Special Focus: Malt Analysis
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Understanding Malt Analysis Sheets -- How to Become Fluent in Malt Analysis Interpretation by Greg Noonan |
No two batches of malt are alike. The only sure way to predict their effect on your brew is to ask for and know how to read malt analysis sheets.
You are a serious grain brewer. Whether you brew professionally, as a hobby, or as an obsession, you take pride in your beer. You do everything you can do to reproduce each of your recipes accurately from brew to brew. Or do you?
Like most serious brewers, you probably adjust your hopping rates to reflect the alpha-acid content of each new lot of hops you purchase, but do you adjust your grains for changes in color, moisture, and extract potential? Do you know that a mere 2% increase in the moisture content of a new lot of malt accompanied by a matching drop in the extract potential can drag the density of a 12 °Plato (S.G. 1.048) wort down to 11.5 °P (S.G. 1.046) or increase the cost of malt 31/2%? Do you know that the color of dark-roasted malts commonly varies by 25-50 °L from lot to lot, or that one maltster's "dark crystal malt" may be 40-45 °L while another's is 80-90 °L and someone else's is 120-130 °L?
Even slight changes in malt specifications may have perceptible consequences, combinations of lot-to-lot variances in the color, moisture, and extract content of malts can seriously alter a recipe's results. Whether you brew at home or at work, the more you know about the malt you use, the better and more consistent your beer will be. You can enjoy that gain without suffering any pain -- understanding and using malt analysis sheets is neither difficult nor unpleasant.
Literacy Is PowerAny maltster should be willing to provide a lot analysis sheet. The malt analysis reveals the suitability of a malt to the mashing capabilities of the brewery and the brand's flavor profile, and it defines any adjustments that may be necessary in brewhouse procedures. At minimum, every lot analysis should provide the color, moisture, extract, total and soluble protein, mealiness (friability or vitreosity), and size assortment of the malt. For base malts, the brewer will also want to know the diastatic power.
Maltsters often provide typical analyses with ranges instead of lot-specific analyses. Nevertheless, lot-specific analyses should be available upon request. Similarly, a complete lot analysis is not typically performed on specialty malts, but may be available upon special request.
Base malts: "Base" barley malts provide the bulk of the wort's soluble extract and the enzymes that produce it. The base malts, in order of ascending color, are Pilsener, lager, pale, mild, Vienna, and Munich. The last two, however, are most commonly used at only 10-25% of the grain bill for mild flavor contribution.
Specialty malts: Color or specialty malts include caramel, crystal, toasted, and roasted malts. These malts may contribute significant color, flavor, mouthfeel, and aroma to the beer in varying degrees, but will not contribute enzymes to the extract.
Typical North American Malt Analysis -- Two-Row Brewers Malt
Variable
Typical Value
Color
1.4-2 °L (3-4 °EBC)
Moisture Content (MC)
2-4.3%
Extract (DBFG)
80-81%
Extract (DBCG)
79-80%
Difference (FG/CG)
1.1-1.8%
Diastatic Power (DP)
110-160 °Lintner (385-520 °WK)
Total Protein
11-12%
Soluble Protein (SP)
5-5.4%
Soluble Nitrogen Ratio (SNR)
43%
Glassy/Half Glassy/Mealy
0%/2%/98%
*These figures were taken from the charts compiled for the Brewers' Market Guide"World of Malts" feature. European equivalents are shown in parentheses.
Although wheat malt contains enzymes and in some beer styles is used as part of the base grist, it is usually considered a specialty malt. It may be used to broaden flavor, increase a beer's head and body, and decrease its color.
Differences in origin: Large American breweries prefer high-protein malts, especially six-row barley malts, to offset the large percentage of adjuncts they typically use in their grists. The increased protein makes up for the adjunct's deficiencies in diastatic power and protein content.
European barley malts are typically derived from two-row barley and range from 8 to 10% protein. Traditional British malts are more completely and evenly converted and thus are more readily mashed than traditional German malts. Malts made from American barley have significantly higher protein content than either of their European counterparts (North American two-row typically has 10-12% protein, six-row 11-13% protein), but their starches are generally as completely converted as traditional British malts. Protein levels in both two- and six-row North American barley have been about 1% lower than normal for the past couple of years. (See also "A Comparison of North American Two-Row and Six-Row Malting Barley" on page 54 and "North American Barley Quality: The 1996 Crop" on page 61 of this publication.)
