Scotch Whisky 101 — Why Styles Differ

In this three-part “101” series, Napa Valley Wine Academy instructor Liz Pirnat explores the world of Scotch Whisky. Napa Valley Wine Academy offers WSET Level 1 and WSET Level 2 (online) in spirits immersion courses. 

Part II

How is it that every Single Malt Scotch is so unique when they all use the same basic ingredients?  

There are a number of factors that affect the taste of Scotch. While the basic ingredients (water, malted barley, and yeast) are the same, each ingredient and the distillery process impact the final product.

Basic Ingredients

Scotch Grain
Scotch Grain


Each distillery uses a local water source. The extent to which the water impacts flavor is something of a debate, but most distillers swear by their proprietary water.


With barley, it could be local or farmed elsewhere. It could be malted in a trading floor or done by machine.  


Barley grown in summer versus the fall can alter flavors, as well as whether it is local or from far away. 


While many distillers use a basic brewers yeast, some are playing with unique yeast for making the distillers beer.  


Each of the five regions (Lowland, Highlands, Speyside, Islay, and Campbeltown) has their own unique style, there are even sub-regions breaking apart these longtime established regions.  

Personally, I find the distillery recipe to drive the unique style of each Scotch. The main ingredients they work with are the basic ingredients outlined above, but also include peat, distillation operation and equipment, and maturation.



Peat is decaying organic material found in the fields of Scotland. It can be burned and has a distinct aroma. The best comparison is to think of peat like hickory or cherry wood chips that are used in smokers for BBQ. The peat (both wet and dry) is burned and to create a smoke and distinct aroma. 

While Islay Scotch is where you most commonly think of peat being used, it can be found in use all over.  When peat is discussed in whisky, it’s referencing how much peat was used to smoke the barley and also peat aromas and flavors. 

Distillery equipment and operation.

Each distillery has its own pot stills. Each still will have its own unique shape and size and shape of the neck, and how it is heated, how the spirit is cooled, will vary from distiller to distiller. Each factor will impact flavor. Even the number of distillations can vary. Distillation is done at least twice, but some are up to three times distilled.


All Scotch whisky must be aged for at least three years in cask. Scotch-makers uses a mixture of used barrels. The most common are Bourbon and Oloroso Sherry barrels. Some even use wine barrels from Port, Sauternes, and Burgundy, to used Chilean wine barrels, Italian Barolo barrels and even crossing into spirits with use rum barrels. 

There will also be multiple barrel selections, a blend of the above options, or first-fill in one barrel and second fill in a different barrel. Each barrel type gives its own unique flavor.   

Bourbon barrels tend to give more vanilla and honey aromas. Oloroso Sherry barrels will add a darker color.

The size of a barrel will vary. A wine barrel holds 220 liters, hogshead holds 250 liters, butt holds 500 liters—the smaller the barrel the more contact with the wood the whisky will have.

Napa Valley Wine Academy offers WSET Level 1 and WSET Level 2 (online) in spirits immersion courses. 

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