Chill. Relax. Take it easy. Pull up a pew, take a load off. Chilling - assuming you are not talking about anything that goes in a fridge - is good. Who doesn’t want to chill? It’s a great pastime, lovely and indulgent and in these days of not having enough time to ourselves, a bit of a luxury.  

Well, whiskey drinkers, that’s who don’t want to chill. In fact, non-chill filtered whiskey is very much a thing, and to chill or not to chill is a question that apparently has no answer. But what exactly is chill filtered whiskey?

Chill filtering is when the distillery cools the spirit to 0°C or lower. This process removes any impurities (such as fatty acids) that might have occurred during the spirit’s barrel ageing. As the spirit cools down, or chills, the impurities clump together (much like sediment in a bottle of wine) and cause flocculation (floc). Floc makes the whiskey cloudy which, to the naked eye, is just not very pretty. In chill filtered whiskey, the liquid is filtered at this low temperature to create a perfectly clear, limpid drink. The actual filter used is a secret closely guarded by the distillery; it can be anything from paper to metal to incongruously, crushed seashells and even earth. The chill filtering process is only used in whiskeys of 46 ABV (alcohol by volume) or less. Higher strength whiskeys (above 46.3 ABV) are less volatile and therefore easy to manage when it comes to change in temperatures.

Chill Filtered Whiskey vs. Non Chill Filtered Whiskey

So, why would you subject a perfectly good whiskey to a chemical process that, many feel, affects the taste of the drink? Well, there is no right answer. Sorry. 

Chill Filtered Whiskey

The chill filtering process is a refining process that removes what’s known as long tail esters. 

Esters are formed during the whiskey’s fermentation, at the stage of whisky production in which the yeast converts the sugar glucose into ethanol. Ok, that’s fine, but why remove them? The answer is simple: aesthetics. These esters, basically fatty proteins, cloud when water or ice is added to the spirit - think of the French aperitif Pastis and you get the idea. While that may be desirable when you’re playing pétanque on the Riviera, it’s not everyone’s cup of tea when it comes to their single malt back at home. 

Non-Chill Filtered Whiskey

Certainly having a tumbler full of gorgeously translucent whiskey is better looking, but does removing the esters remove any taste? Well, some purists would say yes. The esters are the very thing that give the whiskey its particular flavour, texture and mouthfeel. So, if the whiskey tastes multi faceted, chances are it is a non-chill filtered version. Definitely, if the drink clouds when adding water. In fact, non-chill filtered whiskey is considered so superior that its non status is considered a big plus. Manufacturers will emblazon the words “non-chill” on their labels, marketing it as higher calibre and often, charging prices to match. It’s assumed that non chill filtered whiskers are higher quality whiskeys - which is not always true.

So... who’s right?

This is where it gets complicated, as always when entering a world or objectivity, subjectivity and opinion. The to chill or not to chill question has been running for decades, and many experts claim in blind tasting tests that there is little difference in taste. A 2014 experiment by Whiskey.com seems to confirm this: German whiskey connoisseur Horst Luning gathered together 111 of the world’s most respected whiskey enthusiasts and asked them to blind taste 1,331 different Scotch whiskies. Of the 111, under half (45%) could identify the chill filtered versions. Both versions received the same quality ratings. So, we’re still no closer to knowing who’s right and who’s wrong.

To read about Luning’s experiment, click here. 

Thus, it could be argued that chill filtering whiskey is uniquely cosmetic - if the process in fact does not alter the taste, then surely both filtered and non chill filtered whiskeys are the same? Again, it goes back to personal preference: some brands have larger yields and like the consistency in clarity and taste that chill filtering brings. Craft producers like the body and soul that non chilling brings, arguing that chill whiskey lacks pizzazz and is far less sophisticated. 

But that doesn’t mean all chill filtered whiskeys automatically taste diluted or inferior. Many brands such as The Dubliner and Dead Rabbit produce big, bold and flavoursome whiskeys that are just as worthy non chill versions such as The Dublin Liberties. We would even wager that without being told not everyone would be able to tell the difference by taste alone. So is chill filtering really necessary? The jury is still out. The proof it seems, is in the glass.