“The principle is the same whichever cask type you’re using, but beer casks don’t add additional layers of flavour to a whiskey in quite the same way that wine or fortified wine casks do when used as finishing casks, the flavours from beer casks are typically imparted in a shorter time and as a result more challenging to predict,” says Iain Wood, operations manager, Teeling Whiskey.
So, how can master blenders be successful matchmakers, and select casks that will have a meaningful relationship with their whiskies?
“Tasting the beer and nosing the cask gives you an idea of what to expect, but it’s not a direct translation of the beer character into the whiskey. IPA casks typically give citrus, apple and a hoppy character, while stout casks impart coffee, chocolate, butterscotch and softness on the palate, but there’s still a lot of work to be done to understand exactly what happens during the maturation process,” says Dave Quinn, master of whiskey science at Midleton Distillery (Irish Distillers).
Having selected a type of beer, distillers supply their own casks to the brewery to be ‘seasoned.’
“We send Bourbon barrels to three local breweries – O’Hara’s fills them with stout, while Rascals fill with coffee stout, which has an Irish coffee note and a different influence to stout, which is more robust. Five Lamps fill our casks with red ale, which is slightly less intense than stout,” says Darryl McNally, master distiller, Dublin Liberties Distillery.
A variation on Bourbon barrels are casks previously used to age rum in the Caribbean, which Teeling sends to Galway Bay Brewery to be seasoned with imperial stout for at least two months (though these ex-rum casks were originally ex-Bourbon barrels).
Once casks have been seasoned, breweries bottle the beer as a limited-edition, and return the empty casks. However, the staves retain a certain amount of ‘residual beer’ which has been absorbed by the oak, and filling the cask with whiskey prompts this liquid to leech from the staves and integrate into the whiskey. This is considered the greatest influence during the finishing period, which raises the question of how, and how soon, the flavour profile evolves.
“When we first filled stout-seasoned casks we were looking for dark chocolate, coffee and roast barley notes from the stout. You can capture these three notes all together though they don’t all peak at the same time, as flavours can increase then plateau or even disappear. Chocolate notes for example get better every week, but after 12 to 16 weeks they’ve gone. So, the question is when to stop? The only way to decide is to keep sampling. We end the finish at around four to six months, whenever it’s ready, as each cask can be slightly different,” says Iain Wood.
The particular influence a beer-seasoned cask exerts on the whiskey also depends of course on the style of the whiskey. Jameson Caskmates Stout Edition, for example, is matured in ex-Bourbon barrels and then finished for five months in ex-Bourbon barrels that have been seasoned for two months with stout.
“It’s still definitely Jameson, which has apple pie and a bit of Christmas cake, but the whiskey acquires additional coffee, cocoa and butterscotch notes, which are discernible in stout. The texture of the whisky also becomes softer on the palate,” says Dave Quinn.
The Jameson Caskmates series includes an IPA Edition, while the approach has also acquired a certain global reach.
“As part of the Jameson Caskmates family, we send our barrels to be seasoned by craft brewers around the world, including Australia, Canada and the USA, to create hyper-local Jameson Caskmates whiskeys. Brewers use the casks to produce a limited-edition beer, then we bring the barrels back to Ireland and use them to finish Jameson. This whiskey is then bottled and sent back to the city where the brewery is located,” says Dave Quinn.
Finishing Irish whiskey in beer casks may be a recent focus, but it’s also a traditional approach – brewers originally used wooden barrels which were freely traded with distilleries (until stainless steel kegs came in and became the norm).
IPA, stout and porter have an integral link with whiskey, as malted barley is a core ingredient. Murphy’s Irish dry stout, for example, is brewed from barley and malted barley, while another Irish dry stout, Guinness, is brewed from malted barley which is also roasted. Imperial stout typically has a higher ABV, at around 8% ABV, compared to stout at around 4% ABV. Red ale is also brewed from roasted barley, which can be used in a porter as well.
“We use casks seasoned with porter made from chocolate malt, which is roasted to bring out toffee, cocoa and chocolate notes. We apply a finishing period of six months to a year to seven-year-old malt which has been aged in Bourbon barrels, this adds toffee, cocoa and chocolate notes to the whiskey, which already has a biscuity, malty, honey, vanilla and caramel character, with light, fruity citrus and a little spice,” says Kevin Keenan, founder, Glendalough.