Today we do something I actually wanted to do for a long time now – we explore the impact chill-filtering has on a spirit. This has been made possible by Wild Turkey, who always sold a chill-filtered version of their Rare Breed Bourbon but decided to release a non-chill filtered version of the very same Whiskey in 2021.

What is “chill-filtration” and why is it used?

Chill filtering is a method that is used primarily in Whisky making to remove any residues found in the spirit, mostly for cosmetic reasons. These residues are compounds such as fats, proteins and esters, which turn cloudy or hazy at lower temperatures, for instance when the Whisky is sipped on the rocks. From a marketing perspective, it should be obvious why this practice is favoured by the big brands. The method is very simple: The liquid is cooled to temperatures between 0-10 °C and subsequently passed through a series of adsorption filters which collect said compounds. As you may know, the congeners, as some of these compounds such as fatty acids or esters are called, are responsible for a large chunk of the flavour of a spirit and removing them doesn’t sound great from a connoisseur’s point of view.

So how big is the impact of chill filtration really? Let’s find out by comparing two versions of the same Whiskey!

Wild Turkey Rare Breed (58,4%): The mash for this supposedly reads as follows: 75% corn, 13% rye and 12% barley with blend components that aged between six and twelve years. These basic numbers should be identical for both version. I will start with a general description of the aroma and flavour profile before going into the differences. Admittedly, we have reviewd this one before but let’s repeat the exercise. Nose: Caramel, honey, corn syrup, toffee and slightly bitter orange are my main associations. Deeper in the glass definitely wood and spices such as cinnamon and pepper. Palate: Not sharp but not smooth either. Cinnamon, fruit cake, bitter orange, honeycomb, caramel, toffee and oak shape the profile. With the second sip I also get notes closer to apple as well as some herbal notes. Finish: More herbs than at the palate, paired with oak and spices, including caraway now. A solid Bourbon, but it isn’t something I’d purchase for sipping personally.

Differences
Nose: It is undeniable: The non-chill filtered version smells heavier, earthier and less clean. Where, relatively speaking, the chill filtered one has a slightly fresh and floral opening (think fresh and ripe orange perhaps), the non-chill filtered one presents itself as much darker, with roasting aromas and an earthiness that is completely lacking in the chill filtered one. Another way to think about this is fresh caramel versus burnt caramel, if you want to take it to the extreme.
Palate: This pattern continues at the palate, even though it is slightly less pronounced here. The profile is essentially identical, but the non-chill filtered version is more earthy, more oaky, less fresh, and definitely “darker”. Once again, it delves in the direction of roasting aromas, whereas the chill filtered Whiskey boasts with fresh caramel, ripe orange and sweet honey.
Finish: Nothing really noteworthy here if, you ask me. Perhaps a bit more oak with the non-chill filtered one, but these might even be nuances that occur between different batches.

Conclusion
I think it became evident: While we are dealing with two Whiskies that share the very same profile, the differences between the two versions are apparent and actually quite a bit bigger than I thought they’d be. Would I be able to tell this outside of a direct comparison? I don’t think so. Would I say that one is better than the other? Probably not, even though I do have a clear preference. What the comparison has shown though is how the method alters the spirit, if it is for the better or the worse is rather a matter of subjective taste I think. At least in this particular case. There’s still one major drawback of this little exercise however: We just cannot know how much we should attribute to the filtration method and how much to possible differences in the components of the blend, after all a spirit is seldom identical from one batch to the other, even with huge blends like these.