The Scotch Whisky Manufacturing Process

by Steve Forrester

The Scotch Whisky Manufacturing Process

Scotch whisky is an alcoholic distillate made in Scotland using cereals that can be considered the most popular spirit in the world, sold in around 190 different countries around the globe. Despite the complexity of the Scotch whisky manufacturing process, the entire process of creating whisky can be broken down into five chief stages. These are malting, mashing, fermentation, distillation and maturation. These processes each have their own sub-stages. The subtle differences in the way that the various scotch distilleries perform these processes are what make each finished scotch whisky so wonderfully unique.

The manufacturing process

MALTING

There are two types of scotch whisky: malt whisky and grain whisky. There are only slight differences in the manufacturing processes of these two types.

The process in which barley is germinated and dried to provide nutrients for yeast development is known as malting. The barley grains are steeped in water and then evenly spread out for 8-12 days on a specially prepared floor called the malting floor. During this period, germination takes place. This process may be done manually or mechanically. The temperature and humidity of the malting room may be carefully controlled to further enhance the process. 

The enzyme diastase produced by the barley grains during germination makes the starch soluble. After the germination phase, the grains are dried. Drying can be achieved by blowing hot air or by heating them on a perforated surface using a kiln in controlled conditions. In the case of grain whisky, other cereals like corn and wheat may be added.

MASHING

Mashing is the process in which the dried barley grains, hereafter referred to as the malt, will be converted into wort – a liquid which will then be fermented. The malt is first ground into coarse particles in a mill. The malt is not ground into fine particles to ensure that it doesn’t stick to the sieves in the later phases of production. This grounded malt is called grist.

The grist is then mixed with hot water and stirred in a large tank called the mash tun. Another enzyme that was produced during the malting phase called amylase breaks down starch into simple sugars when stirred. This “sugary water” is referred to as the wort. In the case of grain whisky, the other cereals are cooked to produce starch.

In modern installations, the wort is then pumped through heat exchangers which cool the wort by extracting heat energy from it. This energy can be re-used to heat the next batch of water for use in a mash tun.  Anything that remains in the mash tun after the wort is drained is called draff. It may be used as fertilizers or animal feed after drying.

FERMENTATION

During fermentation the wort is then transferred into large vessels called washbacks, where yeast is added. Yeast breaks down the sugars (mainly glucose) produced during mashing into ethanol (alcohol), carbon dioxide and heat energy. Chemical substances known as esters are also produced during this phase, which give the whisky its characteristic taste.

The taste of the whisky can be influenced by the fermentation time, the type of yeast added and the temperature maintained during the entire fermentation process. This process usually lasts anywhere between 48 to 96 hours. The wort, which now contains alcohol, is now known as wash.

DISTILLATION

The wash is then drained into a large copper still called the wash still for distillation. Here it is heated and the vapors formed are guided through pipes into condensers. The liquid obtained is called low wine, which is collected into a spirit still. This process separates the alcohol from the yeast and any other un-fermented matter.

This process is repeated once again with the low wine and now the liquid can be considered spirit. The first run of the spirit does not reach acceptable concentration and is drained away to be mixed with low wines in the next batch. Only the heart of the run is collected in a vessel called the spirit receiver.

In the case of grain whisky, a Coffey still is used, and the spirit collected is highly concentrated.

MATURATION

In maturation the spirit collected is stored in an air tight oak cask under controlled conditions. The temperature, humidity, strength of the spirit and size of the cask affect the maturation process. The maturation phase lasts for at least 3 years. During this process the whisky becomes smoother and gains its characteristic golden colour.

Finally, both grain whisky and malt whisky may be blended together to create a whisky referred to as blended whisky. Blending further smoothens the flavour. During this process, sugar and additional water may be added to suit the blender’s needs.

All that’s left now is the drinking! The creation of scotch whisky is close to an art form, and we heartily suggest to all whisky lovers to try to visit a few renowned scotch distilleries in your lifetime to get a feel for it yourself first-hand.




Steve Forrester
Steve Forrester

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