Malt

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Malt is made from germinated cereals such as barley, wheat, oats, rye, sorghum, millet, rice, maize (corn), and pseudo-cereals such as buckwheat and quinoa. However, barley remains the main cereal used for the production of beverages such as standard beer, craft beer, and malt whiskey.

Special malt is the term used to describe malt which is used to contribute specific color or flavor attributes to beer. Malts used primarily for extract like pale ale and pilsner are termed white malts (UK) or base malts (US).

When selecting a malt, it is wise to maintain a healthy cynicism claims made about the properties of each product and what they will do to your beer, because they are all variations on a theme so are not likely to differ markedly to a competitor's analogue. The information provided is primarily there to sell you the grain.

Munich and Vienna malts are in effect darker versions of white (base) malts. It is argued by some that they are not actually special malts as their final processing is not carried out in a roasting drum. They contribute a greater amount of color and flavor but retain diastatic power. Their method of production encourages the formation of highly colored/flavored compounds through non-enzymatic browning. Munich comes in dark and light variants ranging from 15 to 35 EBC. Because of the way they are produced they have high potential for picking up color in the kettle by activation of color precursors. They are produced by germinating high nitrogen barleys until they are well modified but not over-modified and then kilning at elevated moisture levels and slightly higher kilning temperature. The result is a more richly aromatic grain than pale ale malt. Vienna malt is the lighter cousin of Munich made with well modified rather than highly modified barley and is kilned at a lower temperature.

Cara is an abbreviation of caramel. This is a bit misleading because caramelization isn’t responsible for the flavor and color properties of any malt, let alone cara malt, although arguably they do have caramel-like properties. Cara malts are produced by allowing the endosperm of the malt to convert extensively to produce reducing sugars and amino acids and then kilning/roasting moist, at 150-180 °C to facilitate non-enzymatic browning. A range of cara malts are available from various suppliers which give different characteristics but all variations on the sweet, rich, malty and full-bodied theme. Because the endosperm has been heated at elevated moisture levels the enzymes of conversion are denatured and cara malts will not contribute any enzymatic power to the mash.

Crystal malts take the caramelization of the endosperm to the next level. The term crystal refers to the crystalline appearance of the endosperm of the malt. Crystal malts are produced from high nitrogen barleys which are then over-modified and roasted at very high moisture levels. The result is a stewing of the grain and extensive production of colored and flavored compounds through non-enzymatic browning. When the liquified endosperm is dried it sets into a glasslike (crystalline - hence the name) mass. As with cara malts, crystal malts range in color from golden to deep red. There is some crossover between high color cara malts and low color crystals. Crystal malt is thought to contribute to head retention and aid the action of finings. High percentages of crystal malts in grists (grain bills) can give rise to problems with sterile cartridge filters.

Black malts are prepared by roasting a standard malt to high temperature. The high degree of heating causing burning and burnt flavor. Dehusked malts are sold as less bitter and astringent than their standard counterparts. Although it sits comfortably within this style of grain, roasted barley isn’t actually a malt as the grains are not germinated before roasting.

There are breeding programs in all the main barley growing areas of the world which develop new varieties through breeding and selection and unless you start brewing with a heritage variety like Maris Otter or Golden Promise the chances are after a few years the variety you buy will change. This is a good justification for using these premium price varieties. The impact of variety on flavor is however quite a contentious issue amongst brewers. As yet there is little scientific proof that valued/heritage varieties do confer superior flavor and even less showing they provide better brewhouse performance. Most experienced brewers would attest to the fact that the malting company making the malt certainly does have an impact on the quality of the flavor from the malt. One aspect which should not be forgotten in any discussion about the flavor from a particular variety, is that unless the grain processes consistently well in the brewhouse and provides the necessary nutrients to give effective fermentations any innate flavor quality in the grain becomes fairly insignificant.

