Scientists Publish Breakthrough Study in Oreo-Splitting Research

A new study introduces "Oreology," the study of the flow and fracture of sandwich cookies, to investigate if Oreo filling can be evenly split between wafers.
A new study introduces "Oreology," the study of the flow and fracture of sandwich cookies, to investigate if Oreo filling can be evenly split between wafers.
Oreology experiment. Image: Crystal Owens et al/ Physics of Fluids
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It just might be the hottest new career path: Oreologist. This novel field of science endeavors to understand some of the persistent mysteries of the popular Nabisco snack, including whether it’s possible to separate the two wafers of the cookie sandwich in such a way that the creme filling is evenly split.

For Crystal Owens, a Ph.D. candidate in mechanical engineering at Massachusetts Institute of Technology (MIT), the pursuit of an equal creme ratio in Oreos—which are prone to splitting with one side being nearly dry—is a lifelong dream. Now, she has had the chance to lead researchers in testing out the probability of achieving this hallowed outcome using a rheometer, an instrument that measures torque and viscosity of various substances. 

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The experiment revealed that even under laboratory conditions, it is practically impossible to end up with even doses of creme, a result that “confirms that the creme-heavy side is uniformly oriented within most of the boxes of Oreos,” according to an absolutely delightful study published on Tuesday in the journal Physics of Fluids that coins the term “Oreology” and defines it as “the study of the flow and fracture of sandwich cookies.”

“I was personally motivated by a desire to solve a challenge that had puzzled me as a child: how to open an Oreo and get creme evenly arranged on both wafers?” Owens said in an email. “I preferred the taste of the cookies with the creme exposed. If I got a bite of wafer alone it was too dry for me, and if I dunked it in milk the wafer would fall apart too fast.” 

“When I came to MIT, I learned how to use our laboratory rheometer, which twists a fluid sample between parallel disks to measure the viscosity,” she continued. “I originally used our rheometer to test a carbon nanotube-based ink I was designing to 3D print flexible electronics, but one day I realized I had the tools and knowledge to finally solve this challenge with Oreos.” 

Owens and her colleagues took a methodical approach to this important question, and even invented an “Oreometer,” a 3D-printed device “designed for Oreos and similarly dimensioned round objects,” according to the study.

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After twisting Oreos apart with the instruments, the team visually inspected the ratio of creme on each wafer and logged the findings. A number of variations on the experiment were also introduced, such as dipping the cookies in milk, changing the rotation rate of the rheometer, and testing different Oreo flavors and filling quantities. But despite their best efforts, the researchers were not able to find a solution for the problem that has vexed Owens for decades.

“The results validated what I saw as a child—we found no trick for opening up our Oreos,” Owens said. “In essentially all possible twisting configurations, the creme tends to delaminate from one wafer, resulting in one nearly bare wafer and one with almost all the creme. In the case that creme ends up on both wafers, it tends to divide in half so that each wafer has a ‘half-moon’ of creme rather than a thin layer, so there is no secret to get creme evenly everywhere just by twisting open—you have to mush it manually if that's what you want.” 

“This was surprising to me because I had imagined that if you twist the Oreo perfectly, you will get the cream to divide perfectly, but that's just not how the physics works,” she continued. She was also surprised to learn that Oreos aren’t filled with cream, but creme, which  “is actually more of a frosting than a cream like cream cheese or cream fillings in pastries,” and indeed it contains no dairy. “The rheology is similar for the different fluids, though,” she added. 

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While the team has now confirmed the elusive nature of the Oreo, the new study is filled with new revelations about this ubiquitous snack and its intriguing properties. Owens and her colleagues report here, for the first time, that Oreos belong to the so-called “mushy” texture regime. 

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The team affixed cookies to a laboratory rheometer and designed a 3D-printed Oreometer to study the influences of rotation rate, flavor, amount of creme, and environment on Oreos. Image: Crystal Owens

The researchers also calculated the “degradation of chocolate wafer strength over time following milk imbibition,” concluding that Oreos experience “significant structural loss” within a minute of exposure to milk, according to the study. These findings presented another string of challenges to Owens’ worldview concerning Oreo cookies.

“I used to think that you need to dunk the cookie and wait for it to get saturated with milk to make it taste best, but the cookie falls apart too fast,” she said. “I used to think that the cookie getting soft meant it had enough milk, but it turns out that it can still feel ‘dry’ and have a lot of milk because it takes time to fall apart once wetted. According to another study I found, the cookie takes up as much milk as it can in only five seconds of dunking, so there is a ‘sweet spot’ in timing before it falls apart.”

As informative as the new study has been for cookie studies—a field that Owens notes has already earned an Ignobel Prize, a parody award, in 1999—there are still many mysteries about these tasty treats that demand explanation. Owens hopes her work will make people think about the scientific concepts that underpin their daily snacks and indulgences.

“With such a convenient name as ‘Oreology,’ I hope our study makes more people familiar with my research field, ‘rheology’ and the kinds of questions we can answer well,” she said. “It's also a perfect visual example for how our rheometer works, so it is a great introduction to the field that is relatable. We have shared our 3D printing files and hope people can make and use our device directly to do their own Oreology. I hope this study also simply inspires people to take puzzles that they're curious about in the world around them and use science to find the answers.”

“There are many questions we weren't able to answer fully in our first study, and so we welcome other people to contribute their own ideas and experiments,” she concluded. “We are considering a follow-up on ice cream. For now, we'll just keep Oreos in our break room for ‘taste tests' between other experiments, and maybe we'll find a new puzzle to tackle.”