WHAT INFLUENCES THE FLAVOUR OF WHISKY?

There are several factors that can influence the flavour of whisky, including the type of grain used, the distillation process, the type of oak barrels used for aging, and the length of time the whisky is aged. The type of grain used to make whisky is one of the most significant factors that influences its flavour. The most common grain used to make whisky is malted barley, but other grains such as corn, rye, and wheat are also commonly used. Each type of grain imparts its own unique flavours to the whisky, and the proportion of each grain used in the mixture can also have an impact on the final flavour.

The distillation process is another factor that can influence the flavour of whisky. Different distillation techniques, such as the use of different types of stills and the length of the distillation process, can result in different flavours in the final product.

The type of oak barrels used to age the whisky can also have a significant impact on its flavour. Different types of oak, as well as the level of charring on the barrels, can impart different flavours to the whisky. In addition, barrels that have previously been used to age other types of alcohol, such as sherry or port, can also contribute additional flavours to the whisky.

Let's take a look at some of the finer points of whisky maturation, more specifically the barrels whisky is matured in. There are several different types of casks that are commonly used in the production and aging of whisky, including:

• Bourbon barrels: These barrels are made from American white oak and are typically used to age bourbon. They are charred on the inside, which gives the bourbon its distinctive flavour and amber colour.
• Sherry barrels: These barrels are made from European oak and have previously been used to age sherry. They are often used to age whisky, and can contribute flavours of fruit, nuts, and spice to the final product.
• Port barrels: These barrels are made from European oak and have previously been used to age port. They are often used to age whisky, and can contribute flavours of fruit and sweetness to the final product.
• Rum barrels: These barrels are made from American oak and have previously been used to age rum. They are often used to age whisky, and can contribute flavours of tropical fruit and spices to the final product.
• Quercus alba barrels: These barrels are made from American white oak and are typically used to age whisky. They can contribute flavours of vanilla, coconut, and spice to the final product.

In addition, there is still some additional information and terminology about whisky barrels that is important to cover.

First-fill: 

First-fill refers to a whisky barrel that has been used to age whisky for the first time. First-fill barrels are typically made from oak and have been charred on the inside to give the whisky a distinctive flavour and amber colour.

First-fill barrels are often used to age whisky because they are able to impart more flavour to the whisky than barrels that have been used previously. This is because the wood of the barrel has not yet been fully saturated with whisky, and so the whisky is able to extract more flavours from the wood.

The length of time that a whisky is aged in a first-fill barrel can vary, but it is typically aged for at least three years in order to be classified as whisky. The specific flavours imparted by the barrel will depend on the type of oak used and the level of charring on the inside of the barrel.

Single cask: 

Single cask whisky refers to whisky that has been aged in a single, individual barrel, as opposed to being blended with whisky from multiple barrels. Single cask whisky is often bottled at its natural cask strength, which means that it has not been diluted with water before bottling and will have a higher alcohol content than whisky that has been diluted.

Single cask whisky is typically produced in small batches and is often considered to be a more premium product due to the unique characteristics and flavours imparted by the individual barrel. The flavour of single cask whisky can vary significantly from one barrel to another, even if they are produced at the same distillery and aged for the same length of time.

Single cask whisky is often bottled and sold as a limited-edition expression, and it can be difficult to find as it is produced in such small quantities. It is often sought after by collectors and connoisseurs due to its unique flavour profile and rarity.

Cask strength: 

Cask strength refers to whisky that has not been diluted with water before bottling and is bottled at the strength at which it comes out of the cask. Cask strength whisky is typically bottled at a higher alcohol by volume (ABV) than standard whisky, which can range from around 50% to over 60% ABV.

Cask strength whisky is often considered to be a more premium product because it has not been diluted and retains all of the flavours and aromas imparted by the cask. It is often bottled as a limited-edition expression and is sought after by collectors and connoisseurs due to its unique flavour profile and higher alcohol content.

Because cask strength whisky has a higher alcohol content, it is often recommended to be served diluted with water to bring out the flavours and aromas. The specific amount of water to be added will depend on personal preference and the specific characteristics of the whisky.

