“Biologically Aged” Cocktails: Bartenders Take on Fermentation

On different sides of the world, two bartenders are using everything from champagne yeast to koji, a mold used in the production of miso and sake, to ferment cocktail ingredients. Carey Jones on how microbes are finding their way into your cocktail glass.

Before the advent of barrel-aged cocktails, the order of operations in creating a drink was clear: distill spirit; age in barrel (should it be required); mix cocktail; serve.

Recent developments upended that order—namely barrel-aged cocktails, which added another step sending entire cocktails into a barrel for aging. And while alcohol is usually produced long before any notion of a specific cocktail comes into the picture, a few enterprising bar folk have begun to augment that order too—by using yeast to produce their very own fermented cocktail ingredients.

In unrelated bar programs, 5000 miles apart, Ryan Chetiyawardana of White Lyan in London and Jeff Josenhans of Grant Grill in San Diego have begun working with yeasts—and, in the case of Chetiyawardana, koji mold—to explore how they might impact texture and flavor in drinks.

To understand the years of R&D behind Chetiyawardana’s “biologically aged” cocktails, one must understand the barman himself, a boundary-pushing bartender with a background in biology. A glance over the menu at his London bar tells you as much.

There’s the vodka-based Bone Dry Martini, made with an actual bone tincture of roast chicken bones dissolved in phosphoric acid. There’s the Moby Dick Sazerac, which employs ambergris (a sperm whale excretion highly valued by perfumers) to lift and elevate aromas just as it does in a bottled fragrance. (“It sounds like a gimmick ingredient, but isn’t; the translation of aroma is unlike anything else, it lifts flavors right off your tongue,” he assured me.)

But far more radical than unconventional ingredients is his utter reworking of the cocktail process, in the name of quality and consistency. Every cocktail is pre-batched and bottled. No juices; fruit is too unpredictable. No ice. There are few ingredients White Lyan doesn’t adapt to its own purposes, starting with its water: London tap, filtered to a high purity, with precisely calibrated minerals added back in. Spirits? Chetiyawardana works directly with distilleries (he won’t divulge which) to develop custom products. With white spirits, he specifies the distillate, buys it in bulk, and cuts back to proof with his own water.

“If we can’t control it, we don’t use it,” Chetiyawardana promises.

Which is why his recent experiments with biological organisms might seem unlikely. For a man with a Steve Jobs-ian compulsion to manage a product end-to-end, it may seem self-defeating to pursue a project with the unpredictable process of fermentation. Calibrating a cocktail’s pH with citric acid, say, will go exactly as expected if ratios are all in line. But living organisms add variables that are impossible to fully control. “We’re at the mercy of a living thing,” he laughs, “and the results can be completely unexpected.”

“Essentially, it’s making cocktails according to the champagne method.” For The Mule, Josenhans cold soaks muscat grape juice, fresh ginger and Cascade hops together. After several weeks, he filters the infusion, adds champagne yeast and allows it to ferment in the bottle, producing a buildup of carbon dioxide. It rests “on the lees”—on its own yeast—before the dosage, in which Josenhans adds sugar and vodka, and then re-corks the bottles. From beginning to end, the process takes about three months.

Chetiyawardana long found himself fascinated by the complexity of flavor that yeast and molds introduce—whether in sherry, fine hams or miso, whose production involves the koji mold. “It wasn’t just the flavors,” he says, “but how you can’t create them yourself; how there’s a third party involved.” (He’s called the process of introducing yeast to proto-cocktails “biological aging,” though not in the same way sherry fans might understand wines maturing under a layer of yeast known as flor.)

In his years pursuing the project, Chetiyawardana has gone to great lengths to understand how various microorganisms behave. He consulted with Harvard microbiologist Rachel Dutton, who helped him understand what different microbes might contribute, flavor-wise. Early experiments proved surprising, but after hundreds of trials, he began to settle on yeast types and understand the parameters that would allow them to thrive.

When applying this knowledge to cocktails, whiskey-based drinks were prime candidates. “With whiskey, you take something that’s made from barley—which is largely neutral —and it develops this whole gauntlet of flavors. Of course some of that comes from the barrel, but so much is from the yeast and its alchemy.”

