Foamy Beer Helps Prevent Spilling, and Now We Know Why

It turns out that beer foam serves a useful purpose. Adam Barhan [CC by 2.0]/Flickr

There are differing opinions about the benefits of having a healthy head of foam on your beer. Those who prefer a hearty head believe it's the sign of a fresh, healthy brew, while detractors might see it as the sign of a sloppy or stingy pour. But Princeton University researchers have made a discovery that scores one for the pro-foam crowd: Foam on a beer means it's less likely to spill, reports Morning Ticker.

Less spilling is surely something all heavy beer drinkers can appreciate — and this is a benefit that extends beyond just boozing. A foamy or frothy head on any kind of beverage (yes, this goes for coffee too) will help to ease the burdens of the clumsy drinker.

The answer as to why foam helps keep your drink in its container might seem obvious at first blush: The bubbly cap prevents liquid from sloshing around. But the science behind this phenomenon hadn't been uncovered until the Princeton team investigated.

The experiment began by filling a container with water, dish soap and glycerol (a substance used to make liquids more viscous). Five uniform layers of tiny bubbles were then created within the liquid, to reveal the effect of the different layers on the motion of the fluid.

Researchers then got to sloshing it around. As foam built up, they observed (using a high speed camera) how the behavior of the liquid began to stabilize. It was found that five layers of bubbles could lower the height of the waves in the liquid by about 10 percent. This is likely due to a diffusion of energy. Foam rarely comes into contact with a mug or glass, meaning it doesn’t share the energy burden bubbling liquids do.

Helping to solve the problem of beer spillage may not seem like a profound use of research time, but the Princeton team believes that their experiment can extend beyond the beverage industry. Businesses that deal in sloshing liquids of all varieties — for instance, the oil industry — could stand to benefit from the foam study.

"The potential applications are much bigger than just beer," said study author, Alban Sauret. "This study demonstrates that a relatively thin layer of foam effectively damps sloshing. Our findings suggest that foam could be used in various industrial processes in which sloshing needs to be minimized."