Stripping flavor out of whiskey is not a practice typically associated with spirits one might wish to drink. Most of the effort distillers invest in their products is, as you would assume, dedicated to creating and enhancing flavor: selecting base grains, controlling fermentation, monitoring the maturation process over years in cask, and so on.
But chill-filtration, a method of removing flavor from whiskey, has become a widely adopted technique among many of the world’s leading distillers. And its use—or rather, its absence—has become a beacon for aficionados seeking big, brawny, full-flavored whiskies.
Indeed, chill-filtration is a mildly controversial practice among whiskey faithful, considered by some to be a perfectly harmless way to clarify and fine-tune the final product, and by others to be an unnecessary intervention that can mute the vibrancy of a whiskey’s flavor.
What’s going on here?
The basics of chill-filtration
All whiskey, after it matures, is filtered to remove solids and sediment from the barrel. Many whiskies go through additional filtration to sift out proteins, fatty acids, and other compounds that, at about 46% alcohol-by-volume (ABV) or lower, can create a haze called flocculation, or floc. Chill-filtration is just what it sounds like: the whiskey is cooled to 32 degrees Fahrenheit (or colder), then passed through a series of filters that catch the large compounds, effectively de-floccing the liquid.
Why use chill-filtration at all?
Mostly for looks. Most producers who chill-filter do so because they worry consumers may be turned off by a bottle of hazy liquid (or worry it might be flawed).
But a handful of producers elect to chill-filter for flavor control, noting that the technique can highlight certain characteristics in the whiskey that would otherwise be masked. For example, if a whiskey has heavy oak tones, chill-filtration can tamp down on bitterness to showcase sweeter flavors, and can remove some of the chewy or astringent tannins that overpower the palate.
Chill-filtration, or the lack of it, is not an indication of a whiskey’s quality; it’s a fining method, a step of the production process at which distillers and blenders can make different choices, just like they do at every other stage.
Why doesn’t everyone use chill-filtration?
Distillers who forgo chill-filtration almost always do so to preserve maximum flavor and body in their whiskey. Retaining the compounds that chill-filtration removes contributes texture and viscosity to a spirit—qualities many whiskey makers wish to enhance in their products. To ensure their whiskey remains free of floc, these distillers typically choose to bottle their whiskey at or above 46% ABV.
From a drinker’s perspective, those who prize deeper flavor and a richer mouthfeel tend to prefer their whiskies non-chill filtered, though they may be unaware of just how many of their favorite whiskies undergo the process.
The chill-filtration Mendoza line
If a whiskey is under 46% ABV, it’s almost guaranteed to have undergone chill-filtration (though there’s no requirement to disclose it on a label). But because floc tends not to occur in whiskies above 46% ABV, once you cross that threshold, it’s quite rare to find a whiskey that’s been chill-filtered.
You’re already drinking chill-filtered whiskey
Chill-filtration has been in use for decades and became widely practiced in the whiskey industry starting in the 1990s. Distillers around the world do it, and it’s common across all styles. Not every whiskey is chill-filtered, but chances are high that you’ve got a bottle of chill-filtered whiskey on your shelf—even if it’s a small shelf.
Most mainstream bourbons, Canadian whiskies, blended scotches, and Irish whiskies are chill-filtered, while many single malt scotches, and almost all craft whiskies, are not. Distillers may advertise—on the bottle label or their websites—that a whiskey is non-chill filtered, but not everyone who eschews chill-filtration bothers to say so in a convenient place.
An at-home taste test for bourbon nerds
Performing an apples-to-apples comparison between filtered and unfiltered whiskies can be difficult because chill-filtered whiskies tend to be lower proof than those that aren’t. Luckily, Wild Turkey offers curious drinkers an opportunity to conduct such an experiment with ease.
Wild Turkey chill-filters every whiskey it makes with two exceptions: its Master’s Keep series and Russell’s Reserve Single Barrel. For these purposes, you’re interested in the latter because the distillery also makes a regular version of Russell’s Reserve that is chill-filtered. To compare the two, you’ll need to dilute the single barrel version to match the regular bourbon’s 45% ABV. (You can calculate how much water to add using a tool like this one.)
As you taste, you should notice that the bourbon that hasn’t been chill-filtered displays a richer, fuller texture, along with deeper flavors. Specific aroma and palate notes may vary simply based on maturation differences, but overall, the non-chill filtered Russell’s Reserve Single Barrel should seem more amplified and vivid, like watching television in high definition rather than standard definition.
But! You may discover you like the chill-filtered version better. There’s nothing wrong with that. Maybe it has a smoother feel on your palate or highlights certain flavors you prefer. But experiencing the difference should help you understand why chill-filtration arouses the occasional barroom debate among whiskey connoisseurs.