Chill Filtration....What does it really do?

A while back my whisky club purchased our first cask of whisky, a 15 year old Highland Park from Gordon & MacPhail. Out of this cask I purchased 10 bottles and quickly polished off 3 in every sort of circumstance you can imagine, neat, water, rocks, ice, you name it....and due to that I grew to know this whisky like the back of my hand.....could tell when my palate wasn't spot on, when I was having a good day or a bad day.

Because of that I decided to do an experiment of chill filtering 3 whiskies that I knew well, my Dram Full Highland Park, Octomore 6.2 and a 7 year old sherried Adelphi Glenrothes bottled for Australia, and then chill filter. Afterwards I would do blind tastings with myself and other people to see what folks thought when they had no idea what they were tasting.

A few weeks ago I decided to take the plunge and do something that had been rattling around in my brain for the last several years and that was to chill filter my own whisky.

I did this following the trail blazed by my very good friend Matthew Fergusson-Stewart via his epistle on Malt Maniacs,

maltmaniacs.net/…/….

In essence I brought the temperature of these three bottles, the Dram Full Highland Park, Adelphi's Glenrothes 7 year old, and Bruichladdich's Octomore 6.2 to zero degrees, and then strained the whisky through multiple coffee filters until the whisky poured clean.

At zero degress all 3 whiskies were very cloudy, the Highland Park the most so, which allowed me to strain the fatty oils out easier.

Some observations, first off the Highland Park took the longest to strain, with the FIRST filtration taking roughly 5 minutes for 100mls to move through the filter.

Second they each took roughly 6 times through a filter to move cleanly through.

Third I chose these whiskies as I knew all three very well, and to be honest, nothing's sacred. I came within a nose hair of chill filtering a 30 year old single cask of Port Ellen, but decided I didn't have quite enough to make it worthwhile.

Fourth with all three whiskies, both in blind tastings and in known tastings, the chill filtered whisky performed more poorly then the non chill filtered whisky, although I reckon this is due to each whisky being as cask strength as opposed to the typical 40-46% abv.

Fifth all three chill filtered whiskies were MUCH hotter then the non chill filtered versions, with less flavor coming through, along with a much thinner mouthfeel. The Highland Park held up very poorly, becoming as described by several people as "smelling and tasting like acetone." The Adelphi Glenrothes and Bruichladdich Octomore 6.2 held up much better, being palatable, unlike the Highland Park, but losing a fair bit of their complexity, mouthfeel, flavor and aroma. However I expect this heat is why cask strength whiskies are never chill filtered.

Interesting note was that the importer for my cask, when initially told of my results, was VERY upset, thinking it was a slight against Gordon & MacPhail. Last week he came to my shop and tried the chill filtered Dram Full Highland Park which he imported for us, blind. He thought it was very young, incomplete and possibly under 3 years old Australian whisky....when I told him that it was our cask, which at 170 bottles we could have sold 3 times due to the rave reviews, he was in shock.

He has since contacted G & M and been informed that they typically chill filter at 7 degrees which could explain the heat in my chill filtration as mine was done at 0.

The abvs on the whiskies were: Dram Full Highland Park 15 year old bourbon barrel: 53.9% Adelphi Sherried 7 Year old Glenrothes: 67.6% Bruichladdich Octomore 6.2: 58.2%

Last my next goal is to now repeat the process with whiskies at roughly 40-46% to see how normal commercial whiskies hold up.