All alcoholic beverages, such as wine, beer or brandy, are made by fermenting juice that contains sugar. Juice with sugar can either be made using the pulp of the fruit (grapes, for example) or by converting starch into soluble sugar.

The starch of the barley grain has been used for centuries to make beer.

The starch of the raw barley grain will not dissolve in water or ferment. It must be converted into soluble starch that can ferment.

‘Germination’ of the barley grain makes the conversion possible. It is the first stage of the ‘malting’.

To trigger the germination, the grains are humidified and exposed to air. The barley grains are soaked in water (soaking). They are left spread in layers of 10 cm thick on the floor of the malt house. The barley grains start to sprout:

The embryo of the grain produces different enzymes that will break down into raw starch, convert crude protein and begin to produce maltose sugar.

On the first day shoots appear. After thirty hours the shoots start growing branches, they become longer and entangle.

The process starts in the heart of the barley grain that contains the embryo. The seedling grows towards the tip underneath the seed coat to become a shoot. When the shoot has the length of the grain, the germination is stopped by drying the malt (called green malt at this stage).

This is done in two phases by "kilning". The green malt is spread on a large sieve made of steel strings. Then it is exposed to a stream of hot air (50 °) that dries the grains. Next the temperature of the air is brought to 85 ° or higher. This is the "heat wave" which gives the malt its color and the specific aroma. As a last step the malt is cleaned, i.e. the grains are peeled to get rid of their rootlets. At this stage the malt is ready for brewing.

Orge maltée Malted barley, by Peter Schill (Self-photographed) [CC BY-SA 2.0], via Wikimedia Commons

Malt touraillé Mix of roasted malt (darker) and clear malt