The art and science of distillation is steeped in an often arcane, byzantine history filled with alchemists, doctors, and more than a few quacks. Secrets were common—and they often still are, as distillers tend to hold successful, carefully developed techniques close to the vest.
So, it’s no surprise that I often run into new distillers who seem utterly stressed about learning the whole enterprise. Compared to our brewing and winemaking counterparts, distillers have relatively little access to educational resources to help them actually learn and hone their chosen craft. The past decade has seen plenty of industry folks step up to the teacher’s blackboard to help, but I’d argue that we’re still behind our sister industries.
One topic that new distillers repeatedly bring up in my lectures and workshops is the method for making “cuts.” These days, it’s common for even casual consumers to hear about a distiller working with the “heads, hearts, and tails.” While they may not wholly understand those terms, many consumers at least have an idea—thanks to the rapid rise of distillery tourism—of what those various liquid fractions are. “Heads are bad.” “Hearts are the good stuff.” “Tails get redistilled.” … You know the drill.
However, for the new distiller who actually needs make the call on these things, it gets trickier—and that’s when the heart palpitations set in. How do you decide when to make a cut from heads to hearts? Aren’t the heads dangerous? What about the tails? Distiller’s use their noses to do all this stuff, right? How can I possibly learn to smell what someone else smells? Am I going to risk killing my customers and making spirit so bad that my whole company and its employees are driven to bankruptcy?!
Take a deep breath. Calm down. Go to your happy place and have a cookie while you’re at it. I can assure you that none of this is really all that difficult.
[PAYWALL]
The Cuts, Explained
We’ll start with a complete breakdown of a typical batch-distillation process.
Post-fermentation, your alcoholic “wash” is sitting somewhere between 7 and 10 percent ABV, and there are aromas galore. It’s now time to distill. So, we turn up the heat, and eventually the liquid inside the pot begins to boil. Because we’re starting with a wash, we plan on doing a double distillation. This first run is fairly simple, then: We’ll just collect all the liquid that comes off the still. The word “cut” isn’t even in our vocabulary yet.
Once we finish the first distillation, we have our “low wine”—probably around 20 to 25 percent ABV, and about one-third the volume of the initial wash. Time for that second distillation, so we load the still with our low wine and turn the heat on. The same thing happens as before—things start to boil. However, here is where we have to start paying attention because it’s during the second distillation that we’ll make our cuts.
The first liquid fraction that comes off the still is the heads, mostly composed of low-boiling-point compounds—though as we’ll see in a bit, boiling point isn’t really the most important parameter here. The heads are typically rich in solvent-smelling compounds such as ethyl acetate (fruity, solvent-like) and isoamyl alcohol (banana, solvent-like) along with many ill-mannered chemical guests trying to crash our distillation party. The heads just smell bad, and only in the rarest situations would a normal person with a well-functioning set of nostrils consider keeping it. (Believe it or not, however, there are instances where not cutting the heads might be appropriate.)
Eventually, the solvent smells give way to aromatics more akin to your base fermentable, whether that be grain, fruit, molasses, agave, or circus peanuts. As those solvent notes disappear, you can begin to feel more comfortable that you’re in the hearts fraction. Here’s where you make the cut: Simply redirect the flow of liquid from the container into which you were running the heads to a tank devoted solely to your hearts.
Essentially, the hearts fraction is your product spirit. That’s the liquid that will move forward to whatever subsequent distillery process you have planned—be it cask maturation, charcoal filtering, tank resting, or flavoring. However, like all things related to pot distillation, the hearts fraction is constantly evolving and changing—it’s not a static entity. The alcohol percentage of the distillate coming out of the spirit pipe slowly lowers over time, and the flavors ebb from clean and bright to more pungent and, eventually, sour.
At some point, the beautiful aroma of your hearts fraction seems like it’s withered and receded into a sad bitter existence—a pale image of its former glory. And that’s when we know we’re in the tails.
Look Beyond Your Nose
What I’ve just described is a generalization of pot-still events. However, I’ve mostly described it in terms of sensory descriptors—not, in my humble opinion, the best way to make the cut off a still.
We’ve all seen the marketing copy in our favorite spirit mags or on our most-read liquor blogs. Some PR wordsmith will throw up some schlock about how “only our master distiller knows how to make the perfect cut off the still by paying careful attention to the beautiful aromas of our distillate,” or some such nonsense.