Typical British Malt Analysis -- Pale Ale
Variable
Typical Value
Color
2-3.5 °L (4-6.5 °EBC)
Moisture Content (MC)
2.8-3.3%
Hot Water Extract (HWE)
303-315 L°/kg 7M
Cold Water Extract (CWE)
17-20.5%
Total Nitrogen (TN)
1.4-1.7%
Soluble Nitrogen Ratio (SNR)
36-45.5%
Diastatic Power (DP)
40-65 °Lintner (124-212 °WK)
Screenings <2.2 mm
0.45%
Friability
90-100%
*These figures are taken from the charts compiled for the Brewers' Market Guide"World of Malts" feature. European equivalents are shown in parentheses.
Standardization of measurements: Lot analysis figures are standardized based on the American Society of Brewing Chemists (ASBC) or the European Brewing Convention (EBC) standard mashes for easier comparison. Although these standard mashes are made under very efficient laboratory conditions that give higher yields than any brewer commonly achieves, the figures do provide a useful tool in predicting malt character and performance, even across lots, and for making comparisons between malts. For example, lot analyses are given on a "dry basis"; that is, the parameters listed in an analysis are adjusted to give values as if the malt were oven-dried to 0% moisture content. This convention facilitates comparisons between lots and eliminates the need to adjust for varying moisture percentages.
Mastering the Critical VocabularyColor (°SRM, °L): The color of any malt varies from lot to lot, and the color range of a malt type varies widely from maltster to maltster. From the maltster's point of view, it is of some advantage to have a unique color range because it makes switching malts and malt suppliers more difficult; a brewer contemplating switching suppliers would have to make serious adjustments in the brewhouse program. To some extent, this diversity can also benefit brewers by offering them more options.
In the United States, color is expressed in terms of the Standard Research Method (SRM) values set by the ASBC or in °Lovibond, an older method of visual measurement upon which SRM is based (the two measurements are essentially equivalent). In European lot analyses, color may be measured according to a visual method developed by the European Brewing Convention (expressed as EBC units). The formula °EBC = (°L X 2.65) - 1.2 gives a reasonably accurate translation to °Lovibond values. European maltsters are considering still another switch to a different method of measuring color; however, until the new method is accepted, the EBC-to-Lovibond conversion method will generally still apply. Conversions provided in the "World of Malts" feature (pp. 70-112) are based on this formula.
Moisture content (% m.c. or MC): The closer a malt is to 1.5% MC, the less it risks mold growth and the less flavor and aroma it loses over time. For this reason, colored malts should never be "slack," that is, over 4% MC. The upper limit for acceptable moisture content in any malt is 6%. The moisture content generally reflects the quality of the malting itself; high MC malt may be poorly malted or kilned.
Typical Continental Malt Analysis -- Munich Malt
Variable
Typical Values
Color
4-12 °L (10-30 °EBC)
Moisture Content (MC)
3-4.8%
Extract (DBFG)
76-82%
Difference (FG/CG)
1-2%
Total Protein
10.5-12%
Total Soluble Nitrogen (TSN)
4.4-5.2%
Kolbach Index
38-45%
Diastatic Power (DP)
50-60 °Lintner (176-194 °WK)
Screenings <2.2 mm
0.65%
Friability
80-90%
*These figures are taken from the charts compiled for the Brewers' Market Guide"World of Malts" feature. European equivalents are shown in parentheses.
British ale malts have the lowest MC of the base malts, followed by Munich, Vienna, Pilsener, and lager malts. Caramel malts trap more moisture during drying than do other malts, and consequently caramel malts are noticeably gummy by nature and usually have the highest moisture contents of any malts (3.5-6% MC), although the lower value would still be preferred.
The brewer needs to take into account the moisture content of each lot and calculate the real extract potential of each lot or suffer the consequences of varying wort color, density, and beer flavor.
Extract yield measurements: Extract (% DBFG). This acronym stands for extract yield, dry basis, fine grind, and is determined using an ASBC laboratory mash. As mentioned previously, the measurements are adjusted for a uniform 0% moisture content. The fine-grind extract percentage indicates the maximum soluble yield possible for the malt. The higher the DBFG extract, the more soluble the material and the less husk and protein. Any base malt that doesn't give at least 78% DBFG extract is substandard.
