This blog provides information for educational purposes only. Read our complete summary for more info.

Kyle Brown

Owner of Clawhammer Supply

In this guide, we'll show you how to make bourbon whiskey from start to finish. This will include step by step descriptions of recipe creation, grain milling, mashing, fermenting, distilling, and aging, blending, and bottling. To make sure we provide the most valuable and accurate information possible, we've enlisted the help of Jesse Wilson from the "Still It" YouTube channel. He’s a master distiller whose expertise is highly sought after by both home distillers and professional distillery owners.

It must also be noted that this article is for educational purposes only. While it is legal to make a bourbon mash in the United States, it is illegal to distill bourbon at home for personal consumption. In fact it's illegal to distill it for any reason without the proper federal, state and local permits. As it turns out, the “land of the free” ain’t so free after all. However, Jesse is from New Zealand where “freedom” is more than a cheap buzzword and home distilling is actually legal. So, we'll be making a mash in the U.S. and Jesse will head back NZ to distill it.

The Definition of Bourbon

Before we tell you how Bourbon is made, we should define “Bourbon.” In other words, what is Bourbon whiskey? The first thing you need to know is that all bourbon is whiskey, but not all whiskey is bourbon. Whiskey is a distilled alcoholic beverage that is made from any combination of cereal grains such as barley, rye, wheat and corn. A bourbon mash must composed primarily of corn (at least 51%). There are very specific distillation and bottling proof requirements. And Bourbon is aged in new, oak barrels. Additionally, it must contain no additives.  All requirements are described in detail below.

But who decides what qualifies as "Bourbon?" The entity that dictates what is and is not Bourbon is the United States Tax and Trade Bureau (TTB). In fact, the TTB oversees all alcohol production in the United States, which includes defining and enforcing the rules and proper procedures for making spirits. Spirit class and type designation are discussed in chapter 4 of the Beverage Alcohol Manual, which defines the various types of bourbon whiskey and their requirements as follows.

*Note: the TTB spells “Whiskey” without an “e.” So, they spell it, “whisky.” However, it’s more commonly spelled with an “e” in the U.S.

Bourbon Whiskey Definition

So, what makes Bourbon, Bourbon? According to Chapter 4 of the TTB’s Beverage Alcohol Manual (BAM), bourbon is, “Whisky produced in the U.S. at not exceeding 80% alcohol by volume (160 proof) from a fermented mash of not less than 51 percent corn and stored at not more than 62.5% alcohol by volume (125 proof) in charred new oak containers.” Note, there is no minimum age requirement for standard bourbon. Additionally, chapter 7 of BAM states that no additional coloring, flavoring, or blending agents may be added unless the label is changed to reflect the additions. More on this below.

Straight Bourbon Whiskey Definition

According to the TTB, straight bourbon is, “Bourbon whisky stored in charred new oak containers for 2 years or more. ‘Straight Bourbon Whisky’ may include mixtures of two or more straight bourbon whiskies provided all of the whiskies are produced in the same state.” Straight bourbon also must meet the basic requirement for bourbon listed above, including having a grain bill that is at least 51% corn, produced at no more than 160 proof, and stored at not more than 125 proof in new oak barrels. The same additive rule mentioned above applies to straight bourbon whiskey as well.

Deceptive Labeling

Although these labeling requirements seem pretty cut and dry, there is a bit of gray area baked into the rules and the number of companies that take advantage of this is much more common than one would think. First, the TTB in fact does allow additives to both bourbon and straight bourbon, provided that the label is changed to reflect this. For example, chapter 7 of BAM specifically mentions that if “FD&C Yellow #5 is added to straight bourbon whisky….the product is now a distilled spirits specialty and must be labeled with a statement of composition such as ‘STRAIGHT BOURBON WHISKY WITH FD&C YELLOW #5 ADDED’"

So, the question is, how prevalent does this labeling need to be and how easy would it be to create a straight bourbon whiskey with additives that actually seemed like it was just, well, straight bourbon whiskey, without additives? The answer to that deceptive labeling of bourbon and other spirits is much easier than one would think. This problem is also a lot older than one would think!

