This week I look at the malting process, how we commonly group malts and the impacts for beer brewing.
The Malting Process
The malting process starts with raw barley grain, harvested from the field. The grain is dry when brought into the malt house, but the first step is to immerse the grain into water to raise the water content up enough to get the barley seeds to sprout.
Within a day or so the barley will sprout and moisture is maintained for the next few days as the small seedling (called an acrospire) begins to grow. Small rootlets will also form at the base of the seed. In a traditional malthouse this was often done over a floor (aka floor malting), and the seeds are raked several times a day to turn them over and avoid too much moisture or heat. Later the “Saladin” box was invented with corkscrew augers that rotated the germinating grain in the box.
In a modern setup, malting is instead done in a slowly rotating drum. The process starts with a static steep to initiate germination, and then the drum is rotated to during germination and early growth. The seed is allowed to grow for several days until the acrospire within the grain reaches approximately the same length of the grain husk itself. This malting process develops the enzymes that will be needed in the mash.
Most of these modern systems use the same drum for kilning, which is the next step. During the kilning step, the grain is tumbled with hot air running through it to halt germination and also dry out the malt. By varying the time and temperature used during kilning, the malster can also develop the color and flavor of the malt. The rootlets and other debris are also separated from the malt during this process leaving only the malted grain.
The Four Malt Groups
Depending on the temperature, humidity and time used in the kilning process you can make the four basic malt groups. These are base malts, kilned malts, caramel/crystal malts and roasted malts.
- Base Malts – Are made using the exact process above, but kilned slowly at low temperature so the malt dries with a light finished color. Malts in this group include: pilsner malt, pale malt, Vienna malt, mild malt and lighter colors of Munich. These malts tend to be clean and malty with hints of toast. The mild, Vienna and Munich malts have a hint of caramel aroma.
- Kilned Malts – These malts are dried in a method similar to base malts but the temperature is raised at the tend to lightly toast the malts. You can create many kilned malts in your oven by toasting your own malt at low temperature. Malts in this group include Munich malt, amber malt, melanoiden malt, honey malt and brown malt. The flavor varies widely with color. The major difference between kilned and caramel/crystal malt is that the kilned malts lack the fruity/raisin flavors. Lighter malts like Munich and amber have a cookie or biscuit flavor. Melanoidin malt has a soft cookie/cake maltiness but without the toasty flavor. Honey malt has some caramel flavor. Brown malt, which is on the edge of the harsh zone, has deep, toasty mocha flavors.
- Caramel/Crystal Malts – These malts are dried in a special way. Rather than going directly to drying in the kiln, these malts are kept wet and held at the standard mash conversion temperature of roughly 152 F (67 C) for an hour or so before they are dried. Darker versions are toasted much like the kilned malts. The net effect of this is that the interior of the malt gets converted into simple sugars. In essence it is mashed within the husk. This develops the sweetness and fruity flavors that are characteristic of crystal malts. These malts include the very light Carafoam and Cara-Pils, Pale Crystal 10-30L, Medium Crystal 40-60L and dark Crystal malts (80-140L) as well as Special B. While Carafoam and Cara-pils are largely flavor neutral, light and medium Caramel/Crystal malts add sweetness, caramel aroma along with fruity flavors like raisins, figs and apricots. Medium to dark Crystal malts add toasted flavors, burnt sugar, toasted marshmallow and dried fruit flavors like figs and prunes. Very dark malts like 80-100L and Special B can be very harsh as they are in the harsh zone. These include burnt toast, burnt marshmallow, tannins, and coffee flavors. These dark malts should be used sparingly.
- Roast Malts – Roast malts are kilned and dried and then roasted at very high temperature. These malts include light chocolate, chocolate, carafa, and black patent. There is also stout roast (also called roast barley) which is technically not a malt as it is raw barley roasted at high temperature. The light chocolate malt is actually a bit harsher than regular chocolate because it is on the edge of the harsh zone. Chocolate malt has a sharp, coffee like roast flavor and is actually more piercing than black malt. Carafa has a deep bittersweet chocolate flavor that is smoother and creamier than black or chocolate malt. Carafa is also available in “dehusked” or “debittered” versions which removes the husks and tannins resulting in an even smoother chocolate flavor. Black patent has a deep, bittersweet chocolate flavor with a coffee or espresso note. Finally stout roast/roast barley has a dry, acrid coffee finish like Guinness beer.
That’s a quick summary of the malting process and major malt groups. For me, understanding the four major groups helps me to better remember the flavors associated with a particular malt and better apply the malts to achieve a particular flavor in a finished beer.
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