Why do we twist Oreos apart — and why does the creme always only stick to one of the separated cookie wafers?!
A team of mechanical engineering students at MIT decided to get to the bottom of this conundrum. MIT News:
In an experiment that they would repeat for multiple cookies of various fillings and flavors, the researchers glued an Oreo to both the top and bottom plates of a rheometer and applied varying degrees of torque and angular rotation, noting the values that successfully twisted each cookie apart. They plugged the measurements into equations to calculate the cream's viscoelasticity, or flowability. For each experiment, they also noted the cream's "post-mortem distribution," or where the cream ended up after twisting open.
In all, the team went through about 20 boxes of Oreos, including regular, Double Stuf, and Mega Stuf levels of filling, and regular, dark chocolate, and "golden" wafer flavors. Surprisingly, they found that no matter the amount of cream filling or flavor, the cream almost always separated onto one wafer.
While the creme conundrum persisted, the researchers did notice something: it always stuck to the side of the cookie that was facing inward in the package, suggesting that "post-manufacturing environmental effects, such as heating or jostling that may cause cream to peel slightly away from the outer wafers, even before twisting."
There's a lot more to unpack in the full paper, titled "On Oreology, the fracture and flow of 'milk's favorite cookie®'," in the American Institute of Physics journal's Physics of Fluids special.
MIT engineers introduce the Oreometer [Jennifer Chu / MIT News]