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How Does Barrel Type Influence Fine Whisky?

We all know the world of whisky to be a hugely varied one, which presents us whisky fans with a beautiful array of characteristics, aromas, flavours and textures which continually surprise and seduce from bottle to bottle. Indeed, this is a major factor in the popularity of whisky as a spirit; once you begin exploring different styles from different regions, or bottles made according to particular traditions (as well as those which revel in ripping up the rulebook and branching out into the bizarre), you’ll begin appreciating the sheer range of notes, bouquets, and flavours on offer.

However, in order to truly appreciate such variety, it’s well worth asking yourself where this variation comes from. The answers to such a question are many - it’s partly down to the style of whisky being made, the local preferences when it comes to flavour and character, the types of grain and mash being used, the terroir (that is, the characteristics of the land on which the grain is grown and the quality of the water used, as well as the climatic conditions in any vintage year), the length of time for which the whisky is aged… the list really does go on and on and one.

It’s important to remember, though, that one of the key sources of flavour and aroma in whisky comes directly from the barrel. Just like with wine, the barrel really is key when it comes to the final product, and not just due to the way that wooden casks, barrels, and barriques assist with gradual and steady aging. The wood itself contains plenty of flavour and chemical compounds responsible for producing aroma and taste in the bottle, and different wood types from different parts of the world (as you might expect) produce different characteristics. Furthermore, whisky barrels more often than not have a history outside of the whisky industry… and it’s the previous lives and uses of these barrels which is perhaps most significant of all when it comes to the resulting taste and character of our favourite spirits.

In this week’s article, we’re going to be taking a closer look at the role that barrels and casks play when it comes to bringing flavour and distinction to your favourite whiskies. We’ll be looking at the primary influences that different barrel types bring, and hopefully shedding some light on one of the more mysterious aspects of the art of distilling. Enjoy!

A Massive Array of Barrel Types

It’s impossible not to be impressed by the massive range of barrels and cask types being used every day in the whisky industry. Every whisky maker and distiller has to make careful choices based upon the type of casks they want to use - a choice based primarily on the flavours and aromas they’re attempting to achieve, but also often influenced by other factors, such as availability and cost (French oak barrels and barriques, for example, are nowadays hugely expensive and increasingly difficult to get hold of).

The principal categories of barrel types can be split into a handful of different types. These are as follows:

Size

If you’ve ever been on a distillery tour, it’s likely you left feeling impressed by the sheer size of the barrels sometimes used, or possibly even surprised by how small the individual casks actually are. Sounds contradictory? Not at all - like everything else in the whisky world, there’s a massive range when it comes to barrel sizes, and they vary from enormous to really rather small indeed.

Most distilleries nowadays will use standard-sized barrels, such as the American Standard Barrel, also known (unsurprisingly) as the Bourbon Barrel. At two hundred liters capacity, it’s a fairly impressive display of cooperage, and because Bourbon has to be made in new white oak barrels, the distilleries tend to get through quite a lot of them. However, the ASB is only the tip of a large iceberg, which includes a large number of official barrel sizes. These include:

  • The Butt - 500 liters

  • Quarter Cask - 125 liters

  • Hogshead - 238 liters

  • Madeira Drum - 650 liters

  • Cognac Barrel  - 300 liters

  • Bordeaux Barrel - 225 liters

  • Barrique - 225 liters

  • Bloodtub - 50 liters

It’s generally believed that the smaller the barrel, the more intense the flavour of the natural wood will be. However, this is something which is fairly open to interpretation, and is pretty difficult to really quantify. It’s probably fair to say, however, that whiskies made in smaller barrels will show more variation from bottle to bottle - something which is increasingly prized by the more ‘craft’-type distilleries out there.

Different Woods, Different Flavours

Alongside the size of the barrels used, the actual type of wood the barrels are made from is also significant. There are two principal woods used in the barrels which make their way into distilleries around the world: European Oak, and American (or White) Oak.

European Oak is a slow-growing tree, and one which produces a high quality wood which has a somewhat less dense grain that its American counterpart. It grows all across the European continent, from the UK to Turkey, although the most prized oak trees are those which grow in the ancestral forests of central France (and those are the ones which command eye-watering prices at auction). European Oak contains a higher tannin level than American Oak, and as such, whiskies aged in European Oak barrels tend to have a more bitter, complex, spicy flavour.

