While each distillery has its own unique recipe for making malt whisky, by and large, they all follow a basic recipe. The process of making whisky, although strictly regulated, gives the master distiller plenty of scope to leave his own style. Each step in the process affects the character of the malt. Let us find out how Uisge Beatha is produced and how the aromas get into the whisky. Read the detailed guide about how to make whisky.
Ingredients – What is whisky made of?
Whisky is made from surprisingly few basic ingredients. Essentially barley, water and yeast.
- Barley – Malted Barley is one of the most important ingredients of a Malt Whisky. Different types of barley can be used for the production of Malt Whisky. However, unlike grapes for wine, for example, barley is seldom selected on the basis of taste. Instead, technical criteria such as grain size, nitrogen and/or moisture content are used. Why is this so? Three main arguments are given. Firstly, the contribution of barley to the taste of the whisky is relatively small, and secondly, it is precisely the difference in taste between different Barley varieties negligible and finally, the distillation process eliminates the remaining characteristics.
- Water – Water has a high value in whisky production. The hardness, the amount of dissolved minerals and the peat content of the water are only some of the aspects that influence the taste.
- Yeast – Yeast fungi serve to convert sugar into alcohol. The Scotch whisky industry has a rather pragmatic attitude towards yeast. The contribution of yeast to the taste of the end product is negligible. The only thing that is important is the efficiency in the production of alcohol. As a consequence, the same yeast strain is used throughout the Scotch whisky industry. In Japan, the second large single malt country, distilleries are experimenting with different yeast strains and try to create certain aromas in the finished malt whiskies by selecting the yeast.
How to make whisky?
A grain of barley consists mainly of starch. The process of malting makes the barleycorn think it is time to grow. To achieve this effect, the barley grains are first bathed in water and then germinated in a cool, moist environment. During this process, enzymes are activated which later convert the starch of the barley into sugar. The difficulty is to stop germination at the right moment. For this purpose, the germinating barley must be dried again.
To dry the malt and stop germination, the malted barley is dried over a heat source. There are different ways of drying. Drying over hot air, e.g. by wood or coal fire. The heat stops germination and kills fungi and other pests. This type of drying has little influence on the taste. Drying over peat fire/ peating.
When the distillery decides to kiln the malted barley over a peat fire, the malt is not only dried but also takes on the smoky taste so typical of many distilleries. The oils (phenols) in the peat smoke combine with the surface of the barley
grains and later in the whisky they give the special smoky taste for which Scotch Whisky is so famous. The more peat smoke the barley is exposed to, the stronger the later smoke aroma. Most mainland malts are only relatively lightly peated, while whiskies from the islands, especially Islay, are known for their strong peat and the resulting smoky taste (exceptions prove the rule!).
(c) Grind Coarsely
In the next step, the finished malt is transported to the distillery and ground into coarse grist.
The malt grist is mixed with hot water (63.5°C) in the mash tun. As soon as the malt grist comes into contact with the water, enzymes are activated and the processing of starch into sugar (especially maltose) begins. A very sugary liquid, also known as wort, is produced, which is separated and collected through the perforated bottom of the mash tun. The process is repeated twice in order to extract as much sugar as possible, and in the next step, the wort is pumped from the mash tun into the fermentation tank (washback). The speed at which this process is carried out has an influence on the later taste of the whisky.
- slowly: The distiller slowly pumps the wort out of the mash tun. He gets a clear wort which produces a distillate without a strong grain character.
- fast: If the producer decides to pump out the wort quickly, he will get a cloudy wort which will still take some of the solids out of the mash tun. The distillate then takes on a dry, cereal-like, nutty character.
After the wort is cooled and pumped into the fermentation tank (washback), yeast is added to the liquid and fermentation can begin. During fermentation, the yeast converts the sugar in the wort into alcohol. Over the length of the fermentation process, the master distiller can determine the character of the final whisky.
- Short fermentation (~48h): If the master distiller chooses short fermentation, the distillate will show a more pronounced maltcha-racter.
- Long fermentation (> 55h): if the distiller chooses the long fermentation route, the wash produces esters, which give rise to lighter, more complex and fruity aromas.
The fermentation process is very similar to that of brewing. The mash produced after fermentation – wash or beer – has a beer-like alcohol content of five to eight per cent by volume. The washbacks are either traditionally made of wood or stainless steel. The material of the fermentation tanks can contribute to the final expression of the whisky. Especially the wooden washbacks, despite regular cleaning, develop their own microclimate over the years.
