In 2015, when Alex Day and Devon Tarby sought to “crack the code” on a perfectly transparent root beer–like cocktail for the now-closed Walker Inn in Los Angeles, they found that the key was adding a bit of lactic acid to vanilla syrup.
To develop a root beer syrup with vanilla flavor and robust texture, Day, now partner at the hospitality group Gin & Luck, recalls that lactic “created that creaminess without the baggage of ‘cream’ proper.”
Since then, powdered lactic acid dissolved into simple syrup has become a go-to secret ingredient for the Gin & Luck team (which includes Death & Co.), used to imply “creaminess” without the density of dairy or nut milks.
Of course, science-minded bartenders have long employed acids to mimic or amplify flavors, using citric acid in place of fresh juice, or malic acid to create the tart pucker of Granny Smith apples. Lactic acid in particular references the tang of yogurt or kefir, but also adds a subtle richness to drinks. Most often, lactic acid powder is dissolved in water, giving cocktails like White Lyan’s Creamy Martini a fuller mouthfeel. But dissolving lactic acid into simple syrup makes it a more natural addition to cocktails, and gives syrups a “rounder” texture, says Day.
Day first learned about alternative acids—“specifically citric acid to brighten up flavors in syrups”—while working with Eben Freeman at Tailor, an influential late-aughts New York bar known for its pioneering work in molecular mixology. He also credits as inspiration Dave Arnold’s groundbreaking work with acids, including lactic and malic acids, as well as Fix the Pumps author Darcy O’Neil, for researching and then reviving Lactart, originally an 1880s product made with lactic acid that is intended to enhance the flavor of food and drinks.
Today, lactic-laced simple syrup appears in a wide range of Death & Co. drinks, sweetening and balancing citrus in sours and highballs and making an appearance in more spirituous drinks, where, Day says, “we may use a quarter- or half-ounce just to give an impression of creaminess or richness.”
The Vanilla Lactic Syrup is a particularly versatile player. For example, in Tyson Buhler’s Pompadour, built on a split base of rhum agricole and Pineau des Charentes, the sweetener accents the rum and plays up three-quarters of an ounce of lemon juice.
Over time, the Vanilla Lactic Syrup has evolved. A relatively elaborate version, involving an immersion circulator to infuse the syrup with a split vanilla bean, appears in Death & Co.’s second book, Cocktail Codex, published in 2018. (A more streamlined, home-friendly version was developed later.) Death & Co. alum Natasha David brought the syrup to Nitecap, her now-shuttered New York bar, and includes it in her recently published book Drink Lightly, where it’s featured in drinks like the Crimson Sour, made with blood orange juice, cacao nib–infused Campari and sweet vermouth.
An adaptable base itself, the vanilla syrup also works well with fruit flavors. For example, Death & Co. added orange extract and sparkling water for an “orange cream soda” effect, echoed in David’s Highball to Heaven, which mixes one part orange juice to two parts Vanilla Lactic Syrup, to create what she calls “Orange Cream Syrup.”
Similarly, Death & Co. channels the classic combination of strawberry and cream by combining a clarified strawberry mixture with the Vanilla Lactic Syrup to create Strawberry Cream Syrup, which the bar uses in the Twist of Menton, a Last Word variation. (Day notes that a well-strained dollop of strawberry jam would create a similar flavor.)
Adding just a small amount of lactic means “a syrup that’s bursting with vibrant strawberry and just has a bit of creamy roundness to it,” Day says. Instead of complicating a drink by adding additional flavors, this technique “enhances the complexity of [existing] flavor.” That’s the beauty of the lactic acid syrup—it creates a boost that, when done right, is almost impossible to detect.
“You take a sip and the mouthfeel is incredible, but you can’t pick out what it is,” Day explains. “I find subtlety to be the greatest execution of some of these ingredients.”