America is one of the world's largest producers of whiskey and there are numerous different types, each with their own unique ingredients or production methods. The six different categories are bourbon, Tennessee, rye, corn, wheat and blended whiskies. Whiskey was introduced to America by the immigrants and pioneers that went over to the continent from Scotland and Ireland in the 1700s. These settlers were forced to use different raw materials to produce their whiskey due to the different climate and soil conditions. This included mixing different grains together during the mashing process depending on what was available. Over time, these different recipes of grain mixtures have evolved so that now, American whiskey bears very little similarity to Scottish or Irish whiskies. The industry has strict laws about the naming or categorising of the whiskies and here I will explain the differences.
Many people believe that these whiskies are so named due to their location. All bourbons are made in the state of Kentucky but there are in fact no working distilleries in Bourbon County. Most are situated in the north east corner of the state and the name actually refers to the production method. Bourbons must contain at least 51% corn (maize) in the mash and the new spirit must be distilled below 80% ABV. The new spirit must then be matured in new American white oak barrels for a minimum period of at least two years. American white oak has a high level of natural oils in the wood (called vanillins) and these give all American whiskies their distinctive vanilla and woody flavours. The combination of using new barrels and the higher temperatures and differing surrounding climate, mean that American whiskies mature much faster than those produced in Scotland and Ireland. Also, no colourings or flavourings can be added to a bourbon whiskey. There are seven different bourbon distilleries in Kentucky and these produce numerous brands of whiskey, all using unique recipes. The seven distilleries are Bernheim, Buffalo Trace, Four Roses, Jim Beam, Maker's Mark, Wild Turkey and Woodford Reserve.
There are very few differences between these and bourbons, as the grain/corn percentages in the mash and the ingredients are the same. The two main differences are that Tennessee whiskey can only be produced in the state of Tennessee and that the new spirit is filtered through charcoal, once it has been distilled. This process takes 10 days and the charcoal that is used must be from the sugar maple tree. After this has occured, the maturation procedure is the same as that of the bourbons. There are only two distilleries currently in operation in Tennessee - George Dickel and Jack Daniels.
Most rye whiskies are used in the production of blends, but some are released in their own right and called 'straight rye'. These can be produced at any distillery but the laws dictate that at least 51% of the mash mixture must consist of rye. similarly to the bourbons and Tennessee whiskies, the ryes must be distilled at less than 80% abv and must be stored in new American white oak casks for a minimum of two years. Some well known rye whiskies are Pikesville, Rittenhouse, Sazerac and Van Winkle.
This was the first type of whiskey that the new settlers to America distilled as corn or maize was the easiest thing to grow. The mash mixture must consist of at least 80% corn and does not necessarily have to be aged. If it is aged then it is normally for a short period (no longer than six months) and in regular wooden barrels or ones that have been previously used for maturing bourbon.
Wheat whiskies are very rarely released as the majority that is produced goes into blends. They must contain at least 51% wheat in the mash mixture but are then matured in the same way as bourbon, Tennessee and rye whiskies.
These are a very common and cheaper alternative to any of the other American whiskies. They are different from Scottish or Irish blends in that only a small amount of the whiskey used has been matured (usually bourbon or rye) and this is then blended with neutral spirit. Only 20% of the blend is actually matured whisky with the other 80% being the neutral spirit.