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Whiskey Overview: From Irish Whiskies to Bourbon Mash Bills

Whiskey Overview: From Irish Whiskies to Bourbon Mash Bills

When it’s your turn to belly up to the bar, or relax and sip a spirit after a hard day’s work, why not mix things up a bit and step out of your usual routine by ordering one of these very popular types of whiskeys: Bourbon, Scotch, Rye or Irish Whisky. You’ll be glad you tried something new and different, and you may even have a new favorite mixed drink to enjoy when you decide to have a drink.

If you’re strictly a wine or beer guy or gal, you may be surprised at how tasty these four stronger drinks can be, and when ordered properly and prepared skillfully by an experienced bartender or mixologist, your time at the local pub may be transformed into a much more meaningful event—one that drives you to learn more and more about wine and beer’s distant cousins—Bourbon, Scotch, Rye and Irish Whisky.

In an earlier article, we discussed how “whiskey” also known as “the water of life” is an umbrella term for the four spirits mentioned here, and today, we’re going to take a closer look at the world of whiskey and the differences (and similarities) between these four distinct drinks.

The only exception to the rule for the umbrella term of “whiskey” is that whiskey/whisky can also be used to describe a distilled drink that is made from corn, instead of from grain. Before going any further, let’s first make sure we understand what is meant by “distilled spirits.” In simplest terms, distillation involves using heat or cold to purify a liquid and separate its components.

So, a distilled beverage (commonly referred to as a “spirit”) is an alcoholic beverage produced by distillation of a mixture produced from alcoholic fermentation.

And what is fermentation? It’s the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms. In whiskey production, the components of grains or corn are broken down by other substances (at a distillery), and this is the fermentation process.

The fermented substances are then distilled, and it’s the fermentation and distillation processes that—after some time has passed—produce the distinct tastes bourbon and Scotch drinkers love so much.

The terms “whiskey” and “whisky” are the same thing: “whiskey” is the American spelling and “whisky” is how it’s spelled in Europe and Canada. Canadian Whisky is an entirely separate topic that we will tackle another day. For now, these four are enough to get us started.

Irish Whisky

Who doesn’t love great-tasting Irish Whiskies added to their coffee after a delicious, decadent meal? I did not realize Irish coffee was even a thing until well into my 30s. Yet once I found out, it was played an important role in some mornings. But what is Irish Whisky and how is it different than other whiskies? Irish Whiskey’s history is quite simple, really.

Irish Whisky is made in the Republic of Ireland or in Northern Ireland, and nothing made outside of Ireland can ever be referred to as an Irish Whisky. Similar to Scotch, Irish Whisky must be distilled to an alcohol by volume (ABV) of less than 94.8%.

The Old Bushmills Distillery in Northern Ireland has the honor of being the first whiskey distillery and is the oldest licensed whiskey distillery in the world. Also, Irish Whisky must be made from yeast-fermented grain mash in such a way that the whisky has an aroma and flavor derived from the ingredients used in the distillation process. If two or more distillates are used in the process, the label must read “Blended Irish Whiskey.” Finally, true Irish Whisky is aged for at least three years in wooden casks.

4 Types of Irish Whiskey:

  • Grain Irish whiskey is produced using no more than 30% malted barley in combination with other whole unmalted cereals—usually corn, wheat, or barley—and is distilled in column stills.
  • Malt Irish whiskey is produced using 100% malted barley and distilled in pot stills.
  • Pot Still Irish whiskey is made from a mash of a minimum 30% malted and a minimum 30% unmalted barley, with up to 5% of other cereals added, and is distilled in pot stills.
  • Blended Irish whiskey is a mixture of any two or more of the styles of malt, pot still, and grain whiskey.

Scotch Whisky


Scotch is a distilled spirit made from malted barley; many Scotch recipes only contain three ingredients: barley, yeast and water. Different distilleries make small changes here and there to make a an unconventional mash bill producing a wholly unique style. Some decide to use unmalted cereal grains, unmalted barley, or other unmalted grains to try and stand out in the scotch whiskey world.

Scotch may include whole grains of other cereals and even caramel coloring to get that perfect, distinct color a Scotch master distiller always want to achieve. In order to be a true Scotch, however, the drink must be made in Scotland, and it must contain no fermentation additives. Also, in order to be a true Scotch, no short cuts can be taken during the fermentation and distillation processes.

The biggest discerning quality of Scotch whiskies is whether it’s single malt whiskey or blended (more than one malt). A single malt Scotch goes through one distillation process whereas blended Scotch is a mix of barrel-aged malts and grains. Single malt Scotch is often aged ten or more years.

While the debate of which type of Scotch is superior, most experts will tell you that blended Scotches deliver a wider range of flavors with a superior balance of flavors and complexity of ingredients. But because blended Scotch is what is used in mixed drinks, it’s considered less fancy and refined by many experts.

