Getty Images/Mark Newman
Westward Whiskey master blender Miles Munroe was wandering through the distillery’s new barrel warehouse this past spring, stopping to pull samples from a variety of barrels that caught his fancy. It’s a diverse collection, ranging from blends of pinot noir and stout casks to port, rum, and Brazilian amburana wood. But one that drew particular excitement was an acacia cask—a novel wood type to find in a whiskey rickhouse, and one that delivers an intriguing assortment of flavors.
“Acacia can produce floral and citrus notes, along with soft honeyed flavors, and with Westward it brings out the orange zest that hides in the aroma and adds jasmine and honeysuckle character,” says Munroe. “What I really like about this wood is that it has pretty low tannin content compared to other wood types, so there's less astringency and softer tannin complexity extracted.”
Munroe's interest in acacia was piqued by a visit to the Royal Botanic Gardens in Melbourne, Australia in 2021, where he learned of Australia’s enormous acacia biodiversity, with nearly 1,000 different species. After that visit, he tracked down some acacia casks previously used to mature wine. “It gave us great results, and even surprised me with some aspects, like the deep color change,” he says. He then began sourcing new casks from two producers in France, and has continued playing with variables including differing toast levels, and how best to work with virgin acacia casks versus the used wine casks.
“Both have their great uses and I've loved using both,” Munroe says. Thus far, he's deployed acacia casks for allocated single barrel releases in Taiwan, as well as for added depth and softer mouthfeel in blends released as part of Westward's limited-edition Whiskey Club series. It’s likely to be worked into the fold for future Milestone releases, the brand’s annual signature solera-system matured expression. “Because acacia is used mostly for white wines, there isn't as much influence as there is with reds, and since wine has such a lower ABV than whiskey, a distiller will get more extraction and more use out of a used wine cask. New casks are pretty influential, but with softer tannins [this wood] won't be as overpowering as oak.”
What to Know About Acacia Casks
Acacia, sometimes known as thorntree, includes about 1,300 species and comes from a wide swath of the planet including Australia, Europe, the Americas, Africa, and southern Asia. This sturdy wood has long been used for maturing French white wine and is also prominent for flooring, cabinetry, and furniture.
Beyond Westward, acacia wood has been used by Japanese rice whisky producer Ohishi, while Irish whiskey makers have taken a particular fondness for it, with Teeling, Bushmills, Killowen, and Method and Madness among those who have dabbled with it. That's thanks to Ireland’s rules that allow all types of wooden vessels for aging whiskey—as opposed to scotch whisky, for example, which stipulates the mandatory use of oak.
“Acacia is a strong wood and it's believed that it has been around for more than 20 million years, with fossilized charcoal deposits that appear to have parts of the tree preserved in them,” says Alex Thomas, master blender at Bushmills, which first released its Distillery Exclusive, finished in acacia wood for over a year, back in 2018. “The Distillery Exclusive is subtly spiced by the casks, with warming hints of nutmeg, with the liquid featuring honey and floral notes complemented by sweet vanilla and dried fruit flavors, finishing with a hint of cinnamon and a whisper of wood.”
Teeling has experimented with myriad types of wood over the years, with its Wonders of Wood series devoted to showcasing a few of the finest results. With acacia, the distillery released a 14 year old acacia-finished single-cask bottling through Chicago-based retailer Binny’s in 2020. Teeling continues to look for more uses, sourcing sustainably harvested acacia from Africa and collaborating with a specialty cooperage to construct the casks. “The point of using unique woods is to challenge the mindset of what whiskey can be,” says Teeling master distiller Alex Chasko. “The unique flavor garnered from fully matured Irish whiskey in acacia is sweeter, with more floral, honey, and roasted nut aromas than you would get from oak.”
At the micro distillery housed within Midleton Distillery, Irish Distillers previously included a limited-release acacia-finished expression under its Method and Madness label. “Initially matured in a combination of bourbon and sherry casks, the dense acacia wood imparts rich, nutty, and chocolaty flavors in our Method and Madness Acacia Wood release,” says Barrett Stapleton, the micro distillery’s head distiller. “The result is a well-balanced liquid, with a nose of wood spice and sugared almonds, a palate of coffee beans, dark chocolate, and chile, and a finish of fading spice and charred wood.”
Acacia casks are sturdy, hard, and don't leak, and while they’re more expensive than bourbon barrels, they’re still cheaper than sherry casks or pricier woods such as mizunara. “Acacia is a great wood to work with, as it's malleable under heat, which makes it easy to shape, it's quite dense, meaning it's not leaky and doesn't absorb too much liquid as it matures,” says Finbarr Curran, the wood planning and maturation team lead for Irish Distillers.
Bushmills and Irish Distillers note that acacia's density makes for a slower maturation time, though others note that its larger pores counteract that to some degree. “It escalates exposure to compounds like lignins, vanillins, and those soft tannins,” Munroe says.
Virgin acacia and used wine casks are both being used, and while finishing has been the most common application, most see the potential for full aging within acacia as well. “I'm experimenting with full maturation in acacia to see what effects it has on aging time and development,” says Munroe. “I'm also looking to put some of our fermentation experiments into these casks at some point, such as the single malt we made recently with a Rhone wine yeast. I think it will be a fantastic flavor combination.”
It's a new era for this ancient wood, with no established doctrine on how it could or should be used. For those with their eyes on experimentation and innovation, it’s a fun prospect to imagine more of these expressions.