Bottled in Bond Bourbon Definition

Spirit production was very loosely regulated in the early days of the Union. All manner of additives were included to “improve” the products. For example, tobacco was sometimes added to darken the color. Obviously this free-for-all scenario where any distillery could add whatever they wanted to recipes, barrels and bottles threatened to compromise the integrity of the entire industry. For this reason, the U.S. government intervened and created the “bottled in bond” program in 1897.

Bottled in bond is a tax incentive program for distilleries that produce spirits according to very specific requirements. Bottled in bond bourbon must be produced in a single season by a single distillery and distilled to be no stronger than 160 proof (80% alcohol by volume). It must then be aged in a new charred oak barrel at a federally bonded warehouse for at least 4 years. After that it must be bottled at 100 proof (50% alcohol by volume) under the supervision of a government official. Also, only water can be added to bourbon that has been bottled in bond (to adjust proof). Additives are prohibited.

As mentioned earlier, label discrepancies abound in the world of distilled spirits, but the bottled in bond program seems to be a bit more closely looked after these days. Spirits in this category tend to be more plainly labeled and are less likely to actually contain additives.

Kentucky Straight Bourbon Definition

The final bourbon definition we’ll discuss is Kentucky straight bourbon. This spirit essentially has the same requirements as straight bourbon whiskey, but it must be produced within the state of Kentucky. Also, in some cases a single bourbon may meet several of the definitions above at once. For example, Heaven Hill’s Bottled in Bond Kentucky Straight Bourbon Whiskey meets the requirements to be labeled “bottled in bond” and “Kentucky straight bourbon.”

Where is Bourbon made?

There is a lot of confusion about where Bourbon can be made. The spirit technically originated in Bourbon County, Kentucky. However, Bourbon can actually be made elsewhere. But where?

Regular Bourbon, Straight Bourbon, and Bottled in Bond Bourbon can only be made in the United States. Kentucky Bourbon and Kentucky Straight Bourbon can only be made in Kentucky.

Making Bourbon

First of all, is it legal to make bourbon mash at home? Yes, absolutely. It's the same process as making beer and the final ABV of a properly made bourbon mash will be similar to a strong beer. Is it legal to distill bourbon mash at home in the United States? Unfortunately, no. As we mentioned, we actually did make the this mash recipe but we relied on our friend Jesse, who lives in New Zealand, to distill it.

What better way to explain how bourbon is made than to actually make some and describe the process, which is what we’re going to do here. We start with raw grain and we end with bourbon in a glass. Our goal is to make a top shelf bourbon whiskey, akin to Heaven Hill or Pappy Van Winkle. Bourbon is actually made in a 5 step process:

1. Mashing
2. Fermentation
3. Distillation
4. Aging
5. Blending and Bottling

Mashing is generally the term that is used to describe the “cooking” of the grain that will eventually be fermented and turned into alcohol and includes the following general steps:

• Bourbon recipe creation
• Gathering ingredients
• Preparing equipment
• Milling grain
• Mashing, or converting grain starches into sugar

Bourbon Recipe Details and Ingredients

As mentioned above, bourbon is made from fermented grain and must be at least 51% corn, so corn will always be the primary ingredient in any bourbon. As we'll explain later, corn starch must be converted to sugar before fermentation can take place. Malted barley is generally used to facilitate this process and it's almost always included in the list of bourbon ingredients. The third ingredient is almost always rye or wheat. Rye will produce a more aggressive or "spicy" bourbon while wheat provides a more mellow drinking experience.

The recipe we've created below will result in a more refined, smoother bourbon. At the heart of our recipe is 14 pounds of corn. We've included 2.8 pounds of 6-row barley. And we've also included 3.25 pounds of malted wheat. And of course we’re going to need some water to cook all of these grains in as well so the recipe will also include 9.5 gallons of water. Yeast nutrient is optional, which we'll explain later. And yeast is required for fermentation.

Here are the ingredients for a 5 gallon bourbon mash:

• 9.5 gallons water
• 14 lbs. flaked corn
• 3.25 lbs. wheat malt
• 2.8 lbs. 6-row pilsner malt
• Yeast nutrient
• Distillers yeast

We've designed this recipe with three things in mind:

• Style, flavor and aroma,
• starting alcohol by volume, and
• starch conversion potential (diastatic power).

