Whisky Chill Filtration Explained
Filtration is the process of filtering a whisky prior to bottling, in order to remove matter from the whisky. A common but divisive form of filtration employed by some distillers within the industry is chill filtration, as Heritage Lounge will explore in this article.
At lower temperatures, fatty acids in a whisky may clump together, and lead to a hazy or cloudy whisky, or even floating clumps of residue. This process is known as flocculation, or ‘floc’ for short. Chill filtration is a process that is undertaken by distillers to remove these compounds.
It involves chilling the whisky, to temperatures of around 0 degrees, or even lower, which is possible of course, because we are dealing with a spirit not water. This chilling encourages flocculation. Subsequently, the whisky is run through various filters to remove the particles or residue that contribute to haze.
This reduces or eliminates the risk of flocculation occurring in the future, after bottling – for example, during the process of transport as part of the export trade through cool or refrigerated environments. This cloudiness may also appear in a non-chill-filtered whisky when ice or a cool mixer is added to the liquid.
Arguments for chill-filtration
A haze may offput consumers who are unaware of what cloudiness or haziness means. People may prefer the appearance of a chill-filtered whisky, which is why it is often a process employed by populist distilleries, or those who target the amateur side of the market with limited whisky knowledge or appreciation.
Some whisky makers argue that removing these compounds can allow more subtle flavour characteristics to come to the fore.
The arguments against chill-filtration
Many high-end whisky distillers, as provided at Heritage Lounge, reject the chill-filtration process, arguing that filtering in this way can remove compounds that contribute to flavour of a whisky, as well as its mouthfeel.
Distillers who wish to eliminate haze, but who want to retain these flavourful compounds, can do so in several ways – one being to produce a whisky with a higher alcohol content. It is generally said that above 46% alcohol content will prevent flocculation from occurring.
Distillers may note the relevance of water and make decisions accordingly. Purer water, with less minerals such as calcium and magnesium, may reduce the flocculation risk. Also relevant to the debate, is the fact that malts contain different lipids, or fats, and hence certain malts will be more prone to floc.
Choosing a side
Chill filtration, or lack thereof, has certainly been hijacked by the world of whisky marketing. However, a certain consensus has emerged among purists, that alcohol content should be above the floc point and chill-filtration should be avoided.
Whisky bar, cocktail bar, Parramatta bar, and pillar of the Sydney nightlife, Heritage Lounge, features a Vault Menu containing world-class whiskys. Most of these are non-chill-filtered, including Laphroaig The Ian Hunter Story 30 Year Old.
Ultimately, everyone will have to draw their own conclusions about chill filtration. The best way to decide is to observe the behaviours of the very best distilleries; and to sample their product for yourself at Heritage Lounge.