Posted in: Science Posted: February 25, 2015

Beer Foam: Scientists Defend Bartenders Who Ensure You Beer Glass Is Frothy – Foam Prevents Spillage.....

Beer foam has never been a desired trait on a tall glass of pint, but scientists claim that the foam plays a very vital part. The foam on top of your beer glass ensures lesser spillage.

Fluid physicists from Princeton and the École Normale Superieure de Cachan in France have concluded that beer needs a foamy upper-crest to ensure it doesn’t spill. They drew the conclusions after studying the fluid dynamics of beer and more importantly by noticing beer “sloshes around” less than water when the bartender hands out a cold one to you. Explaining the inspiration behind the study, Alban Sauret, a scientist at the French National Center for Scientific Research said,

“While I was studying for my PhD in the south of France, we were in a pub and we noticed that when we were carrying a pint of Guinness…the sloshing almost didn’t happen at all,”

Sauret followed up on the pressing scientific enigma and according to him it’s the foam that stops beer from sloshing all around the place, where water would have easily spilled. Through experiments that involved high-speed cameras, water and glycerol, researchers found that the foam atop beer acts “as a stopper”.

image: http://cdn.inquisitr.com/wp-content/uploads/2015/02/setup.jpg

High Speed Camera Recordings Proved The Foam Prevented Beer From Sloshing Around Much

According to the authors of the study, when a bartender hands a customer a pint, the movement creates tiny waves in the drink. This is not a common practice for all drinks because bartenders tend to place other beverages very carefully, ensuring no spillage. But they are generally sloppy when it comes to beer.
When these tiny waves become too big, the beer tends to spill over. In many cases, these waves can be considered as ripples in the pond which get gradual reinforcement and eventually become too much. However, the frothy foam “helps to dampen those waves”.
Interestingly, there is an additional function that the foam serves. Owing to surface tension, the foam atop the beer clings to the edge of the glass and not only makes these tiny waves “shorter” in height, but also act as an anchor for the liquid that is trying to leave the confines of the glass.
The same principle applies to all frothy drinks, promise the scientists. Foam-topped drinks like lattes too, would spill a lot more if they were served without the foam. Researchers suggest people to observe glasses of plain water or cups of plain black coffee and the importance of foam will become clear.
All the research behind a small amount of foam is not just to help bartenders justify serving a little less beer, assure the scientists. Foam can work as an industrial dampener while transporting liquids like oil or pressurized gasses which are in liquid form. Adding a little foam to such liquids should reduce sloshing and ensure safety while transportation.