Style, Flavor, and Aroma

We'll describe this in greater detail in just a moment, but our recipe is 51% corn, which satisfies the basic requirement of corn composition in a bourbon. It also contains wheat, which will produce a smoother and more mellow final product

Starting ABV

We'll dive into this in greater detail during the section on distillation, but what needs to be explained now is that this recipe is designed to produce a 10% ABV whiskey wash. Wash is the name for fermented mash. We could add a lot more grain now and probably double this number, but at the expense of quality. Since we're shooting for a top shelf drinking experience, we've capped the pre-distilled ABV to 10%

Diastatic Power (or Degrees Linter)

Starch conversion is quite a heady topic and we explain it in more detail during the section on mashing. The short of it is that enzymes contained within malted grains are used to convert grain starch into sugar during the mash. Because barley and wheat are the only malted ingredients we're using in this recipe, we need to make sure it contains enough enzymes to convert the starch in the corn.

The total capacity a particular malted grain has to convert starch into sugar is called its diastatic power. And the sum of the diastatic power given the total volume of grain used is called the total Lintner. To determine whether or not our malted barley and wheat contain enough enzymes for full starch conversion, we plugged our recipe details into a diastatic power calculator. According our math, this recipe should work out just fine.

Recipe Caveats

A couple of very significant caveats should be mentioned regarding the ingredients we’re using. First, we aren’t using sweet corn straight off a cob. We also aren’t standard dried corn. Regular ol’ dried corn is actually somewhat difficult to cook relative to other cereal grains. It must first be cracked or ground, if possible, and then cooked for 90 minutes or more at 185 Fahrenheit or longer. It absorbs a lot of water and can be kind of a pain to work with.

We’re what is referred to (in the United States) as “flaked maize.” This is a fancy word for corn that has been dried, has had the germ, oil, and much of the protein removed and is what is called “Pregelatinized.” This type of corn doesn’t need any sort of processing before mashing. I.e. it does not need to be milled. And it doesn’t need to be cooked either (beyond the standard mashing protocol).

The second caveat is that we aren’t just using raw barley, we’re using malted barley. Why? Long story short, malted barley contains enzymes that will convert all of the starch in the mash grain into sugar. Yeast will later convert the sugar into alcohol during the fermentation process. Raw barley doesn't contain the necessary enzymes to complete the conversion. More on this in the section on mashing.

The last point we need to make is that bourbon is probably most often made with corn, barley and rye. Rye tends to produce a more sharp and spicy flavor profile. Replacing the rye with wheat results in a lighter more mellow drinking experience, which is what we're after with this recipe. Also, there is no TTB labeling requirement for a wheat addition, but the recipe we've created here would colloquially be referred to as a wheated bourbon.

Brewing Equipment

We don’t have the luxury (or the burden) of owning and operating a commercial distillery, so to make this recipe we’ll need to scale it down to a manageable size. We’re using Clawhammer's 20 gallon brewing system and our still is just over 8 gallons, so we’ve scaled this recipe down so it produces just over 5 gallons of liquid for distillation. 

Milling Bourbon Grain

For reasons that will become obvious in the next step, we need to crack open the grain to gain access to the insides of the kernel. We also need to increase the surface area of the grain itself. Running it through a grain mill cracking it in half, and breaking it into smaller pieces accomplishes this goal.

All grain needs to be milled before mashing. However, the thoroughness of milling that is required is contingent on the method of brewing is being used. Because we aren’t making a massive commercial sized batch we can use a brewing method that will make our lives easier. That said, we’ll be using what is called the brew in a bag (BIAB) method. BIAB consists of using a stainless steel mesh basket to hold grain during mashing. The gain basket is removed after mashing is complete allowing the entire mash process to be completed with a single kettle. This type of brewing typically tolerates finely crushed grains quite well. In fact, a finer crush will actually improve mash efficiency. Here is the bullet point for the recipe:

• Double crush barley and wheat at .03 inches.
• Milling flaked maize is optional

We’ll run our grain through a high quality grain mill set to about .03 inches wide, which roughly the thickness of a standard credit card. This is good information to remember because a handy trick to set the crush on a mill is to actually get out an old credit card and stuck it between the rollers of the mill. Push the mill rollers inward until they put slight pressure on the card, then tighten the set screws.