See also acidulated malt

Malted cereals other than barley are classed by many jurisdictions as adjuncts. They are produced in relatively small amounts. Some are used in brewing European-style beers; others are used in the manufacture of opaque beers, distilled products, foodstuffs, and confectionary. These malts are made from temperate-zone cereals (wheat, rye, triticale, and oats) and also from tropical cereals (sorghum, corn [maize] and rice). Only barley and oat grains in the temperate-zone cereals are husked. Wheat, rye, and triticale are huskless, and this can give rise to malt house problems.

Malt types can influence the flavor and color of beer. Dark malts are important to the production of certain beer types. These characteristics in dark malt are the result of a Maillard reaction that is initiated due to the killing temperatures used in the production of such malts.

Unmalted barley is an unsuitable material for making beer by itself. It lacks the necessary enzymes for brewing, it is not easily friable for milling, and it produces a highly viscous extract that is defcient in amino acids and lacks the color and flavor required for making a good quality product. During malting, selected and prepared barley is steeped in cold aerated water for 40-50 hours, followed by 3-5 days of cool aerated germination. During this time the shoot and rootlet grow and important enzymes form and act. The grain is then dried by kilning with warm air that fixes the properties of the malt and imbues malt with its unique flavor.

• Base malts such as Pilsner, lager malt, and pale ale malt are produced by germination at 15-17°C (59-63°F) and dried in a cool airflow to about 8% moisture. These malts are kilned at low temperatures of 50-70°C (122-158°F) before curing at a final temperature of 70-85°C (158-185°F). Pale ale malts are typically given kilning temperatures of 60-90°C (140-194°F) and are cured at up to 105°C (221°F) to develop higher color (3-5 SRM) and more flavor. The flavors expressed are lightly grainy with hints of toast and warmth. Note that these temperatures are ranges of typical conditions that maltsters might choose at their discretion—there are no standardized recipes for specific types of malt.
• Highly-kilned malts are base malts (or base malts that have not been fully cured) that have been kilned to a higher color, such as pale ale, Vienna, Munich, and aromatic malts. The highly kilned malts are heated dry (3-10% moisture) at low temperatures (120-160°F/50-70°C) to retain their diastatic enzymes. Aromatic and Munich malt are kilned at higher temperatures than base malts (195-220°F/90-105°C) to produce richly malty and bready flavors. Only Maillard reactions are involved; caramelization reactions occur at higher temperatures. The congress mash pH of these malts drops by a couple tenths from that of the base malt. The higher curing temperature reduces or eliminates acid-producing microflora.
• Caramel malts are produced by roasting green malt, i.e., malt that was not dried by kilning after germination. These malts are put into a roaster and stewed at the saccharification range of 150-158°F (65-70°C) until starch conversion takes place inside the husk. Afterwards, these malts are roasted at higher temperatures of 220-320°F (105-160°C), depending on the degree of color wanted. Heating at these temperatures causes both caramelization and Maillard reactions. The maximum color achievable is about 150 SRM or 300 EBC.
• Roasted malts include amber, brown, chocolate, and black malt. These malts start out green like the caramel malts above, but are kilned to a lower percentage of moisture (5-15%) before roasting. Amber malts are produced by roasting fully kilned pale ale malt at temperatures up to 335°F (170°C). These temperatures give the malt its characteristic toasty, biscuity (cookie), and nutty flavors. Brown malts are roasted longer than amber malts, but at lower temperatures, and achieve a very dry, dark toast flavor, with color equal to that of the caramel malts.
• Chocolate malt starts out with more moisture before roasting than brown malt, but less than caramel. The roasting process begins at about 165°F (75°C) and is steadily increased to over 420°F (215°C), where the malt develops chocolaty flavors. Some degree of caramelization occurs, but the majority of the flavors are from Maillard reactions and some degree of pyrolysis (controlled charring). Black (Patent) malts are roasted to slightly higher temperatures of 428-437°F (220-225°C) producing coffee-like flavors. Roast barley is produced in a similar manner but the difference is that it is never malted to begin with. Again, the majority of flavors come from Maillard reactions and pyrolysis.

