Barley must be malted before it is mashed. The starch of unmalted barley is too complex to be readily converted to sugars, so the grain must pass through a series of steps to activate its constitute enzymes. The first is steeping.
During steeping, or soaking, many enzymes in the grains are either formed or activated, and the starchy endosperm mass is solubilized to gummy polysaccharides. During sprouting, the hydrolytic enzymes inside the developing plant embryo increase and penetrate the endosperm, reducing proteins and hemicellulose to soluble fractions. Polysaccharides and protein are reduced nearly proportional to the degree of the acrospire growth until both are arrested by kilning.
The acrospire, or germinal stem of the barley plant, is grown to the full length of the kernel in British malts, almost fully modifying the endosperm to readily saccharified polysaccharides. American “brewers’” malts are less completely modified, and traditional continental malts modified the least of all. The acrospire growth of continental malt may be stopped when it is only one-half the length of the grain, in order to minimize the loss of starch by the digestion of the endosperm by the germinating embryo. The lesser degree of conversion is responsible for the lower enzyme strength and greater nitrogen complexity of continental malt. Haze-forming proteins that remain in continental malt must be decomposed during a low-temperature mash that is unnecessary when using British malt and most modern malts.
American malts are sprouted more fully than traditional continental malts. Acrospire growth is usually two-thirds to three-fourths the length of the kernel, but because American barley, especially six-row, is of much higher nitrogen content than traditional lager malt, its enzyme strength is correspondingly greater. High kiln temperatures can be held longer than with continental malt without risking a serious depletion of the malt’s enzyme strength. Traditional continental malts require a protein rest to degrade large proteins, and albumin in excess of the amount required for body, head, and yeast nutrients. Although American malt can usually be infusion mashed, it is more often given a protein rest to reduce the potential for chill haze.
The barley to be malted is examined, and if it is judged suitable, steeped to thoroughly wet the endosperm mass and float off dust, debris, and lightweight, unmaltable grains. The kernels are stirred in an aerating fashion into water at 50 to 65 degrees F (10 to 18 degrees C), which is allowed to overflow the steeper to carry off the debris, then soaked for two to four days (preferably in alkaline water) to 35 percent moisture content. The water is drained, and the moist grains are turned several times during steeping to increase oxygen uptake by the respiring barley. The barley may be aerated for up to twelve hours before it is re-covered with water. Kernels are periodically removed and the extent of the moisture penetration is determined (wet endosperm is off-white). The grains will have swollen 1 ⅓ times their original size. Before sprouting, the malt should be of 45 percent moisture content.
Steely or nitrogenous barley must be wetted even more completely. The moisture content is verified by weighing a sample of the moist grain, drying it completely at a low oven temperature, and reweighing the dried grain; the weight loss should generally be 40 to 45 percent.
The white tips of the rootlets may be just emerging (chitting) when steeping is complete.
Barley may be sprouted in many different ways, but the traditional floor malting produces the most uniform growth as well as the mellowest possible malt. The grain is laid eight to twelve inches thick (thirty-inch maximum) on waterproof concrete, at an ambient temperature of 45 to 60 degrees F (7 to 15 degrees C), for six to ten days. It is wetted and turned periodically to aerate it and to keep the temperature at an even 50 to 70 degrees F (10 to 21 degrees C).
Cooler temperatures encourage greater enzyme production and soluble-carbohydrate yield by impeding acrospire and rootlet growth. Reducing the initial sprouting temperature to below 55 degrees F (13 degrees C) produces the mellowest and most enzyme rich malt. Temperature control is achieved by lowering room temperature and reducing the depth of the sprouting grain to allow the heat being produced by the respiring grain to dissipate.
Growth should start during the first day, as the embryo internally forms immature rootlets; during the second day, the grains are wetted, then aerated by lifting and turning. This is done regularly thereafter. Growth speeds up, and by the fourth day rootlets usually have appeared.
Generally, the acrospire will have grown to one-half the length of the kernel by the sixth day of germination.
