Uttering the phrase ‘chill filtered whisky’ in a room full of whisky enthusiasts is sure to spark raucous debate. It’s a relatively common process when it comes to how scotch is made but it still divides opinion. Some purists will say that non-chill filtered expressions are better, while others are sure that chill filtration elevates the aesthetic and flavour of whisky.
So, what’s the truth? In this article, we tell you all you need to know about chill filtration, including what it is and what impact it has on the whisky.
What Is Chill Filtration?
Chill filtration is the process of cooling an alcoholic liquid down to about -1C and pushing it through a series of metal or paper filters. It removes certain elements and residues, including fatty acids and esters that can make scotch whisky look cloudy.
To understand how this cloudiness or ‘haze; occurs, it’s important to look at what whisky is made from and how these residues are produced in a little more detail:
Fatty acids are organic acids that can be found in the grains used to produce whisky, such as barley. During the fermentation process, these acids are produced by yeast as it breaks down sugars in the grains.
Esters are compounds formed during fermentation when acids react with alcohol. They contribute to the fruity and floral aromas and flavours of whisky. The combination of acids and alcohols during fermentation produces a variety of esters.
Why Does It Need To Be Cold?
Whisky gets its taste and smell from the compounds it contains, most of which are soluble in the water-ethanol mixture characteristic of all alcoholic drinks. However, some compounds are only soluble at certain temperatures.
So, when the whisky is diluted with cold water, or simply gets cold enough, ester and long-chain fatty acid molecules clump together to form small particles known as micelles. These scatter light, making the liquid appear cloudy, in a phenomenon known as chill haze or whisky haze. You can only see the compounds, and therefore filter them, when the liquid is cold.
Does Removing The Whisky Haze Actually Affect Flavour, Or Is It Superficial?
Human perception of flavour is complicated, so some of us will find whiskies less palatable if they’re hazy. It’s difficult to define what’s a true difference in flavour and what’s just perceived. Over the years, this has been debated constantly.
A clearer liquid can be seen as a sign of quality, but some people feel that by filtering out specific compounds, you’re taking away flavour or changing the mouthfeel. In taste tests, non-chill-filtered whiskies are often judged as “fuller”, “rounder” and “richer” than their chill-filtered counterparts.
How to taste whisky properly is a bit of an art form but if you want to assess the difference between chill-filtered whisky and non-filtered whisky types, it’s the best way to do it. Take the time to appreciate every aspect of the whisky including its appearance, aroma, flavour, and mouthfeel. Make notes about your experience of each expression and compare your findings.
How Do I Know If A Whisky Has Been Chill Filtered?
Determining whether a whisky has been chill filtered can be challenging, as it is not always explicitly stated on the label. However, there are some indicators and clues that may suggest whether a whisky has undergone chill filtration:
Some whisky producers include information on the label indicating whether the whisky is chill-filtered or non-chill filtered. Look for terms like “non-chill filtered” or “natural colour” as potential indications.
The distillery’s official website or promotional materials may provide information about their production methods, including whether they chill-filter their whiskies or not.
Non-chill filtered whiskies are sometimes bottled at higher alcohol strengths (cask strength or higher ABV). The rationale is that at higher alcohol concentrations, the haziness-inducing compounds are less likely to precipitate out of the solution. As a general rule, if a whisky has an ABV of 46% or above, it probably hasn’t been chill filtered.
Whisky reviews, whether on websites, magazines, or forums, may offer insights into whether a particular whisky is chill-filtered or not. Experienced reviewers may mention this aspect when discussing a whisky’s appearance or mouthfeel.
Contacting The Distillery
If in doubt, you can reach out to the distillery directly. Many distilleries are open to answering inquiries about their production processes and can provide information about whether their whiskies undergo chill filtration. Of course, you can always arrange a distillery visit and ask in person too!
So, is chill filtered whisky better than non-chill filtered whisky?
Our founder, George Smith didn’t have the option to chill-filter The Glenlivet. These days, we chill-filter most of our expressions.
It’s a process that is now commonplace in whisky production and it is carried out to improve the aesthetic appeal of the spirit and ensure consistency of clarity and mouthfeel across different batches of the same whisky.
However, the preference for chill-filtered or non-chill filtered whisky is subjective and depends on individual tastes and priorities. Neither is inherently ‘better’ than the other; instead, it’s a matter of personal preference.
We’d recommend conducting some taste tests of your own to see what you think. The Glenlivet has plenty of chill-filtered single malts to choose from, including our Founder’s Reserve smooth scotch whisky as well as a selection of non-chilled filtered expressions such as our Nàdurro first fill whisky.
To learn more about the many intricacies of whisky, check out our whisky guide and our look at rare whisky. For inspiration on how to drink whisky, browse through our whisky cocktails including winter drinks and Old Fashioned variations.