The researchers of the Massachusetts Institute of Technology decided to find out what happens to Oreo cream filling when cookies are divided into two halves. In addition to curiosity, it will help them develop new inks for 3D printing.

To study this cookie, scientists have printed on a 3D printer device – Oreometer. The device uses rubber bands and coins to control the moment of force applied to each side of the cookie during separation. Adding a coin to one of the sides rotates one of the two cameras and separates the Oreo.

After testing different types of Oreos, the researchers confirmed what every American from the age of three knows – usually the cream sticks to one side, regardless of the type of Oreo.

They also proved that the twisting speed matters. If you try to split the cookies quickly, it will take more effort. Interestingly enough, the cream was distributed more evenly when using older cookies.

Scientists suggest that the reason why the filling sticks to one of the pieces of cookies lies in the production process.

“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,” says Crystal Owens, Ph.D. at the MIT.

An article with a study of cookies was published in the journal Physics of Fluids. The experiment was conducted within the framework of rheology – the science of fluidity and deformation of matter. Researchers have determined that according to how the filling responds to the load, it can be classified as soft – not brittle hard, or stretchy.

They also learned that the force required to deform the filling is the same as for mozzarella – and twice as much as for peanut butter and cream cheese. The researchers suggested that if the surface of the cookies was rougher, it could better adhere to the filling and the cream would be more evenly distributed in two pieces.

The study was also of practical importance. One of the researchers’ 3D printing fluids belongs to the same class of materials as Oreo cream.

”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,” says the scientist.