The malt production

The starting point of malt Whisky production

Glendronach - Classic Malt Base
Glendronach - Classic Malt Base

For single malt whisky production, barley malt is used as the starting product. This article deals with the production method of malt and the necessary technical equipment and rooms. Those who do not yet know the basic production method of single malt whisky can inform themselves beforehand in this video and article.

Barley malt, as the name suggests, consists of barley. But the harvested barley grain cannot be processed directly into beer or whisky. The starch stored in the barley grain must first be broken down into sugar before the yeasts can begin fermentation. To find out exactly how this happens chemically, please read our article From Grain to Alcohol.


In the past and today

Tamdhu - distillery and malt house

Although the production of barley malt basically always proceeds in the same way with soaking, germinating and drying, two different production processes have emerged in the past: Malt Floor and Saladin Box. Today, most of the malt for whisky production is produced in so-called drum maltings exactly according to the specifications of the distilleries. What you are reading here is a look back into the past.

Below are photos of various maltings for illustration. Only Tamdhu still had the Saladin boxes until 2010, where you can produce a lot of malt in one batch due to the layer of malt being over a metre thick. So Tamdhu still produced the malt for Macallan, Glenrothes and other distilleries in the group with its Saladin boxes. All the other small maltings still running use simple malt floors and have only a small malt output. Whenever you see photos of Tamdhu here, please be aware that it was a large-scale malt house.

Port Ellen - Grand Maltings

Over a hundred years ago, there were only malt floors on which the distilleries - just like the breweries - germinated their barley into barley malt. The first step towards automation was the Saladin boxes, which automated the germination of the barley, but did not bring any advantages when it came to drying the malt. Today, drum dryers are used for drying on a large scale, but we will not go into these in detail in this article.

Only a few distilleries still have their own small malt houses. Admired by many and regarded as particularly authentic, the malt from these maltings costs the distilleries far more than the industrially produced malt from specialised large maltings (e.g. Port Ellen).

The chemical process


In the production of barley malt, an ideal, warm and humid environment is simulated for the barley grain to germinate. What has to happen happens. The barley grain activates its solar energy stored in the field and converts the built-up starch into sugar. Sugar that the 'small factory' barley grain would like to convert into cellulose to grow roots and a sprout with leaves.

But after breaking down starch into sugar, man interrupts this process by drying it and uses the malt sugar (maltose) to make a sweet, watery liquid (engl. wort). To do this, the malt is first coarsely ground. The sugar is then dissolved with hot water and finally fermented together with yeast to make beer and then distilled.


Bowmore - Grain/Malt Truck

Today, the barley is transported to the distillery by truck. 40-ton trucks, fully loaded with dried barley, drive to the distilleries. It makes no difference if a distillery no longer has its own malt house. In this case, the truck delivers finished malt straight away. But here we consider the rare case of the distillery having its own malting plant. There are only less than 10 of these distilleries left: Balvenie, Bowmore, Glen Garioch, Glen Ord, Highland Park, Laphroaig, Speyburn and Springbank. Except for Speyburn and Glen Ord with pneumatic drum maltsters, the other distilleries now only produce some of their malt on their own malt floors, mainly for reputation with visitors.

Tamdhu - Sampling with the Monkey

Now, before 30 cubic metres of barley are taken into the silos of the malting plant, the distillery has to take a sample and check the quality of the barley. Only if the barley meets certain quality criteria such as density, moisture, starch content, germination capacity, nitrogen content and purity does the inspector allow the barley to be accepted. The amount of ripening fungi and pests is also checked. To take the sample from the truck, the inspector uses a special sampling arm called a monkey.

Corn weevil (Sitophilus granarius) Photograph by M.E. Brown, ADAS, Slough Lab

The whole load of barley is pumped with compressed air into one of the silos for storage. Here the barley waits for further processing. A serious barley pest is the grain weevil. It likes to hide in the barley and can feed and multiply there.

Balvenie - Steeping the Barley

Anyone who has ever bitten into a raw grain knows how hard these dried grains are. Before germination , these grains must therefore be soaked for several days. During this time they really soak up water, which they need for the biological triggering of the germination process. The soaking process takes about two to three days. It goes without saying that the same pure spring water is used for this as for dissolving the sugar.

After soaking the barley in the large and small maltings, the further procedure differs between malting floors and Saladin boxes in the degree of automation.

Bowmore - Malt Base

With the help of simple tools such as wheelbarrows and rakes, the soaked barley is spread out on the malt floors at a height of around 8 to 12 cm.

The malting floors must be properly ventilated so that no fungi or bacteria attack the barley. But that is not all. The barley must be turned regularly because the biological reaction heats the barley in the middle layer. To ensure that all barley is finished evenly, the maltster makes sure that the barley is not overheated and that it is turned and mixed completely. Despite all this, the result remains 'sub-optimal'. In this respect, even the best maltster has to bow to the results of the modern large-scale malting plants.

