The Middle Cut
A meeting of chemistry and nature, the creation of alcohol is both simple yet remarkably complex. Fermentation occurs spontaneously in the world around us; rotting fruit transforms into alcohol through wild yeast and the right conditions. But whisky needs human intervention – and at precisely the right moment.
Whisky still undergoes all the basic requirements of alcohol production: malted barley is milled and mixed with water, which allows enzymes to break down the starch to produce a malty mash. The draff from the barley is filtered out – squeezed, in our unique case – leaving a sugar-rich liquid known as wort, pronounced ‘wert’. Yeast is added to enable fermentation to take place, where those sugars are converted into ethanol and its byproduct carbon dioxide – a head-shaking gas, as anyone who has strayed close to a washback will tell you. What we have now is essentially a beer. Yeast, having had too much of a good thing, die out when the alcohol level rises too far. So far, so normal.
But we want whisky, therefore another important specific and controlled process ensues: distilling. This merely concentrates the weaker alcohol by separating the water element from the spirit by the processes of evaporation and condensation. When we do this on a farm by farm basis, keeping each crop’s individuality intact, we capture in spirit the influence of terroir. A unique crop, a unique wort, a unique spirit.
THE KEY TO IMMORTALITY
Alcoholic distillation was first discovered, it is generally agreed, by an Arabic al chemist in Syria around 800 AD. Jerber was searching for the water of life, the key to immortality, when he stumbled on al kohl by using his al ambic- a pot still. While water vaporised at a 100° Celsius, he discovered that beer’s alcohol did so at a lower temperature – around 78° Celsius. And when that alcohol vapour strikes a cold surface it condenses back in to a liquid, drop by drop.
Arak, the original alcohol, means beads of perspiration. And we call this process distillation, from the Latin distillere, meaning to create droplets or beads. Drop as dew, distil as rain, the distiller’s prayer.
To gain a higher – and purer – concentration of alcohol, the process is repeated in pot still distillation a second time. First the wash still separates and concentrates the 8% ABV (alcohol by volume) of the wash. As a ‘beer’ it also contains water, yeast and unfermentable matter. The wash still then produces a spirit of around 25% ABV, which is known, somewhat confusingly, as low ‘wines’.
The spirit still turbo-charges the 25% ABV up to 70% ABV – even 80% if repeated a third time. Yet at this stage, the 25% ABV is bolstered to 35% ABV by the addition of the heads (or foreshots), the impure alcohol we didn’t want from the previous spirit still distillation run.
Inside the spirit still’s alcohol there’s the good, the bad and the ugly. Or rather, if we’re being pedantic, depending at which temperature it vaporises at on its way up to 100° celsius, the bad, the good and the ugly in that order.
The skill of the distiller is to cut out the good stuff from the bad and the ugly. The art of the accountant is to stretch it.
The spirit still distillation is divided in to three phases, which is determined by two ‘cut’ points, a manual intervention of this process. The new make spirit – what will go into a barrel to become Waterford Whisky – must be initially separated from the undesirable, and deadly, as well as the weak and dissolute.
Because the devil is in the detail, the points at which we intervene are determined by the eyes, the nose and the mouth of a distiller. Attention is key.
Some may make the cut points between the phases based on a pre-determined metric. But we prefer the judgement of human senses. Nosing and tasting are just as important as seeing what the high-tech data, controls and sensors indicate. They are inextricably linked.
As each of our farm’s crop is subtly different thanks to terroir, to decide when to make the all important cut our distillers must work with what the barley tells us –not by the book, custom or indeed precedent as is the way with much of the whisky industry. A cut point is rarely ever the same.
It’s inevitable that the decision when to cut really is the most important part of the distillation process. It is these decisions that allow us to make the highest quality whisky we can with ingredients at our disposal.
Time and consideration are needed. Indeed, it is the very reason our stills run ‘low and slow’ – against industry convention. Such a pace gives our distillers a slow-motion appreciation of the vital phases of the spirit run; it allows them to see – and nose, and taste – with absolute clarity when to make their decisions, which will differ from farm to farm.
