They ran tests that included using a rotation rig to observe trial run after trial run of variations on twists and pulls. They used a load frame to test force on the cookies, measuring tensile load and displacement. "It’s interesting from an engineering standpoint since the cookie is similar to many modern composites: a strong brittle layer (the wafer) for strength coupled with a weaker ductile layer (the cream) for toughness," said Cannarella.
They ran tests on hundreds of Oreos and brought in friends to put the Oreos through "real world" testing. Stepping back from a problem that they weren't making headway on, they noticed something. In every package, the cream was always on the same side of the cookie. "It was easy to make the leap that it’s a feature of the manufacturing process," said Quinn.