Chill Filtration of Whisky
The technique of chill filtration can be used to produce an extremely stable whisky. This could be the result of removing C12-C18 saturated and unsaturated fatty acids and their esters by using a low temperature to achieve maximum haze formation.
Many of these compounds have a significant effect on the flavour of the spirit so, in practice, whilst the whisky is much more stable, there could be a detrimental effect on flavour. It is for this reason that the practice of chill filtration is the subject of much debate.
- Filtration at 3 to 7 degrees C is commonly referred to as attemperation and many whiskies are filtered within this range. The effect on flavour is minimal and chill haze stability is normally good although higher malt content whiskies could be expected to show a haze under certain conditions.
- Filtration at -5 to 0 degrees C would be correctly called chill filtration and a distinct effect on flavour could be expected. Whiskies filtered at this temperature would be very stable although a slow deposition might occasionally be encountered.
- Filtration at -10 to -5 degrees C would offer maximum protection BUT could have a very significant effect on flavour.