Look, sensory is important. Our noses are finely tuned instruments that can detect aromas in smaller quantities than some lab techniques. They are also part of the human organism, which makes them inconsistent at best and highly fallible at worst. What if you have a cold? Did you eat some spicy food last night? Smoker? The list goes on, and that’s before we even get to trying to teach someone else in your distillery how to perform cuts by sensory…
So, what are you supposed to do?
Sensory is great, and there is a certain prideful romance about the whole thing as a distiller—but it should not be the sole thing on which you hang your decision-making hat. There are other parameters worth considering.
In my own distillery, as well as those of my students and clients, I teach people to perform distillation cuts by checking five things:
- time
- alcohol concentration
- volume collected
- vapor temperature
- and, yes, sensory
When the still begins running off spirit—the beginning of the heads—my team starts a timer for 35 minutes. When that timer goes off, they know that the cut to hearts is about to come up. They start checking the alcohol concentration—about 74 percent ABV—the volume collected—usually around 50 to 60 gallons (2 hectoliters), or about 3 percent of the 1,700-gallon charge in the still—and the vapor temperature—about 184.5°F (84.7°C), which is also an indirect indicator of the vapor alcohol content. They use sensory determination as a backup check on the other physical values.
Once they make the cut to hearts, the team keeps a close eye on the clock. For all our whiskeys, we know that the hearts duration is about three and a half hours. After that, we know that it’s time to start checking the alcohol concentration coming off the still, and that we cut to tails for our rye at 62 percent ABV.
A couple of things are important to note here. First, these values may or may not work for your still or the product you’re trying to make. They align with my equipment and the whiskeys that we produce. Your mileage may vary, so to speak, if you use the same numbers.
Second, and perhaps most importantly, the reason these specific numbers work for us every single time is that we are hyper-particular in our methods, and we do exactly the same thing for every batch. We closely monitor our mashes with the same temperatures and rest durations. We run the fermentations for the same length of time, with tight temperature controls. The distillation begins with the same number of proof gallons at the same charge strength (25 percent ABV), and we set the steam to a specific value via an electronically controlled globe valve.
If your inner artist is currently screaming about how boring that all sounds, allow me to counter with the fact that all this same-y sameness makes our distillate consistent from batch to batch. And it makes our lives a hell of a lot simpler.
Other Methods to Know
There are other ways you can use to decide on cut points.
One is called the demisting test. Historically practiced in Scottish single-malt distilleries, the demisting test is a simple method for determining when to cut from heads to hearts. To do it, take a sample of distillate and mix it with an equal volume of distilled or reverse-osmosis filtered water. If the sample is cloudy, then you’re still in the heads fraction. If it’s clear, then you can comfortably cut to hearts.
That method works because the heads contain myriad compounds that easily come out of solution when diluted to below 46 percent ABV, subsequently forming a haze. When compared with other cut methods, I’ve found the demisting test to be incredibly accurate—though I add a word of caution: If the still is charged with liquid above 30 percent ABV, then the emerging distillate may be so high in alcohol that an equal-parts water dilution won’t be enough for haze-forming compounds to come out of solution, and the test can give you a false positive. That means you run the risk of cutting to hearts too early.
Another method you may run across is known as “the three pearls.” This is an old cognac technique used to determine when to cut from hearts to tails. When you think the tails cut is drawing near, take a clean glass and collect a sample. Make sure your hands are clean, cover the glass with one hand, and give the liquid a few shakes. You should see a whole mess of bubbles form, and most of them will dissipate pretty quickly. However, if you’re at the tails cut, you’ll see two or three bubbles cling to the side of the glass because some of the tails compounds are causing an increase in liquid surface tension.
As with the demisting test, this method is shockingly accurate—but it does take some practice, and it can feel a bit like reading someone’s future from tea leaves.
The Chemistry of the Cuts
So, why do good cut fractions matter in the first place? To understand that, we need to take a deeper look under the chemical hood.
Whether you’re producing whiskey, rum, brandy, or something else, batch-distilled spirits are all beholden to the same underlying latticework of physical laws and phenomena. So, while there are certainly sensorial differences between the various spirit categories, they all share very similar compound classes.
Let’s consider the heads. You’ve likely heard that the heads contain vast amounts of methanol, and since methanol is toxic to humans, you need to cut as much of the heads out of the spirit as possible to make a safe-to-consume beverage.
