Chill-Filtration

Whisky is normally chill-filtered to prevent cloudiness at lower temperatures. But what influence does this process have on the taste of the Whisky?

Why is Whisky chill-filtered?

Being natural is very much in vogue. Whether it's food or cosmetics, many people strive for a natural lifestyle. It is also important for many Whisky lovers to enjoy natural Whisky with a full aroma.

In this context, the question arises: If 'non-chill-filtering' is so trendy, why do so many major Whisky producers still use chill-filtration? Especially since chill-filtration is a time-consuming and costly business: you need temperature control equipment, filters, manpower, energy and time.

How does chill-filtration work?

The Whisky must first be cooled down to 0-4° C. Some producers even cool it down to -10° C, which makes the Whisky even less prone to cloudiness. For Whisky later begins to cloud when enjoyed below the temperature to which it was cooled down during chill-filtration.

After it has been brought to the desired low temperature, the Whisky is pressed through a paper filter consisting of about 20-25 layers. Logically, these filters must be replaced regularly. In addition, there is always a residual amount of Whisky left in the filter, which results in a further loss for the producer.

There are said to be some thrifty Scottish Whisky producers who save themselves the trouble of cooling down in winter and simply press their Whisky through the filter at outside temperatures of around 0 degrees.

Nevertheless: If you save the process of chill-filtration, you save money, working hours and resources.

What happens during the chill-filtration process?

The clear advantage of chill-filtering: there is no cloudiness. But where does this cloudiness actually come from? To answer this question, we must take a look at the composition of Whisky. Whisky consists of at least 40% alcohol. Then there is 59% water and 1% other substances that provide the taste. These include, for example, esters, phenols, aldehydes, ketones and tannins, and also proteins and lipids. These lipids, that is, fats or fatty acids, do not dissolve as well in water as alcohol. The chemical bonds between water, acid and carbon form small 'balls', also called micelles. These balls now become visible in the liquid as a grey film, which causes the haze.

Especially when non-chill-filtered Whiskies are cooled down or the solubility of alcohol is reduced by adding water, this haze can be seen. When the Whisky gets warmer again, it usually loses the haze as the micelles dissolve. There are special cases where the micelles become so stable that they do not dissolve again.

Different Malts contain different lipids and therefore do not tend to this cloudiness to the same extent. Of course, there are also different filters and filter methods. It is difficult to judge how much distilleries filter their Whiskies, as there are also bottlings that become cloudy, even though there is no mention of 'non chill-filtered' on the bottle.

It is often stated that above 46% alcohol content there is no cloudiness. However, this statement should be taken with caution. This is partly due to the different normal coarse filtering methods used by the companies, and partly due to the extent to which Whisky is supplied with the lipids described above in its production process: the more, the cloudier.

Does non chill-filtered Whisky taste better than chill-filtered?

Whisky being chill-filtered in a fridge
Whisky being chill-filtered in a fridge

In a study by the Malt Maniacs, who blindly tasted various chill-filtered and non-chill-filtered Whiskies, it was concluded that it is not possible to judge by taste whether a Whisky is chill-filtered or not. Even the opposite seems to be the case: In 13 out of 16 cases the test persons preferred the chill-filtered version of the Whisky over the non-chill-filtered one.

The conclusion of the Malt Maniacs study reads as follows:
Chill-filtered Whisky tastes different from non-chill-filtered Whisky. Non chill-filtered Whisky does not taste better. And Whisky connoisseurs are typically not good at finding out what is chill-filtered and what is not. Chill-filtration does not necessarily make the Whisky change as expected.

Whisky.com has also conducted a large-scale blind test with over 1,000 individual samples and more than 100 experienced connoisseurs. For this purpose, non-chill-filtered Whiskies were sampled and evaluated once original and once chilled in a refrigerator, filtered through diatomaceous earth. We achieved the same result as the Malt Maniacs. There is even a slight tendency with weakly matured Whiskies for chill-filtration to have a positive effect on the taste.
These figures hold - to say the least - explosives for a whole industry! The principle "I only drink non-chill-filtered Whisky" is hard to rethink, as it means that you are denying yourself some of the really good Whiskies.

At the end of the day, the chill-filtering issue is probably more of a philosophical one. In the past - before the refrigeration machine invented by Carl von Linde in 1920 was widely used - you couldn't cool, so you couldn't filter. The question now is: Do you want to go back to that time with your taste and reject modern technology? Of course, this would also have disadvantages, because after all, people did not live that long in the past. On the other hand, the more alcohol we drink, the less long we live - and whether the Whisky is chill-filtered or not - is most likely irrelevant in this respect.