Despite having been around for well over a century, the Oreo cookie has managed to retain certain mysteries. Why, for example, does it never come apart evenly? Though different Oreo-eaters prefer different methods of Oreo-eating, an especially popular approach to the world’s most popular cookie involves twisting it open before consumption. That action produces two separate chocolate wafers, but as even kindergarteners know from long and frustrating experience, the crème filling sticks only to one side. It seems that no manual technique, no matter how advanced, can split the contents of an Oreo close to evenly, and only recently have a team of researchers at the Massachusetts Institute of Technology sought an explanation.
This endeavor necessitated an investigation of the Oreo’s rheology — the study of the flow of matter, especially liquids but also “soft solids” like crème filling. Like all scientific research, it involved intensive experimentation, and even the invention of a new measurement device: in this case, a simple 3D-printable “Oreometer” (seen in animated action above) that uses pennies and rubber bands.
With it the researchers applied “applied varying degrees of torque and angular rotation, noting the values that successfully twisted each cookie apart,” writes MIT News‘ Jennifer Chu. “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.”
Crystal Owens, a mechanical engineering PhD candidate working on this project, puts this down in large part to how Oreos are made. “Videos of the manufacturing process show that they put the first wafer down, then dispense a ball of cream onto that wafer before putting the second wafer on top. Apparently that little time delay may make the cream stick better to the first wafer.” But other physical factors also bear on the phenomenon as well, as documented in the paper Owens and her collaborators published earlier this year in the journal Physics of Fluid. “We introduce Oreology (/ɔriːˈɒlədʒi/), from the Nabisco Oreo for “cookie” and the Greek rheo logia for ‘flow study,’ as the study of the flow and fracture of sandwich cookies,” they write in its abstract. For a scientifically inclined youngster, one could hardly imagine a more compelling field.
Based in Seoul, Colin Marshall writes and broadcasts on cities, language, and culture. His projects include the Substack newsletter Books on Cities, the book The Stateless City: a Walk through 21st-Century Los Angeles and the video series The City in Cinema. Follow him on Twitter at @colinmarshall or on Facebook.