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What is Chill Filtration and Why is it Used in Whisky Making?

If you’re a lover of Scotch whisky or any other type of whisky, you probably know a few basics. You likely know some fun whisky facts, different ways to enjoy it, and maybe even a little bit about some of the different whisky-making regions around the world. But, even if you’ve heard of it, you may not know that much about chill filtration. Until now.

WHAT IS CHILL FILTRATION?

It’s the process of cooling an alcoholic liquid down to about -1C and pushing it through a metal or paper filter. It removes certain elements that make whisky look cloudy.

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. But some compounds are only soluble at certain temperatures.

So when the whisky is diluted with cold water, or simply gets cold enough, 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. You can only see the compounds, and therefore filter them, when the liquid is cold.

DOES IT ACTUALLY AFFECT FLAVOR, OR IS IT SUPERFICIAL?

Human perception of flavor 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 flavor 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 flavor or changing the mouthfeel. In taste tests, non-chill-filtered whiskies are often judged as “fuller”, “rounder” and “richer” than their chill-filtered counterparts.

 

George Smith didn’t have the option to chill-filter The Glenlivet. These days, we chill-filter most of our expressions – all, in fact, other than The Glenlivet 12 Year Illicit Still. Why not do some whisky tasting of your own and see what you think.