Tiny Bubbles in My Food

Amid the negative reports and editorializing about the horror of Big Food and how everything we eat is likely to make us fat, unhappy or prone to develop 1,001 deadly diseases, it’s always nice to see a bit of food-science geekery pop up in the news. In this case, it’s the announcement by Nestlé that the company is using zero-gravity research to develop a better understanding of foam technology to better apply it to designing food and beverage products.

In a July press release, the company explained that scientists at the Research Center in Switzerland are working with the European Space Agency (ESA) on experiments designed using parabolic flights’ temporary lack of gravity to produce the “perfect bubble.” Why zero gravity? It turns out that one of the forces acting against a stable foam is gravity, because it causes the liquid film between the bubbles to flow downwards. Gravity can cause the film to break, which makes the foam collapse. In addition, the weightlessness in zero-gravity conditions causes bubbles to be evenly dispersed rather than floating to the top. How cool is that?

The scientists loaded six small samples of water and milk protein in an instrument that analyzes the structure of foam on the ESA plane. You’ve probably seen those aircraft where people get to experience momentary weightlessness—and sometimes accompanying nausea. The plane made 30 parabolas, each of which creates about 20 seconds of weightlessness where the measurements could be taken. “During those short periods, we study the milk protein closely to see if it makes foam and how stable the bubbles are,” said Dr. Cécile Gehin-Delval, a scientist at the Nestlé Research Center. “Gaining a better understanding of foam may help improve the texture of our products.” The stability of foams is an important factor in everything from beer to whipped topping to avant-garde culinary foams. Research is also showing that manipulating the aeration of certain products, like ice cream, can create consumer-acceptable texture and mouthfeel with a lower calorie count.

This is just one step in a line of inquiry. The science of bubbles, or foams, is actually quite complex and not entirely understood. A 2010 Scientific American article that discusses foam physics tells us that the bubbles within foams seem to somewhat inexplicably form a structure that obeys three universal rules indentified by Belgian physicist Joseph Plateau in 1873. No. 1: Whenever bubbles join, three film surfaces always intersect at every edge. No. 2: Once stabilized, each pair of intersecting films forms an angle of exactly 120°. No.3: Wherever the edges meet at a point, there are always four edges, and the angle is always the inverse cosine of -1/3 (about 109°). Bubbles that do not follow the rules quickly pop, as do bubbles that are too small to withstand the resulting surface tension.