(f) Whisky Distillation
In the next step, the mash is pumped into the first copper still and a raw spirit, the so-called “low wines” with about 23% alcohol, is produced. The distillation process is carried out a second time in a second copper still, the so-called “spirit still”. This second distillation separates alcohol, odorous substances and flavours from the water and concentrates them. The result of the second distillation process is the so-called fine distillation.
The influence of copper on whisky
A major factor in the final taste of the distillation is the copper of the stills. Although no copper is left in the finished whisky, the copper walls of the still act as a catalyst and help filter certain elements from the finished distillate. The master distiller can influence this to some extent by the length of the contact time between alcohol vapours and copper:
- Long contact with the copper: A long contact of copper and alcohol vapour makes the firing easier and milder. Accordingly, particularly high stills produce a lighter fire. A distillery from the Highlands is a good example. The Glenmorangie distillery has the highest stills in Scotland (5.4m) and is world-famous for its light whisky.
- Short contact with copper: A short contact of copper and alcohol vapour makes for a heavier whisky. The effect can be produced by a fast distillation or especially small stills.
After distillation, the alcohol vapour must be returned to the liquid state. For this purpose, the steam is led into condensation systems. The type of system has an influence on the final taste:
Shell and Tube
A shell and tube consists of a hollow cylinder filled with cold water, which contains a large number of copper tubes. When the alcohol vapour touches the cold tubes it cools down and becomes liquid. The relatively high ratio of steam to the copper surface makes whiskies produced with Shell and Tube lighter in character.
Traditionally, Scottish distilleries have used so-called worm tubs for condensation. The alcohol steam is cooled down in a long copper pipe, which is located in a water tank. The contact with the copper is rather short, so the whisky is comparatively heavier.
(g) Spirit safe and the separation of foreshots, heart and feints.
In the spirit safe, the master distiller separates the fine fire produced in this way into three parts: the heart, the foreshots and the feints. The middle run is controlled by a counter, which determines the tax on spirits to be paid later. The “foreshots” and “feints” are not used in the next step but are recycled and added to the raw distillate in the next distillation process.
The times at which the distiller’s master distiller makes the cuts for the separation of the foreshots, middle and fines also influence the taste of the whisky. During the continuous distillation process, the aromas in the distillate change – while light, filigree aromas predominate at first, oily, rich aromas are added later. If the master distiller now wants to produce a light whisky, he will set the cut early. If the whisky is to become heavy and rich, he will do so later.
The middle course constitutes the “New-Make”. This is the part of the brandy that is finally put into oak barrels for maturation.
(h) Barrel Maturation
The new-make is usually diluted with water before it is filled into oak barrels in order to achieve an alcohol strength of about 63.5%, which is ideal for maturing. Subtractive, additive and interactive maturation processes take place during the barrel ageing process, which lasts several years. Subtractive maturation ensures that the aggressive, metallic character of the new-make is removed from the finished whisky. Additive maturation refers to the enrichment of the whisky with aromas from the cask. Interactive maturation is the exchange of aromas between wood and whisky, which gives the finished malt its complexity. The duration of the maturation, size and previous content of the cask (typically e.g. Bourbon, Sherry or Port), the freshness of the cask (1st Fill or Refill) and possible finishes in other types of casks have an enormous influence on the taste.
(9) Composition & Bottling
In the final step, the master blender selects an individual or several barrels from the distillery’s barrels for bottling. In the case of Scotch Whisky, the casks have been matured for at least 3 years, but usually for much longer. From these barrels, the master blender composes the final malt whisky. Contrary to the common misconception, a Single Malt Whisky usually consists of different casks. If the whisky comes from a single cask, it is called a Single Cask bottling. After the selection of the casks, the question remains whether the whisky is to be cooled before bottling, a process that removes esters and fats from the whisky and ensures that it does not become cloudy even at lower alcohol content and temperatures.
Cooling filtration can also lead to the removal of flavour carriers. Many whisky lovers reject this. Wether you add sugar couleur to the whisky to unify the color is essentially a question of style. Since whisky is a complex natural product, every cask and every vintage is slightly different. Sugar Couleur is basically tasteless and influences the taste of the whisky at most on a psychological level.
If you have any questions about this guide “How to make whisky”, you are invited to use the comment section below.
Find more information in the following interesting articles:
What Is Single Malt Scotch Whisky?
What is Blended Scotch Whisky?
Whiskey or whisky – what is the difference?