Specialty malts can be divided into two basic categories, those that are simply heated, and those that go through a special process to caramelize the sugar (crystal AKA caramel malts). In each group there is a wide variety of colors available. These malts are used for the color and character that they provide. Unlike pale malts, dark malts should be used as fresh as possible in order to retain their aromas. These special malts do not have emailing activity due to the high processing temperature.

Crystal malts are believed to improve beer stability.

Malt analyses available do not reliably predict a malt's brewhouse performance, and brewers have yet to agree on what set of analyses should be used to specifically define a malt.

Coloured and special malts' flavours change and decline with age and so these materials should be used fresh and their lab worts should be tasted and smelled to see that they are `normal'. Although chemical `marker' substances, such heterocyclic, nitrogen-containing Maillard products, have been sought, to allow flavour to be quantified indirectly by chemical analyses, this approach has had little success.

Traditional analyses of malt do not always reflect potential brewhouse performance.

There are many special malting barley varieties from the past that are being used to make specialty malts today, such as Klages, Golden Promise, and Maris Otter.

It's long been a consensus that the traditional malt analysis specifics provide limited information about brewhouse behavior, and the usefulness provided for determining the effect of the malt on wort or beer quality is virtually non-existent. These days, a malt analysis is very much like a risk management tool—it is used to give some idea about how much a particular batch of malt may vary from previous batches. In other words, the use of the specification is to minimize variation rather than predict brewhouse performance. It is a point of reference to compare different suppliers, different crop years, and new varieties and to match raw materials purchasing to customer requirements. As such, it is a well-established benchmark. However, in some ways the malt analysis directs the brewer in how to avoid process difficulties by adjustment of the grist or mashing conditions based on the variance. A malt analysis doesn't necessarily help with selecting a malt because malts with apparently the same analytical specification can have widely different performance in brewing practice.

A traditional malt analysis can be subdivided into five key groups: starch conversion, carbohydrate conversion, carbohydrate extract, color, and enzyme potential.

When setting a specification for a colored malt, it is not advisable simply to increase the color in the hope that you can then use less in the grist. For example, lower color crystal malts are sweet and fruity, whereas higher color crystal malts are treacly and more bitter.

There is clearly much to be gained by understanding malt flavor in more detail. The low-tech grinding and wetted-porridge method allows the more obvious differences in flavors to be appreciated by almost anyone with a reasonable ability in sensory analysis and with improved levels of training and description some very elegant profiles and troubleshooting are possible.

See The Handbook of Craft Brewing chapter 1 for a discussion of how to read a malt analysis.

• Base Malts With A Story – Heirloom, Terroir, & Traditional Malts, and an overview of the Organic Malt Portfolio on YouTube
• https://www.sciencedirect.com/science/article/pii/B9780127999548000010
• https://www.hausmalts.com/

Malt that has not been adequately modified during the malting process may benefit from a 113–126°F (45–52°C) protein and beta-glucan rest; see Mashing. This rest increases degradation of beta-glucan and protein so that the starch can be accessed. The protein rest therefore helps increase yield and attenuation. However, such a low mash-in creates problems such as poor head retention due to the excessive protein degradation. Therefore a "protein rest" should be reserved only for poorly modified malts. The increased amino acids (FAN) from a "protein rest" is generally unnecessary since the FAN is usually adequate without it.

Unfortunately, simply adding a protein rest may have little to no effect, because after initial degradation by the β-glucanases at lower temperatures, many more high molecular weight β-glucans are liberated during the maltose rest at 62–65 °C. These can no longer be broken down, because the β-glucanases have already been denatured due to the increase in temperature. A reliable and almost complete degradation of β-glucans can be achieved, however, if the β-glucan solubilase activity is initiated in the mash before the β-glucanase rest occurs. The temperature optima of both enzymes (endo-β-1,4-glucanase: T opt. approx. 45 °C; β-glucan solubilase: T opt. approx. 62 °C) make infusion impossible. Therefore, an ample sized portion of the mash needs to be separated from the main mash, and the insoluble β-glucans must be liberated at an elevated temperature; see Decoction mash. Due to its considerable volume, this portion of the mash must be cooled with cold liquor prior to being returned to the main mash. Afterwards, β-glucan degradation occurs once the entire mash is allowed to rest in the mash tun at a lower temperature. This process should be considered a salvage technique for malt otherwise giving very poor extract, and it should rarely if ever be needed.

