Ever bought a bottle of whisky, and it turned out looking hazy, or have floating particles? Often looking like white specks or thin, tissue-like sediment, these bits might cause you to think that the whisky has been contaminated or have floating pieces of wood and cork.
While whiskies do occasionally contain some char that have escaped the sieve before bottling, the reality is that floating particles or haziness are naturally occurring lipids that have precipitated out due to cold temperatures. This happens occasionally in whiskies that are non-chill filtered, a process that starts by chilling a whisky down to near 0-degree temperatures. This causes the fatty acids and oils to clump together, after which it goes through a series of fine filters to produce a clear spirit.
There are pros and cons to having chill-filtration: on the pro-side, it ensures that no sedimentation or haziness occurs, which is great for brands who don’t want customers worried that their whiskies have been tampered with or contaminated.
On the flipside, however, chill-filtering strips out those precious natural oils and congeners (organic compounds other than ethanol) that come from ageing a spirit in an oak cask.
These are key components in creating a whisky’s unique flavour and mouthfeel, which is why many craft distilleries choose to skip chill-filtration. They do, however, do a simple filtration, which basically runs the whisky through a barrier filter (like a sieve) to remove particles of wood and char before being bottled.
So the next time you see floating sediments or haziness in your whisky, don’t panic! It’s actually a good sign that your whisky is less processed, and has more flavour and richness of mouthfeel.