The Distillation, Maturation & Blending of Whiskey

Single Malt Whiskey Part 2

photo of whiskey glass half full on rock

By: Kris Bohm: Distillery Now Consulting, LLC  

Welcome to Part 2 of my article on the technical breakdown of the production of single malt whiskey. If you missed the first half of this article Technical Breakdown for Single Malt Whiskey Production, grab the last issue of Beverage Master Magazine, give it a read then come back right here to read the second half. Single Malt is an amazing, distilled spirit that is produced in countries all around the world and it can be made utilizing many different methods. This article will focus on a method of production employed throughout Scotland and also by some distilleries in the United States to produce single malt whiskey. We will discuss in depth one method on how this type of whiskey is distilled and matured. This half of the article focuses on the distillation, maturation and blending aspects of making malt whiskey and breaks down the steps of this classic method.

  Below we will breakdown the distillation method and expected production yields. With this data in hand we can explore barrels and barrel types, maturation times and expectations, then dive a bit into the process of blending barrels to reach a finished product of bottled whiskey. Let’s dive in and make some single malt!

  Single malt whiskey production from malted barley was first developed and refined in Scotland over several hundred years and the results of that production method produces some of the arguably finest malt whiskey in the world. For the purpose of this article we are breaking down step by step this classic method of whiskey making to better understand the processes that were developed by distillers who came before us. It is important to stress that malt whiskey flavor profiles can vary massively, when you taste a whiskey at one distillery versus another they rarely taste exactly the same. This is important to consider as there is no specific right or wrong flavor profile when it comes to single malt.

  In the first half of this article (In the December – January 2024 Beverage Master issue, page 42) we left off with a fermenter full of distillers beer made from malted barley, ready to be distilled into whiskey. In case you didn’t know, distillers beer is quite different from a beer made to be drunk as beer itself. Distillers beer does not have any hops added to it and is typically fermented rather fast. Distiller’s beer is usually only 3-7 days old when it is ready to be distilled. When a distiller’s beer has completed fermentation it is ready to be distilled immediately. At this time the beer is around 9% ABV. Some distillers have higher or lower ABV beer but 9% is a reasonable expectation. Now that our beer is done fermenting lets distill it.

  The beer is going to be pumped from the fermenter to a copper still where the beer will be heated up and the alcohol distilled out of it. The stills used for distilling single malt whiskey are batch stills that do not typically have any rectification plates or a dephlegmator. In the distilling process a distillery will employ multiple stills to complete the process of making whiskey. The still used for distilling the beer is referred to as a wash still. There is a second still used in a distillery for redistillation is called a spirit still . Both wash still and spirit still have a design that allows many flavors, oils congeners and character from the beer to carry over into the distillate. During the first distillation of the beer a rough unfinished product is produced called Low Wines Low Wines are the sum of all the alcohol distilled out of the beer along with some water, some oils and a ton of flavor. The distilled low wines are not a finished product as the concentration of alcohol is too low and the resulting distillate has too large of a concentration of water. To complete the distillation of the whiskey the low wines are put into the spirit still and redistilled. During this second distillation the heads and tails cuts are made which remove methanol and oils from the whiskey. The portion of the whiskey that is kept is often referred to as the hearts. This second distillation will yield a clear whiskey known as new make. New make will can be as strong as 75% ABV or as weak as 55% ABV. The new make is diluted with some water then put into barrels. Below is a chart that breaks down volume of distillation and expected yields from the distillation.

  The stills themselves employed in the process of distilling single malt whiskey plays a strong role in the influence of the flavor profile of the whiskey. In Scotland and in other whiskey producing countries, single malt whiskey is almost exclusively distilled in copper pot stills using the traditional batch distillation method. This method of distillation is intensive in both its use of energy and labor, but produces a flavor profile that is difficult to replicate using a more efficient  continuous column still for distillation. Because the flavor profile of malt whiskey produced through batch distillation is unique, distillers today still employ the traditional methods of batch distillation in making malt whiskey. Traditionally malt whiskey is twice distilled. One reason for this double distillation process is tied to flavor. There are many oils and congeners in distillers beer and in distilling whiskey more oils and congeners are carried over into the distilled whiskey when it is twice distilled in a pot. These oils and congeners play a large role of flavor in the finished mature spirit and are essential to create the complex flavor profile of single malt whiskey.

