Understanding Malt Spec Sheets
Just as no two batches of beer are exactly alike, neither are lots of malt. A major reason is the barley itself. Variations in rainfall, soil nutrients and temperature during the growing season, along with storage and handling conditions, all affect the crop from year to year, region to region and even from field to field. This impacts such values as kernel size, starch, protein and moisture content. And despite strict modern quality control procedures, there are also subtle variations from lot to lot even at the same facility.
Of course, maltsters know this and therefore blend barleys before malting and blend lots of the same kind of malt after malting. And, some differences — most notably kernel size — can be tightly controlled by screening.
The remaining differences, however, can be significant enough to affect the gravity and color of the beer. For example, an increase of one percent in the moisture content of the base malt, along with a corresponding decrease in the extract potential, will lower the original gravity (OG) by more than one point. And the color of black roasted malt among different lots from the same maltster can vary by 40 degrees Lovibond (°L).
None of this, though, should be cause for despair among brewers who seek the highest levels of consistency. This is because maltsters analyze the malt they produce and release the results in the form of a malt lot analysis. A malt spec sheet allows brewers to determine the characteristics and quality of the malt we use, select between different malts and also allow us to alter the amount of malt in a recipe or the procedures we use for handling it. Malt spec sheets are available from virtually every malt producer to anyone who requests it. Some sheets give an average analysis, others are reported on a lot by lot basis. Even those brewers who are more of the “relax, don’t worry, etc.” school of homebrewing can benefit from this information. Making malt
Before discussing malt lot analyses, it may help to briefly review the basics of malting. In malting, barley kernels are steeped in water, until the root sheath just penetrates the husk. The barley is then removed from the water and allowed to germinate. Once the rootlets have grown sufficiently, the wet malt is heated (kilned) to dry the malt. After kilning, the rootlets attached to the barley kernels are removed.
Readers are leaders
To create a malt lot analysis, a sample of the finished malt is carefully analyzed in a laboratory. Standardized testing procedures are used to test specific qualities that are significant to brewers. Most commercial breweries require that a lot analysis accompany each malt shipment they receive. Homebrewers and small craft brewers can request one from their malt supplier.
If you buy malt in quantities of less than a full bag, it’s possible to obtain the lot number (printed on each bag) from your local homebrew shop and contact the maltster directly, who will be happy to provide the information via telephone, fax or e-mail. A couple of them have a feature on their web sites for viewing lot numbers online.
As you might expect, the vocabulary of malt lot analysis is technical, but it’s not that hard to learn to interpret. Come along with us as we examine a typical lot analysis and explain the various entries. It’s a lot less personal than going on the couch with Dr. Freud, and we predict you will enjoy your beer more than the doctor did his cigar.
The terms for the values reported in each malt lot analysis vary slightly, depending on the maltster. These values can be grouped into several categories, including color, moisture, extract, modification, proteins and physical characteristics. For base malts, there is also data on diastatic (enzymatic) power.
In living color
In North America, color is measured in SRM (Standard Reference Method) units or degrees Lovibond, an older visual method that is essentially the same scale. The palest Pilsner malt has a value of 2 SRM, while the blackest roast malt can be more than 600 SRM. Europeans use a corresponding but different scale known as EBC (European Brewers Convention). The two systems can be converted using the following formulas:
EBC = (L * 2.65) + 1.2
L = (EBC – 1.2) / 2.65
It should be noted that the resulting beer will have a color darker than the malt, due to boiling and other reactions that occur during the brewing process.
Make mine dry
Moisture in malt contributes to mold and accelerates spoilage. Brewers pay for convertible starches and extractable sugars in their malt rather than water, which they add at mashing time. However, it’s not possible for malt to be bone dry, and a small amount of moisture is inevitable and even desirable. British pale malts typically have the lowest moisture content, on the order of 3–4% by weight, while Continental and North American base malts are in the area of 4–5%. Caramel and crystal malts have the highest moisture content, up to 6%, resulting in a slightly gummy character in mashes with high percentages of these. In any case, malts with a moisture content much above 6% are best avoided, as this is an indication of problems during malting.