This will be the final cut: the whisky the world will one day see, taste and enjoy.
THE FIRST PHASE
At around 85° Celsius, known collectively as heads or foreshots, the first distillate appears in the spirit safe. It is harsh, full of foul smelling compounds comprising of acetone, ethyl acetate and acetaldehyde.
Funnily enough, we really don’t want our final whisky to taste of nail polish remover. So this is run off to the low wines tank. We also run the stills very, very slowly. Our heads run is about 30 minutes in duration at 300 l/hr.
The sense of smell is what helps us here; tasting is not recommended. Methanol will kill, after first destroying one’s ophthalmic nerve – the origin of blind drunk.
As temperature rises, around 87° celsius, things are beginning to smell an awful lot better, but still this impure spirit would give a very bad hangover. We are getting there though, slowly and patiently, checking the whole time.
THE MIDDLE CUT
As the still temperature approaches 87° Celsius, the foreshots are dissipating, leaving a smooth and soft distillate. More nosing: we won’t be detecting harsh compounds now. A little tasting is possible. A sample drawn will be cloudy, a blueish tint; ten minutes pass and the fruitiness miraculously appears, getting close; a few more minutes (roughly 30 in total) and a sample remains clear when water is added. We are now ready to turn the valve to collect the middle cut.
Also known as the hearts, which will be our whisky, steam is slightly increased, the flow is now a slow 450 l/hr, and the spirit runs to a dedicated collection tank – the unimaginatively named Intermediate Spirits Receiver – for the next 5 hours or so.
As the spirit continues to run, the still temperature rises past 90° Celsius so the spirit strength correspondingly falls, degree by degree, from 75% ABV, down to 70%, to 69%, 68%…
THE FINAL CUT
As the ABV falls so does its character. Less desirable qualities such as certain fusel oils begin to appear. If we were distilling on time alone, like much of the industry, there’s every chance they might creep into our spirit – a risk that is unacceptable to us.
Some accountant-led distillers may even suggest this is acceptable particularly if spirit yield is preferred over purity.
But we’re looking for ultimate purity, we don’t want any such undesirables in our spirit. And so by close observation the final cut is made around 66% ABV. For us middle cut is over, though for some accountant-led operations it may last longer. We call it the ‘cut to tails’.
At the turn of the valve the tails/feints, the rapidly weakening spirit, is now collected in the feints receiver tank. If you were to taste this, it would be harsh. But that would be foolish as the aromas coming off the distillate should suffice in letting you know it’s not right anymore. A damp cardboard mustiness can now be detected.
Now at full steam ahead, the alcohol strength rapidly falls away 40%, 30%, 20%… finally, as the still temperature reaches 100° Celsius, nothing but steam is being vaporised and condensed: water alone now runs through the spirit safe.
But the spirit’s journey is not over. Between the heads and tails (or the feints and foreshots) lies the middle cut, the heart of the distillate. This will go for cask maturation in our warehouses to surface in several years’ time as Single Malt Waterford Whisky.
The feints and foreshots will live to fight another day too. Together they will join the 25% ABV low wines collected from the first wash still distillation, the cycle begins again with the next run of the spirit still.
ART OR SCIENCE?
Many people talk of the art of distilling. Perhaps. But when distillation is automated, it has more in keeping with science, even the original alchemy.
The automatic opening and closing in the right sequence, of the myriad of valves and pipes that constitute a distillery, may be devoid of human input, sure. There is a limit to the romance one can find in hand operating a valve.
But for our distillers, the art comes from learning the intuitive reactions to the stills and new make, to nose and taste; to use the sophisticated biological machinery in the human body to work alongside the high-tech data provided by the sensors and readings.
Only then is the distiller able to catch these distinct fractions in the spirit. To make these cuts according to what each new crop of barley tells them. To let the field speak. To allow terroir to shine through in the distillate.