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A Brief History of the Slurpee, a Frozen American Icon

How 7-Eleven perfected 50 years of brain freeze

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For millions of people across the world, nostalgia tastes like a sweet and icy sip (er, slurp) of a 7-Eleven Slurpee. When you pull the lever on a Slurpee machine inside any 7-Eleven store on the planet, the fizzy, fluffy frozen beverage likely tastes just like the first one you ever tried. Introduced to the market in 1966, the Slurpee is arguably the world’s most popular (non-alcoholic) frozen drink. On July 11, also known as "7-Eleven Day," 8,000 locations across the country handed out more than nine million free cups of Slurpee.


Slurpee has firmly staked its claim in the American consciousness in a number of ways. The inventor of the frozen margarita machine, a Dallas restaurant owner named Mariano Martinez, cited the Slurpee machine as his inspiration for changing the face of the classic cocktail. Outside of the store, Slurpee has closely linked itself with events unfolding in popular culture. In the '70s, a promotional single called "Dance the Slurp," released on 45 rpm records, proved so popular it was played on mainstream radio. On eBay, thousands of listings hawk special-edition plastic Slurpee cups from the 1970s and beyond emblazoned with images of Scooby-Doo, The Hulk, and Spider-Man for upwards of $20 each. The Simpsons weaved the drink into the fabric of its world — its parody, the Squishee, became so linked to the real-life Slurpee that 7-Eleven partnered with The Simpsons Movie in 2007 to sell the show's fictional beverage from collectible cups.

There are, of course, other frozen drinks — the ICEE, Slush Puppie, and Freezoni among them — but none have come close to matching Slurpee’s pop-culture prominence.

The beginnings of the slushy drink, in general, can be traced back to a man named Omar Knedlik, who, in the late 1950s, used parts from an automobile air conditioner to build a rudimentary frozen beverage machine. According to a 2010 Mental Floss article, the original idea was conceived after Knedlik, who operated a Dairy Queen franchise in Kansas City, stashed some soda pop in the freezer when the soda fountain in his restaurant went kaput. He worked with an artist to develop a brand for his new slushy drinks, introducing the world to the ICEE, a gas-station staple in its own right. But it was from that same frozen drink machine that the Slurpee was born: 7-Eleven licensed the ICEE machine technology from Knedlik in 1965.

How does that machine work, exactly? In its 50-year history, the actual slushy machine has not changed dramatically. It, like most machines, has gotten smaller over time, but the mechanics (which for Slurpees are, of course, a 7-Eleven corporate secret) have largely stayed the same. That simplicity of process has everything to do with ensuring that Slurpees made in Detroit, Michigan taste like Slurpees made in Dallas, Texas.

In 7-Elevens today, the modern-day Slurpee machine is fitted with a barrel surrounded with refrigerant used to keep the mixture cold. The Slurpee mixture flows into the barrel, begins to freeze, and is scraped away from the sides of the machine to form those fluffy ice crystals. Part of that chemistry is thanks to the drink’s most crucial ingredient, sugar, which acts as a sort of "antifreeze" that prevents the drink from freezing too hard, like a cube of ice.

"Sugar is a depressant to the freezing process. When you put sugar in water, that water will no longer freeze at the typical temperature of 32 degrees," says University of Wisconsin-Madison food scientist Dr. Maya Warren. "I liken it to salt. When it snows, we put salt on the ground to break up the ice. That helps lower the point at which the ice freezes, and sugar does the same thing."

The Slurpee machine itself is "kind of like a soda machine and an ice cream freezer all in one."

The Slurpee machine itself is "kind of like a soda machine and an ice cream freezer all in one," Warren says. "It adds carbonation while freezing the mixture." Frozen drinks don’t necessarily have to be carbonated, but the Slurpee’s addition of CO2 "helps make the drink smoother," says Warren. "People like the fizziness. People love soda, and people love cold, frozen things. Why not make it drinkable like a soda, where you still have that fizz? They’re light and fluffy, and people really like that. It’s a great marketing tool."

According to 7-Eleven director of proprietary beverage brands Rusty Smith, by the 1960s, there were more than 1,000 7-Eleven stores across North America, and it became clear that there was a demand for frozen drinks. "Obviously ice cream has always been popular, but frozen beverages have a natural affinity with kids," says Smith. "In the early years, 7-Eleven was known for penny candy and video games, and we wanted to have something proprietary that would get kids in our stores."

