First off there are a few things to keep in mind:
- Scotch can only be called ‘scotch’ if it’s made in Scotland. But don’t go to Scotland and ask for scotch – there it’s just ‘whisky’.
- Bourbon can only be bourbon if it’s made in the USA, mostly in Kentucky
- Traditionally, whiskey spelled without the ‘e’ (whisky) is scotch but some makers of whiskey are dropping the ‘e’ these days to give their brand a perception of higher quality.
With that in mind, the processes for making scotch, whiskey, and bourbon are similar but with some subtle differences.
Before the barley is fermented and turned into mash, it is encouraged to start germinating by heating it over a peat fire – which also adds to the flavour. Different distillers in Scotland use a stronger or weaker level of peat flavour to differentiate their product.
Scotch has to be aged for at least three years in barrels that have already been used for bourbon, wine, or sherry.
Whiskey is made in much the same way with the barley malted (soaked, germinated, and dried) before being ground and mixed with hot water to form a mash. The mash is filtered, fermented, and distilled before being put into barrells for maturation.
Tennessee whiskey is different again as it is filtered through sugar maple charcoal to add a unique flavour. Then you have rye whiskey which has to be made from 51% rye.
Note: Due to the Prohibition era, Amercian distillers can’t boast the long uninterrupted lineage of some European distilleries.
All bourbon is whiskey, however, the mash for bourbon must contain at least 51% corn and at the end of the process must be less than 160 proof. By law, the mixture must be stored in charred oak containers and contain no additives.
While all are basically the same thing, there are subtle differences in the processes for making scotch (whisky), whiskey, and bourbon. What they are called can also depend on where in the world they are made.