Only the activity of beta-amylase correlates well with the determination of diastatic power, DP, as it is usually determined.

Isoenzymes of β-amylase from different barleys have different temperature sensitivities. Barleys with the more stable enzyme give malts which yield the most fermentable worts.

Many hundreds of potentially active flavour substances are derived from malts or adjuncts and include aldehydes, ketones, amines, thiols and other sulphur-containing substances, heterocyclic oxygen-, nitrogen- and sulphur-containing substances and phenols.

Diastatic power, the total activity of starch degrading enzymes in barley malt, is considered to be an important quality characteristic for malting and brewing. Several hydrolytic enzymes contribute to diastatic power, however, including alpha-amylase, beta-amylase (main contributor), limit dextrinase and alpha-glucosidase. Of these enzymes, beta-amylase is laid down during grain filling and alpha-amylase, alpha-glucosidase and limit dextrinase are synthesized during germination, predominantly in the scutellum and aleurone layers. Diastatic power, like other quality attributes in barley, has been reported to be determined by a complex interaction of genetic and environmental factors.

The activity of mainly alpha-amylase, beta-amylase, and limit dextrinase is collectively called "diastatic power" (DP). In the brewing industry, DP is a key parameter of malting quality since it is an estimate of the capacity of the malt to degrade starch into fermentable sugars. Methods for estimating the diastatic activity of malt are generally based on its ability to generate reducing sugars. The main units and criteria used to measure the DP of a malted cereal are:

• Degrees Lintner (°L), defined by the JECFA (the Joint FAO/WHO Expert Committee on Food Additives) and the IoB (Institute of Brewing) as follows: "A malt has a diastatic power of 100°L if 0.1 ml of a clear 5% infusion of the malt, acting on 100 ml of a 2% starch solution at 20°C for 1 h, produces suffi cient reducing sugars to reduce completely 5 ml of Fehling's solution." For a complete description of the method see http://www.fao.org/ag/agn/jecfa-additives/specs/Monograph1/Additive-270.pdf . The DP is around 35–40 for standard barley malts, but it can be as high as 100–125 for lager malts, and over 160 for some high-protein North American malts which have far more enzymatic power than they require to hydrolyze the starch from the malt. Therefore, they enable the brewer to use these malts as an amylases source in the case of unmalted starch adjuncts addition.
• Degrees Windisch–Kolbach (°WK), used by the EBC (European Brewery Convention), which can be converted to Lintner units as follows:

  DPL = ( °WK + 16 ) ÷ 3.5

• Sorghum diastatic units (SDU), used by the SABS (South African Bureau of Standards) especially for sorghum, and not easily comparable to ºL and ºWK.

Diastatic power highly correlates with the level of beta-amylase, however the actual efficiency of starch degradation is also influenced by the levels of other starch-degrading enzymes. Therefore higher diastatic power does not necessarily produce wort with higher levels of fermentable sugars in the mash.

Beta amylase is considered the principal enzyme responsible for diastatic power.

The quality of barley malt is determined by its extract and the degree of fermentability of that extract (apparent attenuation limit [AAL]). For the commercial malt trading, diastatic power (DP) is often used as an approximation for AAL since DP is more simply and quantitatively measured, particularly because there is a significant impact of yeast strain or source on alcohol yield. DP is a measure of starch hydrolyzing enzymes that are the combined activity levels of β-amylase, α-amylase, limit dextrinase, and α-glucosidase.

Although the DP specification generally gives an indication of potential malt starch degrading capacity, brewers are increasingly losing confidence in the value of the DP parameter. To illustrate brewers concerns, a series of commercial case studies were presented in Evans et al., (2007) which provides examples of where the DP specification was of questionable value or in some cases downright misleading.

