If you take a look at the wine and beer worlds you’ll find that producers utilise a vast array of different yeast types – local availability, historical application and desire to produce a wide diversity of flavours all underpin markets that recognise the difference that yeast can make to their eventual products. But, zoom in on Scotland and you’ll find (increasingly) that the industry is firmly in the grip of utilising a single strain of Saccharomyces cerevisiae. Neutral, high yield yeast strains have replaced the distillers and brewers yeasts that were once common 50 years ago. Efficiency is now king – increasing yield through reducing fermentation times. But, ask around about the influence of yeast on both flavour and texture and depending on where you are you’re likely to get a different answer.
In the US, some bourbon producers (Four Roses for example) cultivate and nurture yeast strains to combine with different mashbills to produce a wider variety of expressions. But, in Scotland, I’ve been told on a number of occasions that there is a feeling that yeast type doesn’t make any difference. To my mind this runs counter to both logic, but also to how many of the distilleries position their raw ingredients. Countless brands spend paragraphs of marketing copy and copious hours on tours highlighting the qualities of their water sources – suggesting that their locality and purity makes a key difference to the quality of their whisky (despite it being repeatedly heated and generally buggered around with) – yet yeast rarely get but a nod.
Regardless, if you look at where the industry is at with regards to experimentation and innovation, there seems to really only be two avenues left to explore – barley and yeast. There’s less experimentation left in the wood than there once was – decades of shaving, toasting, re-racking and finishing have resulted in a new normal – playing with barrels is now commonplace – accepted and expected. If the height of experimentation in the 21st Century is Macallan maturing first in sherry and then finishing in ex-bourbon, you should start to question quite how much rubber there is left to lay on this road.
Loch Lomond are no strangers to experimenting with yeast. Production Director John Peterson who joined the distillery in 1990 had a prior career working within the beer industry – studying fermentation as a research scientist for Whitbread. The distillery takes a similarly investigative view on fermentation as it does on distillation (with its unusual still setup). Whereas M and MX strain yeasts are still the most commonly used strains of yeast, Lomond have been exploring alternatives for over a decade.
The distillery is perhaps the ideal proving ground for playing with yeast – the long fermentation times (90-120 hours) far outseed the lifespan of the yeast (around 60 hours). What this means in practice is that there’s a period of time after the active yeast fermentation has ended where lactose molecules are able to develop and consume the proteins leftover by the yeast, creating a more fruity eventual wash. To date, it seems that Chardonnay wine yeast has been the most successful alternative strain trialled at the distillery – but even that is an oversimplification as there are countless proprietary products on the market all with different strengths and weaknesses – only some of which will probably prove suitable outside of a vinery environment.
Loch Lomond’s Inchmurrin 2007 single cask provides an opportunity to see what the distillery has been able to produce using Chardonnay yeast as a fermentation agent. It’s a pretty little thing conceptually – a single washback with 25 kilos of pitched yeast, distilled on a single still (the rectifying one) and then matured in a single cask (refill ex-bourbon ‘#5834) for 9 years. 276 bottles were produced at an ABV of 58.4% and offered as a distillery exclusive in mid-2017.
Nose: Pears, white grapes and old cartooned orange juice provide a fruity backdrop for creaminess to sit atop - Chantilly, vanilla ice-cream float, even a clean cotton Yankee Candle. A damp dog come in from the rain sits with forest mosses, bracken and soils whilst honey spread toast and allspice mingles. Reduction reveals some dried fruits – golden raisins and dehydrated peaches, baking spices and a slice of New York cheesecake.
Taste: The arrival packs a wallop – a piquant mix of pepperiness, stone fruits and toffee that develops steadily into an attention-grabbing metallic minerality. It’s part geological and flinty, part made-made with graphite and powdered zinc. To say that it’s sharp does it an injustice, it’s positively piercing. The back-palate offers a more malty outlook with toasted cereals joining cashew nuts, raisins and sultanas. Water reduces some shrillness allowing a greater emphasis from the fruit elements – apricot, melon and lychee, whilst also introducing a not-menthol, menthol sensation throughout the mouth – a vaporous cooling numbness without any mint whatsoever – baffling.
Finish: Short, with fading pepper and bone-dry chalkiness.
This single cask Inchmurrin is left-field even by Loch Lomond’s standards. Whilst the cask influence feels incredibly restrained, the spirit has undeniable been altered by the Chardonnay yeast – the result combines the fruity characteristics of the make with a tranche of aromas and flavours drawn straight out of a mineralogists’ notebook. It’s a little hard to unpick what’s going on here – and undiluted, my palate railed against the strident crystal-sharp qualities presented. However, there’s undeniably complexity in this experimentation, and properly reduced, both likeability and drinkability are high.