There are several different methods of reusing oak barrels to age whisky, including:

-          Finishing: This method involves aging the whisky in a barrel that has previously been used to age another type of alcohol, such as sherry or port. The whisky absorbs flavours from the barrel, which gives it additional complexity and depth.

-          Refreshing: This method involves rejuvenating the barrel by toasting or charring the inside of the barrel. This helps to refresh the flavours imparted by the barrel and can give the whisky a more complex flavour profile.

-          Double-barrelling: This method involves aging the whisky in one barrel and then transferring it to a second barrel for further aging. This can help to further refine the flavours of the whisky and add additional depth and complexity.

-          Solera aging: This method involves aging the whisky in a series of barrels, with the oldest barrels at the bottom and the newest barrels at the top. As the whisky ages, it is transferred from one barrel to another, with some of the older whisky being blended in with the younger whisky. This method can result in a more consistent flavour profile, as the blend of different ages of whisky helps to balance out any variations in flavour.

Whiskey cask types

Whiskey casks are the wooden vessels used to store, age and transport whisky. Not all woods are suitable for whiskey cask usage, as a number of factors can affect their flavour.

These factors include:

• Type of wood used.
• How it was treated and seasoned.
• Shape and size of the cask.

Each type of wood imparts different flavour characteristics to the whisky, depending on its properties. For example, American white oak imparts sweet vanilla notes while European oak gives a spicy character. Latest addition being cherry wood by some pioneering distilleries such as Middleton.

Seasoning of casks

Prior to being filled with spirit which will turn into whisky in the cask, wooden casks must be “seasoned” by being filled with predecessor liquids such as:

• Spirits such as bourbon (American whiskey) or rum.
• Fortified wines such as sherry or port.
• Wine.
• Even beer can be used for seasoning.

This process helps to open up the pores of the wood so that spirit can penetrate more easily during maturation. It also helps to draw out some of the tannins in the wood which can give an astringent flavour if not properly prepared beforehand.

Charring of casks

The charring process is another important part of preparing a cask for maturation. The inside of the cask will be set on fire in order to create a layer of charcoal which helps to filter out unwanted compounds during maturation such as sulphur compounds which can give off unpleasant odours and tastes in whisky.

Toasting of casks

Casks may also be subjected to “toasting” which involves heating them over open flames at high temperatures in order to caramelize some of the sugars present in the wood. Again, giving off desirable flavours such as nutty or honeyed notes that would otherwise not be present if left untreated.

Whisky cask sizes

Casks come in various sizes depending on where they are made and their purpose – typically these range from 50 litres all the way up to 500 litres. Though there is no standardized size across different producers.

• Big cask usually means over 400 Liters (132 US gallons). Big sizes include Butt, Port Pipe, Puncheon and Madeira Drum.
• Medium cask means 200-400 Liters (53-106 US gallons). Medium sizes include American Standard Barrel (ASB) referred as Bourbon barrel, any Hogshead, Barrique, Cognac and Bordeaux casks.
• Small cask means below 200 litres (53 US gallons). Small sizes include Quarter cask and blood tub.
•  

Many distilleries use smaller casks such as 25-40 litre barrels because they mature faster than larger barrels. Yet they offer less complexity due to having less contact with surface area compared to a larger cask over time; this makes them ideal for finishing whiskies or creating quick-maturing blends where complexity isn’t required.

By contrast, many Scottish distilleries prefer larger 250-500 litre sherry butts due largely because these allow for prolonged maturation times. Which allow for greater complexity in flavour profile over time, compared with smaller ex-bourbon barrels – making them ideal for creating single malts with deeper layers of flavour and aroma profiles.

Below you can find complete table of various cask sizes:

Overall, there are numerous factors that can affect how whisky matures when stored in wooden casks. These include type of wood used, seasoning techniques applied prior to filling, level of charring/toasting applied before maturation begins and finally, the size of the cask employed throughout its lifetime.

Each one of these factors play an integral part in helping craft unique flavours found within any given whisky expression today. And the distillers have gotten quite