The whisky production process is made up of 5 distinct steps and they are as follows:
The next stage in the whisky production process takes the product of the fermentation process, or wash, and distills it twice (or in some cases, three times) so as to attain a spirit with a higher level of alcohol. This process is known as Distillation.
The stills at Bowmore
At the end of the fermentation process, the wash is transferred to the first still known as the wash still in order for the first stage in the distillation process to begin. The wash still is then heated up and the wash starts to evaporate and rise up the neck of the stills before making its way over the swan neck of the stills and being condensed back into a liquid though the use of worm tubs or condensers.
The product of this first stage of distillation is known as low wines and it has an alcohol percentage of between 25-30% abv in general (although this can fluctuate). The low wines are then transferred to a holding tank known as a Low Wines & Feints Receiver, where it is mixed with the feints which were collected from the previous distillation run from the spirit stills.
The combined low wines and feints are then transferred into the spirit still, where the distillation process is then repeated and the spirit is condensed back into a liquid. However, this time round the spirit passes through a piece of equipment known as the spirit safe, where the master distiller will be keeping a close eye on the spirit.
The spirit safe
The master distiller then uses a number of hydrometers located within the sprit safe in order to measure the alcohol level of the spirit. The spirit itself falls into three categories:
- The foreshot, which is the initial part of the spirit run which is hazardous and is then collected and discarded.
- The middle cut or heart, which is the desired alcohol range that the stillman is looking to collect for the maturation process.
- The feints, which fall below the desired alcohol range and are then collected and sent to the Low Wines & Feints Receiver in order to be distilled again later.
The heart of the distillate is collected, filled into barrels and matured into whisky
The heart of the spirit contains the necessary esters and flavour compounds that the master distiller is looking to incorporate within their desired version of whisky and it is watered down to the distillery's specific filling strength (usually somewhere in the region of 63.5% abv but this tends to vary) before being filled into a variety of casks and then stowed away in warehouses to mature.
Different distilleries observe different spirit cuts due to their desire to capture certain esters and flavour compounds which are critical in the crafting of their whisky and the distillation process plays an integral role in determining the final character of a whisky.
A prime example of this would be Caol Ila and Lagavulin. Both distilleries are known to have their malted barley peated to the same phenol specifications and yet the spirit style is decidedly different, with Caol Ila being lighter and Lagavulin being much heavier.
Part of the reason for this has to do with the spirit cuts, as Caol Ila has a spirit cut which begins at 75% abv and ends at 65% abv. Lagavulin, on the other hand, begin their spirit cut at 72% abv and end at 59% abv, thus ending up with a wider range of flavour compounds.
The fruity and estery compounds tend to be found higher up in the spirit cut and this contributes to the character of Caol Ila, which is lighter and exhibits more of a fruit note. Lagavulin, on the other hand, has a spirit cut which is slightly lower and wider and this allows for the more pungent esters and phenols to manifest themselves in the final product.
Another important factor which influences the final character would be the size and shape of the stills used at the distillery. In the case of Caol Ila, their still sizes are as follows:
Wash stills: 35345 litres
Spirit stills: 29549 litres
These are relatively large stills and correspond with the production capacity of Caol Ila, which is the largest distillery on Islay and produces approximately 7 million litres of spirit on an annual basis.
Lagavulin's stills, on the other hand, are different:
Wash stills: 12300 litres
Spirit stills: 12900 litres
While Lagavulin's stills are much smaller in size than Caol Ila's, the important thing to note would be that the spirit stills are larger in capacity than the wash still. Lagavulin is also known to fill their stills to the brim, thus ensuring as little copper contact as possible and resulting in a richer, more robust and full-bodied spirit.
Different shaped stills also tend to affect the character of the spirit, although not as much as the size or spirit cut.
Another aspect of the distillation process to take note of would be the angle of the lyne arms. Different distilleries tend to prefer different spirit characters and the angle of the lyne arm can play a big role in determining that character.
The angle of the lyne arm on the stills can result in the following characters:
Upward angle: Lighter and cleaner spirit due to more copper contact
Straight: Relatively balanced spirit with a fair bit of copper contact
Downward angle: Heavier and more pungent spirit due to less copper contact
The steepness of the angle can also affect the level of copper contact. In the case of Caol Ila, the spirit descends the lyne arm at a regular downward angle whereas in the case of Lagavulin, the spirit descends the lyne arm at a gentle downward angle.
Other factors such as whether the stills are direct fired (such as at Glenfarclas) or heated by steam coils will also play a role in determining the final character of the spirit and the use of worm tubs (which lead to a more sulphurous character in the new make spirit) or shell and tube condensers (which lead to a less sulphurous character in the new make spirit) are also critical factors.
The distillation process plays a huge role in determining the final character of the spirit and is second only to the maturation process, which we will be delving into in the next post.
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