The making of Irish Whiskey

Even today, Scots and Irish argue about who first produced the water of life (uisge beatha). But no matter who is right: Irish whiskey and Scotch whiskey have common roots, but developed differently over time. The history of Irish whiskey is full of ups and downs. Nowadays, Irish whiskey is on the rise again and is becoming more and more popular.

Compared to Scotland, Ireland has another type of whiskey: pot still whiskey. It contains malt and grain whiskey, but both may only be distilled in pot stills. However, since the mash is made not only from malted barley but also from unmalted barley, the final product may not be titled 'malt'. Nevertheless, it is distilled in pot stills. If all the components of the whisky come from one distillery, it may be called 'single pot still' - analogous to single malt.

Interesting side note: Ireland produces so much whiskey that the demand for grain could never be met from domestic production. Therefore, a lot is imported.

Depending on the purpose, water can be taken from rivers or lakes, but the water quality of most rivers is not high enough for whiskey production. Most distilleries get their water from local sources.

To make malt whiskey, the barley has to be treated differently than for grain whiskey. Initially and during the great rise of the Irish whiskey industry, the barley was collected during harvest time and stored in silos at the distillery. In the picture below you can see how the barley was transported to the malt floors on the higher floors in the Midleton distillery.

After many improvements, today's process differs significantly from traditional methods. The barley is malted by the large malting companies, which produce more efficiently and supply both the whiskey and beer industries. The desired peat content can be precisely specified.

After the starch has been broken down into sugar by enzymes, this must be extracted from the grain. Malt mills grind the malt into a coarse substance called "grist". Grist is not as fine as flour and still contains all the components of the husk.

The grist is mixed with hot water to wash out the sugar. Grist and water are mixed three times in mash tuns, each time increasing the temperature until it reaches 95 °C. The last time, the least amount of sugar is dissolved out. The last pass dissolves out the least sugar. This water is used for the next batch in the mash tun. The sweet water produced by mashing is called "word" in English and is then used for fermentation. The remaining mash is used as animal feed.

For alcoholic fermentation to take place in unmalted barley, the starch must be converted into sugar without the help of natural enzymes. Therefore, the grain is milled and cooked under pressure. Two things happen at the same time: the starch is released from the hulls and the long starch molecules are split into shorter sugars. The resulting sugar solution is also called word in grain whiskey.

The word is cooled down to approx. 20 °C. Then yeast can be added. The solution is left in the wash backs for 48-96 hours. During this time, the yeast works and converts the sugar into alcohol. The yeast cultures also produce lots of CO2 and excess heat. When the wash backs are in a cold environment, the fermentation process is slower and the whiskey is said to taste better. In the large distilleries, the resulting CO2 is captured, bottled under pressure in steel bottles and sold to the industry.

Wash backs used to be made of pine wood because the resin they contained made the wood very resistant to bacteria.
Today, most wash backs are made of stainless steel and sometimes equipped with cooling systems to precisely control the speed of fermentation.

During fermentation you can see CO2 bubbles rising. But be careful when you look into one of the peepholes. The rising alcoholic vapours are very pungent. The floors of the washrooms are always made of mesh and the rooms are well ventilated so that no CO2 can accumulate and suffocate the workers.

The Irish whiskey industry was the first to produce whiskey in large quantities. At that time, distilling on copper stills was the only distillation process. To meet the demand, most distilleries built huge pot stills, as can be seen in the museum at Old Midleton distillery. These pot stills consisted of large pieces of copper plate riveted together and were usually heated with coal. Cleaning these stills was tedious and exhausting.

There was a separate room under the stills that was used for the coal fire for heating. The workers had a bell and a cord to communicate with the master distiller above in this noisy, busy environment.
The large pot stills in these distilleries needed cooling after the Lyne Arm. This was done either by a steady flow of cold water or with the help of a sufficiently large heat sink in the form of a large tub.

The distilling process begins by pouring the wash into the first pot still, called a wash still. The still is then heated and produces an alcohol solution of about 20 to 25 % vol. called Low Wines.

By heating the wash still to a certain temperature, the lighter alcohol evaporates and rises up the neck of the still. The rest of the wash remains in the still. The alcohol vapour is then cooled and collected in spirit receivers.

To obtain whiskey, the process must be repeated. The first batch of low wines is then poured into the second pot still, the Spirit Still, which is usually slightly smaller and produces alcohol at 60 to 70% vol. At Bushmills and New Midleton, the classic process of triple distillation is still used. The raw whisky does not yet really taste like whiskey, but the shape of the still determines the later taste. To turn the raw spirit into whiskey, it has to mature in barrels for at least three years.

If you want to learn more about distillation in pot stills, read this article.

The first decline of Irish whiskey began with the invention of column stills for column distillation in Scotland. The invention came from a man named Aeneas Coffey, who made it possible to distil unmalted grain in the stills. This allowed a continuous and more efficient distillation of cheap whiskey and the Column Still was nicknamed the Coffey Still.
Nowadays, Irish whiskey, mainly grain and blended whiskey, is also distilled in column stills. High-quality malt whiskey, on the other hand, continues to be distilled on pot stills.

In the column still, the alcohol is separated from the wash by fractional distillation. The wash is poured in at the top and flows down through the still. Steam is let in at the bottom and rises against the flow of the wash. The alcohol can evaporate more easily and rise upwards in the still. In the end, the different components of the wash are distributed over the entire still. The lighter alcohols are found at the top, while water and residue collect at the bottom. Most distilleries have more than one column still to achieve better alcohol separation.

A column still consists of several sections screwed together. Within these sections there are other levels that slow down the flow of liquid downwards but allow the vapour to pass from the bottom to the top.

The Irish mature most of their whiskey in ex-bourbon barrels from the USA. The American oak makes the whisky soft and mild.
Some of the special bottlings are aged in ex-sherry or other wine casks, which are usually made of European oak. The flavours created in these casks are more intense and sometimes bitter due to tannins, but also fruitier due to the wine residue in the porous oak.

During the maturation period, part of the liquid evaporates, which is called Angels' Share. As the whiskey matures, it becomes darker and softer.

In the early days of Irish whiskey production, whiskey was stored in shallow warehouses called dunnage. The barrels were rolled into the warehouses and stacked horizontally in up to three layers.
Today, demand is higher and the process more streamlined. The barrels are stacked upright on pallets and stored in higher warehouses. A new tap hole has to be drilled into the lid of the barrel to fill and empty the barrels and taste the whiskey maturing inside.
Tasting the individual barrels is extremely important and leads to the process of blending, the blending of different barrels.

After the whiskey has matured long enough, it is blended in large steel tanks so that it can be bottled. Immediately before bottling, the Irish whiskey is filtered. Most brands use cold filtering to prevent the whiskey from becoming cloudy when it is cooled by ice cubes in the glass.