Cask-finished spirits: have they got us over a barrel?

Finishing a spirit in a wine, sherry or port cask is becoming ever more sophisticated, with distillers searching out barrels from specific wine producers. But can you really tell the difference between whisky or gin finished in a barrel that previously held Corton grand cru rather than basic Bourgogne Rouge?

Words by Peter Ranscombe

In terms of their flavour profile, it’s hard to imagine two more unlikely bedfellows than wine and whisky – the first with its diversity of styles and terroir, the other with its nuanced aromas yet penetrating warmth. But nowadays there’s no escaping the link between the two, in the form of oak. Gone are the days when old wine casks were simply recycled into planters and sold at garden centres – instead, more and more are now heading to whisky heaven to be used for increasingly popular “cask finishes”.

To become Scotch whisky, newly made spirit must mature for at least three years in oak barrels in Scotland (10 or 12 years is more common). Most of that time will be spent in either bourbon barrels – which American bourbon distilleries can use only once – or sherry casks. In the past, those casks came from bodegas, but today’s sky-high demand means most are made specifically made for the whisky industry and simply seasoned for two years with sherry.

For the final months of maturation, some whiskies are transferred into more exotic casks for “finishing”, with the Scotch extracting flavours left behind in the wood by the barrels’ previous occupants. Again, sherry has traditionally dominated – with Oloroso barrels making up the vast majority, but Fino, Amontillado and Pedro Ximénez (PX) also used – while ruby and tawny port were also popular.

Bill Lumsden of Glenmorangie: "I went crazy buying casks"

Now, a wider range of wine casks is being used, stretching from reds like Amarone and Bordeaux through to sweet wines such as Sauternes and Tokaji, and even taking in Champagne base wines along the way.

The master blender credited with triggering the trend is Bill Lumsden, Glenmorangie’s distilling director. The company, and others, had used the technique before – Glenmorangie’s 1963 vintage, released in 1987, was finished in sherry casks; its port wood finish, unveiled in 1994, was the first to make finishing a selling point.

Then, when Lumsden took the top job in 1998, the finishing programme was greatly expanded. “I’m a scientist by training and love to experiment,” he said. “I love wine and went crazy with my cask purchases.”

With its Tokaji influence, A Tale of Cake reminds Lumsden of his favourite pineapple upside-down cake

Lumsden splashed out on expensive casks from Sauternes’ Château d’Yquem, Burgundy’s Domaine de la Romanée-Conti, and his favourite – SuperTuscan Sassicaia. Fortified wines like Malaga and PX proved popular with whisky fans; Lumsden also experimented with different species of oak.

While the original aim was simply to extend the Glenmorangie range beyond its then sole bottling, Lumsden has since refined his creations based on their taste. Finishing times vary, with Glenmorangie’s Nectar d’Or spending 15-18 months in Sauternes casks, while its Lasanta and Quinta Ruban lie for 18-24 months in sherry and port vessels respectively.

Most wine casks are only used once: “After that, they’ve lost most of their wine goodness,” Lumsden says. Not everything has gone to plan; Lumsden’s first foray into Tokaji casks tasted “sublime” after nine months but was “ruined” by Hungarian oak tannins after three years. He’s now returned to Tokaji with “A Tale of Cake”, his latest finish, which reminds him of his favourite pineapple upside-down cake. Similarly, Lumsden initially wanted to increase the flavour intensity of the Quinta Ruban port finish, so he initially lengthened the finishing to four years, before bringing it back to two-and-a-half years to stop the dark chocolate notes from masking the marshmallow and Turkish delight that were signature elements of the whisky.

Gregor Hannah of Lady of the Glen: "The story is important"

It’s not only giants like the LVMH-owned Glenmorangie, with its handy suite of sister brands from its parent company’s portfolio to choose from, that use wine casks for finishing. Smaller bottlers are following suit, too. Gregor Hannah, who founded independent bottler Lady of the Glen in 2012, buys casks from wineries in which to finish whiskies from well-known distilleries. He’s found peated whiskies, like Islay’s Caol Ila, work well in red wine casks, such as Amarone.

“Our customers want to know the cask’s journey,” he says. “If they can see a cask comes from a specific winery, then that feeds into the story, which is really important.”

Other spirits are getting in on the act, too. At the end of last year, Irish brand Samuel Gelston unveiled a limited-edition whiskey finished in Pinot Noir barrels from actor Sam Neill’s vineyard in New Zealand; Sam is a distant cousin of Johnny Neill, the distillery’s owner.

Meanwhile, Salcombe Gin has continued its special edition Voyager Series by collaborating with Sauternes’ vaunted Château Climens, following its partnership with port house Niepoort, which itself previously worked with rum producer Dictador. Dictador has since turned to the Royal Tokaji Wine Company in Hungary for a collaboration; Irish gin label Shortcross opted for Bordeaux fifth growth Château Cantemerle’s casks; while Rudd Estate in Napa Valley has supplied both Cabernet Sauvignon and Sauvignon Blanc barrels for American producer No 209 Gin.

Photo finishes: San Francisco's No 209 is finished in barrels from Napa's Rudd Estate, while Salcombe Gin's Phantom goes into barrels from Sauternes' Château Climens

There’s no doubt that different casks have different effects on different whiskies. Bourbon barrels used for the first time can provide 60% of the flavour, rising to 70% or 80% for sherry butts. The degree of toasting to make the wood malleable for the cooper to shape the barrel has an impact, along with how heavily the bourbon distillery has charred its barrels. The alcoholic strength of the spirit going into the barrel also influences the chemistry between the wood and the liquid.

Quercus alba, an American oak, adds coconut and vanilla flavours, while French oak is spicier and injects ten times more tannin. The tiny gaps between the barrel’s staves let the “angels’ share” – mostly simpler chemical compounds – escape, while the acids and alcohols left behind will have time to form esters, the flavour building blocks found in flowers, fruits, and other foods.

Putting whisky into a wine cask for finishing creates the opportunity for its acids and alcohols to form different esters with the wine residue that has seeped into the staves of the barrel. The spirit’s alcoholic strength of 50% (or higher) also allows it to extract different compounds from the wood that the wine’s 12-15% wasn’t able to reach – and reach the wine, too.

Salcombe Gin being poured
Gin and Sauternes come together in Salcombe Gin's Château Climens-finished bottling

But can a few months in a wine cask really alter the taste of a spirit that’s already spent a decade in a barrel? And will the average drinker really be able to tell the difference between the particular style of wine or location of vineyard?

“We’re edging into the murky world of marketing,” says Matthew Pauley, assistant professor of distilling at Heriot-Watt University in Edinburgh, and founder of consultancy firm Distiller’s Nose. “But, let’s be honest, if marketing didn’t exist, then we wouldn’t have much of an industry.

“Giving whisky a marketable quality is every bit as important as adding sensory organoleptics [smells and flavours]. Let’s not be churlish, and turn our noses up at a perfectly good story.

“Could a consumer tell the difference? Potentially. If you had a horizontal tasting of various cask finishes then I think they would be able to pick out differences from one to the other.”