Why is it necessary to distill whisky?
Without whisky distillation, there is no whisky – because up until the distillation process, the production of whisky is similar to beer brewing. Therefore, you shouldn't be surprised if you hear that at the beginning of distillation, "beer" is put into the still. Only through whisky distillation does the "beer" (called "mash" in German) become a raw whisky that can mature in casks.
The mash actually resembles the beer that ends up on supermarket shelves – with the difference that the mash from whisky production is more germ-ridden than ready-to-sell beer. In this article, we will use the term "mash" for the beer to clearly distinguish the liquid from ready-to-sell beer.
After the whisky distillery has distilled the mash into raw whisky in several runs, the distillate is filled into casks. There, the whisky must mature. Even during the distillation process, the whisky is given a flavor direction. For this, the master distiller makes the finest decisions in the second distillation process, which make the difference between a good and a bad, a harsh and a mild whisky.
A few key facts on the side: Tequila is produced completely differently through steam cooking in ovens, and Cognac is made from wine, which is directly heated and later liquefied again in cool pipes. Liqueurs can be produced through two different processes: either also through distillation or through maceration, where fresh fruits or plants are mixed with neutral alcohol and then sugar is added. For non-alcoholic beverages, the process is reversed: the alcohol is removed here by de-alcoholization.
How is whisky distilled correctly?
To distill whisky, the mash must be further processed. Given the similarity of the mash to beer and its low alcohol content of five to a maximum of ten percent compared to whisky, the stillman has a lot of work ahead of him. He starts by putting the mash into the first still and heating it, causing the alcohol to evaporate. Water is also contained in the mash. However, this does not evaporate with it, as the boiling point of water is above that of alcohol.
In the first still, the alcohol evaporates and moves into the second still. It is then re-liquefied, and through the first distillation process, the mash has become "low wine" – not the familiar wine. This has an alcohol content of 20 to 25 percent after the first whisky distillation. From now on, the distillation of whisky becomes more demanding: In the second step, to professionally distill whisky, the alcohol is further concentrated and purified. It is at this point that the finesse of the master distiller and the whisky distillery becomes apparent. Why is that? Read on!
In the second distillation process, distilling whisky: How many impurities do you allow, sir?
Hardly any whisky connoisseur thinks when drinking that every whisky still contains impurities even after distillation. It is precisely these impurities that characterize the diversity of flavors of different whiskies. Distillers – and likewise the Scots and Irish – argue about whether and how many impurities should be in the whisky. The Irish even use a third distillation process for further purification and to distill whisky in their own way. Most Scots vehemently oppose this; more on that in the next section.
For now, it should be noted that during the second distillation, in addition to further concentration of the alcohol, impurities are also filtered out. When the distillers distill whisky in the second still, they have three viewing windows to three chambers. In these chambers, they see the foreshot, middle cut, and feints of the distillation process.
- Foreshot: The distillate produced at the beginning of distillation is unsuitable for human consumption. It contains components that smell unpleasantly like glue and taste furry. The majority of these components are intercepted. The drinkable spirit, the middle cut, is obtained from the foreshot.
- Middle cut: The aroma compounds contained here determine the quality of a distillate. Only this middle part is used by the stillman for further whisky.
- Feints: After the middle cut, the feints are produced. The distiller must carefully separate the feints, as they contain undesirable substances, such as inedible fusel alcohols.
The art of whisky distillation lies in the distiller finding the right moment when the foreshot has ended and the middle cut can be opened. The finished distillate then goes into the "spirit receiver." The distiller relies on years of experience, three small viewing windows, and a few basic measuring instruments (thermometer, hydrometer) to decide how to distill the whisky. He cannot taste it in between, as the still is closed and sealed.
By deciding how many impurities from the foreshot and feints are allowed into the middle cut and thus into the raw whisky, the stillman gives the whisky a flavor profile. If the distiller were to distill the whisky so that it contained a high amount of impurities from the foreshot, a sharp taste would result. The substances from the feints, on the other hand, give the whisky a harsh taste. Various specific aromas, such as a vanilla or caramel note, are obtained by the maturation in casks following distillation. The casks carry the aroma of what was stored in them and transfer the flavor to the whisky. Alternatively, the inside of the casks is coated with a specific flavoring agent to impart a specific taste to the whisky.
Two stills are common, three are rare
It has become established practice to distill whisky twice. This means that the alcohol is evaporated and re-liquefied twice. Double distillations are most common in Scottish whisky distilleries and globally. Irish distilleries, on the other hand, almost all take their own path when distilling whisky.
In Ireland, it is common to distill whiskey three times. The third process serves for further filtering of the alcohol and increases the alcohol content of Irish raw whiskeys (in Ireland, whisky is spelled with an "ey") to approx. 80%, while raw Scotch from Scotland reaches approx. 70%.
Due to the high alcohol content, Irish Whiskey tastes more neutral and is lighter. The smaller amount of impurities compared to Scotch also contributes to this. In contrast, Scotch is characterized by distinctive flavors and is stronger. The Scots defend this taste with the argument that it is the rough edges of a less pure whisky that give it its soul.
Ultimately, however, both in Scotland and in Ireland, distilleries can be found that distill whisky two or three times and thus deviate from their norm. Thus, you should be able to find both double and triple distilled whiskey at distilleries in both Scotland and Ireland.
If you would like to join us on a flavor journey to the Scottish Isles, then feel free to read our blog article about it.
Distilling whisky using various methods and still shapes
Whisky distilleries usually distill whisky using a specific method and maintain this method for decades. Distilleries have the choice between continuous and discontinuous distillation processes.
Discontinuous in this context means that the still is refilled with mash again and again, and the total of two to three distillation processes are carried out separately. If the process is continuous, distillation is done in one continuous process without having to refill or clean the stills in between.
Distillation using the discontinuous method is common. You now know how distilleries distill single malt whisky, for example, as it is distilled in two to three distillation processes in stills. This method with two to three distillation processes is called the pot still method.
The continuous distillation method is called the column still method. It enables the production of large quantities of whisky because the still columns (in the continuous process, distillation is not done in pots) do not need to be cleaned in between, and distilleries can therefore distill whisky without interruption. Although good quality can also be achieved with the column still method (also called "Coffey still method"), the pot still method is considered the method that produces the most intense aromas and flavors and with which the highest quality whisky can be distilled.
In addition to the methods, the way distilleries distill whisky also differs by the shape of the still. Onion-shaped stills are common. Due to the constriction of the neck at the top of the still, these stills allow for a more precise separation of impurities in the whisky. This makes it easier for master distillers to regulate the taste when they distill whisky. There are also stills where the reflux of impurities is reduced by the descending course of the "Lyne Arm" (a pipe that runs upwards from the still), allowing more impurities to enter the whisky, which then tastes stronger.
Unlike the shape of the still, there is usually a clear line when it comes to the material of the still: it should be copper. The copper ions react with unwanted compounds and filter impurities out of the whisky more effectively. Even if a certain level of impurities is desired, this level should be well controllable during the distillation processes. Therefore, copper is used as the standard material for stills, and the extent of impurities for master distillers, when they distill whisky, can be regulated more precisely. Stainless steel is mainly used in the continuous distillation process to reduce the maintenance requirements of the still columns.
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