When you see a number following the name on a Scotch bottle, the number indicates how many years the Scotch was aged. Scotch tastes similar to bourbon but has a distinct smokiness that lingers on the palate after you swallow it. Scotch drinkers will tell you that adding a few drops of water to the glass will reveal and enhance the subtlest flavors of the liquor.

Bourbon Whiskey

The word “bourbon” can only be used to refer to this spirit when it’s made in the United States. Bourbon must be distilled to no more than 80% alcohol (160 proof), and bourbon has no minimum aging period like Scotch does. To be labeled as “straight bourbon,” the spirit must be aged in bourbon barrels no less than two years, and it can have no added flavoring, coloring or other sprits.

On the other hand, blended bourbon may have those three things added to its distillation process. The age on the bottle of bourbon must be the age of the youngest whiskey in the mix.

The type of grain that makes up a traditional bourbon mash bill are corn, rye, and malted barely. Here are some mash bill facts:

* for reference, the ratios listed below denote Corn % / Rye % / Malted Barley % *

  • Heaven Hill Bourbon Mashbill: 78/10/12
  • Wild Turkey Bourbon Mashbill: 75/13/12
  • Jim Beam Bourbon Mashbill: 75/13/12

Why Is Tennessee Sour Mash Not Bourbon?


Now that we’ve defined what bourbon is, let’s explore some of the things it’s not. One of them is Tennessee sour mash. So what’s the difference?

Almost everything about Tennessee sour mash whiskey meets the criteria for bourbon: 51% corn? Check. Made in the US? Check. Aged in new oak barrels? Check. And the strengths match up, too. 

The difference is what is called the Lincoln County Process. In the Process, the spirit is filtered through maple charcoal before aging. That gives the whiskey a bit of a head start on acquiring the complex woody flavors it can acquire in the barrel. We’re not sure this really counts as an “artificial” flavoring, but it’s considered one for the purposes of the law. 

Feeling slighted, Tennessee hit back with a 2013 state law that requires all Tennessee whiskey must use the Lincoln County Process. An exception was written in for Benjamin Prichard’s Tennessee Whiskey, 

So what’s up with the sour mash? Sour mash is actually a process that’s common to bourbon and Tennessee whiskey. Sour mash is when you use spent mash from a previous batch as a starter for your new batch, similar to the way you use an old bread starter for sourdough. 

Single Barrel, Small Batch, and Cask Strength Bourbons

So, what’s the difference between a single barrel and small batch bourbon? Both of these bourbons are hand-picked by the master distiller. 

As the name implies, a single-barrel bourbon comes out of a single barrel. The distiller picks one barrel that he believes has a particular character that’s worth preserving. Although all bourbon technically is going through the same distillation process, put into very similar barrels and aged in basically the same place, there are still subtle variations in materials and conditions that can create distinct flavors. Selecting a single barrel bourbon gives you a chance to sample a unique flavor that will probably never exist again. 

With small-batch bourbons, the master distiller selects a few barrels to be blended and bottled together. There’s no maximum number defined for a “small batch,” but it’s usually about a dozen. These are also unique flavors, but because they’re created by design and combining larger quantities, it’s more likely that this flavor will be repeatable—and reliable. 

But whether the bourbon comes out of a single barrel or several, bourbon is often diluted as it’s bottled to reach proof. But if the bourbon is bottled as it comes out of the barrel, it’s called cask strength. The bourbon went into the barrel at 125 proof, and it could still be that, now, although that’s unlikely. But it will definitely be at least 80 proof. Cask strength is sometimes called barrel proof. 

Bottled in Bond


Back when America was great, you could put anything you wanted in a bottle and sell it as bourbon. People tried to pass vodka, gin, rum, and anything else they wanted as bourbon, adding color with tobacco, iodine, or anything brown they could find. This didn’t just make terrible bourbon, it was making people sick.

But in 1897, the US passed the Bottled-in-Bond Act, the first consumer protection law in US history. It stated that a Bonded Spirit had to be aged at least four years, bottled at exactly 100 proof, and be distilled in one location. Few spirits these days meet all the requirements of the Bottle Act, but those that do produce a very reliable quality. 

Rye Whiskey


Rye whiskey is similar to bourbon but it requires rye grain, which makes it a bit “spicier” than other whiskies. Most of the rye whiskey production and consumption consumed in the world is in the United States. Some of the unique attributes of rye whisky include:

  • 51% of the recipe is rye grain
  • Rye is aged in new, charred-oak barrels
  • It’s matured for a minimum of two years

Once you’ve got the 51% corn requirement satisfied, the rest of your grain bill can be anything else you want, but the two big contenders in bourbon are wheat and rye. 

If a bourbon contains more wheat than rye, it’s called a wheater. If it’s more rye than wheat, it’s called a high rye bourbon. But, remember, to be a bourbon, it still has to have 51% corn. If it tips too far to those other grains, it becomes a wheat whiskey like Burnheim or a rye whiskey. 

There you have it: the basic information you need to understand the differences between Scotch, bourbon, rye and Irish Whisky. Next time you stop by the tavern for a drink, give something new a try. You just may become a Scotch or bourbon aficionado!

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