Coined by advertising executive Bob Stanford, the "Slurpee" name is derived from the "slurp" sound that the drink makes when it is sucked through a straw. The Slurpee made its official debut in 1966 — in two flavors, Coca-Cola and cherry — and was an instant success. (Unfortunately for Knedlik, he didn’t exactly possess the same kind of marketing genius that 7-Eleven had in its advertising agencies and marketing executives. Originally, Knedlik wanted to call his version of the beverage "Scoldasice," but he eventually went with the word "ICEE." After selling his machines to 7-Eleven, Knedlik received royalties from the chain for 17 years until his patents for the original ICEE machine expired.)

Today, in the store, 7-Eleven employees don’t have to do much to actually make the Slurpees that fill your cups. In the beginning, store employees would have to pour Slurpee mix into the top of the machine every morning. Now, they simply attach the five-gallon "bag in a box" of Slurpee to the machine in the store’s back room and allow it to do the rest of the work. "It was always really important for us to ensure consistency," says Smith. "We know what’s in the formula, we know what the machines are supposed to do."

"Carbonated soft drinks are unforgiving when working with flavors."

That punch of Fanta Wild Cherry flavor you get from the first sip of a Slurpee comes straight out of that "bag in a box," and it isn’t easy to achieve. The flavor of frozen beverages is often watered down by ice crystals, which means that the syrup must be extremely concentrated to deliver the same kind of powerful taste you’ll find in a glass of soda.

"Carbonated soft drinks are some of the most unforgiving products when working with flavors," says Dr. David Thomas, a Dr Pepper Snapple Group food scientist who’s worked with 7-Eleven to develop Slurpee flavors. "Add to that the frozen element, and you have an even greater challenge. To replicate a carbonated beverage, the flavor concentrate has to be many times stronger for the frozen version."

As such, the development of Slurpee flavors involves combining multiple flavor compounds to achieve the perfect "cherry" or "Coca-Cola" taste. Many Slurpee flavors, like Dr Pepper, are highly complex, closely-guarded company secrets. At present, there are dozens of flavors that rotate through Slurpee machines across the globe every month.

Photo: 7-Eleven/Facebook

In addition to the Slurpee flavors available at every machine, 7-Eleven also produces a number of regionally-available flavors that have, to varying degrees, developed cult followings. In Detroit, Michigan, one of the world’s largest consumers of Slurpees, you’ll find Vernors Ginger Ale. Ohio’s Slurpee machines feature Faygo Cotton Candy soda. In Texas, Big Red and Dr Pepper are wildly popular.

But while candy-inspired and soda-mimicking flavors are what Slurpee’s best known for, according to Smith, the chain is working on ways to make its product more attractive to the 58 percent of Americans who are trying to cut their sugar intake. In 2012, 7-Eleven introduced Slurpee Lite, a drink made with artificial sweetener saccharin instead of the usual high fructose corn syrup. Each eight-ounce serving of Slurpee Lite contains around 20 calories, compared to 66 calories and around 16 grams of sugar per eight-ounce serving in a regular Slurpee.

"Now, kids interact totally differently. They’re getting a Slurpee and posting it on Snapchat."

The chain is currently working on ways to offer a broader range of Slurpee Lite options, with plans to introduce a "much healthier" flavor made with real juice. In the coming months, the chain will introduce the first nationally-available Slurpee made with real sugar. It’s also working on a Slurpee that’s sweetened with stevia, a natural calorie-free alternative.

The change in Slurpee’s consumer base may ultimately impact the future of the Slurpee in a big way. "Customers always like the ability to customize," says Smith. "How do we provide a level of customization inside the store? Maybe it’s even a different machine." Some of that change is already happening. In Michigan, 7-Eleven offered a lemonade Slurpee that could be customized with various flavors, much like modern soda fountain machines that allow you to add cherry, lime, or orange flavoring to drinks like Coca-Cola and Dr Pepper. The chain has also experimented with mix-ins like Pop Rocks candy.

Despite its relatively quiet first 50 years, expect change for the Slurpee to come at warp speed in the coming decades. "In the next five years, we expect Slurpee and our stores to change as much as they did in the last 50," says Smith. "When I was a kid, the biggest rite of passage was asking your mom to go to 7-Eleven to get a Slurpee. You take your bike, you hang out in the parking lot with your friends. Now, kids interact totally differently. They’re getting a Slurpee and posting it on Snapchat. It’s changed that much in just 20 years."

Lead Photo: Sorbis/Shutterstock
Amy McCarthy is a writer and editor in Texas, from where she serves as editor of Eater Dallas and Eater Houston. She enjoys lipstick, cocktails, cooking, and fighting with celebrities on Twitter.
Editor: Erin DeJesus

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