Balvenie - Sweeping up the malt

Speaking of bending: In the past, much of the turning work was done with the malt shovel. After 30 years of turning malt with the shovel, the workers tended to have permanent deformities of their skeleton. This occupational disease was aptly named 'monkey shoulder'.

Tamdhu - filled Saladin Box circulating rake moved forward

The mixing and aeration in the Saladin boxes at Tamdhu was completely different.

A rake driven by electric motors regularly drove along the side rails through the barley layer, which was more than one metre high. The grains were evenly mixed through large, helically curved plates. Since the rooms were controlled in temperature and humidity by air conditioning and ventilation, the conversion rate between starch and malt sugar in these apparatuses was incomparably higher than on the malt floor.
The large Tamdhu malthouse had a whole floor full of these saladin boxes, which were in operation around the clock. The Saladin boxes were emptied via the suction pipes visible in the foreground.

Balvenie - spreading the malt on the kiln floor

The following drying process takes place in the same way for large and small maltings. When the barley grain - we prefer to call it malt now - bursts open and begins to form its roots and germ, the germination process is interrupted. This is because the build-up of the germ consumes the sugar from the malt, which is then no longer available for fermentation.

Stopping the germination works by heating and drying. Heating to more than 70 degrees destroys the enzymes (amylases) released by the barley grain for germination and drying ensures that moulds and bacteria no longer affect the fresh malt.

Laphoraig - Kiln Fires in the Kiln

The still damp malt is spread on a perforated drying floor above a fireplace. This kiln is also called a kiln. These kilns were used as early as 6,000 BC and could reach temperatures of up to 900°C at that time. Kilns were used, among other things, to dry pottery, tobacco or even malted barley. The drying floor, on which the barley is spread, is placed above the hot fire source. Often, the floor is made of taut steel wires that are spaced less than the diameter of the malt grains. Some distilleries use peat as fuel, the smoke from which gives the malt and thus later the whisky a special, smoky aroma.

Benriach - Kiln firing

The hot exhaust air from the kiln fire is conducted through the spread layer of malt, thus extracting the moisture from it, which escapes into the open air via the pagoda-like clad chimneys. A kiln floor is almost impossible to walk on when the fire is burning underneath. The over 70 degree heat, combined with extremely high humidity, immediately takes your breath away. Glasses and lenses of cameras fog up immediately.

Highland Park - Kiln with Padog Roof

If peat is added to the drying fire, an acrid smoke develops which provides the smoky aroma in the malt whisky. The different smokiness of our malt whiskies depends strongly on how long the malt used was allowed to kiln over peat fire and/or normal fire.

Glenlivet - malt store with mechanical transport

After kilning, the malt can be kept for a few weeks before it is coarsely milled in the malt mill to dissolve the sugar with hot water. The process of mashing is examined in detail in the following article.

Malting today

But which malt is better? The malt from your own small, time-honoured malt house or the malt from the large malt house? With the exception of a few journalists, the experts are unanimous. Almost without exception, the traditional malthouse, which is run by muscle power, is considered to be less good.

Why is that the case? Where does this assessment come from? It is extremely difficult and requires a lot of experience to create and maintain a climate on a simple malting floor where barley can develop and germinate optimally. No sooner does the weather change outside than the temperature or humidity is no longer in the optimal range. And in Scotland the weather changes often. The least damage is done if the change in weather only means that germination no longer starts optimally and the process is slightly delayed. It gets worse when mould forms or bacteria and fungi multiply on the malt floor. Added to this is the introduction of dirt by mice, rats and cats.

Since single malt whisky is very much linked to its traditions and must remain so, the big distilleries like Highland Park, Bowmore or Laphroaig are not turning their backs on the ancient art of hand malting. But our greatly increased demand for these great malt whiskies has led the distilleries to switch to three shifts of production, 7 days a week, since the mid-90s. Production is only interrupted for a few days a year for necessary maintenance and repairs.

But the expansion to three-shift operation on more than 300 days a year alone shows the tradition-conscious connoisseur that malting by hand alone in the distilleries is no longer possible. The buildings of the malt houses were designed for normal 8-hour productions and a tripling of the output could not be supported by the existing malt floors. Often part of the old malt floors were converted for other purposes such as visitor centres and shops. So today we are confronted with the fact that even the distilleries with their own maltings can only produce a part of the malt (about 15% to 30%) in the traditional way - a worthy and beautiful tribute to the old tradition.

Barley grows in temperate latitudes in many countries today. For a long time now, Scottish barley production has not been able to keep up with the demand for whisky and beer and so Scotland imports some of its barley but also finished barley malt from many countries, including Germany.