Irish and Scotch Whiskies differ in taste due different distillation processes. Scotch Whisky is distilled twice, where as Irish Whiskey is distilled three times. Irish Whiskey, like Scotch, is a barley derivative meaning it is often cut with neutral grain spirits. The malt half, sprouted barley with oats, is dried in a closed kiln so there is no smoky flavor.
Irish Whiskey, from Ireland, must be aged in seasoned cooperage for at least four years. Usually they are aged seven to eight years before bottling. There are several types of Whiskey common to Ireland:
Types of Irish Whisky
- Single Malt – Irish Single Malt Whiskey is made from 100% malted barley distilled in a pot still.
- Single Grain grain whiskey made from grains distilled in a column still. Grain whiskey is much lighter and more neutral in flavor than single malt and is almost never bottled as a single grain. It is instead used to blend with single malt to produce a lighter blended whiskey.
- Pure Pot Still Unique to Irish whiskey is pure pot still whiskey (100% barley, either mixed malted and unmalted, or single malt, distilled in a pot still). The “green” unmalted barley gives the traditional pure pot still whiskey a spicy, uniquely Irish quality. Like single malt, pure pot still is sold as such or blended with grain whiskey.
- Blended Whiskey Usually no real distinction is made between whether a blended whiskey was made from single malt or pure pot still.
Scotch Whisky, made in Scotland, must be aged in seasoned cooperage for at least three years, although most single malts are offered at a minimum of eight years of age. Some believe that older whiskies are inherently better, but others find that the age for optimum flavor development changes drastically from distillery to distillery, or even from cask to cask. Color can give a clue to the type of cask (Sherry or Bourbon) used to age the whisky. Sherried Whisky is usually darker or more amber in color, while Whisky aged in ex-Bourbon casks is usually a golden-yellow/honey color.
Scotland is traditionally divided into five whiskey producing regions: The Highlands, Speyside, The Lowland, Islay and Campbeltown.
Malt whisky production begins when the barley is malted – by steeping the barley in water, and then allowing it to get to the point of germination. Malting releases enzymes that break down starches in the grain and help convert them into sugars. When the desired state of germination is reached, the malted barley is dried using smoke. Many, but not all, distillers add peat to the fire to give an earthy, peaty flavor to the spirit. The dried malt is ground into a coarse flour called “grist.” This is mixed with hot water in a large vessel, called a mash tun. The grist is allowed to steep.
This process is referred to as “mashing,” and the mixture as “mash.” In mashing, enzymes that were developed during the malting process are allowed to convert the barley starch into sugar, producing a sugary liquid known as “wort.” The wort is then transferred to another large vessel called a “wash back” where it is cooled. The yeast is added, and the wort is allowed to ferment. The resulting liquid, now at about 5-7% alcohol by volume, is called “wash” and is very similar to a rudimentary beer. The next step is to use a still to distill the mash, which will result in a purer form of alcohol.
There are two types of stills in use for the distillation: the Pot Still (for Single Malts) and the Coffey Still (for Grain Whisky). All Scotch Whisky distilleries distill their product twice except for the Auchentoshan Distillery, which retains the Lowlands tradition of triple distillation.
For Malt Whisky, the wash is transferred into a wash still. The liquid is heated to the boiling point of alcohol, which is lower than the boiling point of water. The alcohol evaporates and travels to the top of the still, through the “lyne arm” and into a condenser – where it is cooled and reverts to liquid. This liquid has an alcohol content of about 20% and is called “low wine.”
The low wine is distilled a second time, in a Spirit Still, (in Irish Whiskey a second, smaller pot still is used), and the distillation is divided into three “cuts.” The first liquid or cut of the distillation is called “foreshots” and is generally quite toxic due to the presence of the low boiling point alcohol methanol. These are generally saved for further distillation.
The “middle cut” is placed in casks for maturation. At this stage it is called “new make.” Its alcohol content can be anywhere from 60%-75%.
The third cut is called the “feints” and is generally quite weak. These are also saved for further distillation.
It is at this point the Irish and Scotch distillations differ. The “middle cut”of Irish Whiskey is distilled for a third time in a pot still. This is why Irish Whiskey is said to be triple distilled.
Once distilled, the “new make spirit” is placed into oak casks for the maturation process. Historically, casks previously used for sherry were used. Nowadays these casks previously contained Sherry or Bourbon, but more exotic casks such as Port, Cognac, Calvados, Beer and Bordeaux wine are sometimes used.
The ageing process results in evaporation, so each year in the cask causes a loss of volume as well as a reduction in alcohol. The 0.5–2.0% lost each year is known as the “Angel’s Share.” Many Whiskies along the west coast are stored in open storehouses on the coast, allowing the salty sea air to pass on its flavor to the spirit.
Vatting and Bottling
With Single Malts, the now properly aged spirit may be “vatted”, or “married”, with other Single Malts (sometimes of different ages) from the same distillery. The whisky is generally diluted to a bottling strength of between 40% and 46%.
Occasionally distillers will release a “Cask Strength” edition, which is not diluted and will usually have an alcohol content of 50–60%. Many distilleries are releasing “Single Cask” editions, which are the product of a single cask that has not been vatted with Whisky from any other casks.
Many Whiskies are bottled after being “chill-filtered”. This is a process in which the whisky is chilled to near 0°C (32°F) and passed through a fine filter. This removes some of the compounds produced during distillation or extracted from the wood of the cask, and prevents the Whisky from becoming hazy when chilled, or when water or ice is added. Chill filtration also removes some of the flavor and body from the Whisky, which is why some consider chill-filtered Whiskies to be inferior.
Types of Scotch Whisky
There are two major categories of Whisky, single and blended. Single means that all of the product is from a single distillery, while Blended means that the product is composed of Whiskies from two or more distilleries. A Scotch Whisky blend can easily be the result of a marriage of as many as thirty or forty malt Whiskies, together with five or more grain Whiskies. The secret of fine Scotch Whisky, therefore, lies in the art of the blender. On his unique ability depend the polish, smoothness, and uniformity of the Whisky.
- Single Malt Whisky is 100% Malted Barley Whiskey from one distillery.
- Grain Whisky is produced primarily from corn with a small amount of barley malt. Grain Whisky in Scotland is Whisky and not grain neutral spirits, as those used in blending Bourbon. The majority of grain whisky produced in Scotland goes to make Blended Scotch Whisky.
- Vatted Malt Whisky also called “pure malt,” is one of the less common types of Scotch: a blend of single malts from more than one distillery and with differing ages. Vatted malts contain only malt Whiskies, no grain Whiskies, and are usually distinguished from other types of Whisky by the absence of the word ‘single’ before ‘malt’ on the bottle, and the absence of a distillery name. The age of the youngest Whisky in the bottle is that used to describe the age on the label, so a vatted malt marked “8 years old” may include older whiskies.
- Blended Whisky: Blended Scotch Whisky constitutes over 90% of the Whisky produced in Scotland. Blended Scotch Whiskies generally contain 10–50% Malt Whisky, blended with Grain Whisky, with the higher quality brands having the highest percent malt. Master blenders combine the various malts and grain Whiskies to produce a consistent “brand style”. Blended whiskies frequently use the same name for a range of Whiskies at wildly varying prices and (presumably) quality.
Content provided by Keith Cox, Martin Wine Cellar