1224ctt foaming beer lo res

[Image above] Credit: Matt King; Flickr CC BY NC-SA 2.0

Ever open a beer only to be met with a gushing front of frothy bubbles?

Although sneaky pranksters can also induce overfoaming with a little tap to an open bottle (science behind that here), gushing without bottle tampering can be blamed on little molecules called hydrophobins.

Freakin’ hydrophobins.

But don’t fear for your beer—Belgian researchers say that magnets may be able to help.

Hydrophobins are surface active molecules that are found in fungi. Although they’re part of normal fungal function by providing attachment to solid surfaces, hydrophobins are no fun in beer.

Hydrophobins get into beer from fungi present on the grains, like barley, that go into beer brewing. Once in the beer, the molecules cause gushing because they self-assemble and create nucleation sites for CO2, cascading an onslaught of bubbles when the beer is opened.

1224ctt beer foam lo res

Bubbles! Credit: Evan Leeson; Flickr CC BY-NC-SA 2.0

Throughout the long history of beer, food engineers have proposed a myriad of solutions to decrease hydrophobins in brew. One popular strategy today is to add hop extract (which is just what it sounds like) to bind and neutralize hydrophobins. Extract molecules tends to aggregate, however, so better ways of dispersing the extract would allow it to work better as an antifoaming agent.

After successful use of magnets for mayonnaise emulsification, a team of researchers from the University of Leuven (Belgium) wondered whether magnets could also have a place in beer brewing to distribute hops extract.

The team’s research, published in the Journal of Food Engineering, shows that magnets can effectively break up hop extract into smaller particles—increasing surface area of the extract to interact with hydrophobins—which helps the extract suppress foam more effectively.

Less extract to achieve the same antifoaming activity means savings to brewers and also less effect on the beer’s taste (because hops add a bitter—although sometimes desirable—flavor). According to the paper, one brewer (Orval Brewery) that is already using a magnetic dispersal system gets the same antifoaming effect by adding just 30% of the recommended amount of hop extract to their brew—which equates to significant savings for the brewery.

Hooray, beer—and hooray, magnets!

The paper is “Effect of a magnetic field on dispersion of a hop extract and the influence on gushing of beer” (DOI: 10.1016/j.jfoodeng.2014.08.008).