How Irish Whiskey is Made

There is an ongoing debate whether the water of life (uisge beatha) was first produced in Ireland or Scotland. Either way, Irish Whiskey and Scotch Whisky started similar, but developed differently over time. The history of Irish Whiskey has ups and downs. Nowadays Irish Whiskey is recovering and becoming popular again.

The Grain

Irish Whiskey is produced from barley, wheat and corn. The amounts used depend on the type of Whiskey. Naturally the grain contains a lot of starch within its shell. This starch needs to be converted to sugar which is needed for the fermentation where yeast transforms sugar into alcohol. Most sugar can be extracted if barley is malted. If it is not malted or wheat or corn is used, the grain is cooked under pressure in order to cut the starch into sugar.

The best Whiskeys are produced from malted barley. However it is also the most expensive and laborious. In the following we describe all types of Irish Whiskeys.

Interesting fact: The Irish Whiskey production is so great that the whole country could never fulfill the industry's demand with its regionally grown grain. Therefore much is imported from the continent.

Water is very crucial for the Whiskey production. It is needed in many steps of the production like steeping, mashing, cooling or reducing the Whiskey to bottle strength. In former times most of the power used in the distilleries often came from waterwheels. Below is a picture of the waterwheel of the Old Midelton distillery.

Depending on the use the water can be taken from rivers or lakes. However the water quality in most rivers is not high enough for the Whiskey production. Most of the distilleries thus take their water from water from local wells.

During the early ages and during the great rise of the Irish Whiskey industry, the barley was collected during the harvest season and stored in the silos at the distillery. The barley then had to be steeped and transferred to the malting floors. In the picture below you can see how the Midelton distillery transported its barley to the malting floors at the higher levels.

The barley has to be steeped in water to start the natural germination. It was then spread out on malting floors by hand with various tools. During the next five days the grain had to be turned regularly to ensure a even growth and to guard the malt from attacks of the all present mould. After enzymes inside the grain have transformed the starch into sugar the germination process needs to be stopped. Therefore the grains are dried until only 4% moisture remains.

After many improvements today's process differs from the traditional methods. The barley is malted in the big malting companies that produce more efficiently and supply both the Whiskey and Beer industry. The desired peat level can be specified exactly.

Here we see one of the trucks from the big malters unloading the malt into the silos at the Bushmills distillery in northern Ireland.

Milling

After the starch has been converted by enzymes into sugar, it needs to be extracted from the corn. Malt mills grind down the malt into a coarse substance called grist. This grist is not as fine as flour and still contains all the elements of the shell.

The grist is mixed with hot water to wash out the sugar. Three times grist and water are mixed in mash tuns. Each time the temperature is increased until 95 °C. The last time the extracted sugar is least. And this last water is used for the next batch in the mash tun. The resulting sweet water is called wort and goes on to the fermentation. The remaining mash is used as animal feed.

Milling and Mashing

Grain that is not malted still contains starch. For the alcoholic fermentation to work, it needs to be transformed without the help of natural enzymes into sugar. Thus the grain is milled and then pressure cooked. Two things happen together. The starch solutes out of the husks and the long molecules of the starch are cut into shorter sugars. The resulting sugar solution is called wort, the same as with Malt Whiskey.

Pot Still Distillation

The Early Start

The Irish Whiskey industry was the first to produce Whiskey in large quantities. Back in the days the only distillation method was the pot still distillation. In order to satisfy the high demand most of the distilleries built huge pot stills like the ones you see in the museum of the Old Midelton distillery. These pot stills were large pieces of sheet metal copper riveted together. They were mostly fired by coal. Cleaning them was a long and hard job.

The big stills of the distilleries needed cooling after the lyne arm. This could be either done by a steady flow of cold water or by providing a large enough heat sink in the form of a big tub.

The process starts by filling the wash into the first pot still called wash still. It is then heated and produces an alcohol solution called low wines with about 20 to 25 vol %.

By heating the wash to a certain temperature the lighter alcohol evaporates rise up in the neck of the pot still. The rest of the wash remains in the pot. The vapor is then cooled down and gathered in spirit receivers.

The first fall of Irish Whiskey began with the invention of the column still distillation in Scotland. This process allowed a continuous and more efficient distillation of cheap Whiskey. The invention came from a man named Aeneas Coffey, who made it possible to distil unmalted grain in the distillation columns. This allowed a continuous and more efficient distillation of cheap Whiskey and the Column Still was given the nickname Coffey Still.

Nowadays Irish Whiskey, mainly Grain and Blended Whiskey, is also produced on column stills. High quality Malt Whiskey is still produced on pot stills only.

The column still uses fractional distillation to separate the spirit from the wash. The way it works is that the wash is inserted high and flows down through the still. At the bottom steam is inserted and rises against the stream of wash. The alcohol is more likely to evaporate and rise in the still. In the end the different elements in the wash are distributed through the whole still. The lighter alcohols are at the top and the water and residue are collected at the bottom. Most distilleries have more than one coloumn still to have a better separation.

A column still is made of many sections that are bolted together. Inside these sections you have even more layers that slow down the flow of the liquid downwards, but lets the steam rise through from below.

Cask Selection

The Irish mature the majority of their Whiskey in Ex-Bourbon barrels from the US. The American oak makes the Whiskey smooth and a bit mellow. Some of the special bottlings are stored in the more expensive Ex-Sherry or other Wine casks. The Wine casks are usually made of European oak. The flavours are more intense and sometimes bitter from the tannins but also more fruity from the residue of the Wine in the porous oak.

During the maturation period some of the liquid evaporates. This is called the angel's share. As the Whiskey matures the spirit becomes darker and smother.

In the historic days of the Irish Whiskey production the spirit was matured in flat dunnage warehouses. The casks were rolled into the warehouses and stored in lying positions up to three layers high.

Today the demand is higher and the process is a bit more streamlined. The casks are put upright onto pallets and stored in higher warehouses. A new bunghole has to be drilled on the upper end of the barrel and enables to fill, probe, and empty the casks.

The tasting of the individual casks is very important and leads to the blending process.

After the Whiskey has matured long enough it is vatted in large steel tanks for bottling. Right before bottling the Irish Whiskey is filtered. Most of the brands choose to chill the Whiskey before filtering. This is done to prevent the Whiskey from becoming cloudy when ice is added to the drinking glass.

After filtering the Whiskey is bottled and shipped internationally for you to enjoy your dram of Irish Whiskey.