Our Irish whiskey education series kicks off with a style of whiskey that is completely unique to Ireland: single pot still whiskey.

The Americans have bourbon, Scotch is the spiritual home of single malt and in Ireland, there is a whiskey that can only be made there: single pot still. The signature flavour of Irish whiskey, it’s unique for being made from unmalted as well as malted barley.

The unmalted barley is the essential ingredient, the outlier addition that provides a distinct creamy mouth feel as well as nutty, oily, spicy flavours. Taste a single pot still Irish whiskey and you’ll unmistakably know every time. 

The Irish Whiskey Technical File established in 2014 dictates that a single pot still whiskey must be made from a mash bill of non-peated malted and unmalted barley to a minimum of 30% each, with the option to contain up to 5% of other cereals like oats, wheat, and/or rye added if required. It can also only be made in Ireland. 

Barley being harvested

Barley is the key to pot still whiskey.

Why unmalted barley?

You hardly ever see unmalted barley in whiskey production and there’s a practical reason for this. To do some technical mumbo jumbo for a moment, barley is a complex carbohydrate. That means that in order to access the glucose that you’ll convert into alcohol, you need enzymes to break down the proteins around the starch and these are created by the malting process. Unmalted barley can’t produce alcohol on its own. So why have it at all? 

It’s difficult to know exactly when unmalted barley became a feature in Irish whiskey. The introduction of a malt tax in 1785 was a pivotal moment. Using unmalted cereals in their mash bills meant distillers reduced the amount of duty they paid, so there was a clear incentive. However, the history of pot still is more complex than excise avoidance, and we know that Irish whiskey makers understood the impact unmalted barley had on complexity and texture before the malt tax was introduced.

Redbreast and Robin the mascot

Redbreast is one of the leading examples of pot still whiskey

The power of pot still

Throughout the 19th century, Irish whiskey was a world leader in spirits. Pot still was regarded with the status single malt enjoys today, favoured by those who drank Champagne and Cognac, reserved for special occasions, and in demand as far and wide as China, Uruguay, and India.

With the decline of Irish whiskey’s popularity throughout the 20th century, examples of pot still whiskey became increasingly few and far between. The demand for its bold, complex style diminished to the extent that Jameson Irish whiskey stopped being a full pot still whiskey and instead became an accessible blend in 1968. 

The candle never truly blew out, however, and over the last few decades single pot still brands like Redbreast and Spot whiskey have grown and today the style is made at distilleries up and down the country at the likes of Bushmills, Tullamore DEW, Teeling, and more. 

Today, there are proposals in place to adjust the technical file and allow more of the other grains to move more in line with historic mash bills. This demonstrates the passion Irish whiskey producers have for this geographically protected, unique style of whiskey and the potential they see in it. It’s a part of Irish distilling heritage and there’s no better time to acquaint yourself with it than St. Patrick’s Day. Sláinte!