Extract (% DBCG). Whereas DBFG is a measure of the quality of the grain itself, DBCG (extract yield, dry basis, coarse grind) gives a better indication of the degree of starch modification that the grain underwent during malting, and it more closely approximates the crush achieved in the brewhouse. The DBCG rating alerts brewers to the amount of yield they can target (see chart for acceptable ranges). In reality, however, production breweries are not as efficient as lab equipment, so DBCG values need to be reduced by 5-15% to reflect the actual yields likely to be obtained in a given brewhouse.
Brewhouse extract yield can be calculated using the following formula (all percentages are expressed as decimals for purposes of calculation):
Brewhouse Yield = (DBCG - MC - 0.002)X Brewhouse Efficiency
For example, using typical figures:
(0.715 - 0.035 - 0.002) X 0.90 = 0.6102
In this example, actual extract yield to be expected would be 61%. This calculation can be extended to give the approximate density (as °Plato or specific gravity) that a charge of malt will give to a volume of wort. The extended calculation simply multiplies the yield by a constant to arrive at °P or specific gravity (S.G.) of 1 lb of malt in 1 gal of wort:
°P = (DBCG - MC - 0.002) X Brewhouse Efficiency X 11.486
S.G. = (DBCG - MC - 0.002) X Brewhouse Efficiency X 46.214
For example:
S.G. = (0.715 - 0.0035 - 0.002) X 0.90 X 46.214 = 28.1998, or S.G. 1.028.
Hot water extract (HWE). British maltsters commonly quote a different extract value based upon how many liters of wort at S.G. 1.001 a kilogram of a malt will give at 68 °F (20 °C), and list it as hot water extract, or L°/kg, at 7M (ground at 0.7 mm on a Bühler-Miag mill, or coarse grind) or at 2M (fine grind). Divide the figures by 386 to get DBCG or DBFG, respectively, expressed as a decimal. HWE for two-row lager or pale shouldn't be less than 300 at 2M, 295 at 7M.
Grind difference (% FG/CG). The fine grind/coarse grind (FG/CG) difference indicates the modification of the malt, and maltsters often use it instead of the DBCG value; either can be readily calculated from the other if the DBFG value is listed. A "steely" or vitreous malt, one suitable only for a mash cycle that includes a protein rest, will have an FG/CG difference of 1.8-2.2%, while a mealy and well-modified malt eminently suited to infusion mashing will have an FG/CG difference of 0.5-1.0%.
Cold water extract (CWE). British maltsters rarely give FG/CG values; instead they sometimes quote CWE. The CWE is the amount of extract that is soluble in cold water (68 °F [20 °C]), and this value has a loose relationship to the FG/CG difference as an indicator of malt modification. A CWE of 19-23% indicates the malt is acceptable for infusion mashing; lower values indicate the need for low-temperature mash rests.
Other measurements. Continental maltsters often give the FG/CG value as DLFU or give a Hartong or VZ 45° value instead. Like the CWE value, the VZ 45° measures low-temperature extraction, but at a warmer temperature (113 °F [45 °C]) that takes into account some enzyme action. The corresponding range is about twice as high as that of CWE.
Starch conversion: Diastatic power (°Lintner, IOB). Diastatic power (DP) expresses the strength of starch-reducing enzymes in the malt and is measured in °Lintner (sometimes referred to as IOB or .25 maltose equivalent). Diastatic power, considered together with mealiness/vitreosity (see below), indicates how well a malt will respond to mashing. The DP may be as low as 35-40 for a well-converted, low-protein British ale malt, about 100 for a European lager malt, and 125 or greater for high-protein American two-row malt. Six-row malts can have DPs as high as 160. The latter malts have more protein, and thus more enzymes to reduce far more than just their own starches, while the British malts have enough only to convert their own weight under normal infusion mash conditions.
European terminology. The EBC unit of measurement for diastatic power is °WK (Windisch-Kolbach units). The value of °WK can be converted to °Lintner by the formula DP °Lintner = (°WK + 16) / 3.5.
Visual/Sensory Evaluation
Lot analysis specifications are really best for making comparisons between lots and between products. You can draw your own conclusion by putting the malt through a few simple tests.
Malt needs vary depending on the style of beer to be brewed and the mashing profile to be used. Experienced brewers can often tell just by looking at and handling the malt how it will perform in the mash. Take some time to compare samples of different malts to give you a reference point. Any sample should include a handful of at least 50 kernels for a reasonable analysis. The main rule of thumb is that the majority of the kernels should be of similar size, modification, and color for good milling and mashing, and should show no visible signs of disease (that is, discolored or seriously misshapen kernels). The plumper and larger the kernel, the better. In base malt, the ends should not be vitreous, or glassy. You should be able to easily crush the malt with your fingers. Chewing the malt will also tell you about its friability, or softness, as well as its flavor and aromatics.
