Opening Oreos with perfect precision
Sandwich biscuits are a tasty sweet treat that we often like to indulge in at the Naked Scientists office, and it seems everyone has their own way of eating them. Recently a team at the Massachusetts Institute of Technology has created a device, called an ‘Oreometer’, that can perfectly remove the top layer from an Oreo biscuit for those of that persuasion. And since this just so happens to be our own Otis Kingsman’s preferred method of eating an Oreo, we had him speak to Crystal Owens and Gareth McKinley from the team who made it…
Otis - How do you like your sandwich biscuits? For me, I like to try and snap off the top to get to that individual crunchy layer. But when I do, the biscuit always crumbles. Fortunately Crystal Owens and Gareth McKinley from the Massachusetts Institute of Technology have invented a device which can do the job perfectly.
Crystal - What we found in the lab is that a twisting motion is the best for getting a very clean break of the cream from a wafer. We actually designed a little Oreometer, which is a 3D printed device that you can stick a cookie in. It will provide this twisting motion to an Oreo that's held very carefully by rubber bands.
Otis - So in order to get the top off, twisting is for best motion, as it's all based in the science of rheology.
Gareth - Rheology is the study of the flow of matter. One of the things that rheologists are very careful to do is to define how they twist or pull on things. You need to make sure that you either make things slide, or make things stretch in a certain way. A standard test that we always use is called a 'shearing test'. The goal is to generate a sliding motion of your Oreo biscuit against your Oreo cream. What you find is that the weakest part is actually at the interface between the white cream and the dark biscuit.
Otis - It works by the cream filling being similar to both a solid and liquid state of matter, or as they put it, 'mushy'.
Gareth - Many of our materials are what we would call 'viscoelastic'. That means that they have some viscous properties and some elastic or solid-like properties. The cream in particular is an example of a material that looks solid and is solid if you don't push on it very hard, but when you push on it harder, it will actually flow like a liquid. We say that these materials have a 'yield stress'. What does that mean? It means they're solid below that stress, but when you push on them hard enough, they will flow like a liquid. The combination is that we would describe this material as indeed 'mushy'.
Otis - From their analysis of the Oreo cream, they were able to design the machine around its properties to remove the top layer perfectly.
Crystal - The Oreo cream is much stronger than it is sticky. It tends to just come off from one wafer. If you have the perfect twisting motion on a freshly open pack of Oreos, you will get one wafer that is just bare with maybe like a little tiny bit of cream, and then one wafer that has all the cream.
Otis - These results may seem pretty insignificant at first, but there are actually a few wider applications for it.
Gareth - People like things that don't taste too gritty or don't taste too sticky or don't taste too slimy. Rheology is the science that really allows us to put some numbers to those things, and allows us to control for them. That's really important, particularly as people start to formulate low fat foods or artificial meats. Getting that texture and getting the properties right is an extremely important part of the consumer experience.
Crystal - Even though we published a full study, we haven't even begun to answer all of the questions someone could ask about Oreos. We have freely distributed the design files for someone to make their own Oreometer, to do other tests, maybe with Oreos at different temperatures or with different brands of sandwich cookies.
Otis - That's right. Those with a 3D printer can achieve this level of superi-oreo-ity and aid in the development of oreo-logy. I, however, I'm going to stick to my hands on method.