The Malting Process
The malting process begins with raw barley grains harvested from the field. The grains are initially dry but are then immersed in water to increase their moisture content and stimulate sprouting.
Within a day or so, the barley grains will sprout, and as the small seedling (known as an acrospire) starts to grow, the moisture is maintained for the next few days. At the base of the seed, small rootlets also form. In traditional malt houses, this process was often conducted on a floor, known as floor malting, where the seeds were regularly turned over to prevent excessive moisture or heat. Later, the “Saladin” box was invented, which used corkscrew augers to rotate the germinating grains inside.
In modern setups, malting is typically done in a slowly rotating drum. The process begins with a static steep to initiate germination, followed by rotating the drum during germination and early growth stages. The seed is allowed to grow for several days until the acrospire within the grain reaches a similar length to the grain husk itself. This malting process develops the enzymes required for mashing.
In most modern systems, the same drum is used for kilning, which is the next step. During kilning, the grains are tumbled while hot air passes through them. This halts germination and dries out the malt. By adjusting the time and temperature during kilning, the maltster can also achieve specific colors and flavors. The rootlets and other impurities are removed during this process, leaving only the malted grain.
The Four Malt Groups
Depending on the temperature, humidity, and duration of the kilning process, four main malt groups can be produced. These include base malts, kilned malts, caramel/crystal malts, and roasted malts.
Base Malts –
These malts are made using the same process described above but are slowly kilned at low temperatures to achieve a light color. Examples of malts in this group include pilsner malt, pale malt, Vienna malt, mild malt, and lighter shades of Munich malt. These malts tend to have a clean, malty flavor with hints of toast. Mild, Vienna, and Munich malts also have a hint of caramel aroma.
Kilned Malts –
These malts are dried using a method similar to base malts but with slightly higher temperatures to achieve a light toasting effect. Kilned malts can be created at home by toasting malt at low temperatures. Examples of malts in this group include Munich malt, amber malt, melanoiden malt, honey malt, and brown malt. The flavor varies greatly depending on the color. The key difference between kilned malts and caramel/crystal malts is the absence of fruity or raisin flavors in the former. Lighter malts like Munich and amber have a cookie or biscuit flavor. Melanoidin malt has a soft cookie/cake-like maltiness without the toasty flavor. Honey malt has a caramel flavor, while brown malt, which leans towards harshness, offers deep toasty mocha flavors.
Caramel/Crystal Malts –
These malts undergo a special drying process. Instead of immediate kilning, they are kept wet and held at the standard mash conversion temperature of around 152°F (67°C) for approximately an hour before drying. Darker versions are toasted similarly to kilned malts. This process converts the interior of the malt into simple sugars, essentially creating a mash within the husk. It imparts sweetness and fruity flavors characteristic of crystal malts. Dark crystal malts should be used sparingly.
Roast Malts –
Roast malts are kilned, dried, and subsequently roasted at high temperatures. They include light chocolate malt, chocolate malt, carafa, and black patent malt. Additionally, there’s stout roast (also known as roast barley), which is technically not a malt as it consists of raw barley roasted at high temperature. Light chocolate malt has a slightly harsher profile than regular chocolate malt due to its proximity to the harsh zone. Chocolate malt offers a sharp, coffee-like roasted flavor that is even more intense than black malt. Carafa has a deep bittersweet chocolate flavor, smooth and creamy compared to black or chocolate malt. Dehusked or debittered versions of Carafa are available, which remove husks and tannins, resulting in an even smoother chocolate flavor. Black patent malt provides a rich, bittersweet chocolate flavor with coffee or espresso undertones. Finally, stout roast/roast barley leaves a dry, acrid coffee finish reminiscent of Guinness beer.
This provides a brief overview of the malting process and the four main malt groups. Understanding these groups helps me remember the associated flavors of each malt and enables me to better utilize them to achieve specific tastes in finished beer.