The Optimal Time to Dunk an Oreo, According to Science

iStock // Lucy Quintanilla
iStock // Lucy Quintanilla

Have you submerged an Oreo into a glass of milk and lingered too long? Did you watch in horror as America's supposedly favorite cookie disintegrated before your very eyes? Fear no more! Here's how to find (and elongate) your optimal dunk time.

THE SHORT ANSWER

Dip your cookie for three seconds, give or take. Carry on with your life, dear reader.

THE LONG ANSWER

Well, it depends. Do you prefer a crispy cookie masked in a thin veneer of milk? A cookie that has metamorphosed into unrecognizable gloop? Do you believe in a Goldilocks zone, a Platonic middle-ground that’s neither too dry, nor too spongy, but just right? It’s all subjective. But let’s assume you want an Oreo that is pleasantly soggy and has maintained its structural dignity.

There’s math for that. In the late 1990s, Len Fisher, then a professor of physics at the University of Bristol, sparked a media storm when he argued that a decades-old mathematical formula could predict the perfect dunk time for a cookie. It’s all thanks, he claimed, to capillary action.

Water molecules are adhesive: They cling to solid surfaces. (It’s why water in a beaker shows a meniscus—it’s attracted to the sides of the container.) When water enters a small tube, the liquid can adhere to surfaces in ways that seem to defy gravity: This is why water may crawl up your drink’s straw and why a paintbrush seems to slurp up liquid. That’s capillary action in a nutshell.

On a microscale, a cookie is essentially a series of small, starchy tubes. Fisher writes in his book How to Dunk a Doughnut that a dunking liquid (in our case, milk) is “held in place in the porous matrix by the pressure across the meniscus in the smallest of pores.” In other words, capillary action helps the milk spread through the cookie. In the early 20th century, the American scientist E.W. Washburn cooked up a formula to describe this watery journey.

Washburn's Equation
Lucy Quintanilla

Washburn tested and confirmed his formula by observing ink blots spread through paper. (A simplified version of his equation explains how inkjet printers spit out dry, sharp-looking text.) But it took nearly a century for someone such as Fisher to apply the formula to baked goods: After finding reliable numbers for the variables, Fisher rearranged the equation and solved for T (time).

He discovered that the perfect dipping time for a typical British dunking biscuit with a conventional dip was three-and-a-half to five seconds.

But Fisher never tested Oreos. So in 2016, members of Utah State University’s Splash Lab—an academic group studying the behaviors of fluids—put Oreos to the test. (Splash Lab, we should note, has an appetite for quirky experiments: They’ve studied the fluid dynamics of urinal splashback, analyzed the physics of the perfect skipping stone, and even tested the insulating properties of beards.)

Three researchers gathered Oreos, Chips Ahoy, Nutter Butter, and Graham Crackers and dipped the cookies halfway in 2 percent milk for half a second to seven seconds. After dunking, the team weighed the treats and measured how much milk had been absorbed.

The results: Oreos absorbed 50 percent of their potential liquid weight in just one second. After two seconds, they absorbed 80 percent. The number flatlined briefly for a second. After the fourth second, the cookie maxed out: It absorbed all its possible milk. “This data indicates that for the tested cookies, keeping your cookie in the glass any longer than five seconds does not lead to any additional milk entering the cookies,” their study suggested.

A graph of optimal cookie dunk times.
Oreo cookies absorbed milk at the same rate as Nutter Butter, taking in 100 percent of their liquid weight in four seconds.
Splash Lab

Splash Lab then performed a second test, dunking all cookies for six seconds and attaching them horizontally to a clamp. They waited for the cookies to collapse. The Oreo lasted an impressive five minutes! Compare that to measly Graham Crackers, which crumbled after eight seconds.

The takeaway: Three seconds is enough time to saturate most of an Oreo. There’s no benefit to dunking longer than four seconds. (Unless you want to watch the cookie crumble into your milk. As Splash Lab’s Randy Hurd, a mechanical engineering Ph.D. candidate, told us: “Waiting for the crisp cookie structure to break down is not necessarily a waste of time if that’s what you prefer.” We don’t judge.)

