How is McCarthy’s Irish Whiskey Made

Grain and water selection

The grain

Careful sourcing of the main ingredients is crucial to the success of any recipe. This is especially true when it comes to Irish whiskey. The grain selected for all Irish whiskey plays a central role in determining the final result of the liquid. Irish Whiskey is typically made with barley, wheat, or corn. The amount of each grain used varies depending on the type of whiskey being produced. For example, more wheat may be used if a sweeter whiskey is desired. The grain must be malted to extract the sugar needed for fermentation, where yeast transforms sugar into alcohol.

If the grain is not malted or wheat or corn is used, cooking under pressure is necessary to cut the starch into sugar. No matter which ingredients are used, care must be taken to ensure they are of the highest quality to produce a superior Irish whiskey.

At McCarthy’s when crafting McCarthy’s Irish Whiskey Premium Blend and indeed all of our upcoming releases, quality grain is always at the center of our process to achieve a superb whiskey for you to enjoy.

The water

Like our grain, the water used for McCarthy’s Irish whiskey must be of pristine quality. All water for the production of Irish whiskey should be clean and free of any impurities that could give the whiskey an unpleasant taste. The best water for Irish whiskey production comes from underground sources, such as springs or wells.

The water sourced with excellent care is first used for soaking, also known as steeping the grain, as part of the malting process. It should be at room temperature, as higher water temperatures can damage the starch in the grains. Later, in the mashing and boiling processes, the water must be kept at a consistent temperature to ensure that the enzymes in the mash remain active.

After the maturation period, whiskey is cut with water to achieve the desired proof before it is bottled. Getting the balance right is crucial to ensure excellent flavor liquid. Only the highest high-quality water is used in McCarthy’s Irish Whiskey production. McCarthy’s 5-Year-Old Single Malt Cask Strength is bottled without adding water and is generally 58% – 62% ABV.

The Creation of McCarthy’s Irish Whiskey


Malting is the process of taking a raw cereal grain, namely barley in the case of Irish whiskey, and preparing it for its role in the distillation of the whiskey. Remember that malt is an ingredient in some, but not all types of Irish whiskey.

The malting process begins with soaking the barley in water for several days, which causes the grain to germinate. The germinated barley is then spread out on a malting floor. The malt is turned regularly to ensure fresh air can get at the malt and that CO2 can be released; turning will also ensure even growth of the shoot emerging from the grain. This process can take around three days. Once the shoots have reached a certain length, the malt is ready to be kilned.

The kilning process halts the germination of the malt by removing the moisture and drying it out. After removing the moisture, the malt kernels adopt their characteristic flavor and color.


Milling is the process of crushing the malt kernels in preparation for them to release their sugars. This can be done using various methods. The malt is gently added to a milling vessel which is called a Grist Case, and passed through a series of rollers. These rollers crush the malt to a beautiful result that is not too fine and not too coarse. This helps to release the enzymes that will convert the starch into sugar during the mashing process.


Mashing is when we mix the crushed malt with water to extract the sugars. The water temperature is raised in several stages to get a complete conversion from starch into sugar. The enzymes in the malt will convert the starch into simple sugars, which can then be fermented by yeast. At this point, we want to separate the grain from the liquid using a Lauter Tun. The sweet liquid we are left with is called Wort, which contains maltose. The spent grain used for Irish whiskey is often used in animal feed for quality sustainable farming.


The wort is allowed to cool and is then transferred to a fermentation vessel, where yeast is added. The yeast consumes the sugars in the wort and converts them into alcohol and carbon dioxide. This process is allowed to happen over several days. Patience is essential here, as ultimately, it will contribute to the flavor profile of McCarthy’s Irish Whiskey. The liquid produced from fermentation is known as the ‘wash.’

McCarthy’s Irish Whiskey Distillation

Distillation in Pot Stills

Despite popular thought, not all Irish Whiskey is distilled three times, and not all Scotch Whiskey is distilled twice. McCarthy’s Irish Whiskey Premium Blend is distilled three times in copper pot stills at the Great Northern Distillery in Co. Louth.

A pot still is easily recognizable due to its broad bulb type and kettle shape. Distilleries will often have three pot stills on site. The first stage in the pot still destination is filling the first kettle, known as the ‘wash still,’ with the wash produced during fermentation. The pot containing the wash is heated. This will cause vapor to rise to the top of the pot, which then travels through the Lyne Arm at the top and enters a condenser at the top. Here, the vapor is cooled and returns to a liquid known as ‘low wines’ with a higher percentage of alcohol than in the previous stage, usually around 19%.

In summary, by heating the wash to a specific temperature, the lighter alcohol evaporates and rises in the neck of the pot still. The rest of the wash remains in the pot. This process allows for separating the different types of alcohol, increasing quality.

The low wines produced in the wash are then distilled a second time in an intermediate or middle still, producing a higher alcohol content, usually up to 70% abv. The final distillation still takes place in the spirit, and we are left with a distillate at over 80% or more after this third distillation.

Quality water again plays a crucial role in the production of Irish Whiskey, with its addition to the distillate to reduce the abv to an optimal level, one which will extract the best flavor from the wood cask during the maturation period. Typically, casks are filled at 64% to 70% abv.

Distillation in Coffey Stills

The Coffey Still, also known as a column still and has nothing to do with coffee but rather its Irish inventor Aeneas Coffey, is an essential piece of equipment for any distillery. It uses fractional distillation to separate the spirit from the wash, and it can be adjusted to produce a wide variety of results.

The wash is inserted high into the still and flows down through a series of trays. At the bottom, steam is inserted and rises against the wash stream. The alcohol is more likely to evaporate and rise in the still while the water and other residue are collected at the bottom.

Most distilleries still have more than one column to produce a higher quality product.

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