What do chocolate and concrete have in common? More than you might think.

Chocolate is made by mixing liquid and finely ground cacao beans in a device that bears more than a passing resemblance to a cement mixer. In both cases, stirring tiny granules in a fluid results in a substance with very specific properties — for chocolate, it’s a meltingly smooth mouthfeel, and for concrete, it’s a cohesive, consistent texture.

However, while physicists have studied the physics of mixing concrete, fewer have taken a close look at the forces at work in chocolate conching, as the process is called. Now a team of physicists, funded in part by Mars, the confectionary company, published a paper last week in the Proceedings of the National Academy of Sciences showing just what happens as the ingredients of chocolate are given a stir on their way to becoming a delicious treat.

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When conching was invented in 1879 by Rodolphe Lindt, it could take more than a day of steady mixing for gritty chocolate to grow smooth. Today, it is a shorter process. For this study, the researchers spun cacao powder and a bit of oil in a conching machine for 40 minutes. They took photographs as the stuff went around, then added a different oil that reduces friction during the final phase, which lasted an additional 20 minutes.