I am always asked what the difference is between Bourbon and Scotch whiskeys. The answer I give is always “All Bourbon is whiskey, but not all whiskey is Bourbon”. I follow this with a description of the regulations to make Bourbon, however I thought it might be bice to look at the two whiskeys through the six sources of flavor. Now I am not an expert on Scotch by any stretch of the imagination and I welcome any comments on this comparison from Scotch enthusiasts.
Bourbon: Bourbon has to be at least 51% Corn. It can be 100% corn if the distiller wishes, but it has to be a majority corn based beer. The distiller usually uses rye or wheat as a flavor grain and malted barley for conversion from starch to sugar, but low amounts of barley are allowed with the addition of manufactured enzymes for the conversion. This gives Bourbon distillers a large range of flavors they can produce for their Distiller’s Beer.
Single Malt: As the name implies, Single Malt Scotch is made from malted barley. There is not a lot of variation of flavor from distillery to distillery from the grain itself. Instead the Scottish distillers use the malting process itself to give variation in the grain flavor. They will use peat smoke in varying degrees to flavor the malt. I don’t know if any Scotch distillers are doing so, but they could use brewer malts such as chocolate malt to alter the flavor of their Distiller’s Beer.
Bourbon: Limestone water is the key to good Bourbon in Kentucky, but any iron free water will work. Many big city distillers are using RO or Reverse Osmosis water to make their beer because the ground water is too polluted to use for human consumption without treatment. Other distillers are using water from deep wells or springs.
Single Malt: Once again the fact that it is iron free is an important factor. Some Scottish distillers are getting their water from granite fed springs while others are getting it from peat bogs and the water looks like coffee and gives the beer a heavy peat flavor.
Bourbon: Bourbon distillers have always known that different yeasts make different flavors and made a point to keep their own yeast strain alive for future years. For some families this became a point of pride and a family secret as to where and how the yeast was first propagated. A prime example of yeast is the Four Roses distillery with their five different yeast strains that they keep and use with two different mash bills to create ten different Bourbons.
Single Malt: Up until a fairly recent time, Scottish distillers paid little attention to yeast and its flavor value. Michael Jackson wrote in the 1980s about Scotch and barely mentions yeast, but in his 2005 book “Whiskies of the World” he does mention that the Scottish distillers are beginning to pay attention to yeast and the flavor component derived from fermentation. To this day, you rarely see anything written about yeast and Scotch production.
Bourbon: Bourbon has a maximum distillation proof of 160 and the industry average is closer to 140. The lower distillation proof than that of other whiskeys allows more flavor to come through from the first three sources of flavor. Bourbon also uses the column still with a pot still doubler or a thumper with varying degrees of copper used in making the stills. Recent artisan distillers are often using hybrid stills that are a pot still with a small rectifying column attached. There is a huge variation in the stills used to make bourbon.
Single Malt: The traditional still for Single Malt whisky is a copper pot still. The only variation comes in factors such as the shape of the still or the length of the goose neck coming off the still. The maximum distillation proof is the legal high of 180 even though I doubt very many distillers go that high.
Bourbon: Maturation is a huge difference in these products. Bourbon has to be aged in new charred oak barrels with a maximum entry proof of 125 with only pure water added to adjust the proof. This leads to a lot of barrel flavor in a short time with Bourbon maturing in as little as two years, the time required to be a Straight Bourbon. The variations between distilleries comes in many forms that include char levels in the barrels, barrel entry proof, type of warehouse (iron clad or Masonry), number of floors in the warehouse, where the barrel is placed in the warehouse, whether the warehouse is heated in the winter, is the ware house palletized or are their barrel racks. Climate is important too as the hot summers and cold winters of Kentucky are very different from warehouses found in cooler climates such as upper New York State. Warehouses found in a city will age whiskey different than warehouses found on a hillside out in the country. There is a huge variation in the maturation process in the Bourbon Industry.
Single Malt: Single Malt can use a wide variety of barrels for maturing their whisky. Used cooperage is not only allowed but it is the most common cooperage found in Scottish warehouses. Indeed there are many used Bourbon Barrels being used to make Single Malt Scotch. Many Malts market the fact that they are using Sherry or Port or even Bourbon barrels to make their whiskey. They depend upon these used barrels to pass along flavor from their previous use to the whisky. There is no upper limit to barrel entry proof and indeed many that I have heard range in the mid 130s for entry proof. The weather in Scotland is much cooler and damper than in Kentucky causing the aging whisky to decrease in proof over the years. The warehouses usually don’t have the rack system found in the United States with only single story warehouses where the barrels are either stacked upon top of each other or palletized. The big variable for aging is location as there are many warehouses near the sea, allowing the whisky to get a hint of the salty brine from the sea in the maturing whisky.
Bourbon: Straight Bourbon has to be bottled at a minimum of 80 proof with nothing but pure water added to adjust the proof. The amount of filtration is the big variable in flavor other than bottle proof. It is possible to combine multiple bourbons to adjust the flavor such as Four Roses Yellow label which is a combination of all ten Bourbons made at the distillery, but this is not a common practice.
Single Malt: Single Malt has to be bottled at a minimum of 80 proof and to be the product of a single distillery. They can add caramel coloring to bottling and many do. There are a variety of levels in filtration as well.
There are a lot of differences in these two products. Both are fine whiskeys and deserve respect. I would say that neither are superior to the other as they are both very different. To me it is like eating steak or pork chop, it depends what you are in the mood for as to which is better on that day. I love Bourbon but I also like Single Malts. I never turn down a glass of Talisker in any of its variations. I advise people to enjoy a glass of both of these types of whiskey from time to time.