NYC’s Lullaby Is Pioneering a New Way to Carbonate Cocktails With ‘Girl Cola’

In the age of molecular mixology, carbonated cocktails have become fairly common in bars and restaurants with robust beverage programs. We’re not talking about French 75s and Vodka Sodas, but drinks that bartenders force-carbonate in kegs and dispense via a draft system.

While there’s no denying their appeal, this method of carbonating cocktails only gets them so fizzy. In general, their carbonation levels are often more akin to that of a porter or stout rather than a macro lager or a can of seltzer. This isn’t to say that these drinks are lackluster, but the folks behind NYC bar Lullaby recently sought out a way to make carbonated cocktails as bubbly as possible and make every sip hit like a freshly cracked can of Coca-Cola.

Earlier this year, they debuted a drink that reimagines and improves the established methodology for serving carbonated cocktails on draft. The drink in question? Bar manager Liz Hitchcock’s Girl Cola. Beyond its cutesy name — and equally cute custom drinkware — lies a nearly two-year- long journey of trial and error marked by overflowing kegs, a sawed-off soda gun, and, ultimately, a carbonated cocktail that’s fizzier than anything you might have encountered before.

Girl Dinner to Girl Cola

Hitchcock initially hatched the idea for the cocktail in summer 2023. “The ‘Barbie’ movie had just come out, and everyone was saying things like ‘girl dinner, girl this, girl whatever’ all over social media,” she says. “I kind of was running with that idea, but also I’m the only woman bartender on the team, and I just really wanted to make a ‘girl’ cocktail.”

The initial concept began as a vodka spritz, and then Hitchcock put Ramazzotti (an amaro) and Crème de Noyaux (a stone fruit pit liqueur) into the mix. The resulting flavor, she claims, had a distinct cherry cola-adjacent flavor.

The remaining ingredients fell into place during R&D. These include absinthe, Champagne acid, polydextrose, acid phosphate, and a house-made cola syrup. The next step was carbonating the whole thing.

Getting It on the Gun

As Lullaby co-owner and beverage director Harrison Snow explains, force-carbonating cocktails is a fairly straightforward process at its core. “You’re putting it in a pressurized environment with CO2 and trying to control that environment as best as possible with temperature, pressure, and time,” he says. “Essentially, you want to make sure that any headspace is as close to 100 percent CO2 as possible.”

To achieve this, most bartenders pump CO2 into a solution in a PET bottle (or keg) until it reaches a pressure of roughly 40 to 50 pounds per square inch (PSI). Then, they shake the bottle (or keg) to better incorporate the CO2 into the solution, and chill it to keep the gas suspended in the liquid.

“We had [Girl Cola] on our draft system,” Hitchcock says. “But then we thought it would be really cool if we could figure out how to get it to come out of our soda gun to give it that presentation of being like a cola.”

Credit: Lullaby

To do so, Snow cut the gun in half with a bandsaw, removed all of its components and replaced them with a standard draft line. He installed a valve that was intended to make the gun function similar to a beer tap, but the resulting flow and carbonation level didn’t pack the force the team was hoping for.

“We’ve always had a few draft cocktails and they’ve always been carbonated-ish,” Snow says. “I think it’s something that we — and a lot of bars — have just kind of accepted.” When serving cocktails on draft, the drink loses some carbonation on its journey from the keg to the tap. Think of it like drinking a can of soda through a 50-foot-long straw. By the time the liquid reaches the end, much of the CO2 is gone.

From Fumble to Fizz

The challenge was there: getting Girl Cola to snake its way up from the kegs in Lullaby’s basement to the soda gun without losing any carbonation along the way. Snow and Hitchcock moved the kegs from their walk-in fridge to their freezer. They dropped the temperature of their glycol cooling system that runs parallel to their draft lines. They increased the pressure in their kegs to near hazardous levels, but nothing was working.

“CO2 is only going to stay in a liquid so long as it’s under pressure, and the minute that you release that pressure CO2 starts escaping,” Snow says. “Everything we were trying was only helping so much.”

Finding themselves at an impasse, the team had to think outside the box. That’s when they came across a device called an inline flow control module, which is designed to dispense highly carbonated beers.

“Basically, it’s this little torpedo-shaped thing that controls the flow and changes the pathway of a liquid without changing the size of the opening where the liquid is coming out,” Snow explains. “From what I understand, that creates an enormous amount of restriction in a small space where the liquid is forced to slow down. And since it’s forced to slow down over this really small distance, the loss of carbonation can’t be that large.” Snow opened up the soda gun and attached the flow control module to the tubing inside, and that was the eureka moment.

“All of a sudden, Girl Cola came out really, really fizzy — much more carbonated than any of our other draft cocktails,” Snow says. “Once we figured that out, we ended up replacing many of the components of the draft system and basically tried to mimic the effect of what was happening in the gun throughout the whole system.”

Credit: Lullaby

According to Snow, he and his team are now able to carbonate cocktails at 50 PSI and serve them at 50 PSI, too. To his knowledge, this isn’t something that anyone has ever been able to do with draft cocktails until now.

“A lot of the conclusions we’ve drawn might not be totally grounded in science, but we found something that works,” Snow says. “The crazy part is that it requires the smallest change ever. If you work at a bar and you’re serving cocktails on tap, get a few flow control modules and change your serving pressure to be the same as your carbonation pressure.”

Then, watch the magic happen.

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