While there is a smidge of truth—and I mean a very tiny smidge—to that, the reality is not so clear-cut. (Yes, pun intended.) In a recent study looking at compound concentrations in cognac distillate fractions—a study that aligns with the results of previous ones—the researchers found that just over 65 percent of the methanol in the low wines was distilled into the hearts fraction, with only 2.2 percent landing in the head fraction. Part of the reason for the low number is that, generally, the heads fraction is the smallest of the cuts by physical volume.
But if methanol isn’t a huge contributor to the heads, what is that fraction actually made of? Indicative of the heady aroma associated with the still’s first fraction, solventy ethyl acetate is a major aroma contributor. Also important are isoamyl alcohol and isobutanol, two fusel alcohols that likewise give off a solvent-type aroma.
The hearts are where a lot of medium-chain esters and medium-volatility fusel alcohols find their home. Sensorially, this fraction ideally smells closest to the base fermentables, though that will vary depending on technique and equipment.
The tails follow a similar pattern, in which the compounds coming over have decreasing volatilities and increasing hydrophilicities. One notable compound that often finds its way into the tails is 2-phenylethanol (floral, rose-like aroma). Some does enter the hearts fraction, and that’s a good thing because it’s an important aroma compound for some spirits. However, the bulk of this interesting alcohol is in the tails and stillage.
I should note that this discussion and these details all assume that you’re working with a basic pot still. Perhaps it’s a French alembic Charentais, a copper whiskey-making giant from Scotland, or even a clay-pot type sometimes found in mezcal production. If it’s essentially composed of a pot, neck, condenser, and heat source, then everything I’ve mentioned up to this point should hold true. However, if you’re using a more modern design with a plated column above the pot and pre-condenser cooling, then you have a bit more control over some of these things.
For instance, it’s entirely possible to concentrate much of the methanol in the heads fraction by using a continuous still or a plated-column hybrid still. Hybrid stills can better separate certain aroma- and flavor-active compounds from the heart fraction.
And here we get into the discussion of why you cut at certain points. It all boils down—yes, another distiller’s pun—to the type of spirit you want to make.
Early in my career, I had the opportunity to make a French-style apple brandy, something designed to sit in French oak for many years. I was very proud of the distillate before it went into the barrel. One day, a visiting brandy maker from Austria came to the distillery to learn more about making whiskey. He tried the apple brandy, and I wanted to hear his thoughts. He kindly told me that he felt it was “too tails-y.” I politely disagreed. We had two different distilling philosophies on the table.
In his brandy-making world, the goal was typically to release the spirit as an unaged eau de vie. In my world, however, white spirits were somewhat anathema—and long-term barrel maturation had to be part of the picture.
Generally, if your goal is to release an unaged product, then the cuts need to be more conservative. That is, the heads and tails fractions are often larger at the expense of a smaller hearts fraction. That is because an unaged distillate should taste clean and free of chemical clutter—let the base fermentable be the star of the show.
Conversely, if you think the distillate will stay in a cask for many years to come, then you would be best served by allowing more heads and tails compounds into the heart. The long-chain esters, alcohol, and fatty acids—while sour and a little off-putting in the distillate’s youth—will go on to produce more complex aromatics as they integrate with the wood and its own contributing chemistry.
Cut with Intention
Cut fractions don’t have to be scary. The best way to gain experience doing them is simply to do them. By understanding what you want to make, you can take a more educated approach to the distillation process.
Hopefully, this article has demystified a number of concepts and, um, distilled them down for you. (Last pun, I promise.)
Further Reading
Want to dive deeper into the art and science of distillation cuts? Here are a few sources related to the details in this article.
“Charentaise Distillation of Cognac, Part I: Behavior of Aroma Compounds,” by Gabriela Zanghelini, et al., in Food Research International, Vol. 178 (2024).
“Characterization of Odor-Active Compounds in the Head, Heart, and Tail Fractions of Freshly Distilled Spirit from Spine Grape (Vitis davidii Foex) Wine by Gas Chromatography-Olfactometry and Gas Chromatography-Mass Spectrometry,” by Xiao-Feng Xiang, et al., in Food Research International, Vol. 137 (2020).
“Distillation Techniques in the Fruit Spirits Production,” by Nermina Spaho, in Distillation: Innovative Applications and Modeling, edited by Marisa Fernades Mendes, published by Intech Open (2017).
