Just as modernist cuisine introduced the world to weird-science compounds like sodium alginate and transglutaminase (“meat glue”), the current soda fountain revival has its own vocabulary of thrills. To get a primer, we turned to the people behind the country’s latest entrant, San Francisco’s Ice Cream Bar. The 1930s-style fountain serves G-rated sundaes up front, and in back, drinks made with ingredients that titillate in a whole bunch of really strange ways.

I talked with fountain manager Chris Simpson and menu consultant Russell Davis (of San Francisco’s Rickhouse bar) about the lactarts, phosphates, and other curiosities that show up in Ice Cream Bar’s extensive offerings. Curious customers sit close together on vintage stools, order drinks they’ve never had before, and exclaim: “What’s in this?”

Here’s what’s in that:

Soda water: Not the stuff that comes out of a bar gun, but charged water at the proper pressure level and pH, with pinprick bubbles that tingle like good Champagne.

Double-charged soda water: CO2-charged water with bubbles so fine they’re invisible to the naked eye. In the mouth, they feel a bit like Pop Rocks.

Acid phosphate: This combination of phosphate salts and water lends a strange and wonderful sour note to drinks like the Ice Cream Bar’s Wild Cherry Phosphate, which mixes hints of really delicious cough syrup and sour cherry pie filling. Plain, the acid phosphate has a truly curious sourness that lingers at the outsides of your tongue, and makes your salivary glands work overtime.

Extinct lactart: Davis likens the flavor of lactarts to the water that seeps out of yogurt. Like acid phosphate, it’s sour, though with a milky note. In drinks like the Ice Cream Bar’s Ode to Mr. O’Neil (that would be Darcy O’Neil, author of the seminal soda-fountain revival book Fix the Pumps), the astringent, mouth-puckering quality of the lactart contrasts nicely with rich, smooth chocolate.

Gum arabic: The hardened sap of the acacia tree is commonly found in marshmallows and other gummy candies (it’s one of the ingredients that make Mentos fountains gush). Made into gum syrup, gum arabic makes drinks weighty and thick, without turning too sweet. It makes a drink stick to the sides of your mouth and tongue, where flavors can linger.

Citric acid: If you’ve ever eaten an Atomic Sour Ball, you know the raw burn of citric acid. In the Ice Cream Bar’s off-menu lemon-lime soda, the combination of citric acid and acid phosphate replicates the flavor of fresh lemon, but with an extra little thrill. “That’s what Sprite is supposed to taste like, and doesn’t,” says Simpson.

Photo courtesy of Tracy Benjamin / Shutterbean

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