The Magnus Reserve, the newest cocktail on White Lyan’s menu, adds another layer of living flavor. Chetiyawardana starts by essentially producing a gooseberry wine with fruit, herbs and yeast. As with any fermentation, the yeast eats up the sugar, creating alcohol and other byproducts.

Rather than waiting for rising alcohol levels to kill off the yeast, Chetiyawardana arrests the process by adding Scotch whisky, which elevates the ABV enough to stop fermentation. He then dilutes the wine-whisky combination with water steeped with fruits and herbs, among them rose hips and hibiscus, which impart “a bit of a tannic note.” All this occurs at Chetiyawardana’s offsite kitchen. The resulting cocktail is served from an Enomatic, a wine dispensing system, “which allows us to maintain a controlled environment.”

Now that the Magnus has debuted, Chetiyawardana has turned his attention to the next experiment: He’s developing another “biologically aged” drink for his forthcoming bar Dandelyan, experimenting with the koji mold, which breaks starches into sugars (as it does in the sake-making process). “It produces glutimates which are the essence of umami.”

Over in San Diego, Jeff Josenhans of Grant Grill, in the US Grant Hotel, shares Chetiyawardana’s knack for tinkering and innovating. An early proponent of barrel-aging cocktails, and of growing fruits and herbs for his bar program onsite, Josenhans found himself casting around for a new project several years back. Given the hotel’s robust catering business, with some events calling for 300 cocktails served simultaneously, he wanted to devise a way to create quality cocktails on a large scale.

“This idea of mine—which I call cocktails Sur Lie—solved all of our problems,” says Josenhans. “Essentially, it’s making cocktails according to the champagne method.”

Josenhans starts with a non-alcoholic fruit base. For The Mule, he cold soaks muscat grape juice, fresh ginger and Cascade hops together. After several weeks, he filters the infusion, adds champagne yeast and allows it to ferment in the bottle, producing a buildup of carbon dioxide. It rests “on the lees”—on its own yeast—before the dosage, in which Josenhans adds sugar and vodka, and then re-corks the bottles. From beginning to end, the process takes about three months. The result is a fizzy cocktail whose ginger and vodka evoke a classic Moscow Mule, with citrusy Cascade hops and sweet-floral muscat taking the place of lime.

Produced similarly is La Grenade, a base of hibiscus tea and pomegranate juice, infused with bay leaves and black pepper, then fermented with yeast and cut with cognac and a concentrate of barbera grapes. To serve, it’s poured from the bottle into a coupe, developing a slight fizzy head, and garnished with a bay leaf. The Cosmo: Reinvented, with a similar deep ruby color, is made with cranberry juice soaked with makrut lime, Meyer lemon and tangerine zests before fermented with pinot grigio yeast and finished with vodka and fresh pinot noir juice; it’s poured chilled, straight from the bottle, and served up with a cranberry garnish.

Three years into the project, all three cocktails are still on the menu, thanks in part to large-scale production made possible through a partnership with Temecula’s Middle Ridge Winery. “We use their equipment when they’re not crushing or making their own stuff. It’s a win-win.”

So many bar techniques begin as novelty before spreading across the country and beyond: making bitters and tinctures in-house, putting cocktails on tap, barrel aging. Is in-house fermenting next? It seems unlikely. There are legal and logistical barriers to contend with; making alcohol requires separate permits than serving it. (Both White Lyan and Grant Grill produce these drinks offsite at licensed facilities.)

And, of course, there’s room for things to go wrong. Cocktail creation always involves trial and error, but not the sort that results in bottle-exploding carbon dioxide, overgrown yeast populations or unappetizing off-flavors. These two barmen only succeeded after endless experimentation; Chetiyawardana claims he often goes through hundreds of iterations before getting a cocktail right, and spent years refining his “biological cocktail” concept before it came anywhere near the menu. Both he and Josenhans have built reputations as innovators at establishments that support intense R&D, and therefore have more liberty to play around than the average cocktail bartender.

But whenever new techniques emerge, there’s an eager community of bartenders ready to try their own hands at it. And even if some among them fail, even spectacularly, it’s the occasional successes—or at least glimpses of potential success—that move the industry forward.