1.27.2013

How to Make Whisky

Overview
This post will explore the ingredients, equipment and process used to make whisky. Special attention will be given to Scottish whisky.

Whisky Distillery | Image Credit: eHow




Ingredients
Three key ingredients are used to make whisky: barley, water and yeast.

  • Barley: The quality of barley has great influence on the quality of the end product. Barley selection is largely based on two things: highest sugar content and the lowest price. Much of the barley used to produce Scottish whisky comes from England and South Africa.
Barley | Image Credit: Golden Gate Greenista

  • Water: The quality of whisky also depends on the quality and purity of the water. Scottish water is known for its great purity. Water in the Highlands is often peaty, which gives it a brownish color. Water is used in several steps during distillation. First, it is mixed to the malt grind to produce the wort. Second, it is used for cooling the alcohol leaving the still. Third, it is used to reduce the level of alcohol at bottling. 
Josie's Well Natural Spring Water | Image Credit: Watch Russia

  • Yeast: Brewer's yeast is often mixed with culture yeast to start the fermentation process. The choice of yeast is part of the manufacturing secret of the distillery. 
Yeast | Image Credit: Wise Geek



Manufacturing Steps
The manufacturing process for whisky takes at least three years. A spirit matured in an oak cask for less than three years cannot legally be called whisky. Single malt whisky is often aged a minimum of eight to ten years. Whisky, like any alcohol, is the result of natural chemical alterations of sugar. To produce alcohol, one must first produce sugar.

  • Malting: Malt is the result of the malting process. The barley is made wet and spread on the malting floor for germination to start. A succession of chemical reactions change the starch contained in the barley to sugar, which will later change into spirit. The art of malting requires one to find the right moment to stop the germination process. Depending upon the season, malting takes eight to twenty-one days. Constant attention must be given. Barley must be turned over regularly to ensure a constant moisture and temperature, and to control the germination of the barley grains. The end of germination is signaled by drying the germinating barley over a fire, which is often heated by peat. The smoke of the peat fire will influence the taste of the whisky. Today, many distilleries outsource the malting step to a third party for economic reasons. 
Malt Floor | Image Credit: Tommy Tweed

  • Grinding: Once the malt is dry, it is ground to make a coarse flour called grist. Malt grinding is done with a malt mill in the distillery. Nearly all distilleries use the same kind of mill.
Grist | Image Credit: Vinum Importing

  • Brewing: The grist is mixed with hot water in a mash tun. Generally one volume of grist is mixed up with four volumes of water. In this operation, three successive waters are used, at a temperature between 63% and 95%. A mash tun can contain up to 25,000 liters and has a double bottom with thin perforations to let the wort (sugared liquid resulting of the brewing operation) flow out, retaining bigger parts which will be sold as cattle food. The mash tun has rotating blades to facilitate this process, and the waste is called draff. This operation takes about one hour, and will change the starch into fermenting sugars. This mix of water and grist looks like porridge, and the sugared juice is called wort. The remainder will be brewed three to four times in order to get a maximum of wort. The quality of the wort is controlled by the excisemen because it determines the amount of spirit which will finally be produced. This is the basis of the taxation of the distillery. 
Wort | Image Credit: Chez Mojo

  • Fermentation: Yeast is added to the wort inside of a wash back to begin fermentation. The interaction of yeast and sugar in the wort will produce alcohol and carbon dioxide. Wort begins to bubble during this process. Wash backs are made from Oregon pinewood or Scottish larch, but stainless steel wash backs are growing in number since they are easier to maintain. The result of fermentation is largely the same regardless of the type of wash back chosen. Once the wort has fermented, a beer-like substance remains. Until now, there is little difference between the process of making whisky and the process of making beer. Going forward, however, is where things begin to differ. Beer would be perfumed with hops whereas whisky will be distilled without alterations.
Fermentation | Image Credit: TPE Whisky

  • Distillation: The distillation is the process used to separate alcohol from water and other substances contained in the wash. This operation is the base of all spirits around the world. Distillation occurs in stills which evaporate water at 100% and alcohol at 80%. Alcohol is transformed into vapor and raises into the still before water begins evaporating. Pot stills are used to make Scottish whisky. Size of the still is fixed by law due to historical reasons related to excise rights. Stills are usually made from copper since this material has a great influence on the physical process of separation of water and spirit. The quality of the dram years down the road is partly influenced by the copper surface in contact with the liquids during distillation. The shape, height and length of the still are also important in determining the future taste of the whisky. Traditionally, stills were heated with coal or peat. Today, most are heated with vapor as it allows more control throughout the process. Gasoline is most often used to heat the vapor, but in some cases coal is still used. Scottish whisky is generally double-distilled. The distillation process occurs in two stages in two stills with different capacities and shapes. The first distillation occurs in the wash still with a capacity between 25 and 30 liters and transforms wash into "low wine" at about 21% of alcohol. Wash of the first distillation is called "pot ale" or "burnt ale" and is transformed to feed cattle. The second distillation occurs in a spirit still which is generally smaller than the wash still since there is less liquid in the process. During this phase, only the "distillation heart" (the part between 63% and 72% of alcohol) will be casked for aging.
Copper Pot Still | Image Credit: The Freedom Buzz

  • Aging: The conditions associated with the aging process have great influence over the taste of the whisky. For example, the aging process, casks used, nature of the warehouse, taste of the air and location all effect the whisky's taste. It is said that the quality of the barley, making process and quality of the casks account for 95% of the final quality of a malt whisky. To bear the name "whisky," a grain spirit (malted or not) must be aged for at least three years in an oak cask. Scottish whisky is always matured in second-hand casks using one of three kinds: barrel (+190 liters), hogshead (+250 liters) or butt (+500 liters). Often, whisky is aged for a while in bourbon (American whisky made from corn) casks and then finishes aging in another cask for six to twelve months in order to give the whisky interesting fragrances. The advantage of oak for maturing alcohol is that is is not airtight. Surrounding air enters the cask and some whisky (1% to 2% per year) within the cask evaporates. Evaporation effects the water contained in the cask and can reduce the alcohol percentage. This diminution of alcohol is called "the angel's share."Excise rights are calculated on the amount of alcohol coming out of the still. As this amount diminishes throughout aging, it would not be fair to tax the marketed whisky based on the alcohol percentage it had when distilled. The nature of the warehouse is also important. A damp cellar or a dry cellar will influence the evaporation of the spirit. In a dry cellar with a concrete floor, mainly water will evaporate leaving a dryer whisky with a higher alcohol percentage. In a damp cellar with an earth floor, alcohol will evaporate leaving a rounder whisky with a smoother taste.
Oak Cask Cellar | Image Credit: Drinking Made Easy

  • Bottling: This is the final step before putting the whisky on the market. Unlike wine, whisky does not mature in bottles. For example, a 12 year old whisky stays a 12 year old whisky regardless of the time passed since bottled. When bottled, some residues are left in the whisky leaving a cloudy complexion. This is not always appreciated by consumers, so many distilleries use chill filtering to remove all residues. However, the problem with chill filtering is that it also removes parts of the fragrance and taste. More and more single malts today are not chill filtered. During bottling, the alcohol percentage is reduced. The minimum ABV for whisky is 40%. Most bottles are marketed at this percentage since excise rights are calculated on the alcohol percentage in the bottle. Whisky that is not diluted before bottled is called cask strength. Generally, casks are mixed before bottling to get a more standardized product, much like wine. When the whisky comes from just one cask, it is called single cask. Many distilleries do not bottle but rather outsource this operation to specialized plants. 
Whisky Bottling | Image Credit: Denver Off the Wagon


Sources

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