• Evans, D.E., Li, C. and Eglinton, J.K., (2007) A superior prediction of malt attenuation. In Eur. Brew. Conv. Cong. Proc. Venice Vol. 31:54-66.

A low protein, high starch grain will have a flourier (softer) endosperm which is a result of more amylose, with large granules. Grain hardness is a physical measure and is positively related to traits such as high malt friability, higher wort extract and higher wort fermentability and variation in fermentable sugars where a softer grain is better for these traits. Low protein and low hordein is positively related to higher grain hydration rates, higher friability, and improved malt modification. However, the up-side increase in protein content is an increase in β-amylase as there is a portion bound up in the hordein while some beta-amylase is free. An increase in β-amylase should also result in an increase in wort maltose, but the amount of extract is negatively related protein content, so less starch will be available in the mash.

Diastatic power does not always accurately estimate the level of fermentable sugars generated during mashing or the subsequent wort fermentability. The developing trend is for the brewer to measure individual malt diastatic power enzymes (DPE) levels to more accurately predict and evaluate the starch degrading capacity and potential wort fermentability in order to assess malt quality.

For poorly modified, malt Narziß and Litzenburger found maximal extract concentration at 60°C for isothermal mashing.

The degree of protein modification affects bready flavor and palatefulness, extensive modification of proteins is a cause of empty beer taste.

Aside from determining the ratio between soluble and total protein amount (“Kolbach” index), the breakdown of the network of barley storage proteins dictates the accessibility to starchy reservoirs that will then provide the fermentable carbohydrates. In effect, the Kolbach index is a reliable predictor of the potential degree of starch conversion. Hordeins are known to affect the diastatic power of malt wherein the total hordein grain content negatively correlates with the malting quality (Smith and Simpson, 1983). However, the total hordein content alone is a poor indicator of malting properties, because the composition of cultivar-specific hordeins is unquestionably relevant to the technological parameters. Overall, the relationships between the content of total or individual protein classes and malting traits are conflicting, as brewing is a highly intricate process, difficult to reproduce in simple model systems (Gupta et al., 2010).

Malt freshness has anecdotally been noted to affect beer quality.

Malt quality depends on its variety, growth, storage condition of grains, and the industrial process (Aalbers VJ, Vaneerde P (1986) J Inst Brew 92:420–425)

Premilled malt stored in bags purged with inert gas and low moisture levels has been shown to be stable for several months. cites Evans, E. 2021. Mashing. ASBC/MBAA: St. Paul, MN.

Lipid content can vary by malt. For example, Alexis contains a high amount of hydroxy fatty acids, while Barke contains a marked lower content of these oxylipins.

The amount of oxidized lipids increases the longer malt is stored.

commercial barley malt varieties having lower amounts of lipids tend to yield malts with better friability, and fermentability than those having high grain lipid.

because fermentability is typically an expensive analysis, the DP parameter has been traditionally used as a predictor for it. Traditionally, DP has been considered an indication of the combined level of starch-degrading enzymes, which include alpha-amylase, alpha-glucosidase, limit dextrinase, and beta-amylase. However, many brewers have lost confidence in the value of the DP parameter for prediction of malt quality or potential fermentability. To illustrate brewers’ concerns, a series of commercial case studies was presented by Evans et al that provided examples of when the DP specification was of questionable value or, in some cases, entirely misleading. As an alternative, based on small-scale mashing trials, it has been shown that fermentability can be accurately predicted through a combination of the KI and the balance of activities of the DP enzymes alpha-amylase, limit dextrinase, and beta-amylase and their thermostabilities. cites Evans, D. E., Li, C., and Eglinton, J. K. A superior prediction of malt attenuation. Proc. Congr. Eur. Brew. Conv. 31, presentation 4, 2007.

