On the surface, it’s fairly straightforward. To be called Scotch whisky, new-make spirit must be aged in oak casks no larger than 700 litres for at least three years. In Scotland, of course. But with more than 140 distilleries and myriad approaches across the country, there is more to maturation than meets the eye.
Luckily for Distell – the parent company for, among others, Deanston, Islay distillery Bunnahabhain, and island site Tobermory, which also produces peated malt Ledaig – it has the McCarron-Fernandez duo looking after the cask matchmaking. Fernandez is the master blender. She joined the business in April 2017 from Chivas Brothers and was promoted to master blender three years later. McCarron, master distiller, came on board from The Glenmorangie Company in April 2021 and oversees the entire whisky-making operation from grain to glass. What subsequently formed was the dream team.
They both vibe off each other. There’s a bond clearly built on humour, energy, and mutual respect. “We’re both creative people,” chimes in McCarron. “We’ll both be working on whiskies at the same time, then we’ll work on whiskies together. It all just keeps coming back into this collective idea.”
For both of them, there’s an art to pairing spirit with casks. Simply put, some distilleries are easier to ‘match’. It all starts with a deep understanding of the core character. “Deanston’s simple,” McCarron says. “It’s incredibly waxy new-make spirit.” For Fernandez: “I get a lot of fresh apples, like if you just pick an apple off a tree and bite into it.”
They both agree it’s an easy-to-please spirit, at home with all casks. This is thanks to its obscure waxiness. “It’s the open-top mash tun and crystal-clear wort,” Fernandez continues. “Fermentation is about 85 hours because we need all the fruity esters to come through to help us get that waxy character.” There’s a lot of reflux in the stills, and then an unusual way the spirit is collected results in a film of literal “black gunk”, to quote McCarron. Don’t panic – you can’t see it in the final spirit. But its texture is more than apparent.
Bunnahabhain and sherry maturation go hand-in-hand. “I don’t know who it was that made the decision to pretty much exclusively mature in Oloroso, but I’m glad that person did because it just works fantastic,” McCarron states. He says it’s because the distillery produces tiny amounts, but in big batches, resulting in its signature unpeated, biscuity style. “Definitely there’s a saltiness to Bunnahabhain,” he adds. “Is it because the distillery is right next to the sea? Is that the air, or is it the casks? Who cares? No one’s ever going to narrow it down.”
They both believe that Tobermory is far trickier to match. There’s pineapple and fresh orange peel in the new make, but it’s finicky. They both speak of an ambition to increase the age statement; it just needs longer in oak. “It can be funny,” notes Fernandez, who hones in on American oak and ex-bourbon casks. “You could quite easily put it into a cask type that just doesn’t work.”
Ledaig, the peated spirit that flows from the same stills, is a different story. “It’s just smoky, but it’s different smoke,” reckons McCarron. “It’s like Victorian, industrial, almost dirty smoke. It’s just got an unbelievable intensity to it.”
This is where Ledaig becomes an apparent outlier. On the one hand, it works tremendously in a refill cask. It’s so bold, they let the spirit itself do the talking. And yet, the Sinclair Series, which makes use of ex-Rioja casks, has become a cult favourite.
“It’s an absolute match made in heaven,” Fernandez extols. “It’s about getting that balance of the flavours from the red wine and the peated compounds, and getting the two of them balanced perfectly and not having one overpowering the other.” It almost goes against the grain: phenols from the peat often just fight inharmoniously against cask influences.
So, what’s the secret? How do blender and distiller navigate the compatibility of cask and spirit, especially if it’s a fresh combination? Fernandez makes it sound simple: “It’s about knowing your new make, knowing the cask type that you’re using.” In practice, this looks like keeping experimental casks on the mainland near the lab for close monitoring. “I don’t think you’re ever going to know when you fill a cask if it’s one you’ve not used before,” she details. “You can never say that it’s going to need six months, nine months, a year…” she says, referring to finishes and secondary maturations. “It’s just about experimenting and testing it.”
