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Chill filtration is a method to remove certain substances in the whisk(e)y before it is bottled. The whisk(e)y is cooled to a temperature around freezing point, so that substances such as organic molecules like fatty acids, proteins and esters clump together. The whisk(e)y is cooled down to about -1 Celsius and then pushed passed through a special metal filter at high speed, which traps and removes these lumps.
Balvenie in Scotland, produce both chill-filtered and non-chill filtered expressions; only the latter status is generally mentioned on the label, although it’s not a requirement. If a label doesn’t say “non-chill filtered,” that doesn’t mean that the whisky is, by default, chill-filtered. It’s at the distiller’s discretion to mention it or not.
Glenglassaugh, BenRiach and Glen Grant in Scotland, all of which offer non-chill filtered single malts at 43% ABV.
Why chill filtration?
non-chill filtered whisky can be subject to turning cloudy when chilled, this haze or technically flocullation occurs when colloidal particles come out of suspension. Basically whisky contains certain compounds such as larger alkyl esters and ethyl esters of long-chain fatty acids (i.e. fats or oils) that are soluble in mixtures of solvents (such as ethanol and water) at certain temperatures and relative concentrations (ABV). Flocculation generally doesn’t occur above 46% ABV, hence stronger ABV whiskies do not require chill-filtration. Whisky below 46% ABV may be subject to flocullation should the temperature drop.
The anecdotal story told at many distillery visits concerns the major export of Scotch whisky to the US. Apparently ships laden with Scotch whisky were locked into US ports by a severe ‘Cold wave’. This is a rare climatological event that sees temperatures plummet across North America. Particularly bad cold wave events can lead to the sea turning to ice and thus freezing ships in port. The result was a whole batch of Scotch exports being refused and returned as faulty due to their cloudy appearance – only to return to Scotland crystal clear as this flocullation is reversible upon raising the temperature – adding to the idiom ‘Scotch Mist’ referring to something that is hard to find or doesn’t exist!
Chill filtration is mainly done by the distillery because of a cosmetic nature. Because the consumer doesn’t understand why their whisky get clouded or hazy. They will think there is something wrong with their whisky and won’t drink it or buy it again.
But what it mainly does is it removes certain elements that make whisk(e)y look cloudy. If you put ice into you’re non- chill filtered whisk(e)y it will get cloudy or hazy. This because of the effect water has on the oils and chemical part in the whisk(e)y.
What effect has chill filtration on my whisk(e)y?
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.
But know that a lot of tests have been taken to determine if you can really taste the difference. Most of these test came out negative ..so that’s mean you can’t actually taste the difference.
"Some say its a marketing stunt and other experts say it's a better version of the whisk(e)y. Let's just say in some cases you pay more for less production cost and work a distillery has to do."
So what’s non-chill filtration ?
46% ABV and above
Reversible floc is what we’re mainly concerned about here, because this is the haze that forms at low temperatures and with the addition of water. Give the whisk(e)y a warm and a swirl, and it will go away.
What you’re seeing are ethyl esters of long-chain fatty acids, and larger alkyl esters – formed during the making of the whisk(e)y and linked to factors such as the cut points employed at the distillery in question. Some extracts from cask maturation can also contribute to reversible floc.
But there’s also irreversible floc, which takes the form of very small crystals of calcium oxalate. This can be derived from the water used to reduce the spirit prior to bottling – this should be demineralised as high levels of calcium or magnesium can promote the formation of floc.
And, somewhat ironically, it can also be promoted by the filtration process itself. If you don’t acid-wash your filter sheets prior to use, calcium can leach from the sheets – and there’s that floc again.