The "floor malting" process tends to under-modify malt, and it is somewhat less homogenous.

the inhibiting capacity of malts on the lipoxygenase activity can be attributable to the antioxidant properties of the non-enzymatic browning products and, in particular, to the brown high molecular weight polymers, named melanoidins. These compounds, which are formed during thermal treatments (e.g., kilning and roasting), may exhibit antioxidant activity through several mechanisms. In fact, they may possess reducing properties, chain-breaking activity, oxygen consuming and metal-binding capacity, which can be exhibited simultaneously.

The endo-β-glucanase activity develops faster during floor germination than during pneumatic germination, resulting in a lower malt β-glucan level.

Proteolysis can be controlled by lowering the germination temperature during the late stage to avoid overdegradation of proteins that are beneficial to beer foam. Malt treated this way has lower β-glucan levels without altering other quality attributes. A longer malting time reduces specific viscosity of wort because of prolonged degradation of macromolecules. Therefore, the germination time can be extended to reduce the content of β-glucans in malt, but this leads to higher levels of soluble proteins. The use of malt with Kolbach indices exceeding 41% are undesirable in modern breweries, because the beer will have poor foam, an empty, harsh taste, and an unsatisfactory bitterness.

β-glucan content in barley grain was influenced more strongly by genotypic factors than environmental ones. winter barley cultivars was higher than spring barley cultivars. Low β-glucan content in the malt is the most important indicator of malt quality. This means using grain with low levels combined with good β-glucanase expression.

The level of barley arabinoxylans or pentosans varied somewhat with genotype, but was largely controlled by environmental factors

Arabinoxylans, like β-glucan, are associated with negative malting quality.

Arabinoxylan content is not part of a typical barley or malt analytical profile and, as a consequence, little is known of the relationship between arabinoxylans and other quality parameters.

Thermal treatment of malt during kilning is associated with the formation of products of the Maillard reaction [3,20–23]. Depending on the ratio of reducing sugars and amino acids in green malt, different types of complex compounds are obtained. In addition, the content of reaction products is strongly influenced by the temperature and the duration of the heat treatment. It has been found that the malt roasting processes lead to active pyrolytic and degradation processes and increased accumulation of high molecular weight components with brown color [3,22–25]. These differences in heat treatment affect the quality of the malts. Pale and caramel malts are characterized by the content of low molecular weight colorants, while roasted malts are characterized by content of high molecular weight colorants, known as melanoidins [3]. They have high reduction potential and an intense brown color, which is responsible for the color developed of the roasted malts [3,24].

Malt color is the only stable characteristic that does not change during storage.

Special malts give less attenuation to beer, due to lower diastatic power and lower yeast nutrients content. The less fermentable extract might also be ascribed to Maillard reactions during the production of roasted malt, which compounds are unavailable for enzymatic hydrolysis. The Maillard compounds could also inhibit the metabolism of yeast cell (Coghe et al. 2005).

The higher the amount of caramel malt, the higher the antioxidant activity.

These studies demonstrated that the addition of colour malt generally led to a decrease in oxidative wort and beer stability. The authors showed a significant dependence between the radical generation in the wort and the content of Maillard reaction products. Recent investigations (29) have shown that specific Maillard intermediate products with an endiol structure can accelerate radical generation and the oxidative processes in wort and beer.

Higher roasted (darker) malts extrude more iron, manganese and zinc during mashing. For example, all-Munich wort contains 160-210% more iron than three diverse brands of all-Pilsner worts.

the oxidation stability of finished beer is directly related to the concentration of organic free radicals in malt endosperm. These free radicals are produced by the increase in tem­perature during the malt baking process. Higher temperature results in higher concentration of free radicals (Cortés et al., 2010). This makes a finished dark beer more prone to have an oxidizing taste, but this flavor is overshadowed by the strong candy flavor from Maillard reaction products (Cortés et al., 2010). [...] Various studies have suggested that the presence of a large content of organic free radicals and Maillard reaction products in the endosperm of kilned malt leads to stronger oxidation in the boiling process, forming higher levels of free radicals, thus reducing the potential for endogenous antioxidants and SO2 content in the final beer (Cortés et al., 2010). It should be noted that kilning promotes generation not only of a high concentration of free radicals but also of a high content of antioxidants, especially melanoidins, which play a key role in leading and assisting phenolic compounds in the scavenging of free radicals (Wunderlich et al., 2013; Wunderlich et al., 2012; Zheng, 2017).

