Chill Filtering is a common process in the modern whisky industry but the need for it is debatable and it can have a dramatic effect on flavour.
Whisky in it’s natural state can be cloudy, particularly at low temperatures or when diluted under 46% ABV. Apparently some consumers find this off-putting and even assume that there is something wrong with the bottle they bought. I’ve heard of people returning their purchase and demanding a refund, all because of some clouding in their glass.
Of course, there’s nothing wrong with the whisky. In fact, the clouding, or scotch mist, is caused by oils and fatty acids that give weight and flavour to the spirit. However, it is such a big concern to the industry that a process was developed in order to remove the issue altogether. But, at what cost?
Chill filtering works by cooling the whisky to around 0°C and passing it through an absorption filter. Reducing the temperature like this causes the oils and acids to congeal and catch in the filter.
The process is of no benefit to the flavour of the whisky, quite the opposite in fact. Of course, there are some distillers who refuse to filter their spirit and take great pride in bottling the natural product. Many independent bottlers do the same which is how it should be in my opinion. One would think that in this day and age a simple notice on the label reading ‘may turn cloudy’ should suffice and is hugely preferable to industrially stripping out the heart of the whisky?!
As I’m sure it has become clear, I’m not a fan of chill filtering. I’ve found that most of the best whisky I’ve come across has been bottled without it. That is not to say that filtered whisky is bad, there are magnificent whiskies which have undergone the process but I always find myself wondering if they would have been even better if left alone?
Anyway, chill filtering is something that I will mention from time to time in my reviews and I wanted to cover it in more depth and give some background as to why it matters. Look out for it the next time you’re browsing for whisky – those who avoid the process will usually state it proudly on the label, while a bottle that doesn’t mention it at all has almost certainly been filtered.
Add a little water to the whisky in your glass, does it turn cloudy? If it stays clear, then filtration has taken place and you, like me, can get on with pondering what it would have been like had it’s soul not been ripped out.
See the image below… maybe not the clearest example but it gives an idea… Filtered on the left, non-chill filtered on the right. Can you see the mist?