The question: I just bought a bottle of whisky and the label says "non-chill filtered." What does that mean?
The answer: Most conspicuously, it means your whisky may turn hazy if served on 'the' rocks. But that's not a bad thing. Chill filtering is a step most distillers take to remove chemical compounds such as esters, proteins and acids produced during fermentation and maturation. The spirit is cooled to roughly 0 C, which causes the compounds to precipitate out of the solution. This makes it possible to trap them in a fine filter. Mainly, it's a cosmetic procedure. Whisky bottled at a typical alcohol content of less than 46 per cent will become cloudy if subsequently chilled, either during transport or in the presence of ice.
Technically, the unfiltered compounds might be viewed as impurities, but many people believe, as do I, that they convey extra flavour and texture. The telltale sign is a richer oiliness, which can give the whisky a longer, lip-smacking finish. It's a subtle phenomenon, to be sure, but more and more distilleries are seeing the benefit of skipping the chill-filtering step, especially for higher-end offerings, courting savvy consumers who prefer their spirits au naturel, as it were.
And because most superpremium whiskies, such as pricey Scottish single malts, tend to be served neat rather than on the rocks, cloudiness is not an issue. Besides, if you happen to prefer your full-flavoured Scotch over ice, what's the harm in a bit of fog? It may even remind you of a Scottish mist.
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