If you're very concerned about degree of modification, you could also cut into a handful of malt to expose the acrospire, the embryonic barley plant inside the husk. The length of the acrospire should be three-quarters or greater of the kernel in well-modified malt. Well-modified malt will also float in water.
Conversion time (minutes). Conversion times may be given in addition to or instead of diastatic power. Base malts such as pale, mild, European, lager, Pilsener, Vienna, and light Munich should convert starches to sugars in less than 10 minutes, and enzyme-rich American two-row and six-row malts should take only 5 minutes.
Protein (%): Because proteins are made of nitrogen-based compounds such as amino acids, maltsters use protein and nitrogen values interchangeably; each 1% of nitrogen equals 6.25% of protein. Whether the analysis sheet provides total protein or total nitrogen (TN), the figure represents all the nitrogenous matter in the malt, including insoluble forms.
For all-malt beers, protein values exceeding 12% (1.9% TN) indicate that the beer may haze or present mash runoff problems. European lager and British ale malts are usually below 10% protein. One of the major reasons brewers prefer these malts for all-malt beers is because their protein levels are adequate for head-formation, body, and healthy fermentation, yet low enough to present less chill haze potential than high-protein North American malts.
When adjuncts are used, malts of more than 10% protein are required to achieve acceptable head, body, and yeast nutrition.
Soluble protein (% SP) or nitrogen (% TSN): The amount of protein or nitrogen in soluble form, expressed as a percentage of malt weight. In whichever terms it is expressed, the SP or TSN parameters are used to calculate the soluble nitrogen ratio.
Soluble Nitrogen Ratio (% SNR). This ratio (also expressed as S/T [soluble/total], SN/TN [soluble nitrogen/total nitrogen], or Kolbach Index) is calculated by dividing the soluble nitrogen (or protein) value by the percent total nitrogen (or protein).
The SNR is an important indicator of malt modification. The higher the number, the more highly modified the malt. Malts destined for infusion mashing should have an SNR of 36-42%, or up to 45% for light-bodied beer. At a percentage much over 45% SNR, the beer will be thin in body and mouthfeel. For traditional lager malts, 30-33% indicates undermodification, and 37-40% indicates overmodification.
Brewers can accommodate increases in total protein and SNR by adding or modifying low-temperature rests. Decreases are accomodated by shortening the duration of or deleting low-temperature rests.
Physical characteristics: Mealiness (%). By convention, malt is classified by what percentage of the lot is "mealy," "half-glassy/glassy-ends" and "glassy." Mealy kernels are those in which the endosperm is not more than 25% glassy. The endosperm of malts considered half-glassy is 25-75% glassy (usually as "hard ends"), and the endosperm of glassy kernels is over 75% vitreous (steely).
As a brewer, you want to know if a malt will crush well and how accessible its endosperm will be to mash enzymes. The better and more extensive the malting, the higher the percentage of mealy kernels. Glassy (steely or vitreous) malt gives less extract than mealy malt because it does not crush well and is not readily hydrolyzed in a typical mash program.
Any base malt destined for brewing should be at least 90% mealy; if it is to be infusion-mashed it must be at least 95% mealy. For base malts whose mealiness is expressed as a ratio, mealy/half-glassy/glassy, the ratio should be 92%/7%/1% for decoction and step mashing, and 95%/4%/1% or better for infusion mashing.
Vitreosity. Vitreosity is the inverse of mealiness: it is a measure of a malt's glassiness. In a small sample of kernels, a factor of 1 is assigned to kernels with vitreous, glassy endosperms; 0.5 to half-glassy kernels; 0.25 to those with glassy ends; and 0 to completely modified (mealy) kernels. The sum is totaled and averaged, with a vitreosity of 0-0.25 preferred. This figure is likely to be less reliable because it is based on subjective observations and doesn't clearly define the problem.
Degree of crystallization. Specialty malts that are supposed to be vitreous are often discussed in terms of degree of crystallization. For caramel malts this figure should be above 85%, and for crystal malts, 95% or higher.
