Crystal Malt: Homebrew Science
As a young brewer I fell in love with the aroma and flavor of crystal malt. The rich caramel aroma released as the crystal malt hit the hot water was a daily reminder of why I wanted to be a brewer. As I began to gain more brewing experience I learned how to use this malt with more skill. I realized that along with rich, deep ruby colors comes intense caramel flavors, and that balancing the two was the key to a drinkable beer.
Before diving into science, it helps to have a few definitions. Here are the main types of crystal malt available to American homebrewers.
Crystal malt: This is the British term for saccharified and drum-roasted malt. It can be roasted to different degrees to provide a range of colors. The most common range used in the UK is 70° to 80° Lovibond, which tends to produce deep red colors and a strong caramel flavor. These malts may be marketed as light, medium and dark crystal. They are used in pale, amber and dark ales and lagers, and leave a beer tasting sweeter.
Caramel malt: The American term for crystal malt. American producers tend to market these malts by their Lovibond rating. The most common colors used in the U.S. are 30° to 40° Lovibond, but this statistic is skewed because it includes all the caramel malt used by the big commercial producers, who use it in paler, milder-tasting beers. It’s typically used in pale, amber and dark ales and lagers.
Carapils: This malt ranges in color from 5° to 15° Lovibond. Carapils is used to provide light color, body and improved foam to lightly colored beers. (Briess in Wisconsin makes a caramel malt with a color of less than 2° L, which is a unique product. I used it at around 5 percent in a pale ale to provide excellent body and foam retention but no color). Above 10 percent carapils imparts a distinctive, almost grainy flavor. Some brewers use it in low-alcohol or light beers, in which increased body and foam is needed to counteract the thinness and low flavor.
Caravienna: A darker, German-style crystal malt in the 20° to 30° Lovibond range. Used for amber lagers and Vienna-style lager beers.
Caramunich: A darker German crystal malt in the 50° to 60° Lovibond range. Used in dark German lagers.
Almost all the world’s malting companies offer either one, or a range of, crystal malts. Some companies have succeeded in trademarking specific products they developed. This means other maltsters producing similar malts must use different names. There are many competing trademarked varieties produced by the world’s maltsters, but they mainly fall into the categories listed above.
No matter what you call them, all of the caramel-crystal-cara malts are used by brewers to provide a variety of qualities to their beers. They contribute caramel, toffee, nutty, spicy and sweet flavors. Melanoidin compounds — highly colored, high molecular weight compounds produced during roasting — contribute colors ranging from a slight reddish hue, through ruby red, to a reddish brown. They contribute mouthfeel and palate fullness to a beer, help foam formation and retention and aid flavor stability.
Although crystal malt contains reductones — a class of caramel-type products that are capable of absorbing oxygen in their reduced state — and are thought to act as anti-oxidants, extending the flavor stability of beers, research has failed to show a direct correlation. It may be that beers containing crystal malts contain flavors that mask the effects of oxidation.
Lovibond and SRM
The method used by professional brewers and maltsters to measure beer and grain color involves producing a standard wort from the malt and then measuring the amount of light the wort absorbs using a spectrophotometer. The resulting absorbance figure is reported in Standard Reference Method (SRM) units or their equivalent degrees Lovibond.
Joseph Lovibond was a brewer who, in the early 1920s, developed a system of standard color hues for assessing beer quality. It was known that the “best beer” had a golden-amber color and that as beer aged it picked up red hues. Lovibond attempted to quantify this change using a device he invented, called a tintometer. In actual fact, it’s simply a measure of the amount of light absorbed by a wort or beer at a wavelength of 430 nanometers. This doesn’t really tell us much, other than “what shade of yellow” the wort is. With our eyes we perceive wort and beer as a range of colors, from pale yellow through reddish brown and black, so the Lovibond scale has its limitations.
The figure quoted in a malt analysis refers to the color of an 8° Plato (1.032 SG) wort made from that malt. When calculating the color contribution that malt will make to the color of the wort, an adjustment must be made for the °Plato of your wort. Here is the calculation:
Color contribution = malt color x % of total extract from that malt x wort gravity / 8.
For example, the color contribution from using 14% crystal at 75° Lovibond in a wort at 14° Plato (1.056) would be: 75 x 0.14 x 14/8 = 18.4 L. If you don’t use Plato units, this calculation can still be used, but a change must be made to account for specific gravity degrees. The standard wort is produced at 1.032, and in the example above, the brewery wort was produced at 1.056. Just use the last two figures to provide the correct ratio (56/32). So the new calculation would be 75 x 0.14 x 56/32 = 18.4 L. The brewing process can influence the final beer’s color, however, so allowances must be made when formulating your recipe. Color can be increased by:
• High mash pH.
• Boiling a portion of the mash.
• Maillard reactions in the kettle.
• Direct flame on the boil pot.
• Excessive oxygen pick-up during boil.
• Boiling with old or stale hops.
• Yeast cropped from dark beer, re-
used to ferment a pale beer.
• Oxidation during beer storage
Color can be decreased by:
• Good kettle break.
• Cold break removal.
• Some yeast absorb color compounds.
• Short aging followed by filtration.