American Oak grows quickly, and is cultivated all along the Eastern coasts of the US and in Canada. As such, it is considerably more affordable than its European counterpart. With a tighter grain and higher levels of monogalloyl glucose, it commonly releases the sweeter, vanilla notes associated with American Bourbon into the whisky.

Re-Used Casks Full of Character

While we can go on and on about the influence of the wood type, the size, or the way the wood is treated and the influences these factors have on the whisky, the main way barrels influence the whisky they produce has everything to do with what those barrels were previously used for.

There has been a real increase in interest over recent years in the ‘former life’ of whisky barrels, and even extremely traditional whisky distillers such as The Dalmore and others have started putting more emphasis on experimentation, and seeing how reused barrels can influence their spirits. That old barrels taken from the wine industry are able to deeply affect the qualities, flavours, and aromas of a whisky should come as no surprise. After all, the slightly porous oak wood will have been soaked in wine or other liquids for years at a time, and will have taken on plenty of character from the aging liquids they once held. Think of it like using a wooden cup for drinking wine year after year… and then one day taking a shot of whisky from the same cup. Naturally, there is likely to be a fairly strong residual flavour of wine left on the palate, no matter how powerful the whisky might be!

Let’s take a look at the most common types of barrels that are re-used by whisky distillers worldwide, and list some of the strongest influences those barrels will have on the spirit being aged within.

  • Burgundy and Bordeaux Barrels

The fine wine regions of Burgundy and Bordeaux produce wine barrels which are highly sought-after in the whisky industry. Why? Because both of these wine barrel types imbue whiskies with a gorgeous red fruit and berry flavour, and a deep winey character which can really bolster the distinction of a quality whisky. They’re also likely to impart a dark reddish hue that can be highly attractive.

  • Sherry

Sherry casks are widely re-used by whisky distillers, partly because they’re more affordable than wine barrels, but primarily because the depth of flavour in fine sherry really does come across beautifully in whisky, too. However, it would be a mistake to think that all Sherry casks have a similar effect to each other; Sherry is a highly varied fortified wine, with many different styles and notes. Fino Sherry barrels, for example, will provide whisky with a light fruitiness and sweetness. Amontillado barrels, on the other hand, tend to be nutty and acidic. Manzanilla barrels (perhaps the finest of them all) will provide whiskies with a salty, sea-air character, along with a dryness and freshness that’s utterly irresistible.

  • White Wine Barrels

Whisky makers looking to produce whiskies of surprising and leftfield characteristics will sometimes turn to the world of fine white wine for their barrels. This isn’t particularly common, but when you come across a white wine barreled whisky, they tend to be highly memorable and distinctive. Generally speaking, the barrels used will come from Chardonnay production (which lend crisp, acidic, and tropical fruit notes), the Muscat table wine industry (which brings floral and orchard fruit flavours), or from Hungary’s world-famous Royal Tokaji region (which provides deep sweetness, and dried fruit and mango notes).

  • Port

If you’re a whisky producer looking to inject a real spiciness and fruity sweetness into your whisky, then the chances are you’ll be looking to get yourself some Portuguese Port barrels down to your distillery. This historic fortified wine produces barrels which really bring out those delicious dark and dense spicy notes, alongside touches of dried and candied fruit in whisky. Delicious! The same can be said for other popular fortified wine barrels, including Marsala and Madeira.

  • Rum

Rum casks are proving to be increasingly popular for whisky production, as again, they tend to be more affordable than those used for European wines, and yet really do pack in loads of flavour and aroma. Light rum casks will lend whisky flavours of almonds, vanilla, and sweet, sugary molasses. Dark rum barrels, on the other hand, will bring woodier flavours, caramel tones, and touches of dark fruit and syrup.

Whisky Barrels: A Powerful Source of Flavour and Character

As we’ve seen, the barrels and casks used in the aging of fine whisky really do have a significant influence on the end product. Some would argue that they are, in fact, the primary influence on the flavours and aromas of the whiskies we enjoy, and in some cases, it would be difficult to argue against that point, so powerful are the notes they impart.

As the whisky industry continues to both innovate and honour its own traditions, it’s likely we’ll see plenty of new barrel types arise in the coming years as whisky makers in certain countries look for ways to stand out from the crowd. In the meantime, let’s enjoy the beautiful range and variation that such barrels provide, and continue to revel in the wonderful array of flavours the whisky world continually offers.

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