“One aspect I particularly like is its brittleness and what it does when it breaks,” says researcher Corentin Coulais, who teaches physics at the University of Amsterdam. To optimize mouthfeel, “we gave the chocolate a geometry,” he says, “that would then change the way it breaks.”
In order to give it “geometry,” a 3D printer had to be used to layer 72 percent dark chocolate in various ways. Instead of creating a flat, solid chunk, the machine printed it into a simple S-shape, or zigzagged super-thin layers back and forth multiple times, or swirled it into increasingly complicated spirals. The resulting pieces were fed to 10 eager volunteers. The researchers asked, “How crunchy was it?” “How easy was it to bite?” “How would you rate the overall impression?”
Most crunchy – and at the same time easy to bite – was the chocolate, which was swirled into rather intricate spirals. It was also the best taste experience. “More crunch meant people tended to like it more,” says Coulais.
The researchers also used a machine to crack open the different shapes and see which was the most brittle. They also recorded the sounds of the cracking, because a pleasurable eating experience doesn’t just happen in your mouth, but can be influenced by the sounds in your skull. The overall winner remained this spiral.
However, the spiral is not necessarily the best possible shape; it was simply the best of the few the researchers tested. “I’m sure there would be better ones if you searched more,” says Coulais. It is also not necessary to create them with a 3D printer; This was just a handy way to quickly try multiple options.
Whether chocolate will soon be made differently thanks to this research “is too early to say,” says Coulais. He’s working with a few organizations to see how it could be applied. He’s also helping to put together a team to study the physics of how things break in materials other than chocolate – materials that could be used in vehicles, for example, to make them less dangerous in an accident.
“The idea is to embrace failure,” he says. “If you get an impact of any kind, you know something is going to break.” If you can control how it breaks, “for example, maybe you can direct the energy of the impact away from the passengers.”
Understanding fractures could make life safer – in cars or planes or when wearing helmets. It might make those Halloween treats even tastier, too.
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