DISTILLATION FOR DUMMIES (AND BREWERS)
Well howdy, readers,
Once in a while, a throwaway line or idea from one of these posts sits with me for a week or two, maintaining my curiosity long enough to warrant a full post. This time in particular, it was a casual and brief description of the process of distillation in our Non-Alcoholic beer post that stuck with me, particularly given my erstwhile fascination with cocktails, and the striking parallels between brewing a “mash” for whiskey, and brewing a beer (spoiler alert: it’s the same process).
So this week’s post should act as a reasonably complete primer on the basics of whiskey-making, with a particular focus on that process’s beer-like qualities, and for the sake of argument, I’ll also toss a quick guide into the acquisition of tools for, and legality of, distillation in the United States for those of you undaunted by distilled ethanol’s bleak historical track record.
With that macabre disclaimer made, avast!
From Wine to Low Wines
In order to distill, we need a solution with some alcohol in it. This is done quite efficiently with yeast, and as you may have guessed, it’s the various sugar sources that primarily split the different spirit types. For example, fruit-based spirits (which is to say, distilled fruit wines) are brandies. Peach Brandy in particular was incredibly popular in the early colonial US, so much so that it was once the highest-valued domestically-produced spirit in the US.
Vodka is another interesting extreme, as it’s made from virtually any sugar source, from milk sugar to sugar beets to potatoes. But naturally, our focus is on grain-based “washes,” which is to say beers whose fate is distillation.
Let’s now break down the elements of these washes, as we would for beer styles: by malts, yeast, and everything else.
Malts
The same malts that are used in beer-making are used in whiskey-making, so this is familiar ground. I once remember, in fact, asking for some flaked corn at a homebrew store only to be told that a home distiller had beaten me to the punch and bought them out.
Speaking of corn, as we’ve talked about mashing before (and will again), we’ll just mention the rules pertaining grains and the various whiskeys here, which is to say, state the obvious: Bourbons (which have an elaborate set of rules) must contain at minimum 51% corn; Ryes must contain at least 51% rye, and, while I’m not aware of a fixed rule for Scotch, the drink is famous for its use of peated malt.
We’ve discussed malting and the use of peat (and all kinds of other fuels) before, but the brief version is that in order to get any substantial amount of sugar (read: yeast fuel) out of cereal grains, you have to malt them (trick them into starting to grow, basically, and then knocking them back out with heat and thus dryness), and the Scots are famous for their use of peat, which is “spongy material formed by the partial decomposition of organic matter, primarily plant material, in wetlands such as swamps, muskegs, bogs, fens, and moors.” Neat!
Yeast
Before getting into yeast used for distillation, a disclaimer: I’m no expert on this topic, so my knowledge is gleaned from a few books and posts which is, in fairness, the source of the vast majority of my knowledge. I’m describing school, I now realize.
In any case, while, historically, the yeasts distillers used would have simply been whatever yeast they bred from what I’m had (probably) formerly been beer yeast, nowadays you can buy a reasonable range of commercial yeast strains with two distinct and somewhat obvious traits: they produce high-ABV washes, and they have relatively high attenuations (the percentage of fermentable sugars that they consume, which is proportional to ethanol content). The advantage of the former is due to the efficiency of starting with as high-ABV a wash as possible, since at some point you have to bring your wash to a boil, and it takes way less energy to bring five gallons of 20% ABV wash to a boil than 20 gallons of 5% ABV wash. So since many yeasts can’t tolerate an ABV above, say, 9%-12% or so, a yeast that can ferment up to 15%-20% can save you an entire fermentation tank, potentially (another plus), and quite a bit of energy spent boiling wash. And the advantage of the latter is straightforward: if the yeast eat more fermentables, as long as they’re not compromising flavor, you use less grain to produce the same amount of alcohol (in beer this could hurt mouthfeel and perceptible sweetness, but neither are a problem in whiskey making).
Then there’s my beloved jamaican rum, which is fascinating - I’ll leave the reading to you, since it’s a wild, complicated scenario. I will say that the use of acidity in washes is rare, to my understanding, but very cool.
And due to how recently yeast was discovered, there aren’t any rules whatsoever about yeast use from a product description perspective (i.e. what can be called Bourbon or Rye), as far as I’m aware.
Things beyond the beer parallels
So far, we’ve been more or less in the realm of beer, but what might be unique to whiskey production?
The list isn’t all that long, but it does contain a few interesting items, and my favorite, which I learned about years ago during a tour at the extraordinary Kings County Distillery, is the practice of fermenting washes “on the grain.”
