Malting Process

Malt is often referred to as "the soul of beer" and dates back over 4,000 years. Malt is one of four essential ingredients used in producing craft beer. It is malt that provides color, aroma, flavor, and body to every ale and lager, and can set each beer apart. Although a variety of grains have been used for brewing, barley is the preferred grain for beer. Barley itself can’t be fermented into alcohol, and so it is converted to malted barley, or malt, in a process called malting.

STEEPING

The first and very critical step in creating quality malt is steeping. This is when the grain kernel is cleaned and brought to life with water and oxygen. This is done by immersing or “steeping” the grain in water, followed by an air rest period that allows the water content of the grain to increase.

The absorbed water activates naturally existing enzymes and stimulates the grain to develop new enzymes. The water temperature and aeration are vital for producing high-quality malt.

The steeping process can vary with grain type and size but typically occurs over a period of 24-48 hours. The steeping is complete when the barley has reached a sufficient moisture level to allow a uniform breakdown of starches and proteins.

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Germanating

The second step is to continue the germination process that started in steeping. Here, growth and modification of the grain occurs. From the outside of the grain, rootlets emerge from the kernel, and within the outer husk a shoot – or acrospire – grows. Modification is the breakdown of protein and carbohydrates and results in the opening up of the seeds’ starch reserves. This process typically takes 4-6 days and results in what is called “Green Malt.”

To achieve a high quality and consistent germination process, the maltster controls temperature and moisture levels with regulated airflow and uniform water spray. To avoid grain clumping, non-uniform heating, and varying rates of germination, the grains are separated with periodic rotation. Even with modern equipment and this structured approach, the degree of modification is still gauged by our craft malster with his eyes, his sense of smell, and with his hands. Malting truly is part art and part science.

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Kilning

The third and final step in the malting process is kilning. Convection heat treatment dries the green malt to prevent further germination. If germination continued, the kernel would keep growing and all of the starch reserves needed by the brewer would be used by the growing plant. For most malts, moisture is initially removed from the germinated grain – this is called Withering. Additional drying further reduces the moisture content and prepares the malt for flavor and color development.

Other important results achieved during the kilning process include enzymatic activity and friability. It is the controlled variations in this step that produces the wide range of malt colors and flavors used by brewers in crafting their unique and distinctive ales and lagers.

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Roasting

Roasting is done in 4 distinct stages: steeping, germinating, roasting and cooling. At GWM Malt, grain spends 34-46 hours in steep tanks where we aim for a target moisture of 42-44%. The grain is transferred to germination which lasts for around 4 days in Wanderhaufen style streets. This is a semi continuous moving batch germination process. Once germination is complete, the green malt is then transferred to the roasting drum.

The roasting takes place in two roasting drums. The average roasting time is 2 ½ – 3 hours with an air on temperatures of up to 460˚C. Our roasters take a batch size of 2.4 – 3.5 tonnes. The roasted malt is then transferred to the cooler and spends 35 – 60 minutes there in order to drop the temperature to <15˚C and fix the color and flavor compounds. The malt is analyzed before storage and thereafter awaits dispatch to our customers.

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Deculming

During deculming, the rootlets (also known as culms) that developed during germination are removed using vibrating trays soon after transfer from the kiln. As the grains are very dry, the culms come off very easily. The removed culms are typically sold or processed as animal feed

At the end of the malting process, the grain is dry and brittle with a golden yellow color. In the right storage and hygiene conditions, it can be kept for more than a year.

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Floor Malting

Floor Malting

By the 17th century floor malting was the method being used to malt larger quantities. Floor malting was the only method of malting in use until the 1850’s. A few specialty maltsters in the UK, Germany, and the Czech Republic continue to make floor malts available to brewers, who prize them for the deep, rich flavors.

In floor malting, just as in modern mechanized malting, the incoming grain is first steeped in large vats, in an alternating series of “wet” and “dry” cycles. See malt. Once properly hydrated, the malt is then sent not to a germination chamber, but to a “floor,” where it is spread evenly by hand into an approximately 15 cm (6 inch) thick layer. While on the floor, the germinating grain must be turned by hand twice a day, 7 days a week, to keep it properly oxygenated, to dissipate heat, and to keep rootlets from tangling the malt into an unmanageable mat. The traditional tools for this hard labor are a wooden malt shovel and a special, iron-wrought rake that often weighs up to 70 lb (30 kg). The rake, dragged arduously through the malt, is simply called a “malt rake” or “puller” in the UK, but in Germany it is known by the very strange name of “wohlgemut,” meaning “pleasant disposition.” At the proper germination stage, when the acrospires have grown almost as long as the barley kernels, the moist, green malt is sent to a kiln, where it is spread by shovels in a one-half meter (not more than two feet) thick layer. From then on, the drying process proceeds much as it does in a modern kiln, except very slowly, for perhaps 32 to 48 hours rather than the 24 hours that are now common in industrial malting. The temperature in an old-style kiln with floor malt rarely exceeds 85°C (185°F).

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