The degree of modification can be judged with some degree of accuracy by comparing the length to which the rootlets have grown against the length of the kernel, and by cutting through the hull and examining the endosperm and the length of the acrospire.
| Rootlet Growth as an Acrospire-Length Indicator | |
|---|---|
|
Rootlet Length |
Acrospire Length |
|
½–¾ the length of the kernel |
½ |
|
1–1½ times the length of the kernel |
¾ |
|
1½–2 times the length of the kernel |
Full |
The modification of the endosperm proceeds in the same direction and at approximately the same rate as the growth of the acrospire, although modification tends to exceed acrospire growth in grain malted at lower temperatures.
The green malt should have a clean, wholesome smell and appear plump, with healthy, unwithered rootlets. The endosperm mass should feel chalky when it is rubbed between two fingers. Hard, watery, or gummy malt endosperm is poorly modified.
The objectives of malting for lager malt are even modification, reduction of beta-glucan cell-walls, gums, and protein matrixes, reduction of native starch to “mashable” fractions, and the development of proteolytic and diastatic enzymes. For malts for infusion mashing, the reduction of the sprouted kernel needs to be carried even further. British pale malt must be partially “mashed” as part of the malting program by a longer sprouting cycle and by saccharification at the start of the kilning cycle.
Kilning dries the malt, facilitates removal of the rootlets, and gives malt its character. It also reduces the pH in the mash.
The temperature of green lager malt is generally raised to 90 degrees F (32 degrees C) over twenty-four hours to allow the enzymes to continue starch modification and proteolysis. The lumps of tangled grain are gently broken up after drying has begun but while the green malt is still moist. The temperature is slowly raised to 120 degrees F (49 degrees C) and held for twelve hours to dry the malt, then raised to roasting temperature. It is essential that the malt be bone dry before it is heated above 120 degrees F (49 degrees C) so that enzyme destruction is minimized.
Domestic lager malt may be kilned-off at 130 to 180 degrees F (55 to 82 degrees C), while British pale-ale malt is dried to 2 to 3 percent moisture content and kilned, usually at 200 to 220 degrees F (94 to 105 degrees C). Temperatures for Czechoslovakian and Bohemian malts are raised very slowly from 120 to 153 degrees F (49 to 67 degrees C) to completely dry the malt before it is roasted at 178 degrees F (81 degrees C). Dortmund is roasted at 195 to 205 degrees F (90 to 95 degrees C). Enzymatic malts are slowly germinated at cooler than usual temperatures for six-row, high-nitrogen malts. They are slowly dried to 6 to 8 percent moisture content and cured at below 145 degrees F (63 degrees C). Vienna malt is dried to near 5 percent moisture content before kilning for about an hour at 210 to 230 degrees F (99 to 110 degrees C), while Munich malts are brought up to 210 to 220 degrees F (99 to 105 degrees C) for light, and up to 244 degrees F (118 degrees C) for darker Munich (dunkles).
Vienna and Munich malts give richer, maltier flavor and slightly fuller color to beer. Melanoids developed during kilning, especially those that are amino-acid derived, give these malts their characteristic flavor. Melanoids act as antioxidants (reductones), improving a beer’s storage stability. Historically, Vienna and Munich malts were kilned from well-modified malt to ensure good color and flavor development. In modern practice they are likely to be kilned from overmodified barley so that they will be less problematic in an infusion mash. Just as often, however, these malts are made from inferior or high-protein barley, because maltsters expect them to be used only in small (5 to 15 percent) portions of the malt bill. Where they will compose a larger percentage of the grist, the brewer needs to review typical analyses provided by the maltsters and choose high-quality malt suited to the mash program being employed.
Amber malt is made from very well modified grain (slightly overmodified by British standards; similar to mild ale malt) that is dried to 2 to 3 percent moisture content and heated from 122 degrees F (50 degrees C) to 340 degrees F (171 degrees C) over the span of one hour. Some maltsters use lower temperatures, in the range of 280 to 300 degrees F (138 to 149 degrees C), for a longer time.
“Aromatic” and biscuit malts are very similar but employ different kiln temperatures; 240 degrees F (115 degrees C) for a longer time for aromatic, and 430 to 460 degrees F (221 to 238 degrees C) for biscuit. Amber, aromatic, and biscuit malts give intensifying degrees of a coppery color, dry, “biscuity” flavors, and toasty aromatics to beer.
Brown malt is dried before kilning at up to 355 degrees F (180 degrees C) for twenty minutes. It gives a deeper color and a more bitter/burnt flavor to beer.
