Technical Break Down for Single Malt Whiskey Production

Photo of whiskey decanter half filled with whisky with 2 whiskey glasses partially filled with whiskey on a table

By: Kris Bohm of Distillery Now Consulting

Single Malt whiskey is a lively distilled spirit that is produced in countries all around the world. There are many ways to make single malt, and in this two-part article we discuss, in depth, just one of those ways. Distillers have very creative processes, and this is the reason that when you taste whiskey at different distilleries, they rarely taste the same.  In this two-part article we will go through the start to finish process of making malt whiskey and break down the classic method of the production of single malt whiskey.

  Single malt whiskey production was first developed and refined in Scotland over several hundred years and the results of that production method produced some of the finest single malt Whiskey in the world. We will now break down step-by-step this method to better understand the processes that were developed by distillers who came before us.   First, let us define American single malt whiskey as it does have legal definitions and requirements on how this whiskey can be made.

  American single malt is made from 100% malted barley. This precludes malt whiskey from being made with corn, rye, wheat, or any raw barley that has not been malted. The malted grain contributes considerably to the overall character and flavor of the spirit and is what differentiates this whiskey from American bourbon or rye whiskey.

  The second aspect of American single malt whiskey that differentiates it from American whiskey is that single malt can be aged in used barrels or new barrels. Used barrels contribute far less flavor and character to a spirit than new American oak barrels do, such as those used for bourbon production. Single malt whiskey is required to be distilled entirely at one distillery.

  Now that we have defined single malt, let us break down the steps of how single malt whiskey is made and how they emulate the methods used for its production in Scotland.

  The specific types of equipment that are used in the production of single malt play a strong role in the flavors that exist in malt whiskey. A mill is used to crack the malted barley into smaller pieces to aid in sugar extraction and this is typically done by a roller mill. While most whiskey mashing uses a cooker to process the grain in malt whiskey production a lauter tun is used instead of a cooker. The lauter allows for separation of the malted barley from the liquid that the grain is steeped in. The product produced by a lauter is a clean fermentable liquid that is free of grains known as wort. The wort is transferred from the lauter through a pump and through a heat exchanger.  This transfer removes all the wort from the lauter and cools it off in the process then further pumps the wort to a fermenter. There are multiple diverse types of fermenters that can be found in distilleries from open top to closed, stainless, wood and everything in between. The most critical part of a fermenter is that it is sized appropriately to hold all the wort that is produced from the lauter.  The fermenter serves to hold the wort while the yeast ferments it and converts the sugar into alcohol to produce a beer suitable for distilling.

  It is important to point out details about the lauter before we move on to the nuances of production methods. Use of a lauter is essential as opposed to a cooker in malt whiskey production. When a malt whiskey is produced in the grain on method such as how bourbon is produced, the tannins in the barley husk will negatively impact the flavor of the whiskey.

  First is the process of the production of single malt from a bag of malted barley to a distiller’s beer ready for distillation. This recipe example has the potential to produce a single full-size barrel of whiskey. (See Recipe Breakdown chart above)

  Now, we will go over the details on how this process is completed in a single vessel lauter tun. It is important to stress that these quantities and numbers are wholly dependent on the specific equipment being used. It will take testing and trials to determine optimal water quantity, temperatures, and minerals to optimize operation of the equipment. It is best to assess and confirm the operation of equipment and holding temperatures prior to your first mash. If everything is fully assessed before mashing, you should be able to have a successful first mash to make single malt whiskey. It is extremely helpful to develop written operating procedures on your mashing process to create replicable results for every single mash.

Malt Whiskey Mash Operating Procedures

•    Mill in grain per mash bill, Check quality of grind to insure proper crack

•    Add 50 gal of 160-degree water to lauter tun cover false bottom plus minerals for Ph adjustment

•    Turn rakes on and add grain to lauter with 300 gallons of water through hydrator

•    Once fully grained, check temperature of mash and adjust as needed. Target temperature is 150

•    Turn rakes off and let mash rest for 30 minutes

•    Slowly start run-off of wort into grant, but do not rush this process or the mash may get stuck

•    Run-off wort till grant clears, then reconfigure manifold to run off wort to kettle

•    Confirm cooling is functional on heat exchanger

•    Start run-off of wort from lauter tun through heat ex and to fermenter

•    When 50% of wort is run off start sparging with 165-degree water

•    Continue to run of wort slowly till lauter tun is empty of wort or fermentor is full

•    Aerate wort prior to pitching yeast and check plato or brix now

•    Pitch 500 grams Yeast into each fermentor per manufacturer’s instructions

•    Set temperature controllers on fermentor to maintain temperature

•    Check plato daily till ferment is complete, (should take 3-5 days)

  When the distiller’s beer has completed fermentation, then it is ready to be distilled.

  There are more steps involved in the distillation process we must complete before we reach a delicious dram of whiskey. In the second part of our article we will cover the process of distillation and maturation methods of malt whiskey in depth as we finish taking this distillers beer and turning it into whiskey. Single Malt whiskey is a fast-growing category of spirits in North America and has ample space for your distillery to contribute to. If you are considering making single malt whiskey, now is the time to do it.

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