However, things get more complicated if you choose a different kind of dairy.

THE LONGER ANSWER

Your choice of milk could change the optimal dunk time by a few split seconds.

In 2011, researchers published a study in the Journal of Food Science that explained why milk doesn’t immediately turn breakfast cereal into mush: Fats and other solids in the dairy hindered “liquid infiltration,” slowing absorption. The same process is true of cookies, says Jennifer Fideler, a graduate student in food science at North Carolina State University.

Milk, for one, is full of sugars. Sugars are hygroscopic, meaning they hold onto moisture and can prevent liquid from seeping into the cookie. Additionally, fat and carbohydrate molecules are big. They can prevent the water in the milk from infiltrating the cookie’s porous matrix.  “Not only is it likely that the fat content of the milk (whole, 2 percent, skim, even heavy whip!) would affect the rate of moisture migration ... but the fat included in the cookie—and even moreso the cream filling—would help resist the influx of fluid,” Fideler wrote in an email.

Fat content doesn’t just slow down absorption time. It’s also known to enhance the flavor. In 1999, Len Fisher tested more than 200 British biscuit and drink combinations and concluded that milk could make a cookie 11 times more flavorful. (This wasn’t peer-reviewed, and it was sponsored by a biscuit company, so take it for what it’s worth.) “Milk is essentially fat droplets suspended in water and those fat droplets stay around in your mouth and they hang on to the flavour in the biscuit so that the aroma can be released up to the back of your nose,” Fisher told the BBC.

So, if you’re the type of person who dreams of extending the optimal Oreo dunk time while enhancing the flavor, toss the skim milk down the drain and pour a cup of high-fat dairy. Whole milk (3.25 percent butterfat) spiked with half-and-half (generally 10 percent butterfat) could extend your dunk time. But if you wanted to indulge and throw a Hail Mary—and have a few spare notches left in your belt—try dunking in heavy cream (36 percent butterfat). Heck, while we’re at it, why not go all the way and dip it in melted butter (80 percent butterfat).

(We’d like to take this moment to say we are not licensed to give nutritional advice and are not liable for culinary crimes against humanity. So maybe don't do this.)

THE MUCH LONGER ANSWER

If you wanted to boost the optimal Oreo dunk time even longer, there’s another principle you can hack: Water Activity.

Water activity is a measurement of how likely something gives away moisture. It’s measured on a scale from 0 to 1: Milk, for example, possesses a high water activity of 0.98. It readily gives its water away. A cookie, on the other hand, has a water activity hovering around 0.3. It holds onto its moisture and is more likely to absorb water.

Food manufacturers and processors have to constantly contend with water activity. It’s critical in determining a product’s safety, stability, and shelf life: Controlling water activity is the easiest way to prevent—and predict—the spread of dangerous bacteria [PDF]. (That’s because items with a high water activity are more likely to give water away to nasty microorganisms, causing spoilage.)

But for our selfishly sweet-toothed purposes today, water activity is just another factor affecting the critical cookie dipping time. A liquid with a lower water activity will hold onto its moisture more tightly than standard milk, Fideler explains. So, if you wanted to extend the optimal dunk time further, you should try to dip your Oreo into dairy that not only contains lots of fats and carbs, but also possesses a relatively low water activity. With that in mind, we have the perfect recommendation: Sweetened condensed milk. (We don’t actually recommend this.)

Boasting a high butterfat content (8 percent), obscene loads of carbs (166 grams per cup), and a relatively low water activity (.87), sweetened condensed milk is perfect if you’re the kind of person who relishes long dunk times and believes “calories” are just another government conspiracy designed to scare you from chugging modernity’s decadent ambrosias.

Dunk away!

This story originally ran in 2017.

7 Massage Guns That Are on Sale Right Now

Jawku/Actigun
Jawku/Actigun

Outdoor exercise is a big focus leading into summer, but as you begin to really tone and strengthen your muscles, you might notice some tough knots and soreness that you just can’t kick. Enter the post-workout massage gun—these bad boys are like having a deep-tissue masseuse by your side whenever you want. If you're looking to pick one up for yourself, check out these brands while they’re on sale.

