There’s a delightful new piece up at Mental Floss that goes into great detail about a quietly vexing conundrum: How long should you dunk an Oreo in milk? The answer, writer Lucas Reilly found, is three seconds.
Here’s a concern some may not believe could possibly be a matter of scientific inquiry. There’s a careful choreography involved in dunking an Oreo, that wondrous disc of compressed sugar, into milk. Blot it for a mere second and you may as well have eaten it dry. Soak it for too long and it’ll collapse into pieces, demanding you fish it out of your milk with a utensil. Estimating the correct time, one that'll stimulate a beautiful collapse of a biscuit and its cream contents without transmogrifying its texture too violently, is a difficult art to master.
Reilly is recycling the contents of a study conducted last year by researchers at Utah State’s Splash Lab. They took Oreos, Chips Ahoy!, Nutter Butter, and Graham Crackers, and dipped them in tubs of 2% milk from half a second to seven seconds. Across this spectrum, researchers measured how much milk these cookies had absorbed.
The team at Splash Lab was building on a body of scientific inquiry that began in 1999, when then-University of Bristol physics professor Len Fisher discovered how capillary action—the way liquid molecules stick to solid surfaces—could explain the best amount of time to dunk a British biscuit. To explain why a cookie—essentially a collection of “small, starchy tubes”—is catnip for milk, he worked off of a formula devised by American scientist E.W. Washburn, and, through it, determined that three and a half-to-five seconds was optimal for a British biscuit.
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The Oreo’s a different animal, though; so this realization compelled the Splash Lab to build on Fisher’s findings and apply them to mass-market American cookies. (After all, dunking Oreos in milk is something of a national pastime.) In the experiment, Oreos absorbed half of their potential liquid weight at a mere second. By two seconds, they absorbed 80%, flatlining for the third second; at the fourth, they finally absorbed all possible milk.
For reference, the Nutter Butter followed the same trajectory as the Oreo, a fact that's totally unsurprising, given its compositional similarity to the Oreo. Chips Ahoy! cookies absorbed roughly 45% of their liquid weight within half a second, plateauing at 85% after one second until the fifth, after which it absorbed all its liquid weight. Graham Crackers, those feeble foodstuffs, absorbed all of their liquid weight at the one-second mark.
This three-second rule isn’t ironclad for all milks. The more butterfat-rich your milk is, the longer you can dunk, and the more these milks coax the flavor out of the cookies—enhancing, rather than eroding, their flavor profile. Reilly recommends a cocktail of whole milk and half-and-half—or, even more brazenly, heavy cream—if you’d like to prolong that pleasure by a few seconds.
I’ll stick to the 2% and the three-second milk rule. Optimal indeed.
Got an opinion on this wildly important scientific matter? Please let us know in the comments.
Mayukh Sen is a James Beard Award-winning food and culture writer in New York. His writing has appeared in the New York Times, the New Yorker, Bon Appetit, and elsewhere. He won a 2018 James Beard Award in Journalism for his profile of Princess Pamela published on Food52.