Brewers speak of sugars as “extract;” this is, what results in food for the yeast (fermentable sugars) and body for the beer (unfermentable dextrins). Accordingly, it is not surprising that a malt lot analysis contains an entire group of values for reporting extract. The first two are Extract Yield Dry Basis Fine Grind (DBFG) and Extract Yield Dry Basis Coarse Grind (DBCG). These are derived from a laboratory mash conducted with a small quantity of the malt. The method is rather different from actual brewery conditions, but the fine-grind results represent the maximum possible laboratory yield from the malt. For base malts, a DBFG value of less than 78 percent indicates poor quality. As a result of how they are produced, specialty malts will have lower yields, but this is not a problem because they are generally not significant contributors of extract to beer.
The coarse-grind results are intended to demonstrate to the brewer the maximum that can be achieved using a crush that approximates that used by most breweries. This value is still higher, however, than most real breweries (including homebreweries) achieve because the mash is “oversparged” compared to normal brewery procedures. In practice, mashing conditions at a brewery typically result in a yield 5–15% lower than the DBCG value. It should be noted that both of these values are reported on a “dry basis,” that is, as if the moisture content of the malt was zero. This makes it easier to compare different lots and eliminates factoring in the varying moisture content. Of course we know that all malt contains some moisture, and occasionally you may see a malt analysis that expresses the extract values on an “as-is” basis (AIFG and AICG).
Often brewers refer to a malt’s “extract potential.” This is typically expressed as specific gravity that can be achieved with 1.00 pound (455 g) of malt mashed in 1.00 gallon (3.78 L) of water.
The following formula can be used to calculate extract potential:
Extract potential (S.G.) = 1 + (DBFG / 100) * 0.04621
The 0.4621 multiplier in the formula is the extract potential of sucrose (1.04621), against which all extract is measured. For example, a malt with a DBFG value of 80.5% results in a calculated extract potential of 1.0372.
Another important value is the Extract Fine Grind/Coarse Grind Difference (FG/CG). Sometimes a malt analysis will list this rather than the DBCG value. If so, it’s a simple matter to calculate the DBCG by subtracting the FG/CG from the DBFG value. The FG/CG value is an indication of the modification of the malt and its suitability for single infusion mashing. A FG/CG difference of 0.5–1.0 percent is well suited to a single step infusion, while a value greater than 1.5 percent indicates that a protein rest may be advisable.
Maltsters in other parts of the world may use different units of measurements. British malt analyses sometimes report “hot water extract” (HWE). HWE is based on how many liters of wort a kilogram of malt will yield with a specific gravity of 1.001 in water at a temperature of 20 °C (68 °F) using a 7M (0.7 mm) mill gap for coarse grind and a 2M (0.2 mm) gap for fine grind. Divide the HWE values by 3.86 to convert to DBCG and DBFG, respectively. The British equivalent of FG/CG is “cold water extract” (CWE) and represents the percentage of extract soluble in cold (20 °C/68 °F) water. Malts with a CWE of 19–23 percent are good candidates for single temperature infusions, while lower values may require additional lower temperature rests.
Continental maltsters sometimes provide FG/CG data in the form of the Hartong or VZ 45 degree index. This is similar to CWE except that water at 45 °C (113 °F) is used. The resulting value is about twice as high as the CWE.
Eat your protein
Protein values in malt are related to the total nitrogen content (proteins are comprised of nitrogen-rich amino acids). Sometimes a malt analysis will list the total nitrogen (TN) value in percent. In general, brewers want minimal protein in their malt because it has little brewing value except for enzymes and foam.
One percent TN equals 6.25% protein; to convert protein to TN divide the value by 6.25. British and Continental base malts are normally below 10 percent protein (1.6% TN). All-malt beers brewed with malt having a protein value above 12% may exhibit haze problems, which is why North American six-row malt (with protein as high as 14%) is best used with adjuncts that have far less protein. (The situation is actually a little more complex as the kinds of proteins present in a malt also play a role.)
The percentage of protein (or nitrogen) that is soluble in water is expressed as a SP (soluble protein) or SN (soluble nitrogen) value. This is used to calculate the S/T (soluble/total) or SN/TN (soluble nitrogen/total nitrogen) rations, also called the Kolbach Index. The three ratios are equivalent to each other and also can be expressed as the soluble nitrogen ratio (SNR). In all cases, the value results from dividing the soluble protein (or nitrogen) value by the percent protein (or total nitrogen).
