A group of heroes with Ph.D.s at Utah State University’s Splash Lab has used its very particularized skill set to answer one of the universe’s most burning questions. After researching the matter for “several hours a day, for two weeks,” the group claims to have discovered the peak dip time for an Oreo cookie. According to this team of mechanical engineers, it’s four seconds.
Tadd Truscott, who runs the lab, tells Salt Lake City’s KSL that the question about optimized dunking time “kept coming up” with colleagues. Naturally, they all had strong opinions, and proceeded to “kind of argue about it.” To settle the matter, they set up two weeks of milk stress tests to definitively ascertain how long an Oreo can last before falling apart. According to their exhaustive study, the cookie will soak up 50 percent of possible fluids in just one second. By the fourth second, it’s “reached maximum absorption,” so is therefore “best eaten then.”
They assumed most people are after a Goldilocks state — not a disintegrated goo pile, also not a merely damp Oreo. There’s actually a complicated equation that helps out in this situation, if you like math: In the ’90s, a physics professor in England named Len Fisher argued that a formula for fluid dynamics could be used to home in on the ideal dunk time for a cookie. This discovery apparently earned him a so-called Ig Nobel Prize, and he published a book called, confusingly, How to Dunk a Doughnut that explains how milk molecules cling to the pores on a cookie’s surface by a principle known as capillary action. The equation for how far the milk will travel is complicated (it requires calculating surface tension and milk viscosity, and taking the cosine of the milk’s contact angle with the cookie). Fisher did the dirty work, though, and got a three- to five-second time window for British “biscuits,” which are basically American cookies.
Being a Brit, he never realized he needed to specifically test Oreos. Truscott and his colleagues fixed that oversight. They also tried out graham crackers, which, they learned, do not maintain the structural dignity of an Oreo once submerged. (Even though they’re essentially British biscuits, grahams pretty much aren’t meant to be dunked.) As for Oreos, while four seconds is ideal, you should also keep your stopwatch handy — go anything beyond five, and Truscott says you’ll end up with a goopy cookie.