Malt is the product created through controlled germination and drying (or kilning) of barley, and is primarily used for brewing beer. Malt production is a natural biological process during which barley kernels are partially sprouted resulting in the modification of barley endosperm.
This modification involves the breakdown of the cell wall components, the partial breakdown of proteins, and the generation of the enzymes necessary for converting starch into sugars during brewing. This process has been carried out for centuries, with malt originally produced by hand and germinating barley turned using a shovel. Today, malting plants are highly mechanized and automated, and operate 24 hours a day, 365 days a year.
The malting process consists of three stages. Steeping is the first stage of the process, where barley is intermittently immersed in water for about 36-48 hours to initiate germination. Biochemical reactions begin to take place in the steeping stage, as enzymes are released and simple sugars supply energy to the growing embryo. Barley moisture content reaches 42-45% after this process is completed and the germination stage begins.
During the Germination Stage, the steeped barley continues to grow and biochemical reaction occur at a vigorous rate, as enzymes are produced which break down proteins and other cell wall components. The steeped barley is held in tanks about 5 feet deep for about 3.5 to 4.5 days, with air circulated through the germinating barley that is turned every 8 to 10 hours to ensure even germination. Moisture is maintained at about 44 to 47% moisture at temperatures of 57 to 70º Fahrenheit.
The Kilning Stage, the final stage of the malting process, occurs when heated air is circulated through the product to end germination and the associated biochemical reactions. Kilning also develops malt flavor and color, and dries the malt to preserve its quality. The malt, at approximately 4% moisture is very stable and can be stored for several months.
The finished malt is then usually shipped to a brewery, where the brewer crushes the malt and adds water to it. By doing this, biochemical reactions are allowed to continue to take place and starches and protein in the malt are further broken down. A sugar mixture, Wort, rich in maltose and amino acids is created from the malt and is easily converted to ethanol by brewers yeasts.