Single Malt Whisky
Malt whisky is considered the ‘original’ whisky of Scotland. It is made from only yeast, malted barley and water, and must be distilled in pot stills. The distinguished single malt is classified as a whisky that has been distilled at only one distillery, and must be matured for a minimum of three years. Unlike blended whisky, the flavours of single malts are intended to be representative of that distillery’s particular style and individual character. This is achieved by intentional practices at each stage of the distillation process, including how long the barley is malted for, the shape of stills used, and the type of casks chosen for maturation.
Blended whisky can consist of a combination of various malt and grain distilleries. Blending allows distillers to create a more accessible variety of whisky by blending it with lighter spirits, creating sweeter and smoother flavours.
There are three variations of blended whisky: blended malt whisky, blended Scotch whisky, and finally blended grain Scotch whisky.
As the name entails, blended malt whisky uses only barley malts, with no other grain whiskies. This type of whisky (like single malts) can be officially aged, although the age given must correspond to the youngest whisky used within the blend.
Blended Scotch whisky, in contrast, is created from a variety of malt and grain whiskies from different distilleries, produced in Scotland and blended together. This enables the producers to build out more consistent collections. It is quite popular, around 90% of whisky sold made in Scotland.
Blended grain Scotch whisky is created through combining multiple single grain whiskies—but no malt whiskies. This tends to be the lightest of the blending techniques.
Grain whisky is classified as any whisky that is not distilled from malted barley. This includes grains such as corn, wheat or rye, and may consist of a single grain or a combination.
To legally be considered a rye whisky in the USA, the rye mash that is used must be composed of at least 51% rye grain, although it can range up to 100% rye. Often the grain is combined with corn and malted barley, and it is distilled in new oak barrels that have been charred. Furthermore, rye whiskey can be distilled to no more than 80% ABV. To be classified as a ‘straight’ rye whiskey the liquid must be matured in barrels for at least two years. The mouth-feel of rye whiskey tend to spicier and sharper, and with a drier mouthfeel, than other types of whisky.
Corn whiskey is another American style whiskey that must use at least 80% corn in its mash. Of note is that corn whiskey is not matured in charred barrels (unlike rye whiskey or bourbon) and thus cannot be considered a ‘straight’ whiskey. Traditionally farmers would use the cheaper, widely available corn grain, put it in barrels and ship it for immediate consumption. Thus there is no maturation threshold which adds to its rougher ‘moonshine’ image. It tends to have flavour notes of acetone, butter and toffee.
While also made from corn, American Bourbon stands in contrast to corn whiskey in a number of ways. The mash used must be made from 51%-80% corn, and stored in charred new white oak barrel casks for at least two years. As with corn whiskey, Bourbon cannot be distilled above 80% ABV, and cannot have any additives. Bourbon has its roots in Kentucky, although it now is made in multiple states and regions; however it can only be made in the USA. Corn is a sweeter grain, so Bourbon tends to have a sweeter, full-bodied flavour profile, with notes of vanilla, toffee and cinnamon.
Much of the same standards that are used for Bourbon apply to Tennessee whiskey - it has the same ingredients ratios and must be matured in charred new oak barrels. However one step sets it apart, known as the Lincoln County Process. Before being matured, the new-make spirit must undergo a ‘charcoal-mellowing’ process. It is slowly filtered through charcoal that has been made from sugar maple trees, before being stored in barrels. Furthermore, Tennessee whiskey can only be made in the state of Tennessee.
A sweeter, more mellow whiskey, Wheat whiskey is a spirit that has been distilled with at least 51% wheat mash, although some distillers use 100%. The ratio of wheat to other grains like rye or corn influences how spicy the resulting whiskey is. It also must be matured in charred new oak barrels.