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Chill Filtering and Caramel Colouring

In this latest chapter of Whisky 101, I will explore the cosmetic alteration of whisky that sometimes takes place prior to bottling. There are two main processes that are regularly deployed, and often debated: chill-filtration, an industrial process designed to create a crystal clear liquid and colour alteration which involves the addition of colourant, in order to change the appearance of the liquid.

Chill Filtering

When diluted below 46% alcohol by volume, whisky can develop a hazy appearance as a result of fatty acids, proteins and esters congealing. Preferring that their customers not be put off by a cloudy dram, the whisky industry uses a filtration process that strips away the acids and esters that cause the problem in the first place. The procedure is purely cosmetic, with no benefit to aroma or taste. Indeed, many feel it has the opposite effect and a growing number of distillers and bottlers proudly declare that their whisky is “un-chill-filtered”.

Without ever tasting the same whisky both before and after filtration, it is incredibly difficult to say conclusively that the change is a negative one. Certainly in my own experience, the very best whiskies have tended towards the higher strength, un-chill-filtered end of the spectrum and to my mind, it seems strange to suggest that there could be no detrimental effect to flavour. At the very least there must be consequences where mouthfeel is concerned but that of course is a personal opinion and you know what they say about those.

Clear vrs hazy…

This is not an attempt to suggest that chill filtered whisky is of a substandard quality because that is demonstrably untrue. It simply means that some of us will always wonder what certain drams would have been like had they been left untouched. It must also be noted that it is possible to filter at varying levels, with some distillers removing less than others.

In terms of what to look out for, most who avoid chill filtering will shout it from the rooftops but as a general rule, anything bottled under 46% has probably been chill-filtered whilst anything 46% or above has likely been left alone. Be aware, however, that as with any rule, there are exceptions.

Colour Alteration

Colour “correction” refers to the process of using E150 food colouring to darken the appearance of a whisky. This is perfectly legal and is done on many occasions for the sake of consistency. Particularly where blended Scotch is concerned (though this also applies to mass-produced single malts) every bottle must look, smell and taste exactly the same, regardless of where and when it was bought but this isn’t an easy thing to achieve with a product as complicated as whisky.

The creation of whisky is a batch process. Even grain spirit which is made in continuously flowing column stills must then be matured in unpredictable oak casks that can produce radically differing results. Immensely skilled master blenders ensure that all requirements are met so far as smell and taste are concerned but colour is another matter. In order that all batches appear the same, small amounts of caramel colouring are permitted.

Like anything, however, the practice can, at least in theory, be abused. Whisky drinkers have been trained for many generations to believe that dark whisky is good whisky. We think that darker means older and therefore, better. That is, of course, a complete misconception. Whisky that is young and pale can be just as delicious as that which is old and dark but it is said that we first taste with our eyes and there can be no argument as to the appeal of a mahogany-coloured dram. I make no accusation towards any particular company but armed with this knowledge, it is certainly conceivable that some might deploy colouring not for the sake of consistency but to enhance the appearance of their product and that, for an industry that trades on a reputation of provenance, should, in my opinion, be viewed as deception.

Appearance aside, does the addition of E150 colouring affect the flavour of a whisky? Having tasted the substance myself I can tell you it has an incredibly strong, bitter taste but so very little of it is needed to have a dramatic effect on the colour of a liquid. A single drop in a glass of water for example, will create the appearance of a ten year old whisky. It seems unlikely therefore that it has much, if any, impact on the flavour of the dram in your glass. Although, obviously, if enough is used, you will certainly taste it.


Though the two processes outlined above are unrelated, they tend to go hand in hand. Whisky that is un-chill-filtered for example, will often state that it has also been bottled at a natural colour. In the end it simply boils down to different techniques for different markets. The biggest brands have to satisfy millions of customers across the world, time and time again. Consistency and reliability are very much the name of the game. Smaller distillers meanwhile can cater purely to the connoisseur, who won’t send their whisky back when it turns cloudy. These businesses can concern themselves only with producing the best possible product, even if that means it won’t be exactly the same as the last batch. Neither approach is right and neither is wrong, they are simply deployed with different objectives in mind.

In any case, regardless of production method, the most important factor from the consumers point of view is how a whisky tastes. So long as you enjoy it, everything else should be immaterial.

Moran taing (many thanks),

Neill Murphy

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