Staid Spirits Get Shaken Up With Aging in Uncommon Wood

(Bloomberg) -- If you’re a fan of barrel-aged spirit, the value of oak cannot be overstated. For centuries, liquor makers have been laying their liquid down in casks of Quercus, a thick-trunked genus of tree with dozens of species spread out across worlds Old and New. But the time-tested wooden cask is rolling into an era of innovation. From the cane fields of Oahu to the vineyards of Cognac, distillers are suddenly trying on additional sorts of cooperage. Some unexpected flavors are forming in the process. 

Many types of wood are suitable for liquid storage. So why is it that oak has monopolized the medium? At first, it was merely a matter of convenience: Cognac producers of the 1700s needed containers to transport their treasure to increasingly thirsty markets in England and Holland. Oak was abundant in the forests of southern France, and its staves were relatively easy to bend into barrel form. Yet the tight grain of the wood still afforded a dependable barrier to leakage. 

Eventually, merchants (and drinkers) realized that the high-proof alcohol swishing around inside was picking up flavor along the way—lots of it. Not unlike hot water exposed to a teabag, distillate extracts all of its color and much of its taste from its ligneous enclosure. For cognac, this meant that what arrived in the ports of London and Amsterdam was more quaffable than what had departed the distillery months earlier, often with added notes of rich vanilla, toffee, and caramel.

Tradition then gave way to codified law. Fast forward to today and the protected category of cognac is legally required to be aged wholly in French oak. But at least one spirit maker is challenging the rationality of that regulation. “I don’t like when humans put any limitations on creativity,” says Alexandre Gabriel, founder of Maison Ferrand, a cognac house based in Ars, France. “In the post-Prohibition era, we’ve seen a uniforming of techniques across many styles of spirit, and that includes the wood we use for aging. This is more for cost-effectiveness than it is for flavor.” 

A Return to Chestnut Wood

Five years ago, while conducting research for a book on the history of barrel aging, Gabriel uncovered documents from 19th century cognac producers that included invoices for chestnut barrels. It turns out that wood from these trees would frequently work its way into the aging process. Gabriel endeavored to bottle something new by taking a page from the past: putting aged eau de vie into chestnut. The result was Renegade Barrel. Released in 2019, it bore a delicate complexion, surrendering notes of honey and white flower against an appealing nuttiness.

This was a novel drinking experience, to be sure. Just don’t call it a cognac. “I have to call it an Eau De Vie De Vin,” Gabriel laments of the lengthy moniker. In English, it translates to water of life from the vine. “But chestnut barrels were actually a delicacy for cognac in the 19th century—some of the biggest English traders of the time were very fond of it.” 

According to Gabriel, before it was outlawed in 1945, local producers stopped working with chestnut because it is a particularly “thirsty wood”: Annual evaporation through the barrel is about double that of oak. Nevertheless, so enamored was he with its associated flavors that he resolved to continue working with it. “This wood offers such sweet tannins,” he observes. “It’s magical and worth fighting for.” 

Gabriel is actively lobbying for a redefinition of the spirit in recognition of these historically relevant oak alternatives. The main pushback comes from the Bureau National Interprofessionnel du Cognac, or BNIC, the trade group tasked with safeguarding the category’s denomination of origin.

At Maison Larsen, managing director Jerome Durand doesn’t see it as a fight that can be won, so he’s charting a less pugnacious path toward innovation. He helped develop a proprietary steam-toasting method for the oak barrels that age his new Aqua Ignis III cognac. Seasoning the staves this way coaxes out some of those softer chestnut essences—lighter on tannins and astringency—without surrendering the ‘Cognac’ label.

“As far as I know, cognac aged in woods other than oak is not an open topic today in the BNIC,” he says. “Even if there are sometimes local [producers] having discussions about it.”

Rounding Out Rum 

In the U.S., whiskey makers are similarly constrained: “Oak containers” are a necessary ingredient for all bourbon and rye. The same applies to scotch in Scotland. Rum producers, on the other hand, aren’t so encumbered: Their spirit must merely be derived from sugar cane or its byproducts, such as molasses. Most commonly, it is aged in ex-bourbon barrels, but makers are free to age it however they like. On the Hawaiian island of Oahu, Ko Hana is doing just that. The 10-year-old distillery has released the world’s first rum finished in casks of koa wood—a species of acacia found only in this part of the Pacific. 

The influence this particular cooperage exerts on the liquid is profound. It shows a brilliant burgundy hue in the bottle, and it noses far gentler than any oak-imbued offering, exhibiting a fresh pepper characteristic. That same spice carries through on the palate, rendered through a soft, satin-like mouthfeel. It drinks exceptionally easy. Making it, however, was anything but. 

“The ideal wood for coopering a cask is straight-grained with consistent character; that is quite uncommon in koa,” says Robert Dawson, co-founder of the brand. “Koa’s grain structure is less elastic than traditional oak. The koa cask staves do not want to bend to the traditional contoured shape of a cask without gentle air drying and careful encouragement with steam.”

To ensure the sustainability of the endeavor, Ko Hana is working only with naturally fallen trees—even though it ends up complicating the selection process. Ko Hana’s barrel-maker has to find wood with straight grain and consistent density that’s also free from rot. It’s the same sort of koa as that preferred by Hawaiian luthiers to craft world-famous ukuleles. 

Cachaça Gets Eco-Conscious

Ko Hana’s commitment to sustainable sourcing is mimicked by Dragos Axinte, founder and chief executive officer of Novo Fogo Cachaça. The native sugarcane spirit of Brazil is often aged in woods endemic to South America’s rainforest. Examples include amburana, or teakwood, and a nut wood known locally as castanheira. As much as Axinte appreciates the unique characteristics they impart to the liquor, he is wary of the associated environmental costs.

“The most urgent challenge in the case of aging cachaça in native Brazilian wood barrels is that most of the trees used for barrel-aging are endangered at some level,” warns Axinte. “With the beverage market’s growing curiosity about exotic spirits and non-oak tropical aging, the challenge for Brazil’s forests and precious tree species becomes even more fraught: Can market demand and sustainable forest management coexist?”

He believes the answer is a resounding “no” as it applies to most large-scale cachaça makers. But he found a creative workaround for his Tanager expression. It’s finished in araribá—a protected species of Brazilian zebrawood—barrels of which Axinte repurposed from an abandoned house. The drink holds a curious combination of holiday spice, tropical fruit, and even fresh-pressed olives. He can produce only so much, however.

“We got two barrels out of that house, but one broke, so we’re down to one,” he says. “We don’t anticipate finding more of this wood that meets all of our [sustainability] requirements.” Luckily, the finishing is a brief process, so he can cycle through a lot of liquid. Bottles are available in the U.S. for around $50.

Back in the South of France, Alexandre Gabriel believes he can have his unconventionally aged spirit and drink it conscientiously, too. As the owner of Plantation Rum, he’s currently experimenting with a first-of-its-kind Fijian-sourced spirit. The rum matures in barrels utilizing heads crafted out of mango trees that were toppled during a recent hurricane. “A lot of culinary arts are born out of necessity,” he says, equating distiller and chef. “I am determined to do the same. So long as you can do it responsibly, why would you ever take any spices off the spice rack?”

©2021 Bloomberg L.P.