It’s Time To Stop Chilling

Why you could be missing out on taste.

One of the things that will determines how good your whisky will be is the quality of the ingredients in your dram. But the whisky you have in your glass will have more in it than you realise.

Chilling. Potential hazard ahead.

Although the standard three ingredients in whisky are water, malted barley and yeast, the production process will develop many different compounds. The three main types of compounds are Phenols, Aldehydes and Esters. In your dram, these will be present in various sub types, but seeing as I am not a chemist, we won’t go that deep.

Starting with Phenols, these are mainly responsible for the smoky and peaty flavour in whiskies where the malted barley has been dried in a kiln with peat. It is nothing to do with where the water comes from. Phenols are measured in Phenol Parts Per Million (ppm) and this is the level of Phenol in the malted barley, not the finished whisky. Ardbeg is about 25ppm and some of the Octomore bottlings have insanity levels of peat at 167ppm. Thing is, these compounds can be lost at any point in the process, so a high phenolic value doesn’t mean it might taste peatier than a lower number, it’s just a guide.

Moving on to Aldehydes, these are a chemical compounds formed throughout the distillation process, and are formed as a result of oxidisation of alcohol (ethanol). It is also created during fermentation as a by product of the yeast converting sugar to alcohol. These aldehydes are quite pungent, and if you’ve been tricked into sticking your head into a washback and taking a good sniff during fermentation, that ammonia smell is an aldehyde. Other aldehydes are created during maturation as compounds in the wood break down and are exposed to oxygen.

Aldehydes are responsible for a variety of flavours and aromas, such as cinnamon, vanilla, herbal and other slightly bitter tastes. They also help create other aromas and flavours that you can experience.

Lastly, we move onto Esters. When you mix alcohol with phenolic or carboxylic compounds, this creates Esters. They are responsible for the fruity and creamy types of flavours and aromas, such as vanilla, butter, citrus and other fruits. Esters are also created throughout the process from fermentation, distillation and maturation as sugars break down and form various organic acids.

Ethyl Hexanoate – in whisky that’s pineapple or waxy green banana to you.

So why do we need a chemistry lesson??

Well, with the formation of esters and aldehydes, there is a presence of other naturally occurring fatty acids and proteins that will be in the spirit that comes out of a cask. These start to coagulate when the whisky has water and/or ice is added. It also happens when a whisky bottle has been kept in a cold location. This gives a cloudy appearance, and for many this gives an impression there is something wrong with the dram. There isn’t, and all that we are seeing is the esters of long chain fatty acids. Once the whisky is warmed it goes back to its natural colour.

Scotch Mist. Haze in a Glencadam 10 year old @ 46%

The bottlers solution to this is to chill filter the spirit. All whisky is filtered prior to bottling to ensure sediment and particles from the cask do not go into the bottle. This is a simple filtering process, similar to why you’d attempt filter oil in your engine to keep the bad bits out. Chill filtering is slightly different, where the spirit is chilled down to around 0C, which causes the compounds that create the haze to form. The hazy spirit is then forced through a filter (usually a fine metal mesh) which then removes the undesired compounds.

Auchentoshan @40% and cold water. No mist = chill filtered

This is only done in the vast majority of cases for whisky less than 46% abv. Whisky at 46% abv or above doesn’t need chill filtered so much for two reasons. Firstly, there is less water in a 46% whisky, so it doesn’t haze so much. Plus, if we strip out the haze causing fatty acids, we’re left with just more alcohol and less taste.

So why is this a problem?

This is a debate that perpetually continues in the industry. Those who support chill filtration will say it doesn’t change the taste of the whisky. Those who don’t support it say it strips out the texture, plus some of the oils and esters. And that is why I gave a brief over view to compounds in whisky – if you strip out esters and fatty acids which we know provide flavour, how can you not affect taste? It’s impossible not to, but people will still disagree.

What I can tell you in my experience with my whisky journey, most 40% whisky I have had seem to be light, lacking mouthfeel. Not them all, but most of them. It’s almost impossible to gauge what the dram would be like had it not been chill filtered. However it isn’t impossible, and this vindicates my policy of using miniatures of older whiskies bought at auction – as consumers are becoming more aware of chill filtration, producers sometimes upgrade their expressions with higher ABV and becoming non-chill filtered. One such example is the brands owned by Burn Stewart (Bunnahabhain, Deanston, Ledaig and Tobermory) raising the abv to 46%+ and not chill filtering. Comparing old and new may give a guide on the difference the chill filtering makes, but because the expressions may have a different flavour profile, it makes identifying what was lost through chill filtration a bit harder. I’d say the texture would be the easiest to identify in comparison, but that’s just me.

For me, it’s an issue worth mentioning, as it is solely done for cosmetic purposes, and I am more concerned about taste and texture, and so should you all be! You are reading this because you have an interest in whisky, and are (hopefully) not a ponce who worries about how their drink looks if he or she puts ice in it.

As consumers, how do we know if a whisky is Non-Chill Filtered?

Our labels tell us everything. It’s essentially the written contract from the distiller so the customer knows what to expect. We have already looked at age statement, alcohol strength and how they are on the labels, but what about chill filtration? Let me tell you one thing – if it isn’t mentioned on the label, then it’s almost certain if the abv is below 46% then it has been chill filtered. Non-chill filtering is now recognised as a desirable attribute, and if this is the case, the bottle will proudly proclaim it.

Wolfburn Morven. NAS but also 46% and NCF. 2 out of 3.

Or, put your bottle in the fridge. If it turns cloudy, then it is non chill filtered.

Is chill filtered whisky not worth it?

Chill filtering adds another step to the process, therefore makes production a little bit more expensive. So it seems crazy to do it for cosmetic purposes, but I guess producers are just doing what their markets want. It could be that they don’t want cloudy bottles on store shelves or whisky cabinets, but why not put an explanation on the bottle? Glencadam does on at least the 10 year old.

Integrity. Haze explained and Non Chill Filtered

However, as I say in nearly every article I write, we have to let our palate be our guide. I’ve had a few 40% whiskies that are chill filtered that have still been excellent drams and I would easily recommend. These have been reviewed and you’ll see them in the next few weeks. However, if you are not wanting to take the chance, in my opinion when standing in the supermarket aisles, the whisky that states ‘non-chill filtered’ gets an extra point.

Next week we move onto colouring, our final topic to consider when picking a bottle.

Slainte Mhath!


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Photo credits

Road sign – UK.COM

Ester – Public Domain

All other photos – authors own

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