Whereas we always, always ferment “off the grain” in beer brewing, in spirit making, there are proponents of both schools (on and off), which is as it sounds: some whiskey makers will actually just ferment their mash, then sparge the fermented mash once it has reached final gravity (the end of fermentation). This is quite an interesting practice, and one with some environmental advantages (which makes it a fascinating possibility for California beer’s drought-ridden future), but I’ll leave this article about the differences between the two to the curious among you.
A close second place is a practice specific to rum-making, which is absolutely insane: the use of an acidic wash to produce fruity esters for which Jamaican rum is known. Without getting too much into it, I’ll say this: ethyl acetate, which is a compound consisting of ethanol and acetic acid (vinegar), smells like pears and perfume among other things, and is the most common ester in wine.
And finally, I’ve heard somewhat anecdotally (read: I can’t quickly find a source) that hops are more or less forbidden in whiskey making, but there are certainly counterexamples, and the word is that beers whose hop character is “skunked,” or chemically altered by certain frequencies of light (hence the brown bottles), can actually be used to make a decent whiskey.
Distillation, in short
Once we have our booze soup, it’s not terribly hard to create a liquid with a higher ABV; Arabic chemists had started to distill regularly in the 11th century, and the Dutch were only a few...well, centuries behind (gin, or rather genever, having kicked off the western hooch party).
The trick is making a spirit that tastes good and won’t poison you. The idea here is fairly straightforward: there are a wide range of compounds in washes, and each has a different boiling point, so by doing something along the lines of holding our solution at each boiling point one at a time, we can pull off an arbitrarily fine gradation of these compounds.
(A note: the following leans heavily on word-based technical imagery, so feel free to skip it if you’re not riveted by the details of going from wash to whiskey.)
The fineness of this gradation is driven by a few factors, notably by the volume of your wash, but principally by the technology behind your still. To put things very loosely, the old method was to mount a hood, something along the lines of an upside down saxophone, to the top of a big kettle, in which you would boil your wash and condense its vapors which, because they’re coming off of a wash that is gradually increasing in temperature (due to science reasons), consists very roughly of the compounds in your wash, in order of boiling temperature (low to high). In this metaphor, the bell of the sax takes in the vapors, and usually water is passed around the main body of this inverted saxophone to cool and condense said vapors. I haven’t read the thing, but the first picture of this article is a fairly clear illustration of the device, called a Pot Still.
People still use these things in the production of rustic or artisanal spirits, in part because the roughness of these cuts, of these gradations, adds character to resulting spirits, but there is a risk involved as a result of this roughness. The poisonous compound methanol, which has a low boiling point, would easily be all but completely removed by a more advanced still, but because of the fact that this still produces a distillate that at any given times is a mixture of compounds with slightly different boiling points, you have a nonzero chance of accidentally capturing some methanol in your main ethanol distillate. The solution to this problem, and the more general problem of trying to make a clean product with pot stills, is two-fold: you can run a wash through a pot still several times in order to get sharper and sharper cuts between compounds (to a limit), and you can continuously sample (by smelling or tasting) the distillate being produced by your still, and split it into heads (low-boiling-temp compounds), hearts (ethanol and similar boiling-point compounds), and tails (compounds with boiling points closer to water). To go further into any of this would be to begin to write a book on distillation for which I’m ill-suited; check out this instead.
There is, however, a more precise still in use by the vast, vast majority of vodka distillers: column stills. The idea is actually quite beautiful, and most easily visualized with an older variant from which one of our beers gets its name: the Coffey Still. The gist is that you fill a tall column filled with small disc-like sections with the vapors from your wash, and that, if you give the still enough time, to reach equilibrium (and pull distillate off fairly slowly), each disc will contain compounds within a small range of boiling points, with the fineness determined by the number and dimension of the plates, the height of the still, the rate of flow through the still, etc.
You could theoretically recreate a pot-stilled spirit by artfully blending together very exact amounts of each individual compound resulting from a very precise column still distillation, but I’d be surprised if you could realistically capture the nuance, akin to a MIDI violin vs the real article.
Conclusion
On the one hand, it’s tempting to think of whiskeys as just lightly processed beers, or perhaps just fancy Eisbocks, but if my limited knowledge of the actual process of distillation is any indication, clearly a ton of skill and art exists in the processing of these washes, which are themselves unique and only vaguely beer-like creatures.
But hey, if you’d like a beer with some barrel character despite these differences, we have a sick tiki-inspired VNBC beer in cans right now, so swing by and grab some!
Cheers,
Adrian “Hogo Champ” Febre