Slow fermentation can help in bringing a point of difference to a whisky’s flavour profile, and modern consumers are always looking for something new. Ellen Manning reports.

As with anything in life, most producers of aged spirits will argue that creating something great takes time. But when it comes to fermentation, does slower always mean better? In the world of whisky, slow fermentation is touted by some distilleries as a point of difference, adding extra flavour dimensions and making their products stand out from the crowd.

“In terms of whisky, flavour really comes from fermentation,” says whisky expert Dave Broom. “Everyone concentrates on distillation, but distillation – although highly skilled – is about concentrating selected flavours which are already there, and the majority of these flavours are created during fermentation.”

Very generally speaking, the longer fermentation is allowed to continue, the more flavours can develop – especially fruitier notes. “The longer fermentation takes, the more lactic acids are created,” says David Miles, senior whisky specialist at Edrington UK, “which gives some of the floral, fruity and creamy notes that can be very desirable – and therefore one of the main benefits of a longer fermentation.” 

The idea of a slower process creating a better product is something Balblair, one of Scotland’s oldest distilleries, plays on – recently dedicating a new short film, Precious Time, to its ‘unrushed’ process, which includes fermentation up to 60 hours. “At Balblair, time is a defining part of who we are,” says distillery manager John MacDonald. “Balblair is known for its tropical fruit characteristics and long fermentation times play a key role in shaping those, alongside a slow distillation and a gentle maturation in traditional dunnage warehouses here on site.”

Factors at play

If slower fermentation is the key to better whisky, surely every distillery would be doing it. But it’s not that simple. “Fermentation capacity at a distillery is tied closely to the overall capacity of the site – the longer you ferment the less you’re going to be able to produce,” adds MacDonald. Other factors also come into play, says Douglas McIvor, resident whisky expert at Berry Bros & Rudd. “Some parameters are bound by historical set-up of equipment and contribution to blends within a company as to the compounds required to produce various flavours. Environmental factors have to be considered as well as yeast types and grain make ups, so Scotland will be very different to Kentucky in requirements and control.”

While older distilleries’ set-ups are fixed to an extent, newer players have freedom to experiment, says Broom. “It’s two very different camps. One is essentially fixed in terms of how it makes its whisky, the others are that bit more fluid with the way they’re approaching it, because if they’re going to survive they need to create something new and interesting.”

However, running slower ferments isn’t problem-free. “There are risk factors with slower fermentation as bacteria multiply exponentially and can produce lactic acids, sometimes adding ‘baby sick’ notes,” says McIvor. “Margins of error can be tiny and really impact on final quality, and that’s why controls need to be rigorous. In a nutshell, some distillers wish to advance and promote certain natural flavours, but it does not suit every scenario where time-honoured processes work best through long experience/trial and test.”

It’s a fine art, but do consumers actually notice these delicate differences? Broom has noticed a leaning towards the more ‘tropical fruit-style’ whiskies – something older distilleries which already use slower fermentation can take advantage of, and newer brands can embrace as they develop their product.

“There’s a bit of a trend for whisky tiki cocktails and ‘whisky coladas’ and the fruitier flavours undoubtedly play into that camp,” says Broom. “So bartenders who understand their whiskies will begin to pick specific brands. The days of ‘it’s a Scotch whisky cocktail so I’ll grab any bottle off the shelf’ are gone, because bartenders are looking much more closely at what that distillery character is, then using that within a cocktail or using other ingredients to enhance some of those flavours.”

That is exactly what Josh Linfitt, bar manager at Adam Handling’s Ugly Butterfly, does. “When mixing whisk(e)y into cocktails I tend to dilute it slightly with various ingredients to see how they react, which flavours punch through and how the finish of the whisk(e)y is affected. I’m always thinking about how these drinks will eventually be enjoyed and, knowing a vast majority of our guests will be dining with us, we ensure each drink complements our dishes perfectly.” 

Overall, he has noticed a rise in interest in what people are drinking and how it’s made. “After the past few mental years we have all gone through, people in general have taken to learning more about what they are drinking and eating and taking time to understand why they like certain things and not others. This has definitely led us all to drink more quality spirits and better know what to do with them.

When it comes to slower fermentation times in whisk(e)y, it’s pretty obvious that the outcome is all about the flavour. Other than full-on whisk(e)y geeks (who I love a good natter with), most of our guests love to try new things, so by having some of our whiskies on display and a dedicated section in our menu, we can showcase a variety of whisk(e)y flavours, which means there will likely always be something to suit the palate of the drinker.”