As stated, we actually ran our grain through the mill twice to grind it a bit more finely and improve the efficiency of the mash. Both times we collected the crushed grain in a food safe bucket, which also doubles as a cheap fermenter. As for the corn, because it is pregelatinized, we didn’t technically need to run it through the mill, but doing so probably would have increased mashed efficiency and also sped it up a bit.

One final note on milling is that if we were using standard feed corn, we would have wanted to run it through a mill.. Though we would caution against using a new mill for grinding something like feed corn. Corn is extremely hard and will dull mill rollers in short order.

After milling was complete we moved on to the mash.

Bourbon Mash Process

At this point we're ready to begin the actual mash. Obviously, bourbon is high proof alcohol. As we previously mentioned, the alcohol in bourbon is created by the fermentation of sugar by yeast. However, grain is primarily starch (not sugar). The process of mashing is actually what creates the sugar in a bourbon recipe.

To help explain the necessity of mashing, let's first look at the composition of a kernel of corn. Corn is about 75% starch, 10% protein, 5% oil, and the rest is fiber and water. Notice that sugar isn't listed here. Next, let's look at barley. The barley used for brewing is composed of about 80% starch, 10% protein, 10-15% water and 2-3% fatty acids. Notice again how there are no sugars listed. So, where does the sugar come from? It is created by using enzymes found in malted grain to convert the grain starch into sugar.

Buried within the genetic code of all seeds is an amazing function: the ability to convert starch into sugar. This process is activated by malting grain, which produces the enzymes needed for starch conversion. Once grain has been malted and the enzymes have been created, they can then be activated by creating conditions that allow them to begin breaking down starch molecules into sugar molecules. These conditions include moisture, heat, and proper pH. Here's and overview of the process with additional details below?

Bourbon Mash Steps

1. Fill kettle with 9.5 gallons of water
2. Heat water to 147 degrees F.
3. Gently pour grains into kettle while stirring
4. Wait 10 minutes and take a pH reading
5. Adjust pH so it is somewhere between 5.2 and 5.8
6. Allow to sit for 60 minutes while stirring intermittently
7. Complete a starch conversion iodine test
8. Complete a "mashout" at 170 F for 20 minutes

Mash Temperature

Many of the steps in the process of making bourbon can be tweaked in order to create slight variations in the final product. The mash is one of the steps that can be played with a bit.

Sacchrification is the technical name for the process of conversion of starch into sugar during the mash and it's actually completed by two different enzymes found in malted grain: alpha and beta amylase. Alpha amylase is most active at higher temperatures (150-160 F). Beta amylase is most active in the 140-150 F range. Alpha amylase converts starch into longer chain sugar, which can be difficult for yeast to break down. Beta amylase creates highly fermentable short chain sugars.

Because our ultimate goal is to make highly concentrated alcohol, we're looking to create more fermentable sugars than non-fermentable sugars. So we're going to be mashing at 147 degrees Fahrenheit to slightly boost the activity of beta amylase.

Mash Agitation

Commercial bourbon mashing equipment often contains a mixing paddle or rakes that stir water as grains are added and is also used to agitate the grain as it is mashing in order to increase starch conversion. We don't need something like that because we're using a small kettle and we're able to stir by and if we wish. We generally don't do this. Our standard practice is to use hoses and a pump to wort through the grain bed. However, we were being lazy on this particular day and didn't want to have to clean the hoses and pump later. So instead, we just stirred the grains occasionally with a large paddle.

Measuring and Adjusting Mash pH

One of the conditions needed for optimal starch to sugar conversion is proper pH. It's generally agreed upon that anywhere within the range of 5.2 to 5.8 is acceptable for mashing. Starting pH (after mashing in but before adjusting) will vary from batch to batch depending on the natural pH of the mash water, the amount of buffering agents present, and the amount and type of grain being used. Though typically, pH will need to be manually lowered when making bourbon mash because the grain used for distilling is only lightly kilned, which doesn't contribute as much to pH drop as more aggressively kilned, darker malts do.