  Now that you have some freshly distilled new make whiskey it’s time to drink it! Just kidding, we have a few years to go before this whiskey is ready. It is time to put that whiskey in a barrel. One of the wonderful aspects of single malt production is the option to age the spirit in a multitude of different types of barrels. Unlike Bourbon and Rye Whiskey which can only be aged in charred new american oak, Single malt whiskey can be aged in new or used barrels from many places. Malt whiskey can be aged in sherry butts, wine casks, and used rum, tequila or bourbon barrels. The option to age whiskey in a variety of barrels and casks opens creative freedom for a distiller to add unique character to the distillate from the barrel. There are some distilleries that age their single malt in a variety of casks with some whiskey aging in new charred oak barrels and some aging in used barrels. Aging in a variety of barrels creates a diverse profile of whiskey in flavor and color which allows the folks blending the whiskey to have more flavor components to work with. The concentration of alcohol in a new make whiskey when it is put into the barrel is a bit stronger than the strength at which it is bottled. Entry proof is a big factor in maturation. Some folks will fill barrels with whiskey as strong as 62.5% alcohol by volume others will barrel at a much lower 50%. This difference of entry proof plays a strong role in the flavor components extracted from the barrel.

  The whiskey is now in your barrel so let’s hurry up and wait. The amount of time that a whiskey needs to spend in the barrel to fully mature can vary immensely depending on many factors. The biggest factor that determines the required amount of time a whiskey needs to spend in a barrel is the environment in which the barrel rests. In colder climates such as those found in the northern United States and in Scotland the maturation period is rather long for a whiskey to reach its fullest potential. This time period to reach maturation can exceed 10 years. When a barrel is stored in a warmer climate the required amount of time for full maturation of the spirit it’s quite a bit shorter. In places like Texas some distillers have found that single malt whiskey will fully mature in as little as 3 years. Determination as to whether or not a whiskey is fully matured is a hotly debated topic and is best left up to those who need to make the choice as to whether or not their whiskey is ready to be bottled. What flavors make a whiskey taste fully mature is tricky and it is important to point out that a 10 year whiskey aged in Minnesota will not taste the same as a 3 year whiskey from Texas.

  So now that you have tasted some of your aged whiskey from the barrels and the whiskey is tasting mature it is time to blend some barrels together to create a finished product. The process of tasting and selecting the barrels that will be blended together to make a finished product is just as important as the distillation process itself. No two barrels of whiskey will mature and taste exactly the same. Some barrels need more or less time and some whiskey within the barrels will develop different flavor profiles from its neighboring barrels even when those are often made from the exact same whiskey. It is critical to take the time to taste barrels and test out blending of different barrels. The purpose of this blending work is to create a blend that builds the best whiskey possible. This should be done before you start dumping barrels into a tank to bottle the whiskey. When two different barrels are blended together in a tank the resulting flavor profile can be different than the sum of the parts. Because blending will impact finished taste and aroma of  whiskey is of the utmost importance to test out blends before the barrels are actually married together. It is paramount to give time tasting and careful consideration to blending barrels to ensure the highest quality of a finished whiskey.

  There are so many steps and factors that culminate to produce the beautiful and complex spirit known as Single Malt Whiskey. I hope these two articles have helped to fill in some knowledge for those looking to leap into the endeavor of making Single Malt Whiskey. Single Malt Whiskey is one of the fastest growing whiskey categories in America and there is ample room in the market for new brands. If you are wanting to make Single Malt and not sure where to start shoot me an email and let’s connect.

  Author Kris Bohm is the Owner of Distillery Now Consulting. When Kris is not making whiskey you can find him riding his bicycle all around the world.

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