How to make the best crêpes
Researchers Mathieu Sellier (University of Canterbury, New Zealand) and Édouard Boujo (Hydrodynamics Laboratory, CNRS, École Polytechnique) recently appeared in Physical Review Fluids with a scientific article on the best method to make pancakes.
While this subject may appear trivial, the question of how to evenly apply a thin layer of material undergoing solidification goes far beyond the scope of family cooking.
It’s actually a crucial factor many industries must consider, in the manufacture of printed circuit boards, smartphone screens and solar panels, for instance, where the quality of the final product depends largely on the uniformity of the various superposed layers.
From a scientific point of view, making beautiful crêpes means determining the surface kinematics that will ensure the most even distribution of the batter, while also accounting for the fact that it rapidly loses its fluidity during the cooking process.
To find the solution, the researchers tried out two different approaches: a completely random trial-and-error method and an optimization approach based on the theory of optimal control. This mathematical practice involves effectively calculating how one variable—in this case, the thickness of the pancake—depends directly on another, such as the tilt of the pan, for example.
The second approach proved the most effective, as it was very easy to calculate how minute changes in rotational movement could influence the thickness of the crêpe.
So, what is the trick to obtaining the best crêpes in the end? Edouard Boujo, from the Hydrodynamics Laboratory of l'École Polytechnique, let us in on the secret: “Pour the batter into the middle of the pan, tilt it sharply to the side so that the batter runs sideways down it, then rotate your wrist for the batter to spread evenly over the rest of the pan, before turning it horizontally again to fill in any gaps.” If this seems very similar to how most people make their crêpes, we now know that it’s not just coincidence.
The next step in Mathieu Sellier and Edouard Boujo’s research will not be to explore the best way to flip their now-perfect pancake, but rather to develop potential practical applications of their simulations for those working in industry faced with problems in surface finishing.