To measure pH, wait 10 minutes after mashing in. Take a sample of wort from the top of the kettle and measure pH with a high quality pH meter. We wish we could recommend an inexpensive pH meter, but the cheap ones just never seem to work correctly. The only meter we can really vouch for is the MW102. It provides accurate readings, is very reliable, and can be easily re-calibrated.

If pH is low, add lactic acid, stir, and re-test after a few minutes. If pH is low, add calcium carbonate, stir, and re-test after a few minutes. Once pH is somewhere in the range of 5.2 - 5.8, move on. Note, if pH is out of range, the mash will likely still work just fine. Though maximum efficiency may not be achieved.

Mash Time

Mash time is almost always listed as 60 minutes. However, it may take more or less time depending on the type of grain being used. If a lot of cracked corn is being used in a mash, as opposed to flaked maize, mashing may take 90 minutes or longer. However, if flaked maize is used along with a fair amount of malted barley, or if enzymes are added, mashing could take 45 minutes or less. There are two ways to tell if a mash is done. The first method is to measure specific gravity and compare it to the recipe details, if a recipe is being followed. Once specific gravity equals or is higher than the recipe calls for, the mash is likely complete. The second method to measure mash "doneness" is to complete a starch conversion test, which is described below.

Starch Conversion Test

This isn't always necessary, and we rarely do it, but we conducted a starch conversion test to make sure the enzymes in our mash did their job and actually converted all of the starch into sugar. To complete a starch test we took a sample of wort from the kettle (clear liquid only, no solids), dripped it on a white plate, then added a drops of iodine. Tincture of iodine will work (from a pharmacy) will work. Five Star Chemical's Iodophor sanitizer will also work.

If the iodine immediately turns purple or black when dripped onto a sample of wort there is still starch present and conversion is not complete. If it stays orange or yellow, conversion is complete. Note, a very hot sample can give a false positive for starch, so let the sample cool for a minute or two before adding the iodine. Chunks of grain will also indicate a positive. Finally, if left to sit for long enough the iodine will eventually turn purple or black. Look for a change in the first 10 seconds or so.

Mash-out

After the conversion test indicated that our mash was done, we increased the mash temperature to 170 Fahrenheit and left it sit for 20 minutes to loosen the grains up a bit. Completing a mash-out will allow the extraction of more sugar and boost brew house efficiency by about a point.

Completing a mash-out will also flash pasteurize the mash as most naturally occurring bacteria will not be able to survive in this environment. This means that the flavor profile that resulting from this distilled wash will be more predictable, as wild yeast and bacteria will not have a chance grow. More on that later.

Also, consider adding yeast nutrient at this point. More information is provided in the next section.

Pulling the Grains

After mashing was complete we elevated the grain basket above the mash liquid by pulling it out and then suspending it on clips provided with Clawhammer's 20 gallon brewing system. Water soaked grains are extremely heavy and this task pulling such a heavy basket would normally necessitate the use of a brewing pully. However, because we had a few friends over we were easily able to lift the basket by hand. We left the basket in place over the kettle for 10 or 15 minutes then we pressed it to squeeze as much liquid out of the grains as possible.

Fermentation is the stage in bourbon production where the alcohol is created. Without yeast, the production of alcoholic beverages would be extremely difficult and they may not exist at all. There are several components to the fermentation process that are important to keep in mind: specific gravity, temperature, aeration, nutrients, pitching rate, and time.

Bourbon Fermentation Steps

Here is the specific procedure we followed for fermenting our Bourbon mash.

1. Add yeast nutrient
2. Chill wort to 70F
3. Measure specific gravity
4. Transfer to fermenter
5. Aerate
6. Add distillers yeast
7. Ferment for 1.5 weeks at room temperature

This step is optional, but it's certainly a good idea. Low ABV, all-barley mashes contain all of the nutrients necessary for maintaining yeast health and proper fermentation. However, as the relative percentage of corn increases and the ABV goes up, the need for yeast nutrient becomes more necessary. Because this recipe is designed to produce a roughly 10% ABV wash (wash is what mash is called after it's fermented), and corn made up more than half of the grain-bill, we added yeast nutrient.

If yeast nutrient is going to be added, it's a good idea to add it during the mash-out. This way if there is any wild yeast or bacteria present in the yeast nutrient, they will be zapped by the high temperature during the mash-out.

