I have a friend who is an insatiable arguer. It is impossible to win with him because he will drag the argument out to such an extent that you either a.) secede your point so you don't have to think about it any more or b.) die of old age. Sometimes you are wrong, but that is rare.
You would think that I should know better by now to not engage, but alas an argument about whiskey vs. Scotch, how they are made, and why the flavors differ arose on a recent night out. I have to be honest, I don't really remember what I bet or really what my side of the argument was, but I know that by posting this I could potentially lose something.
I am by no means an expert, I just did a few google searches and looked through some of our cocktail books. Here's what I found.
The first step to make any whiskey is to malt barley. Barley is malted by letting it soak in water for a few days. This process turns the starch from the barley into fermentable sugars. Malting is stopped by drying the mixture in a kiln.
In Scotland, the malt is dried using a fire that is often fueled with peat and the smoke comes in direct contact with the malt. This gives Scotch the smoky flavor that it has and separates it from all other whiskies. In coastal areas, the peat will pick up the saltiness of the sea air and will contribute to the flavor of the scotch.
In Ireland, the malt is dried in a closed kiln fired by coal or gas and no smoke comes in contact with the malt - hence no smoky flavor. Also, the Irish spell it whisky, not whiskey.
So, Scotch is whiskey using peat and direct contact with the smoke in the drying process.
Irish whisky doesn't use peat. I think that was one of the arguments.
The next step is mashing and then fermentation followed by distillation. I'm not going to go into these processes because it wasn't part of the argument. Except to say that many whiskeys are distilled 2 times and Irish whisky is distilled a third time and that much of the body, or mouth feel, of the final whisky is believed to come from the size and shape of the stills used in its production.
The final step is aging and by law, Scotch whisky must be aged for a minimum of three years in oak casks. The casks that are used are an important component of the flavor development. Each year in the wood reduces the alcohol content, as the alcohol evaporates through the porous oak. (Interesting side note...the lost alcohol is known as the angel's share. I linked a bar of the same name that is worth a visit.)
Single malt Scotch requires old barrels because new ones would overpower the whiskey. The most common source is American whiskey producers because U.S. law requires that bourbon and Tennessee whiskey be aged in new casks so the old ones are sold for reuse.
I did find some reference to the fact that the microclimate of an area can also lend to the flavor of whiskies, however it is not just the air that surrounds the oak (in fact that seems to be the least important factor.) The quality of the water, rock and peat is unique to each area and thus each whiskey is unique based in part on these components.
To be called a single malt the bottle must contain only a single malt (barley) whiskey distilled at a single distillery. If it contains single malt whiskies produced at more then one distillery then it is called a blended malt or a vatted malt.
American whiskeys are either straight or blended. Straight whiskies contain at least 51% of a certain grain in the mash, in addition to barley, for example to be called Rye whiskey the mash must contain at least 51% of rye. Straight whiskies must be aged in oak at least 2 years. Blended whiskies have at least 2 or more grains in the mash.
American straight whiskies are further divided into Bourbon, Tennessee or Rye. Bourbon whiskies are produced in Bourbon County, Tennessee and can be either sweet (if fresh yeast is used to start fermentation) or sour (if new and residual yeast is used.) Bourbon is made primarily from corn (up to but no more then 80%) but the remaining grain in the mash is either wheat or rye. Makers Mark uses wheat and Jim Beam uses rye if you want to compare.
Tennessee whisky is almost the same as bourbon except that it is slowly filtered through 10 feet of sugar maple charcoal. Jack Daniels is a Tennessee sour mash whiskey.
Rye whiskey is similar to bourbon but must have a minimum of 51% rye in its mash, giving it a slightly bitter flavor.
All bourbon is aged in new charred white-oak barrels and it is this step that imparts the caramel flavor that is characteristic of American whiskies.
And now I don't want to think about bourbon, scotch, or whiskey anymore so I give up and secede the argument....see how that works?!?!?