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A lexicon of terms from the world of whisky.

a b c d e f g h i j k l m n o p q r s t u v w x y z

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Spirit Caramel, aka E150a, is a tasteless liquid used to ensure that whisky has a consistent colour when it is bottled.
Similar to Scotch and Bourbon but has a style of its own thanks to a unique means of production and the influence of Rye.
A wooden vessel usually made of oak, where whisky is stored in order to mature. It is common practise to age whisky in casks originally used for Bourbon (American Oak) or Sherry (European Oak) to impart character to the spirit. Also getting more and more popular is Japanese oak. There are several different cask sizes and variants and they all contribute in a different way to the flavour profile of the whisky. The size of the cask is an important factor for the maturation and eventual flavour and character of the whisky. The ratio of spirit volume to cask surface influences the way in which the spirit mature. So, it is essential that any casks used are of the highest standard and will complement and enhance the malt spirit they contain.

Another important factor in the overall flavour of malt whisky is the charring inside of casks prior to their first use. This releases quantities of vanilla and related flavours into both their first and second fillings and helps to remove off-notes. New oak imparts a dominant woody flavour, but is not desirable in Scotch whisky. So, second-hand casks are always used; those which formerly held bourbon or sherry. Casks are selected on their ability to produce various maturation mechanisms. There are three main types of mechanism – subtractive, additive and interactive – these are known as cask activities.

Subtractive removes immature elements and off notes from new make spirits like sulphur compounds. Additive adds wood-derived flavours from the cask like vanillin and Interactive converts spirit and extractive wood elements to produce mature character.

Whisky bottled at the natural alcoholic strength without being diluted with demineralised water to bring it down to e.g. 40%, 43%, 45.8% ABV which is usual practice for many Single Malts, like Oban or Talisker. However, some whiskies are bottled at their original cask strength, such as the annual Special Releases. An additional taste experience can be obtained from tasting the cask strength malt undiluted, then diluted in the glass to your taste.
There are several cask types whisky can be matured in but whisky must mature only in oak casks of a capacity not exceeding 700 litres. The three main sizes are Butts with 500 litres capacity, Hogsheads with 250 litres and American Standard Barrels (ASB) with 200 litres. Because it can be very confusing we have compiled the main cask types used within the whisky industry, starting with the largest possible option.
  • Gorda (capacity 700 litres)

The biggest type of cask allowed in the Scotch whisky industry made from American oak. This type of cask is not often used for maturation in Scotland and was used traditionally in the American whiskey industry. However, the large size make them useful for marrying different whiskies together for the production blends to round the flavour before bottling.

  • Madeira Drum (capacity 650 litres)

A short, fat and dumpy cask with a very wide diameter and made from very thick staves of European oak. This type of cask is used in the Madeira wine industry and is occasionally used in the whisky industry to finish a whisky.

  • Port Pipe (capacity 650 litres)

Also made from thick staves of European oak and the casks are tall, thin with a long narrow shape. This type of cask is used in the Port wine industry and is occasionally used in the whisky industry to finish a whisky.

  • Butt (capacity 500 litres)

Butts are commonly known as Sherry Butts but how they found the way into the whisky industry is a longer story. Before 1981 Sherry Butts were mainly used as a container to transport the Sherry around the world in wood before the Spanish export regulations for Sherry changed this procedure. After 1981 it was no longer allowed to transport Sherry in casks. Before that change the Sherry was often only for a short time in the casks before the casks were emptied and reused. This short time, often just a few months, was enough for the cask to get a lot of the flavour into the wood and whisky was traditionally the secondary occupant for those casks. After 1981 the availability of Sherry casks for Scottish distilleries was severely impacted due to the new regulations and the general downturn of popularity for Sherry. The result was a huge increase in price and a new business for Sherry bodegas to produce Sherry casks especially for the Whisky industry.

A Butt is a tall, narrow cask traditionally made from thick staves of European oak but nowadays the use of American oak is more common for several reasons like better and cheaper availability, easier handling and flavour.

There are now different types of Butts.

First Fill European Oak Butts

First fill refers to the first time the cask has been used for Single Malt Scotch Whisky. The Butt will have been used previously before, by the Sherry industry in Spain.

Refill European Oak Butts

Refill refers to the process of reusing the cask after its use as a “first fill”. This can be done a number of times until it is deemed exhausted and in need of rejuvenation.

Rejuvenated European Oak Butts

The process of rejuvenation is where we strip out the inside of the cask to reveal a new layer of wood. The new wood surface is then charred or toasted before the cask is filled again.

  • Puncheon (capacity 500 litres)

There are two different types of puncheon cask and the information of the correct capacity varies from source to source. The most common types are “machine puncheon” and “sherry shaped puncheon”.

The machine puncheon is made of thick American oak staves and the sherry shaped puncheon of thinner European oak staves. Both of them are used in the rum and sherry industry and are sometimes used to finish whisky.