Friability. Friability is the measure of a malt's readiness to crumble when subjected to crushing. It is related to mealiness in purpose, and some maltsters use it as an alternive measure for mealiness. Any malt should be at least 80% friable; for infusion mashing, malt should be at least 85% friable.
Size. Size is most clearly expressed in terms of screen separations, but may also be given as simply plump or thin. European malts often list only the percentage of malt that can be sieved through 2.2-mm openings. Brewers will reject a malt if it's more than 1% thin or 2% less than 2.2 mm, because these values indicate unmodified kernels. Other analyses are given in terms of screen separation and brewers will typically see percentages of kernels that will remain on a screen with 5/64 -in., 6/64 -in., and 7/64 -in. openings. Kernels considered thin will fall through the 5/64-in. opening. Generally speaking, the plumper the malt kernels, the better the yield. The uniformity of malt sizes measures how uniformly that malt will crush. Any lot of malt that will crush reasonably well must have kernels that are at least 90% adjacent sizes, regardless of the plumpness.
Supplemental VocabularyThe preceding parameters are of essential importance to any brewer. Several other terms are commonly given in lot analyses as well.
Alpha-amylase or dextrinizing units (DU): While DP gives a ratio for all amylases present in the malt, DU breaks out alpha-amylase. A range of 35-50 DU (dextrinizing units) is acceptable, depending on the malt type and the mash program. Munich malt may be below 10, and pale malts may be as low as 25.
Wort pH: Base malts should give a pH range of 5.5-5.8, with ale malts at the lower end and lager malts at the higher end. The brewer uses these pH values to adjust liquor acidity for the particular lot of malt so that the ultimate mash and wort pHs end up within the optimum range of 5.2-5.3.
Viscosity (cP): Viscosity is a measure of the breakdown of �-glucans (endosperm cell walls) during malting, expressed in cP (centipoise units) and sometimes IOB. A malt that shows a high laboratory wort viscosity (over 1.75 cP) will not run off well during sparging. The higher the viscosity, the greater the need for a decoction program -- or less effectively, a step mash -- to break down �-glucans.
Viscosity measurements given in IOB units should be in the range of 6.3-6.8 (taken at 158 °F [70 °C]).
Odor of mash: "Normal" is the typical reading. The term "aromatic" indicates greater-than-usual malt aroma. Terms are based on ASBC standards.
Speed of filtration: Gives an idea of the levels of �-glucans and degree of starch and protein conversion, also based on ASBC standards.
Degree of clarity: "Normal" to "slightly hazy" are acceptable values.
1,000-Kernel weight or bushel weight: The acceptable range for 1,000-kernel weight is 36-45g. If the weight is expressed as bushel weight, a value in the range of 42-44 lbs is usual.
DMS precursor (DMS-P): This value represents the levels of S-methyl methionine (SMM) and dimethyl sulfoxide (DMSO) in the malt. These compounds will convert to dimethyl sulfide (DMS) when the wort is heated. The DMS-P should be 5-15 ppm for lager malts, less for ales. The more fully modified the malt, the lower the DMS-P levels should be.
Growth: Another way to assess degree of modification. Acrospire growth is often expressed in ranges 0-1/4, 1/4-1/2, 1/2-3/4, 3/4-full, or overgrown. Look for at least 3/4 to full growth for American and British (typically fully modified) malts, and 1/2-3/4 for multirest lager malts.
The World of Malt Is at Your DoorstepLearning how to read a malt analysis sheet is not difficult. Using it to adjust a recipe's grain bill and brewhouse procedures improves batch-to-batch consistency and beer quality. Shouldn't you be using the lot analysis that your malt provider has gone to the trouble of providing?
Greg Noonan has been brewing beer for 20 years and moved to the forefront of the craft brewing industry when he lobbied for legalization of brewpubs in Vermont in 1985. The following year, his classic book Brewing Lager Beer quickly became an industry textbook for both home and professional brewers. Noonan opened the Vermont Pub & Brewery in Burlington, Vermont, in 1988, and opened a second brewpub, the Seven Barrel Brewery, in West Lebanon, New Hampshire, in 1994. Noonan released a revised and updated New Brewing Lager Beer and the Seven Barrel Book of Brewing in 1996. His Brewslave recipe design software for professional brewers is due for release in 1997. Noonan is on the Editorial Advisory Board of BrewingTechniques and is a frequent contributor to other brewing publications and events.
(http://morebeer.com/brewingtechniques/bmg/noonan.html)