How do casks make Bold Whisky Flavours?
We often associate Bold flavours in whisky with how the spirit was matured. Spicy ex-sherry casks will probably come to mind first. However, there are many factors during maturation that will contribute towards how Bold a whisky’s character will be. Join us as we explore some of the key ways in which oak casks can make a whisky taste Bold.
Type of oak
American oak and European oak are commonly used for maturing single malt whisky, although Japanese oak has also found its place. Each species of oak brings a unique chemical structure which will shape a whisky’s flavour. Broadly speaking, American oak is famous for its vanilla compounds whereas European oak brings higher concentrations of tannins.
Size of cask
Spirit in smaller casks will have an increased interaction with the oak as a percentage of volume. Hence small casks, such as quarter casks, can speed up many of the interactive processes between the spirit and the oak, making them Bold in terms of woody characters.
Toasting the cask
Toasting is a heating process for the inside of oak casks as they are being made. The degree of toasting, from light to heavy, will be controlled. Toasting breaks down hemicellulose and lignin in the oak. Sugars within the hemicellulose will caramelise to contribute towards nutty and caramel characters in the whisky. When heated, lignin will contribute towards a range of characters from spices and chocolate to vanilla and fruits.
Cask seasoning
Most casks for maturing single malt whisky will have been filled with another liquid prior. The most common examples being ex-bourbon or ex-sherry casks. The previous maturation of each cask will change the chemical composition of the wood, and therefore impact how it will direct the flavour of the single malt whisky as it matures. A great example is how ex-sherry casks are associated spice and dried fruit characters.
Age of cask
Single malt whisky casks may be re-used four or five times for maturing the whisky. Each time a whisky is matured in a cask it will extract flavour-contributing chemicals from the oak. So the more a cask is used for maturing whisky the less intense its characters will be. This is why virgin oak (or new oak) casks, and first fill casks can create whiskies with vibrant oak-derived characters.
Length of maturation
It goes without saying that the longer a whisky spends inside an oak cask the more woody it will taste. But other processes are at work too. The layer of char within a cask will remove certain compounds from the whisky and oxidation will also occur. This is how whiskies ‘mellow’. However, peated whiskies will gradually lose their smoky and medicinal intensity over time, so peated single malts can seem more Bold at younger ages.
Tannins
Tannins are a key component of oak and although they do not present themselves as aromas in the whisky, they are crucial for mouthfeel. Tannins create a range of sensations in the mouth from grainy and mouth-coating textures to a feeling of dryness. They are important for Bold whiskies because they add structure and texture to the big aromas.
At The Single Cask we categorise all our independent bottlings by mood: Cheerful, Playful, Curious, Easy-Going, and Bold. To discover more about Bold whiskies and what makes them so special, read our latest article here: The Single Cask Whisky Moods: Bold Whiskies.
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