Amber and brown malts contribute considerable fermentable extract to a brew, but the darker-roasted and crystal/caramel malts contribute very little. Caramel and crystal malts give a red to red-brown color to beer. They also increase the sweetness, fullness, foam retention and storage stability of beers; pound for pound, the fully crystallized versions impart these characteristics more than the caramel ones do.
Crystal and caramel (caramalt, carastan) malts are similar products, but they should not be considered interchangeable. Caramel malts have a higher moisture content, are not completely saccharified, and are not kilned to the point that the endosperm is entirely vitrified/glassy. Both are commonly kilned in drums. Both are surface dried at temperatures rising to 150 degrees F (65 degrees C) over an hour’s time, during which period a significant amount of proteolysis occurs. “Caramel” versions of CaraPils (CaramelPils, CaraPilsen) malt are generally raised to 212 degrees F (100 degrees C) within five to ten minutes, then held there for thirty to forty-five minutes without ventilation to “caramelize” the endosperm. After kilning, the temperature is reduced to 175 degrees F (80 degrees C) to cure for forty-five minutes; “crystal” versions of the malt are completely saccharified during kilning. They both increase the sweetness, fullness, foam retention, and storage stability of beers without appreciably increasing the color.
Other caramel malts are treated similarly but are colored at higher kiln temperatures — 240 to 275 degrees F (116 to 135 degrees C). Caramel malts as 5 to 15 percent of the grain bill give a caramel, often raisinlike flavor and “chewy” character to beers. As caramel malt color increases, bitterness and roastiness increase accordingly.
Caramel malts were traditionally used by continental lager brewers, whereas crystal malts were favored by British ale brewers. The distinctive, complex flavors of caramel malts have their place in brewing, but unfortunately, modern maltsters are eschewing the production of crisper-flavored crystal malts in favor of the easier-to-process caramel malts. In fact, most modern maltings no longer make a distinction between caramel and crystal malts.
True crystal malts are completely saccharified in a moisture-saturated environment at 158 degrees F (70 degrees C) for 11/2 to 2 hours. This stewing of the malt liquefies and completely saccharifies it before it is brought up to kilning-off temperatures. Crystal malts are drum kilned at 250 to 275 degrees F (120 to 135 degrees C) for 1 ½ to 2 hours, depending on the color desired. They give flavors that are crisper and cleaner than caramel malts; the lighter-colored crystal malts especially give less bitterness and pungency than caramel malts.
Undermodified (“lager”) malts are used to produce chocolate and black malts. They are generally dried to 5 percent moisture content, loaded in the kiln at 158 degrees F (70 degrees C), and roasted for up to two hours, to 420 degrees F (215 degrees C) for chocolate malt and to 435 to 480 degrees F (224 to 249 degrees C) for black malt, before being quenched by spraying water over the roasted grain.
When using specialty malts, the brewer needs to adjust the amounts lot to lot to keep beer color consistent. Moreover, a chocolate malt, for instance, at 350 °Lovibond, gives vastly different character to a beer than does a “chocolate” malt at 600 °Lovibond. At 2 to 5 percent of the grist bill, roasted malts richen color and contribute a burnt or nutty flavor to beer. They are used at 10 to 15 percent of the grist bill for porters and stouts.
Malts that are kilned over open hardwood (beech wood, fruit woods) or peat fires have special “smoked” flavors (from phenols released from the wood), which are characteristic of certain beers. These malts may be sold as mild, medium, or heavily smoked as measured by the phenol content. For peat malts, lightly peated malt gives 3 to 6 ppm phenols, moderately peated 7 to 11 ppm, and heavily peated 12 to 15 ppm.
In kilning, the maximum temperature is usually held only until the grains are evenly roasted; then the malt is cooled to below 100 degrees F (38 degrees C) and cleaned to remove rootlets and debris. Rootlets are easily screened from the dried grain, but care must be taken that the malt is not injured and the husk not broken during cleaning.
Weight loss during malting and kilning should be roughly 7 to 15 percent. Losses are more extreme where the rootlet growth is excessive or the malt has been caramelized during kilning.
Before being mashed, the malt must be binned for twenty to thirty days in a cool, dry place to mellow it and improve wort clarity.