• Adding water
Maillard Reactions
This is the name for the chemical reactions that result in the colors and flavors associated with crystal malts. The entire class of reaction, named after the French scientist who did much to unravel them, occurs in a wide range of food products, from baked bread to cured meat. Essentially, it is a chemical reaction between an amino acid and a reducing sugar. An amino acid is a naturally occurring acid that also contains a reactive basic amine group (this means it contains nitrogen).
There are 20 different amino acids found in nature and they polymerize to form proteins. A reducing sugar is a simple sugar that has a reactive site available to take part in a chemical reaction. Glucose, fructose and maltose are examples of reducing sugars, while sucrose (household sugar) is not.
Under certain conditions, these classes of compound will combine in a wide variety of ways. The resulting compounds belong to a class of compound known as Schiff’s bases, a class that also contains certain perfumes, dyes, rubber accelerators and liquid crystal display ingredients. These Schiff’s bases will then undergo a number of re-arrangements, known as Amordi rearrangements, to form aldosamines and ketosamines, followed by further polymerization reactions and breakdowns to form a class of compound we have recently begun referring to as reductones.
Reductones are capable of absorbing oxygen and so may offer beer some protection against oxidizing agents. Some reductones will undergo further reactions with amino acids, known as Strecker degradations. These result in Strecker aldehyde compounds, which are important to malt flavor. These compounds include hydroxy-methyl-furfural and maltol, described as smelling “malty.”
Other reductones undergo condensation reactions with amino compounds to produce melanoidins and flavored compounds. These flavored and aromatic compounds include oxygen-, nitrogen- and sulfur-containing heterocyclic compounds, the exact flavor contributions of which are yet to be unraveled, but include caramel, nutty, toffee and burnt.
Over the range of temperature and moisture conditions found in a barley kernel stewing in a drum, a range of these aromatic and colorful compounds will be formed. The exact flavors that result from each reaction is still a subject of conjecture among scientists. What is known for certain is that the oxygen containing heterocyclic compounds provide crystal with caramel and toffee flavors, while the nitrogen-containing heterocyclics tend to be nutty, coffee and roasted.
Caramelization
This term is used to describe a specific type of reaction in which reducing sugar is heated. The sugars lose water molecules from their structure, forming double bonds within the molecule and altering the way light is absorbed and darkening the color. Taken to its extreme end, the molecule will break down completely to carbon, which is black. Commercial brewer’s caramel is produced by boiling reducing sugars in the presence of ammonia, which is essentially a Maillard reaction. These reactions occur in the roasting drum and the malt kiln and contribute greatly to the flavor and color of malt.
Over the range of temperature and moisture conditions found in a barley kernel stewing in a drum, a range of these aromatic and colorful melanoidin compounds will be formed.
Crystal and caramel malt is made in such a way that these reactions are multiplied. First the concentration of the pre-cursors, amino acids and reducing sugars are increased dramatically. The easiest and quickest way to do that is by raising the temperature of the grain to the temperature encountered during mashing and leaving the moisture content of the grain high. This makes a little “mini mash” inside each grain, resulting in a huge increase in sugars and amino acids. The grain is then heated to encourage a range of Maillard and related reactions inside each kernel of malt.
How crystal malt is made
The process begins with selection of barley. Higher-protein barleys are preferred and the malt variety can make a difference to the final flavor.
In the USA, thinner six-row malt grains are often used for caramel malt production, although some American maltsters now are offering caramel malts made from two-row barley. The advantage of this is that the malts need not be milled separately. Far more important than plumpness is uniformity of kernel size and nitrogen content.
To achieve a consistent product out of the roasting drum, a consistent raw material must go in. As Mary Anne Gruber of Briess Malting puts it: “One fat kernel will be underdone, while a thin one will be burnt.” Green malt is sent straight from the germination chamber to the roasting drum, rather than the kiln, at a moisture content of 43 to 46%.
The roasting drum resembles a commercial coffee roaster — it’s a large rotating drum with an inner compartment made of screen that allows hot air to pass through the contents. The malt is heated immediately with the vent open to dry off the surface of the grain, then the drum is closed to allow the temperature to rise without the moisture dropping further and the temperature is raised to 149° to 158° F. At this temperature, enzymes quickly break down the endosperm to produce a lot of reducing sugars and amino acids.
A sample taken from the drum at this point will show a kernel that when squeezed yields a sweet liquid. Depending on the type of product, and the maltster, the temperature may be suddenly or slowly increased to the desired temperature to produce the specific flavors and malt color desired. The final temperature of the highly-colored products may be as high as 320° F, while a low-color caramel malt, such as carapils, will be dried slowly at 130° to 140° F.
The malt is then quickly transferred to a cooling container to prevent further color pickup. In an emergency, maltsters can rehydrate kilned malt to produce crystal malt. This would be a fun option for advanced homebrewers keen to produce their own crystal.
Color range and malt specs
Caramel malt is sold in a wide color range, from 10° L to 140° L. Each malt within that range will have a color range of its own. In the low-colored malts (10° to 40° L), the range may be 2 or 3 degrees units on either side of the stated value. As malt darkens, the range increases to 10 units between 40° to 80° L and to 20 units as the malt reaches the 100° to 120° L range.
It may seem that the final color is difficult to control. This is true! And since maltsters sell their product based on color, one may be tempted to assume that they blend darker or lighter malts to adjust color. However, the roasted flavors of the darker malts are intense and will interfere with the overall flavor contribution. So maltsters deserve some leeway with their color ranges.
