All Irish malt is made from the finest quality malted barley, yeast and water. Indeed distillers prefer to use Irish barley. There is no legal requirement that says it must be Irish but with Irelands long summer days, mild and occasionally wet, give ideal conditions for growing barley. Most distilleries believe that the variety of barley does not have an impact on the flavour, though some do feel that a strain called Golden Promise does impart a different mouth feel to their spirit.
A grain of barley is like a small packet of starch. Malting is basically tricking the barley into thinking it is time to germinate. This is done by steeping it in water and then allowing it to germinate in cool damp conditions. Enzymes are triggered which will convert the starch into sugar, and it is sugar that the distiller needs. To ensure that he gets access to this, he must stop the germination process by drying the barley.
Here we have two options:
Drying the malted barley over hot air will stop germination and will not impart any flavour. 99% of all Irish Malt is dried in this manner.
Here the barley is dried over a peat fire. This will give a smoky aroma to the final spirit. Peat is semi-carbonised vegetation which when burned, gives off a fragrant smoke. The oils, or phenols, in the smoke stick to the surface of the barley.
In this step the malt is taken to the distillery where it is ground into a rough flour called grist.
The grist is mixed with hot water, at a temperature of 63.5¬oC, in a large vessel called a mash tun. As soon as the hot water strikes the grist the conversion from starch to sugar takes place. The sweet liquor, known as ‘worts’, is then drained through the perforated bottom of the mash tun. This process is repeated a further two times to extract as much as the sugar as possible. The final ‘water’ it then retained as the first water of the next mash.
1. Cloudy Worts: If a distiller pumps the worth slowly from the mash tun, he obtains what is known as clear worts. This will tend to produce spirit with no great cereal character.
2. Clear Worts: If a distiller wishes to product a malty spirit with a dry, nutty, cereal character, he will pump the worts quickly and pull some solids throught from the mash tun.
The worts are then cooled and poured into a fermenting vessel known as a washback, or fermenters. These can be made from either wood or stainless steel. Yeast is now added and fermentation begins.
1. Short: In fermentation, years eats sugar and converts it into alcohol, wash. This process is completed in 48 hours. If a distiller takes this ‘short’ option, the final spirit will have a more pronounced malty character.
2. Long: A long fermentation, over 55 hours, allows esterification to take place which produces lighter, more complex, and fruity flavours.
1. All traditional Irish potstill whiskey is triple distilled in copper pots. Copper is hugely important in creating a whiskey’s flavour as copper holds on to heavy elements, the distillers can either prolong or restrict the length of the ‘conversation’ between alcohol vapour and the copper, to create their desired character. There are three pot stills all of the same shape and size. The first distillation takes place in one of the wash stills, which is fitted with a refining column to reflux out heavy elements. The spirit is collected between 25%abv for heavy and 38%abv for light, depending on the style. The Yeast that the Irish whiskey industry use is always the same type and it is not considered to impact on the flavour. Japanese distilleries however will use different strains to produce desired flavours in their malt whiskeys.
2. The distillate stream is cut in the intermediate (feints) still. The weaker feints, between 45% and 75%, will be collected to be redistilled into ‘heavy’ spirit. The stronger feints, between 45% and 85%, will give ‘light’ spirit.
3. This is a run as normal spirit still with the middle cut being collected. The distillation regime does vary; different fill levels, different cut points in the intermediate and spirit stills.
The new-make spirit is then reduced to 63.5%abv and placed in oak casks to mature. These casks have typically been filled with either bourbon or sherry for 1 fill prior to filling with Irish Whiskey. There are three processes happening here:
1. Removal: the cask helps to remove the aggressive new-spirit character.
2. Addition: The flavour compounds in the cask and are extracted by the spirit.
3. Interaction: The flavours from the wood and the spirit meld together to increase complexity.
Time, the freshness of the cask and the type of oak all have a part to play.
Cask Type Options
1. Ex-Bourbon: These casks are made from American oak, a species which is high in compounds and gives aromas reminiscent of vanilla, crème brulée, pine, spice and coconut.
2. Ex-Sherry: These casks are made from European oak, which imparts aromas of dried fruit, clove, incense and walnut. European oak is also richer in colour and higher in mouth-drying tannin.
3. Refill: Whiskey distillers can use casks many times and the more they are used the less effect the species of oak has on the whiskey. These ‘refill’ casks are important in allowing distillery character to be shown. In practice, most distillers will use a mix of all three options as this adds complexity to the palette of flavours.
4. Finishing: Distillers can give the flavour of their whiskey a final twist by ‘finishing’ it. This involves taking a whiskey, aged normally in ex-bourbon or refill casks, and giving it a short period of secondary adding in a very active cask that has previously held sherry, port, Maderia, wine etc., imbuing the whiskey with some of the cask’s character.
Time in Maturation
It takes time to mature whiskey and legally it is not a whiskey until it has spent at least 3 years in maturation. Logically, the longer a whiskey spends in a cask, the more influence the oak will have on the spirit. Eventually, it will dominate the whiskey, rendering it impossible to tell which distillery it came from. A very active cask will produce this effect more quickly than one which has been filled many times, and which may give a neutral effect. The age statement on a bottle, simply tell you how long the youngest whiskey has spent in wood. It does not indicate how active, or otherwise, the cask has been. Old does not automatically equal good.
The whiskey is finally ready for bottling, but even at this stage there are still some final decisions to be made.
1. Chill filtration: This is a method for removing residue. The whiskey is cooled to between -10° and 4°C (often roughly 0°) and passed through a fine adsorption filter. The process prevents the whiskey from becoming hazy when in the bottle, when served, when chilled, or when water or ice is added.
2. Caramel Adjustment: The addition of spirit caramel helps in the standardisation of the colour.
3. Strength: Legally, whiskey must be a minimum of 40%abv, but ‘cask strength’ malts are becoming more popular.