Original photo by Dmitry Kuzmenko/ Unsplash
Milk and cookies go together like peanut butter and jelly, salt and pepper, Jay-Z and Beyoncé. However, there is a right way and wrong way to dunk a cookie in milk, according to scientists. In 1998, a professor at the University of Bristol in the U.K. looked into the ideal method for dunking a British biscuit (aka a cookie) into a drink, using the concept of capillary action — the way fluids move spontaneously through small tubes in porous materials — and Washburn’s Equation, which describes their journey. Eventually, he determined that the typical British biscuit is best dunked for 3.5 to 5 seconds. Using this same technique in 2016, scientists at the University of Utah's Splash Lab determined the perfect dunk time for the much-beloved Oreo. Although the amount of time to get to “perfect” depends on preferred sogginess levels and milk fat content, the Utah researchers determined that three seconds was enough to thoroughly saturate the Oreo without losing structural integrity.
Oops, incorrect!
It's a factThe Oreo looks like the epitome of dessert ingenuity, but it actually got its start as a near-exact knockoff of a cookie called Hydrox, released in 1908. Hydrox eventually lost popularity in part because its name sounded like a cleaning product, but the brand is still around.
Here’s the journey in slow motion. Cookies are porous, and milk travels through the small holes inside them the same way ink does through blotting paper, or a spill through a paper towel. During tests, the Oreo soaked up 50% of its potential liquid weight in one second. That number shot up to 80% at two seconds, flatlined at three seconds, and maxed out at four seconds — meaning the cookie could absorb no more milk. So if the goal was to saturate the cookie but not lose structural cohesion, three seconds was the perfect number. While this test used 2% milk as its dunking medium, the optimal dunking time will vary slightly when using other milk: The higher the milk fat (like whole milk or cream), the longer a cookie can be dunked, but only by mere fractions of a second. Mmmmm, we just made ourselves hungry.
Numbers Don't Lie
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The first “Got Milk?” ad, in 1993, was directed by ______.
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The first “Got Milk?” ad, in 1993, was directed by Michael Bay.
All humans used to be lactose intolerant.
All mammalian young produce an enzyme known as lactase, which allows babies to digest lactose, a naturally occurring sugar found in milk (human or otherwise). As mammals age, their bodies naturally produce less and less lactase, until eventually milk sugars are no longer digestible. But around 10,000 BCE, a genetic mutation in humans took hold near modern-day Turkey that effectively kept human lactase production permanently set in the “on” position. According to some anthropologists, this gave certain cultures a distinct advantage, since this new lactose tolerance added a pool of easily accessible calories to the human diet. A 2015 study looking at the DNA of Eurasians who lived between 6500 BCE and 300 BCE shows that Russian steppe herders likely introduced the mutation to Western Europe. However, humanity’s ability to digest milk isn’t as widespread as you might think. The U.S. Department of Health and Human Services estimates that 68% of the world’s adult population experiences “lactose malabsorption,” and those percentages are particularly high in Asia and Africa.
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
