THINK TANK
Whisky in and out of season
To what extent do the passing of the seasons and variations in temperature affect whisky’s distillation, or ultimately its flavour? Tom Bruce-Gardyne turns the pages on the distillers’ calendar in search of answers
MAIN PHOTOS: MIKE WILKINSON AND PETER SANDGROUND
“The spirit hits the condenser, becomes liquid and trickles down to the bottom when it’s really cold. When it’s much warmer it snakes all the way down the worm as vapour.”
For such a huge, slick, corporate beast as Diageo, there is something endearing about its enduring attachment to worm tubs. Almost a third of its malt distilleries have them, including all the original ‘Classic Malts’, apart from Lagavulin. In the mid-1980s Dalwhinnie briefly joined the 20th century when its archaic, wriggly worms were replaced with modern shell and tube condensers. But the new-make spirit just wasn’t the same, and in 1995 it got its worms back.
As well being a link to the earliest days of whisky-making, worm tubs connect to the idea of seasonal distillation of which Dalwhinnie is a good example. Scotland’s joint-highest distillery (with Braeval) sits in a desolate, windswept bowl beside the main A9 route north, where the average annual temperature is a tooth-numbing 6.6˚ C.
“The very cold water in the winter enables us to condense the spirit vapour very rapidly in the worm tubs and that amplifies the character of Dalwhinnie,” says Johnnie Walker’s master blender Dr Jim Beveridge MBE. “But it’s important to say that having worm tub condensers is probably just as important as the season.”
ABOVE: Dalwhinnie’s exposed worm tubs
A WINTER OFFERING
Generally speaking, any seasonal variation in flavour would be complete anathema to a company like Diageo. As Dr Jim says: “Our primary aim as distillers and blenders is to achieve consistent spirit character at our distilleries all year round, regardless of the season.” But in Dalwhinnie’s case it was decided to make a virtue of the winter worm tub effect, and casks filled in the coldest months were put to one side.
In 2015 Dalwhinnie Winter’s Gold was launched as a non-age statement whisky. The press release talked of a ‘sulphuric’ flavour in the new make that evolved into a ‘honeyed’ whisky after maturation, and punters were urged to try it straight from the freezer for a ‘syrupy mouthfeel’. The sensation of letting the liquid defrost on your tongue until the flavours explode is well worth trying. A malt from the deep freeze can be perfect with a rich, chocolate pudding, though in truth it doesn’t have to be Dalwhinnie.
Dr Andy Forrester, the Society’s spirits educator, explains that in winter inside those worm condensers, “the spirit spends less time in the vapour phase” – this being the critical period known as reflux when there is maximum interaction with the copper. “The way I think of it,” he says, “is that the spirit hits the condenser, becomes liquid and trickles down to the bottom when it’s really cold. When it’s much warmer it snakes all the way down the worm as vapour.”
“It’s important to say that having worm tub condensers is probably just as important as the season.”
“When we designed InchDairnie we knew we were heading for high gravity mashing. This generates a lot of heat, so we put the washbacks outside.”
IAN PALMER
SEASONAL FERMENTATION
But seasonal variation doesn’t end in the worm tub, as Ian Palmer is quick to point out. At his worm-free InchDairnie distillery in Fife, the business of distilling and condensing is kept constant throughout the year. The subtle differences he seeks from one season to the next are achieved earlier during fermentation, which he calls a “very key part” of the process.
“When we designed InchDairnie we knew we were heading for high gravity mashing,” he says, referring to the strength of the brew. “This generates a lot of heat, so we put the washbacks outside.” He explains that they behave differently from winter to summer because “temperature is a very key variable in fermentation performance”.
To magnify the effect, the distillery uses winter barley and ale yeast in winter for a slower fermentation “and a cloudier, more traditional wash which tends to give you a lot more heavy, cereal flavours,” says Ian. Come the summer, InchDairnie switches to Spring barley and wine yeast which “gives us a much clearer wort that tends to ferment faster, because the atmospheric temperature is higher. We’re looking for a lot more esters, more cut grass and flowers.”
Over in Campbeltown, Glen Scotia’s manager Iain McAlister has seen a similar effect with his three external washbacks compared to the six inside. But like most established players he is keen to suppress any difference to maintain a consistent distillery character which can then evolve into different expressions through the interplay of time and wood in the warehouse. Newcomers like InchDairnie may have a lot more freedom to experiment, but the big question is how much any variation in the new make will make it through to the finished whisky after maturation. Time will tell.
“We put the washbacks outside: they behave differently from winter to summer because temperature is a very key variable in fermentation performance”
Owner Francis Cuthbert describes himself as “a farmer who moonlights as a distiller”
Glen Scotia’s manager Iain McAlister has seen a similar effect with his three external washbacks compared to the six inside
FARMING FIRST
Scotch whisky began as a seasonal spirit. It was distilled after the harvest whenever there was grain to spare as a way of preserving a perishable commodity, just like the smoking of fish or curing of meat. It gradually evolved into a year-round industry but even then, distilleries would close for much of the summer due to a lack of water or manpower.
On his grand tour of the industry in the 1880s, Alfred Barnard wrote of Auchentoshan: “At the time of our visit the haymakers were busy in the fields connected with the distillery, and consequently the works were almost abandoned.”
Were the great bagger of Victorian distilleries alive today, he might have found the same reception at InchDairnie’s near neighbour of Daftmill, whose owner Francis Cuthbert describes himself as “a farmer who moonlights as a distiller”. His bank manager probably sees it the other way round given the prices now paid for Daftmill’s releases of its ‘Winter Batch’ and ‘Summer Batch’ whiskies.
As the website explains, it operates ‘on a seasonal basis around the farming calendar’ making whisky in the winter ‘but by spring time we need to get the barley sown, potatoes planted and cattle out to grass so the distillery falls silent.’ The stills are fired up again in June and July. The scarcity of Daftmill, with a production of just 100 casks a year, and the pent-up demand for its first release which finally appeared in 2018, are clearly key to its success. Yet the sense of being in tune with the age-old rhythms of the farm seems to resonate with its fans. Compared to the rigid consistency of a spirit that never varies 365 days a year, a seasonal approach just feels somehow closer to Mother Nature.