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How is Scotch Whisky Made? A Guide to Malting, Mashing, Fermenting, Distilling and Maturing

Updated on May 8, 2014
Checking the barley...
Checking the barley...


There are literally thousands of whisky distilleries across the world. Concentrating mainly in Scotland of course, however they have spread over the planet with more appearing in the Far East, Japan in particular. That said Whisky from other countries has struggled to compete with the classic Scotch single malt. No one really knows whether this is due to the water, the peat, the climate, the ingredients or simply the history and appeal of a Scottish dram. Whisky has to follow some very simple rules in order to be called Scotch.

· It must be made from malted barley and water

· It must be created in a distillery in Scotland

· It must have matured for at least 3 years in oak casks; and

· It must be matured in Scotland.

Despite modern technology and efficiencies the method for making whisky has remained generally unchanged for the last 200 years or so.

A good source of water is essential
A good source of water is essential
A peat fire dries the malted barley  and adds a smoky peaty flavour
A peat fire dries the malted barley and adds a smoky peaty flavour
Malted Barley, notice the germination...
Malted Barley, notice the germination...

What Ingredients Do We Need

3 ingredients are required to make whisky, a 4th, peat is often also added.

Water –Scotland has been blessed with very soft water which enhances the process by absorbing more out of the malted barley than hard water would. It also rains a hell of a lot in Scotland so there is plenty of water. Many successful distilleries were set up by a loch to provide a ready supply of fresh water. Some believe that the naturally high levels of peat in the water in certain areas of Scotland contributes to peaty whiskies, but I’m afraid that is just a myth, the taste of the water will provide no contributions to the flavour of the whisky and the peat comes from the peat fires used to dry the barley.

Yeast – whisky, just like beer requires yeast to convert the sugar from the malted barley into alcohol. Has no real effect on the flavour, but wouldn’t be whisky without it.

Peat – as part of the malting process heat is used to prevent the germination process. The source of this heat are large fires, some distilleries use peat from local peat bogs (of which there are many in Scotland) as a fuel source for the fires. This has the added effect of absorbing some of the smoky, peaty flavours in to the whisky. This process is mostly used on the island malts most notably Islay which is commonly associated with smoky and peaty whiskies.

Malt – The real key ingredient for whisky is Malted barley. This is where barley is germinated and dried as described below. Barley is always used for malt whiskies; grain whiskies can use any other grain like maize or wheat.

Drying malted barley on a 'floor'
Drying malted barley on a 'floor'

Malting Process

Firstly barley is soaked in water to get the germination process going; this causes shoots to grow from the barley.. While germinating the barley will start consuming its own sugar so you don’t want it to go on for too long. At this point the barley is ‘kilned’, this means that it is heated over a large fire to halt the germination process. Here some distilleries add the peat that I mentioned above. The malting process will take between 24-48 hours depending on whether the barley is dried on a large flat plate called a ‘floor’ or rolled around in a drum to air and dry. Once dried the malted barley is ground into a fine powder called ‘grist’ to be mashed.

Great guide to brewing your own whiskey...

The Kings County Distillery Guide to Urban Moonshining: How to Make and Drink Whiskey
The Kings County Distillery Guide to Urban Moonshining: How to Make and Drink Whiskey

A new generation of urban bootleggers is distilling whiskey at home, and cocktail enthusiasts have embraced the nuances of brown liquors. Written by the founders of Kings County Distillery, New York City’s first distillery since Prohibition, this spirited illustrated book explores America’s age-old love affair with whiskey.

A mash-tun mashing malted barley
A mash-tun mashing malted barley

Mashing Process

Mashing is where you convert the starch in the malted barley into sugar which you can then ferment into alcohol. The mashing is done in a ‘mash-tun’, which is a large receptacle where the grist is combined with water and raked or stirred with large mechanical blades. The output of this process is a sugary liquid called ‘wort’; this is filtered out of the mash-tun and then fed back in 3 or 4 times before being collected for fermentation.

Wort fermenting in a wash back, turning sugar into alcohol.
Wort fermenting in a wash back, turning sugar into alcohol.

Fermentation Process

Yeast is now added to the ‘wort’ to convert the sugar into alcohol, this is done in a vessel called a wash back which were historically made of wood, but now often made of stainless steel, much to the chagrin of some enthusiasts who insist you can taste the wood from the wash back. How they would detect that I’m not so sure.

Copper stills absorb impurities from the spirit
Copper stills absorb impurities from the spirit

Distillation Process

All whisky in Scotland is made in copper pot stills. The pot stills are used to evaporate the alcohol which then condenses and is gathered from the neck of the still. The particular sizes and shapes of the stills all contribute to the individual flavours of the whiskies. Copper must be used as it removed some of the impurities from the spirit. The spirit is distilled twice, once in the wash still, then in a smaller spirit still where the spirit that is good enough to be matured is collected.

Whisky maturing in oak barrels
Whisky maturing in oak barrels

And Finally Maturation...

To be called Scotch whisky the spirit must be matured in oak casks, however rarely are new oak casks used. The purpose of the cask before it has been used for whisky is a major contributing factor to the flavour and the colour of the whisky. Often bourbon or sherry casks are used. Under US law bourbon casks can only be used once, which is to the gain of whisky makers all over Scotland as they can use these casks another 2-3 times. Some whiskies are finished in a different cask, they could have 10 years in a bourbon cask and then finish for a few years in a sherry cask, this gives the whisky a different flavour. Glenfiddich Solera is a good example of this. Glenmorangie also finish in different casks and have been known to use port and cognac casks as well as bourbon and sherry.

To be called whisky the spirit must stay in the cask for at least 3 years, but most will spend another 9 years or so in wood before being let out. As time goes on some of the spirit is lost through evaporation, this is known as the angels share. The angels take a fair interest rate of about 1-2% a year. This is a contributing factor to why older whiskies are so much more expensive, simply because by the time they come to be bottled much more of it has been sent to the angels.


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    • dommcg profile image

      dommcg 5 years ago

      Many thanks Rain Defence, indeed it is amazing just what difference the environment and differentiation in the process actually makes. For instance a Laphroaig Quarter Cask is matured in smaller than usual casks (quarter of the size), because of the reduced size the whisky has more contact with the wood so more of the wood flavour is absorbed.

      In the first distillation the alcohol is evaporated and is drained of into another still, this evaporated liquid is called low wine and is the basis for the final whisky, what remains in the first still called 'pot ale' and is usually dried and used for animal feed. Lucky cows...

    • Rain Defence profile image

      Rain Defence 5 years ago from UK

      This is very interesting to a whisky drinker like myself and is actually quite poetic, it conjures up a nice image of the angels, rolling around blind drunk on good whisky :)

      It's quite amazing that something with so few ingredients can have such a varied taste.

      When you say the spirit is distilled in copper stills where the alcohol evaporates, is this just removed from the drink altogether?