Malt is often called the “Heart of Beer” for good reason. Malted barley, or malt, is the basic ingredient used in the production of beer, providing complex carbohydrates and sugars necessary for fermentation, as well as contributing flavors and colors that are uniquely characteristic of beer.
Standard malts and specialty malts
There are two main categories of malt: standard and specialty. Standard (base or brewers) malts contain high amounts of enzymes, complex carbohydrates, and sugars necessary for fermentation. Specialty malts are produced when the length of time, temperature, or humidity of the three stages of the malting process—steeping, germination, and drying—are adjusted to develop unique flavors and colors, or distinctive functionality.
More intense heating decreases the amount of enzymes available for fermentation, so many specialty malts are designed to be used in smaller amounts to contribute unique flavors such as intense malty, sweet caramel, nutty, woody, coffee or burnt, and rich colors ranging from golden to red to black.
Handcrafting specialty malts differs from the basic malting process in that batch sizes are generally smaller, it is a much more labor and resource-intensive process, it involves more laboratory testing for consistency, and it requires the constant vigilance of an experienced maltster who relies upon his senses of sight, taste, smell, and touch to achieve the desired finished product from the beginning to the end of the process.
Barley is the ideal cereal grain for malting and, ultimately, brewing. It is self-contained, having a husk to protect the germ, high starch-to- protein ratio for high yields, a complete enzyme system, self-adjusting pH, light color, and neutral flavor.
In addition to barley, wheat and rye are also routinely malted for brewing. Other cereals grains, such as buckwheat and spelt, can also be malted but the finished malt does not perform in the brewhouse as well as malted barley.
Step 1) Steeping
The basic malting process, although more of an exact science today than when man first dipped baskets of grain into open wells in Mesopotamia 5,000 years ago to prepare it for brewing, remains a three-step process: steeping, germination, and drying.
During steeping water is absorbed by the raw barley kernel and germination begins. Steeping starts with raw barley that has been sorted and cleaned, then transferred into steep tanks and covered with water.
For the next 40-48 hours, the raw barley alternates between submerged and drained until it increases in moisture content from about 12% to about 44%. The absorbed water activates naturally existing enzymes and stimulates the embryo to develop new enzymes. The enzymes break down the protein and carbohydrate matrix that encloses starch granules in the endosperm, opening up the seed’s starch reserves, and newly developed hormones initiate growth of the acrospire (sprout).
Steeping is complete when the barley has reached a sufficient moisture level to allow uniform breakdown of the starches and proteins. One visual indicator that the maltster uses to determine the completion of steeping is to count the percentage of kernels that show “chit.” Raw barley that has been properly steeped is referred to as “chitted” barley,” the “chit” being the start of the rootlets that are now visibly emerging from the embryo of the kernel.
Step 2) Germination
In a process called “steep out,” the chitted barley is transferred from the steep tank to the germination compartment. Germination, which began in the steep tank, continues in the compartment where the barley kernel undergoes modification.
Modification refers to the break down of the protein and carbohydrates, and the resulting opening up of the seeds’ starch reserves. Good modification requires the barley to remain in the compartment for 4-5 days. Germination is controlled by drawing temperature-adjusted, humidified air through the bed. Turners keep the bed from compacting and rootlets from growing together, or felting.
Step 3) Drying
Germination is halted by drying. If germination continued, the kernel would continue to grow and all of the starch reserves needed by the brewer would be used by the growing plant.
Base malts are kiln-dried. typically with a finish heat of 180-190° F for 2-4 hours. This develops flavors ranging from very light malty to subtle malty.
Specialty malts are dried in a kiln at higher temperatures for longer periods of time, roasted, or both. Varying the moisture level and time and temperature of drying develops the flavor and color characteristics of each specialty malt.