The first process in whisky making is finding a plentiful supply of water. Scotland has some of the purest water in the world. Most distilleries are built on good reliable water sources, which can be springs or boreholes. Each unique water source adds to the character and flavour of the whisky.
In areas of the Highlands and especially Islay water will have travelled through peat earth, which gives a brown taint and distinctive flavour to it. This can give a hard quality to the water and many distilleries will use a form of de-ionisation to treat the water. This removes impurities such as mineral salts and leaves a high purity water although many distilleries use hard water as they say it gives a distinct character to their whisky. Water is used in all aspects of production of whisky from malting to
mashing and for reducing alcoholic strength.
Barley forms the foundation of making whisky. Traditionally, barley was grown on site at the distillery or purchased locally from farmers. Over the years more economically viable ways were developed in the production of barley. Malsters took over the growing and malting process in large-scale processes selling bulk quantities of malt back to the distillers. Distillers have the important job of picking quality barley for production; this plays a big part in the final quality of the whisky.
In 1965 a revolutionary barley was developed called Golden Promise, its hardy, fast maturing and superior malting attributes made it the choice barley for distillers for nearly twenty years. Up until then the class of barley had been rather mediocre. Towards the end of the 20th century new varieties of barley had been bred with all the attributes of Golden Promise but giving higher yields, popular examples are optic and chariot. Barley still continues to be a very important part of whisky.
To produce ethanol needed for distilling yeast is required. Yeast is an active compound, which is in the Fungi family. Yeast is added to the mash where sugars such as glucose, maltose and maltotriose are present. The yeast through fermentation converts the sugars into ethanol and carbon dioxide. The preferred yeast in the distilling industry is Brewers Yeast.
Whisky Making Process
Malt whisky production begins when barley is soaked water for 2-3 days this process is called steeping. It is then spread out on a stone floor and allowed to germinate for a minimum of 7 days. The malting barley is turned regularly to release any pockets of heat. A wooden spade called a Shiel was traditionally used to do this, although new more efficient techniques are being used such as drum maltings. The malted barley is next dried in a kiln using coke as fuel, some distillers favour peat as a fuel this gives the malt an earthy and smoky flavour. Finally, the stalks on the barley are removed using a process called dressing.
Today only a handful of distilleries have their own maltings; these include Balvenie, Kilchoman, Highland Park, Glenfiddich, Bowmore, Laphroaig, Springbank, Tamdhu, and Edradour. Even those distilleries that malt their own barley produce only a small percentage of the malt required for production. All distilleries order malt from specialised maltsters.
To start the mashing process firstly, the dried malt is ground into course flour called ‘grist' in the malt mill. The ‘grist' is mixed with hot water in the mash machine at a temperature of 63°C to 68°C and allowed to steep. The solution is run into a mash tun where it is mixed by rotating arms. This process called ‘mashing' allows enzymes developed during malting to convert starch in the malt to into maltose (sugars). The sugary liquid called ‘wort' is run into an underback. The process is repeated 2-3 times with hotter water each time so all possible ‘wort' is captured. The spent barley called ‘draff' in the mash tun is sold on as animal feed.
The mash in certain distilleries can differ. Pot still distilleries use 100% malt mash, this differs in Patent still distilleries where they use 20%-25% malt and the rest is unmalted grain.
The wort is cooled to 20°C-25°C and then transferred to the washback. Yeast is added to the wort, which converts sugars into ethanol and ‘congeners', impurities that contain flavour. Large amounts of carbon dioxide are released and switchers control this. This will last for two days until fermentation becomes less active. The wort then becomes wash a malt beer with a strength of 5-10%.
The wash is pumped into large a large copper still called a wash still where it is heated with steam to the boiling point of alcohol 78°C. The alcohol evaporates and collects at the top of the still where it passes through the lyne arm and into a ‘worm' which is a copper coil immersed in cold water or a condenser. The vapour cools and reverts to liquid, known as ‘low wines'. When the evaporation process finishes a residue is left at the bottom of the still, this is known as ‘pot ale', similar to ‘draff, it is also used as animal feed.
The low wines run into the spirit still where the process is repeated but slower. The liquid produced when cooled runs into the spirit safe where the stillman divides it into three ‘cuts'. The first cut, the ‘foreshot' is the most volatile due to the presence of methanol substances and high alcohol content. The middle cut also known as ‘new make' is collected when the stillman feels the distillate is of required strength and quality, this is run into the spirit receiver and is about 60-75% Abv.
Finally, the feints, which are undesirable and unusable substances, are collected. The foreshots and the feints are transferred back to the wash still for further distillation.
Not all distilleries practice double distillation. Lowland distilleries like Auchentoshan and Glenkinchie and the Hazelburn whisky from Campbeltown are produced using triple distillation where the spirit passes through a wash still and two spirit stills leaving a lighter more refined spirit. Grain distilleries use patent stills, which consist of two columns - an analyser and a rectifier. The process work by continuous fractional distillation, unlike batch distillation, which is used for malt whisky this process is more efficient but produces a whisky with less flavour.
The colourless ‘new make' spirit is filled into American or European oak casks which can be new or second fill. Second fill casks will have held liquid before this could be bourbon, sherry, port Madeira, cognac or wine. Casks come in all shapes and sizes the most common are Hogsheads which can hold 63 to 140 gallons and Butts which can hold up to 126 gallons. By law whisky must be matured in a bonded warehouse for a minimum of three years and to called Scotch it must be matured in Scotland.
Over the maturation period evaporation of the alcohol occurs, about 0.5 to 2% each year this is known as the ‘angels share'. Commonly whisky is matured in casks for about 8 to 15 years and then bottled, although in some cases if a cask is of good quality and evaporation is limited whisky can be matured until 40 years.
Whisky can be bottled as single malt, blended malt or a blend, usually at 40 to 46% Abv. To do it must firstly be diluted with de-mineralised water to reduce the strength of the alcohol. Cask strength whiskies are bottled straight from cask.
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