food or modern industrial materials.

One of the processes that make foam unstable is especially hard to stop. It is called Ostwald ripening, after the German chemist and Nobel Prize laureate from 1909, Wilhelm Ostwald, who already described this process 100 years ago. Hereby, bigger bubbles get bigger and bigger, whilst smaller ones shrink and disappear.

Innovation Society, St.Gallen. Posted: Sep 21, 2017.

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