The S/T is important because it is the best indicator of malt modification, the degree to which germination was allowed to proceed during the malting process. S/T values above 35% indicate highly modified malts suitable for infusion mashing, while values above 45% can result in thin-bodied beer. Undermodified malt (with an S/T of 30–35%) requires multiple temperature rests or decoction.
The power of enzymes
Related to extract and protein values is the “diastatic power” (DP), the ability of the enzymes in the malt to convert starches to sugars. This is important when base malt is used in conjunction with other starch-containing, but enzyme-poor malts, and unmalted adjunct grains. For North American and British malt, diastatic power is measured in degrees Lintner. Well-modified British pale ale malt, for example, may have a DP value in the range of 35–40, indicating that it can convert its own starches and a small proportion of adjuncts, up to 3–4% of the total grain bill. North American six-row malt, with its higher protein content, can have a DP as high as 160, demonstrating its ability to convert a large percentage of adjuncts.
Malt analysis sheets may also list dextrinizing units (DU) as another measure of enzymatic power. The Continental European equivalent unit of measure for DP is degrees WK (Windisch-Kolbach). The two units can be converted using the following formulas:
Degrees WK = (degrees L * 3.5) – 16
Degrees L = (degrees WK + 16) / 3.5
Some malt analyses list the starch conversion time in minutes, in addition to or instead of the DP values. In no case should this be more than 20 minutes for base malt; for North American two-row and six-row pale malts it should be on the order of 5 minutes.
Let’s get physical
A section of the lot analysis concerns the physical characteristics of the malt. Among these is the kernel size, typically expressed in terms of screen separation, that is, the fraction of kernels that do not pass through screens of various sizes. In general, larger kernels will exhibit higher extract yields. Kernels smaller than 2 mm (0.079 in.) can be indications of poor or nonexistent modification. Sometimes the size value is given only in terms of the percentage of kernels that are “plump” or “thin.” Malt that is more than 2% thin can cause problems when it is milled; a relatively uniform kernel size is desirable from this standpoint.
Malt is also classified in terms of hardness. By convention, it is described as “mealy,” “half-glassy” and “glassy.” Mealy kernels have an endosperm (the partially geminated portion at the heart of the kernel that contains the starches) that is 25% or less glassy (hard). Glassy kernels have an endosperm that is more than 75% hard. The remaining kernels (26–75% hard) are said to be half-glassy.
Mealiness is an indication of how well a malt will crush and how accessible the endosperm is to the water and the malt enzymes during mashing. Base malt used for single infusion mashing should be at least 95% mealy. Values of 90–95% mealy suggest multi-temperature infusions or decoction, and in all cases the base malt should be a minimum of 90% mealy.
The opposite of mealiness is “vitreosity,” which is sometimes used as an alternative measurement. A value of 1 is assigned to glassy (vitreous) kernels, 0.5 to half-glassy and 0 to mealy kernels. The percentages of each are summed and averaged; a vitreosity value of 0.25 or less is considered desirable. Friability is the relative ease of crumbling when a malt is milled. It is related to mealiness, and may be reported in its place. All malt should be at least 80% friable, and at least 85% friable for infusion mashing.
The analyses for caramel and crystal malts may list the degree of crystallization. These malts are relatively steely (glassy), and the degree of crystallization should be 85% or higher for caramel malts and at least 95% for crystal malts.
Viscosity measures the breakdown during malting of the beta glucans that comprise the endosperm cell walls. Expressed in centipose units (cP), a value greater than 1.75 cP indicates that a mash with this malt will be gummy and pose potential sparge problems. In this case a beta glucan rest at 95–100 °F (35–38 °C) or decoction mash is advisable.
Mashers of the universe
Obtaining and studying a lot analysis can teach you a great deal about one of the most important brewing ingredients and bring you great rewards in terms of the consistency and quality of your beer. It may or may not overcome your deepest fears and complexes, but it just might let you brew the stuff of your dreams.