What do distillers mean when they talk about the cuts?
Distilling is simply boiling and a still is a big kettle. Most single malt is distilled twice and it all hinges on the fact that water boils at 100c but alcohol at 78c.
First off, we boil an un-hopped beer, the starting point of single malt. The aim in distilling is to separate out the alcohol and leave the water behind, so we boil away, collecting the steam until the boiling temperature slowly rises to reach 100c. We then know we have harvested all the alcohol.
The water left in the still is discarded and what has been collected is the ‘low-wines’. Once we have enough, it’s boiled for a second time.
Now as well as alcohol and water low-wines also contain harmful compounds methanol and acetone. These boil at an even lower temperature than alcohol and therefore the first steam is discarded, this is known as the heads.
Once the heads have boiled off, we begin to collect alcohol again however this time not all of it is harvested. Only the purest is taken for the whisky, this is what boils off first and is called the Hearts. The remaining alcohol contains imperfections such as lipids and fatty acids and these ‘Tails’ are also discarded.
The points between the Heads and Hearts and between the Hearts and Tails are known as the cuts!