When one adds ice or water to a whiskey, some of its organic molecules clump together, making it appear hazy. Many folks mistake this cloudiness for an impurity – rather than – as is actually correct -a sign that the whiskey indeed is pure! People imagine that a whiskey tastes better when it is clear, and so to increase sales, whiskey makers chill filter most of their whiskeys.
Chill filtering is a technique used to remove certain organic molecules from whiskey, in order to remove this cloudiness. It is not meant to affect taste – it is purely a cosmetic change. In this process whisky is cooled to between -10° and 4° Celsius (usually about 0°.) The whiskey then goes through a filter. At this temperature, some fatty acids and esters precipitate out, and get caught on the filter.
Chill filtering doesn’t do much other than make a cosmetic alteration, but by filtering out some of these molecules, it is possible that the taste is affected slightly.
Some distilleries pride themselves on not using this process. Non-chill-filtered whisky is often advertised as being more ‘natural,’ ‘authentic,’ or ‘old-fashioned.’ For example, the Aberlour Distillery’s distinctively flavoured A’bunadh whisky, Laphroaig’s Quarter Cask bottles, and all of Springbank distillery’s whiskies are not chill-filtered, and are advertised as such.
Does it really matter if a whiskey is chill filtered or not? Possibly, but likely not much.
Bill Ricker, comments on Study on the Chill Filtration of Scotch Single Malt Whiskies, by Horst Lüning
This seems to confirm that chill-filtering is irrelevant for most whiskies, and sometimes beneficial, which is what certain portions of the industry have always told us, but we aren’t sure because we distrust that their preferences align with ours.
Would the results be same or different if the samples were limited to heavy, rich whiskies with high and flavorful lipid content? Those seem under represented in the samples.
Rumor has it that certain distilleries chill-filter not just for optic aesthetics – but actually because their unfiltered barrels have nasty compounds, predominately heavy lipid ones, and they benefit, taste wise, from chilled filtration. Much as in USA, Jack Daniels has their “Tennessee process” (Charcoal filtration) to remove certain compounds from their Tennessee Bourbon. I can believe that, but would like a list of which whiskeys need it! We should probably trust them, when it’s needed for taste.
The problem with chill filtration is that it’s seen as beneficial aesthetically because of what otherwise would be clouding in cold storage, mixed drinks, and iced drinks.We wouldn’t want cloudiness in Manhattan, even in an up-priced Single-malt one! I’ve been startled to see cloudy flakes in a bottle stored on the un-heated porch, so I can see how that could be disturbing to customers. But to me, that’s a labeling issue. “NCF / may be cloudy if chilled or diluted”.
Some of us anoraks (whiskey aficionados) are curious what a whiskey tastes like before filtering anyway, just for curiosity. Just as we’d like to taste the white-dog, and we’d like to taste the non-peated Caol Ila and a fine oak Macallan once too.
If a whiskey is not as tasty as NCF as CF, then we’ll accept the CF. But without the comparison, we fear that we’re losing some flavor for the sake of optical clarity. I say all this as a partisan of G&M IBs, so go figure. I trust them more than I trust Diageo to be aiming for single malt flavor rather than for bar-trade optics or keeping the bottling line simple day to day.)
I do wonder if a change in chill-filtering is what changed at Old Pulteny in the last decade. All ages went from being best sipped at 35% to being quite acceptable at 40-46% in a short period of time.
We should take note that esters are a major basis of flavor in whiskey. as they are in many other foods. He is a gloriously beautiful chart of esters and their smells, by James Kennedy Monash.