Few sights at a bar are more deflating than a bottle of beer overflowing with foam. This overfoaming, called gushing, arises when fungi infect the barley grains in beer’s malt base. The microorganisms latch onto barley with surface proteins called hydrophobins. During the brewing process, these hydrophobins can attract carbon dioxide molecules produced by the mashed barley as it ferments, making the beer far too bubbly. Brewers try to tamp down the gushing by adding hops extract, an antifoaming agent that binds to the proteins first.
Now, food scientists in Belgium have hit upon a technological solution: magnets. When the team applied a magnetic field to a malt infused with hops extract, the magnets dispersed the antifoaming agent into tinier particles. Those smaller particles were much more effective at binding to more hydrophobins, blocking carbon dioxide and decreasing gushing, the team will report next month in the Journal of Food Engineering. During tests in a real brewery, the magnets decreased excess foaming so effectively that brewers needed much lower amounts of hops extract—a potential cost-saving measure. Future studies could explore whether magnetic fields alone could reduce foaming on an industrial scale, the team says.