The Magic of Beer and Magnets

Beer foam is a noted fun-killer. Few things ruin the enjoyment of a cold one more than having your hands and clothes drenched in your drink. But now, Belgian food scientists have found a way to prevent this party-foul: with magnets!

So what causes a freshly opened, unshaken beer bottle to overflow? The main culprit is a protein called hydrophobin which dwells within the drink. Hydrophobins are created by a fungus that infects malt grains during the brewing process, attracting carbon-dioxide molecules within the beverage to the surface. Too many carbon-dioxide molecules at the beer's neck can cause the bottle to bubble over when it's opened, much to breweries' chagrin. This spontaneous foam overflow, called gushing, is a different process than what produces a frothy foam head in a freshly poured glass.

To thwart the hydrophobins, brewers add extra hops into the mix. The hops, in addition to giving beer a bitter taste, act as an antifoaming agent that prevents the proteins from binding with carbon dioxide. But even with extra hops, beer can still erupt like a sudsy volcano. The Belgian scientists decided to try magnets after noticing that magnetic fields can disperse particles and help emulsify mayonnaise. So the team brewed a batch of beer in the Belgian Orval Brewery and after adding in the hops, passed the concoction through a glass tube that had a magnet wrapped around it.

What they found was that when the brew passed through the magnetic field, the hops broke apart and spread throughout the beverage, effectively increasing their surface area. With more surface area, the tiny antifoaming particles bound with more hydrophobins than whole hops could, the team reported in a paper set to appear in the January edition of the Journal of Food Engineering.

After the brew was complete, the team found not only that magnetized beer produced less foam, it only took a minute to achieve the results. The information allowed them to experiment with adding less hops, effectively making the beer less bitter.

This article was originally published at http://www.theatlantic.com/technology/archive/2014/12/how-to-keep-beer-from-foaming/383775/