  • Barrique (capacity 225 - 300 litres)

Widely used throughout the wine (225 litres) and cognac (300 litres) industry and are usually used for finishing purposes in the whisky industry.

  • Hogshead (capacity 250 litres)

American Standard Barrels (ASB) get broken down into staves and then reassembled with new ends to produce the slightly larger Hogsheads. This type of cask is one of the most common types of cask used for maturing whisky in Scotland.

First Fill American Oak Hogsheads

First fill refers to the first time the cask has been used for Single Malt Scotch Whisky. It may have been used previously for Bourbon then possibly for Scotch Grain Whisky before being used for Single Malt.

Refill American Oak Hogsheads

Refill refers to the process of reusing the cask after its use as a “first fill“. These casks have already given much of their aroma compounds to earlier fillings of spirit and only a small amount now contribute to the final whisky flavour. Whiskies mature very slowly in these casks, allowing the very essence of the distillery character to be revealed. They tend to be light, delicate and with the aroma of the original spirit. This can be done a number of times until it is deemed exhausted and in need of rejuvenation.

Rejuvenated American Oak Hogsheads

Refill casks are rejuvenated by scraping the interior to remove the old surface, then freshly charred or toasted to produce the new active surface. This quickly takes out any immaturity in the spirit, particularly the sulphur compounds. It also breaks down the cask wood to give vanilla sweetness and other compounds which react to produce extra fruitiness. Rejuvenation lasts for only one filling, after which the casks go back to being refills.

  • American Standard Barrel (ASB (capacity 200 litres))

Made of American white oak the ASB is the most common type of cask and is usually used in the American whiskey industry. Because they can be only used once in the US they get sold to other producers of rum and whisky. To make shipping easier and to reduce costs they often get broken down into staves and reassembled in Scotland as hogsheads.

  • Kilderkin (capacity 82 litres)

More common in the beer industry but in rare occasions also in the whisky industry.

  • Quarter Cask (capacity 50 litres)

This cask is a quarter of an ASB and is used to give whisky flavour quickly because of the ratio of spirit volume to cask surface. The disadvantage of such small casks is the higher evaporation loss.

Typically used for American whiskey produced in Tennessee. The spirit is filtered through charcoal before filled into a cask. Some distilleries filter again before bottling. Other names are “Leaching” or “Lincoln County Process”.
The process of burning the inside surface of the cask in order to create ‘channels’ in the wood to allow interaction between the spirit and wood. Depending on how aggressively the cask is charred the more interaction there will be and the more interaction there is the quicker the spirit matures and delivers flavour and colour. The process of charring is usually only done to American oak casks. Sometimes old casks are re-charred to prolong their useful life.
Whisky is often chilled before bottling to remove natural substances and congeners which can cause the whisky to become cloudy if stored at low temperature or diluted with water.
Another name, or rather a more traditional name, for the new make spirit that first run of the stills.
In 1830, Aeneas Coffey invented the Coffey or Patent Still, which enabled a continuous process of distillation to take place. This led to the large scale production of grain whisky, a different, less intense spirit than the malt whisky produced in the distinctive copper pot stills. Coffey stills were first installed at Cameron Bridge Distillery in Fife by John Haig.
The most popular method of cooling spirit vapours. It is a copper tube from the lyne arm of the still, surrounded by many small copper pipes which are fed with cool water. The spirit vapours condense quite quickly with maximum copper contact.
Chemical compounds produced during the fermentation process. They include esters, acids, aldehydes, methanol and other alcohols. These are strictly speaking impurities, but they are important parts which give most of the flavour. Only the right level of congeners makes it drinkable so it must be carefully judged.
A highly-skilled crafts-person who makes and repairs the casks for whisky maturation by perfectly locking staves of wood together to make a watertight container. This art is called coopering.
All pot stills must be made of copper. Copper is an ideal metal as the way it is utilised with the stills and condensers will make a huge difference to the final spirit. The interaction between copper and condensing spirit leads to a purification process which has a high influence to the character. Take for example Cardhu and Dalwhinnie. Cardhu run their stills very gently and allow the spirit in vapour form to have lots of contact with the copper. This helps to extract some of the heavier compounds such as sulphur. Dalwhinnie, however, don’t want this copper contacts as they want those heavier compounds to carry over into the new make spirit. That’s why they run their stills very hard. The amount of copper contact is called reflux.
During the malting process barley is soaked into water in the steep to germinate. The Couch is a second tank where the wet barley is kept to dry which stops further growth.
There are three different parts during the distillation in the spirit still. It starts with the foreshots, the cut is the middle part which is collected and filled into casks for maturation and the feints are collected at the end of the distillation process. Foreshots and feints are re-distilled. The right point to collect the middle cut is the demisting point. At this point the spirit which comes off the still no longer gets cloudy when water is added.
Cytase is an enzyme that breaks down the cell walls of the barly making the starch accessible for the amylase enzyme to break down the starch into maltose (sugars).