MIT engineers create a device that perfectly twists Oreo cookies apart

Why does the Oreo cream almost always stick to just one wafer cookie when twisted apart?

Oreo cookies

A group of engineers at the Massachusetts Institute of Technology (MIT) has created a device that perfectly twists Oreos apart.

Called Oreometer, the 3D-printable invention was designed to split Oreo cookies with a scientifically precise amount of torque, which is the measure of force used to rotate an object. The Oreometer firmly grasps an Oreo cookie and uses pennies and rubber bands to control the twisting force that progressively twists the cookie open. The device was created to find out why the Oreo cream almost always sticks to just one wafer cookie when twisted apart.

“When I was little, I tried twisting wafers to split the cream evenly between wafers so there’s some on both halves — which in my opinion tastes much better than having one wafer with a lot of cream and one with almost none. This was hard to do when I was trying it by hand,” said Crystal Owens, lead author of the study published on April 19th in the journal American Institute of Physics, and a researcher in mechanical engineering at the MIT.

The hope was that with the perfect twist, courtesy of the Oreometer, researchers could manipulate the cookie’s cream to distribute evenly between the two wafer cookies. To see if that’s possible, Owens and the rest of her team subjected 20 boxes of Oreos to a standard rheology test with the use of the Oreometer. And they found out that no matter what the wafer flavor (regular, dark chocolate, and “golden”) or the amount of stuffing (regular, Double Stuf, and Mega Stuf) is, the cream at the center of an Oreo almost always sticks to one wafer when twisted open.

“We had expected an effect based on size. If there was more cream between layers, it should be easier to deform,” Owens said. “But that’s not actually the case.”

After mapping each cookie’s result to its original position in the box, the researchers noticed that the cream tended to stick to the inward-facing wafer: Cookies on the left side of the box twisted such that the cream ended up on the right wafer, while cookies on the right side separated with cream mostly on the left wafer.

Why does the Oreo cream almost always stick to just one wafer cookie when twisted apart?

“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,” said Owens. “Apparently that little time delay may make the cream stick better to the first wafer.”

The researchers also suspect that it may be a result of post-manufacturing environmental effects, such as heating or jostling that may cause the cream to peel slightly away from the outer wafers, even before twisting.

According to the study, if you somehow manage to split the cream evenly between the two wafer cookies, it likely wasn’t the result of your precise twisting but had more to do with the level of adhesion between the cream and cookie, which changes due to unknown factors before it gets to your hands.

While some may find the study silly, Owens pointed out that the understanding gained about the properties of Oreo cream through this research could potentially be applied to the design of other complex fluid materials.

“My 3D printing fluids are in the same class of materials as Oreo cream,” she explained. “So, this new understanding can help me better design ink when I’m trying to print flexible electronics from a slurry of carbon nanotubes, because they deform in almost exactly the same way.”

Instructions for the Oreometer can be found here.

Source: American Institute of Physics, CNN, Science Daily