1. Actigun 2.0: Percussion Massager (Black); $128 (57 percent off)

Actigun massage gun.
Actigun

Don't assume you need a professional masseur to provide relief—this massage gun offers 20 variable speeds and can adjust the output power on its own according to pressure. Can your human massage therapist do that?

Buy it: Mental Floss Shop

2. JAWKU Muscle Blaster V2 Cordless Percussion Massage Gun; $260 (13 percent off)

Jawku massaging gun.
Jawku

This cordless, five-speed massager uses a design that's aimed to increase blood flow, release stored lactic acid, and relieve sore muscles through various vibrations.

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3. DEEP4s: Percussive Therapy Massage Gun for Athletes; $230 (23 percent off)

Re-Athlete massage gun.
Re-Athlete

Instant relief is an option with this massage tool, featuring five different attachments made to tackle any muscle group. You can squeeze in eight hours of massage time before you have to charge it again.

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4. Handheld Massage Gun for Deep Tissue Percussion; $75 (15 percent off)

Massage gun from Stackcommerce.
Stackcommerce

With five replaceable heads and six speed settings, this massage gun can easily adapt to the location and intensity of your soreness. And since it lasts up to three hours per charge, you won't have to worry about constantly plugging it in.

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5. The Backmate Power Massager; $120 (19 percent off)

Backmate massage gun.
Backmate

Speed is the name of the game here. The Backmate Power Massager is designed for fast, effective relief through its ergonomic design. Fast doesn’t need to mean short, either. After the instant relief, you can stimulate and distract your nervous system for lasting pain relief.

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6. ZTECH Percussion Massage Gun (Red); $80 (46 percent off)

ZTech massage gun.
ZTech

This massage gun looks a lot like a power drill, and, similarly, you can adjust its design for the perfect fit with six interchangeable heads that target different muscle areas.

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7. Aduro Sport Elite Recovery Massage Gun (Maroon); $80 (60 percent off)

Aduro massage gun.
Aduro

Tackle large muscle groups, the neck, Achilles tendon, joints, and small muscle areas with this single massage gun. Four massage heads and six intensity levels allow this tool to provide a highly customizable experience.

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This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links. If you haven't received your voucher or have a question about your order, contact the Mental Floss shop here.


This Innovative Cutting Board Takes the Mess Out of Meal Prep

There's no way any of these ingredients will end up on the floor.
There's no way any of these ingredients will end up on the floor.
TidyBoard, Kickstarter

Transferring food from the cutting board to the bowl—or scraps to the compost bin—can get a little messy, especially if you’re dealing with something that has a tendency to roll off the board, spill juice everywhere, or both (looking at you, cherry tomatoes).

The TidyBoard, available on Kickstarter, is a cutting board with attached containers that you can sweep your ingredients right into, taking the mess out of meal prep and saving you some counter space in the process. The board itself is 15 inches by 20 inches, and the container that fits in its empty slot is 14 inches long, 5.75 inches wide, and more than 4 inches deep. Two smaller containers fit inside the large one, making it easy to separate your ingredients.

Though the 4-pound board hangs off the edge of your counter, good old-fashioned physics will keep it from tipping off—as long as whatever you’re piling into the containers doesn’t exceed 9 pounds. It also comes with a second set of containers that work as strainers, so you can position the TidyBoard over the edge of your sink and drain excess water or juice from your ingredients as you go.

You can store food in the smaller containers, which have matching lids; and since they’re all made of BPA-free silicone, feel free to pop them in the microwave. (Remove the small stopper on top of the lid first for a built-in steaming hole.)

tidyboard storage containers
They also come in gray, if teal isn't your thing.
TidyBoard

Not only does the bamboo-made TidyBoard repel bacteria, it also won’t dull your knives or let strong odors seep into it. In short, it’s an opportunity to make cutting, cleaning, storing, and eating all easier, neater, and more efficient. Prices start at $79, and it’s expected to ship by October 2020—you can find out more details and order yours on Kickstarter.

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.