Are some casks easier than others? McCarron has a surprising take on the most challenging. “Right now, I would say sherry casks,” he says. Unexpected, given they’re the ones he and Fernandez use most often. But it’s because the quality is going up and up. “That’s great, but then you need to balance... If you don’t, you’re going to end up with something that used to taste like milk chocolate, for simplification,” he explains. “In a couple of years, just by following the exact same recipe, it will start to taste like dark chocolate or coffee.” No longer can you say a straightforward two sherry casks to one bourbon cask will result in the same finished malt. “You’re having to play with ratios.”
Across its single malt operations, Distell is well known for its sherry cask offering. Fino, Manzanilla, Palo Cortado, Pedro Ximénez and Canasta are all used alongside the more common Oloroso. All offer very different flavour profiles that affect their use in the matchmaking process. “For Bunnahabhain it’s 99.9 per cent Oloroso that we use for maturation. And that’s the same for anything that we sherry mature for Tobermory,” Fernandez explains. The rest are mostly used for finishing, but some are seeing full maturations.
“If I put Tobermory into Palo Cortado for a long maturation, you might lose it a little bit,” she continues. “Deanston can stand up to that, so we are laying Deanston down in Palo Cortado for full maturations.” She doesn’t want to fall into the “trap” of being known to only use more potent casks for finishes. “We have laid a lot down to mature but we’re just sitting here patiently waiting.”
Virgin oak too is playing an increasingly notable role in the matchmaking. McCarron confirms it’s a passion of his, especially at Deanston, which has become known for its virgin oak bottlings. “There’s a whole series of jumping-off points we can go to,” he says. He’d like to focus on different types of oak as individual releases. “I think you could have in 2023 Scottish oak, in 2024 oak from northern France, and 2025 oak from southern Spain. I’m saying the very obvious ones because we’ve got way more exciting ones than those,” he hints. “Exact forests maybe, all the way down to the tree.”
Any potential matchmaking pitfalls are clearly not hampering innovation. “We are fortunate that we can take risks with Deanston,” Fernandez says. “We put Deanston into any kind of cask and it’s going to work.” And for an upcoming release, that cask is Tequila.
“There are thousands of different Tequilas out there in the market,” she illustrates. “Some are earthy, some are floral... And depending on the Tequila variation it depends on what spirit you would put into it.” Their cask suppliers, she adds, tell them far more about previous contents than you might think. The specific style of Tequila, where the agave came from, how old it was, and how long the liquid was in the cask all influence matchmaking decisions. This is true for every cask, regardless of prior contents. In selecting and ordering casks for the Deanston Tequila release, Fernandez says locality was key.
“Highland Tequilas are known more for their fruity floral character,” she details. “Deanston has that lovely fruity character, that crisp apple, the pears. We wanted something that was going to complement that.” Lowland Tequilas, she continues, are earthier – less compatible with fruit. “I don’t think I would trial lowland Tequila with Deanston. But I would absolutely do it for something like Ledaig.”
For all the liquid-oak agreement, there’s another factor to consider: marketing and storytelling. “It’s not just about pairing the flavours, it’s about us creating a story as well,” she continues. “It’s getting these little nuggets. They’re both made in Highland regions, it’s getting a wee bit of terroir in there.”
Sometimes, she admits, things can be an “absolute fluke”. Take 2004 Mòine Tokaji Cask Finish, one of Bunnahabhain’s limited-run Fèis Ìle 2022 releases. Having never worked with Hungarian wine casks before, she didn’t know if it would be a successful match. “I just felt the notes from the Hungarian wine, and how mellow and gentle Mòine can be for a peaty spirit, would pair phenomenally. Personally, I think it did work really, really well.”
But what if things don’t go to plan? “We’ll keep an eye and see how it starts performing in the cask,” she explains. “If there’s anything we’re not happy with, it’s as simple as not using it. We can place it into quarantine in our system.”
Although it’s a delicate balancing act, successful spirit-cask matchmaking is clearly possible. But where is this thirst for flavour coming from? “It’s human nature,” quips McCarron. “It’s the big thing happening now with single malt,” he says of the wave of interest in more esoteric casks. “But remember, single malt was a new thing 30 years ago.” Back then, Scotch was broadly just ‘fruity’ or ‘smoky’. For him, the lust for interesting liquid is driven by education. “The more people understand, the more they are looking for.”