The activity of thiol oxidase lessens during malt storage, which suggests that this is part of the explanation for why stored malt displays better wort separation than newly kilned malt.

Jaskula et al. [15] showed that the rate of beer ageing is positively correlated with FAN, Kolbach Index, heat-load (TB-Index) and free aldehyde content of the malt. Furthermore, a higher FAN content of the malt, usually coinciding with a higher aldehyde content, results in less flavour-stable beers [15, 26]. Malt contains considerably high levels of free aldehydes, especially Strecker degradation aldehydes are present in high concentrations.

malt modification by roasting increases the sweet wort levels of Fe and decreases Cu

Using roasted malts in beer production has generally been found to lead to higher rates of radical formation, most likely due to higher concentrations of reducing compounds that are able to retain the trace levels of Fe, Cu and Mn in their low oxidation states, which catalyze the formation of ROS.

Malt roasted at 190 �C gave higher concentrations of iron, zinc and manganese in the sweet wort than the pilsner malt. The opposite trend was seen for copper, where the concentration was lowest in the darkest wort. Holzmann and Piendl reported an increase in iron, manganese, and zinc in wort when they gradually decreased the mashing pH from 6.35 to 5.00.[22] The decrease in wort pH, which follows the degree of roasting of the malt, could contribute to the higher levels of these three metals in the darker single malt worts seen in this study.

Spring barley contains more oxidative enzymes compared to winter varieties.

The mineral composition of the malt depends on the variety, place where it was grown, atmospheric conditions, growing techniques and harvest, storage and malting systems. The malting technique is particularly important. A short-germinated and undermodified malt has a different grist composition in husks, grits, and flour than a longergerminated and overmodified malt. In a cereal grain, mineral elements are transferred from the storage tissues to the developing seedling. Minerals are more concentrated in the germ than in the central section, whereas the distal section has an intermediate amount. Rootlets and shoots contain substantially more potassium, phosphorus, iron, zinc, manganese, and copper than kilned malt. Calcium is transported to rootlets but not to shoots, and is more uniformly distributed throughout the kernel than magnesium. High-protein fractions are substantially richer in minerals than low-protein fractions. In differently modified malts, the development of rootlets and acrospires and the extent of metal transport from the central and distal section to the germ end are variable. It can thus be expected that the mineral concentrations in worts derived from such malts will vary. The metal distribution is also highly dependent on protein modification. Consequently, the brewer must carefully plan both malt modification and mashing conditions to achieve a desired mineral level in the wort ( Holzman and Piendl, 1976 ).

A short germinated and undermodified malt has a different grist composition in husks, grits, and flour than a longer germinated and overmodified malt. In a cereal grain, there is a general transfer of mineral elements from the storage tissues to the developing seedling. Minerals are more concentrated in the germ end than in the central section, whereas the distal section has intermediate amounts (7). Rootlets and shoots contain substantially more potassium, phosphorus, iron, zinc, manganese, and copper than kilned malt. Calcium is transported to rootlets but not to shoots (7), and it is more uniformly distributed throughout the kernel than is magnesium (8). High-protein fractions are substantially richer in minerals than low-protein fractions. In differently modified malts, the development of rootlets and acrospires and the extent of metal transport from the central and distal sections to the germ end are variable. It can thus be expected that worts derived from such malts will vary in their metal concentrations. The metal distribution is also highly dependent on the protein modification (6), a characteristic in which the analyzed malts greatly varied (Table 1). As a consequence, the brewer must carefully consider both malt modification and mashing conditions in order to achieve a desired metal level in the wort.

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Potential sources

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