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.

17 Delicious Facts About Peeps

Getty Images
Getty Images

You know whether you prefer chicks to bunnies, fresh to stale, or plain to chocolate-covered. But there’s a lot you may not know about Peeps, everyone’s favorite (non-chocolate) Easter candy.

1. It used to take 27 hours to make a Peep.

A candy Peep being made
Getty Images

That was in 1953, when Sam Born acquired the Rodda Candy Company and its line of marshmallow chicks. Back then, each chick was handmade with a pastry tube. Just Born quickly set about automating the process, so that it now takes just six minutes to make a Peep.

2. An average of 5.5 million Peeps are made every day.

Peeps candies being made
Getty Images

All of them at the Just Born factory in Bethlehem, Pennsylvania. In one year, the company makes enough peeps to circle the earth—twice!

3. Yellow chicks are the original Peep, and still the favorite.

Boxes of yellow chick Peeps
Getty Images

Yellow bunnies are the second most popular color/shape combination. Pink is the second best-selling color.

4. The recipe has stayed pretty much the same.

Cooking up a batch of Peeps
Getty Images

The recipe begins with a boiling batch of granulated sugar, liquid sugar, and corn syrup, to which gelatin and vanilla extract are later added. 

5. The equipment has also (mostly) stayed the same.

Peeps candies being made
Getty Images

Since Just Born turned Peeps-making into an automated process, the chicks have been carefully formed by a top-secret machine known as The Depositor. Created by Sam Born’s son, Bob, The Depositor could manufacture six rows of five Peeps apiece in a fraction of the time it took workers to form them by hand. And that same machine that Bob built has been keeping the Peeps flowing ever since. Until rather recently …

In 2014, the company announced that it was planning to renovate its manufacturing plant, including The Depositor. “It’s a little sad,” vice president of sales and marketing Matthew Pye told Candy Industry Magazine at the time. “Bob Born made it from scratch in 1954 and it allowed us to distribute and grow the brand nationally." 

6. The updated equipment means new Peeps innovations could be coming.

Making Peeps at the Just Born factory
Getty Images

“The investment in our marshmallow making process will allow for more efficiency, more consistency, improved quality, and additional innovation capabilities,” co-CEO Ross Born told Candy Industry magazine about the new depositor, which will be able to produce a wider variety of Peeps in all sizes. “The [old] Peeps line did one thing and one thing very well—cranking out chicks day in and day out. Five clusters, just in different colors,” Born said.

7. Peeps used to have wings.

They were clipped in 1955, two years after the first marshmallow chicks hatched, to give the candy a sleeker, more “modern” look.

8. The eyes are the final touch.

A close up of a yellow chick Peep
Getty Images

The final flourish for all of these squishy balls of sweetness is adding the eyes, which are made of carnauba—a non-toxic edible wax (that is also found in some shoe polishes and car waxes, plus many other candies).

9. Peeps may be destructible, but their eyes are not.

Making Peeps at the Just Born factory
Getty Images

In 1999, a pair of scientists at Emory University—dubbed “Peeps Investigators”—decided to test the theory that Peeps are an indestructible food. In addition to a microwave, the pair tested the candy’s vulnerability to tap water, boiling water, acetone, and sulfuric acid (they survived them all). When they upped the ante with some Phenol, the only things that didn’t disappear were the eyes. 

10. They really are everyone's favorite non-chocolate Easter candy.

For more than 20 years now, no other non-chocolate Easter candy has been able to compete with the power of Peeps. With more than 1.5 billion of them consumed each spring, Peeps have topped the list of most popular Easter treats for more than two decades.

11. There are sugar-free Peeps.

Counterintuitive, we know. But in 2007, the first line of sugar-free Peeps hit store shelves.

12. There are also chocolate-covered Peeps.

Chocolate-covered Peeps hit the market in 2010. Today there’s a full line of them for every occasion.

13. Peeps come in a variety of flavors.

Color and shape (i.e. yellow chick) are no longer the only ways to categorize a Peep. They now come in an array of flavors, including fruit punch, sour watermelon, lemon sherbet, blueberry, and pancakes and syrup.

14. Peeps lip balm is a thing.

Yep.

15. On New Year's Eve, a giant Peep is dropped in Bethlehem, Pennsylvania.


PEEPS®

The drop is done with a traditional chick that flashes different colors at midnight.

16. Believe it or not, Peeps are not Just Born's best-selling brand.

That honor belongs to Mike and Ike. (Sorry, Peepsters.)

17. They're a boon to a creativity.

Blue chick Peeps
Getty Images

All over the country, Peeps have become the preferred media for a number of highly anticipated annual art contests. (You can check out some of the coolest creations from Westminster, Maryland's PEEPshow here.)

Updated for 2019.

10 Amazing Pieces of Peeps Art

“Edgar Allan Peep” by Christian Twamley / Courtesy of the Carroll County Arts Council
“Edgar Allan Peep” by Christian Twamley / Courtesy of the Carroll County Arts Council

Some people paint, some scrapbook, and others create Game of Thrones-inspired dragon sculptures made of 5000 marshmallow Peeps. Candy art may seem like an unusual form of craftsmanship, but it’s more common than you might expect in the lead-up to Easter, when organizations around the country host Peeps art contests.

The aforementioned dragon, as well as the artworks pictured below, were all submitted to the “PEEPshow” contest—a fundraiser for the Carroll County Arts Council in Westminster, Maryland. According to event organizers, the event became the first exhibition of Peeps art when it debuted 12 years ago.

Keep scrolling to see some of the best Peeps sculptures from recent years (2017-2019), and visit the Art Council’s website to see all of this year's participants. (As of Friday afternoon, a Warhol-inspired artwork of "Marilyn Peeproe" appears to be in the lead.)

A space-themed Peeps display
“First Peeps in Space” by International Delight / Courtesy of the Carroll County Arts Council

A samurai sculpture
"Sugar Samurai" by Tristar Martial Arts / Courtesy of the Carroll County Arts Council

The rabbit from Alice in Wonderland
“I’m Late, I’m Late (for the PEEPshow)” by Vivian Davis / Courtesy of the Carroll County Arts Council

A caterpillar sculpture
“The Very Hungry Caterpeeper” by Lia Finch and M / Courtesy of the Carroll County Arts Council

A sculpture inspired by a painting
“Peep with the Pearl Earring” by Sandy Oxx / Courtesy of the Carroll County Arts Council


“Edgar Allan Peep” by Christian Twamley / Courtesy of the Carroll County Arts Council

A Belle sculpture
“Beauty and the Peep” by Candace Birger, Westminster Cake Studio / Courtesy of the Carroll County Arts Council

Fish sculpture
“The Rainbow Fish” by Jen, Justin, Connor, and Jacob Myers / Courtesy of the Carroll County Arts Council

A Gumby sculpture
“Just Gumby” by Sydney Blacksten / Courtesy of the Carroll County Arts Council

A sculpture of a monster
“Percy the Purple Peeple Eater” by the Koontz Family / Courtesy of the Carroll County Arts Council

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