The wort must first be chilled to roughly 70 degrees Fahrenheit to kick off fermentation. Temperatures much lower than than this will cause fermentation to get off to a slow start or it won't happen at all. Temperatures significantly higher than this will cause yeast to be overly active and produce funky (potentially unwanted flavors) and could actually cause the yeast to die.

Chilling wort is generally accomplished by using an immersion chiller, a plate chiller, or a counter-flow chiller. Immersion chillers simply consist of of a coil, which is submerged in to the mash. A plate chiller is a small block with multiple parallel, but separate, plates. Cool water is circulated through one side of the plate chiller and mash is circulated through the other side. A counterflow chiller looks like an immersion chiller but works like a plate chiller. It consists of two pipes, one inner pipe and an external pipe that fits around the inner pipe like a jacket. Mash is circulated through the inner pipe and cool water is circulated through the outer pipe.

In order to determine the pre-distillation ABV as well as to have an idea of when fermentation is complete, we took a specific gravity reading should. This can be accomplished by floating a brewing hydrometer in the liquid. Note, brewing hydrometers are different from distilling hydrometers.

After taking our reading we transferred the liquid to a fermenter. For this type of thing we typically use food grade plastic buckets. They're cost effective, they're durable, and they get the job done.

Exposure to oxygen after fermentation is typically a bad thing but yeast need a bit of oxygen before fermentation begins. To aerate our wort we shook the fermentation buckets for 60 seconds each.

After aeration we pitched distillers yeast. It's always best to follow the directions on the package, but Jesse, our master distiller, eyeballed it. Watch our video on how to make bourbon for more information on this step.

Once the liquid was in the fermenter, we added an airlock and set the bucket aside in a cool, dark room and let it sit for a couple of weeks. At that point we took a specific gravity reading to determine the density of the liquid. We're looking for 1.010 or less. Ideally it will be near 1.000 or even below. At this point fermentation is complete and the liquid is ready for distillation.

If you live in New Zealand you can legally distill this Bourbon Mash. Check out Jesse's video on how to do that below. Also, we've summarized the detailed steps to distilling here as well.

The bourbon distillation process is comprised of several steps. Remember, distilling spirits at home is illegal in the United States. This information is for educational purposes only.

Bourbon Distillation Stripping Run Steps

1. Check final gravity
2. Prepare a pot still for distillation
3. Charge the still (add the wash to the still)
4. Ensure that the liquid completely covers the heating element at all times
5. Secure chilled water supply and drain hoses to condenser before heating still
6. Add an anti-foaming agent to the pot
7. Properly ventilate the distillation area at all times
8. Ensure there is no vapor leaking from the still for every run
9. Ensure that the still is not completely sealed for every use
10. Heat the wash and begin a stripping run
11. Always ensure that distillate is cool to the touch coming out of the still
12. Collect all distillate until the distillate being produced is 5-10% ABV or less
13. Complete 2 more stripping runs with the fresh, undistilled wash
14. Empty and rinse still

Bourbon Distillation Spirit Run Steps

1. Add liquid from all three stripping runs to the still;
2. Apply heat and begin a spirit run;
3. Discard at least the first 50 milliliters, as this could contain methanol;
4. Collect spirits in 450 milliliter container, this is the heads cut;
5. Begin collecting in smaller containers;
6. When harshness subsides, begin collecting the hearts cut;
7. Once the distillate tastes thin and watery, separate into the tails cut;
8. Add water to hearts until proof is 125 or less;

Jesse made quick work of this task. What we've technically made is regular ol' bourbon. Not straight bourbon and obviously not bourbon that has been bottled in bond. So, according to the definition of bourbon, the distilled spirit only needs to be in a new oak barrel for...well, a few seconds, we guess!

Add proofed down hearts to a new, charred, white oak barrel and age until the spirit is rich and complex, yet smooth.

This is another easy step. Because we didn't produce an entire warehouse full of barrels of the bourbon we made, no blending was required. So technically, what we would have made is single barrel bourbon. However, for to to be bourbon it should be at least 80 proof. Many say that 100 proof is ideal. Once the desired proof has been achieved, add to a bottle and cork or cap. Congratulations, you just learned how to make bourbon.