Malt Modification and Mashing Conditions As Factors Influencing the Minerals of Wort1

Malt Modification and Mashing Conditions as Factors Influencing the Minerals of Wort1

ALFONS HOLZMANN and ANTON PIENDL, Institutfuer Brauereitechnologie und Mikrobiologie tier Technischen Universitaet Muenchen, D-805 Freising- Weihenstephan, Germany

ABSTRACT said to give a dry flavor. Trace metals, such as copper and iron, act as oxidation catalysts and impair the flavor stability. High levels of The influence of mashing temperature, pH, mash concentration, and phosphorus, magnesium, and potassium are of importance for the mashing time on potassium, sodium, calcium, magnesium, copper, iron, manganese, and zinc contents of wort was investigated. The metals were dietetic properties of beer. determined by atomic absorption spectrophotometry. Variations in pH and Raw materials and brewing processes exert an influence on wort mashing temperature affect the solubility of the metals more than do mash salts. With barley, these influences are variety, environment, and concentration and mashing time. By means of the analysis of variance, the plant production techniques. Steeping, germination, and kilning relative importance of mashing conditions and malt modification was are significant malting conditions. In mashing, temperature, time, calculated. Potassium, sodium, calcium, and copper are mainly influenced pH, concentration, and grist composition have an effect. Brewing by malt modification; iron is more affected by mashing conditions, whereas water can contain high levels of nitrate and fluoride. Wort boiling magnesium, manganese, and zinc depend on both variables As a diminishes the mineral concentration due to binding metals to the consequence, the brewer must carefully consider both factors in order to precipitated material. With the addition of hops, metals are also achieve a desired metal level in the wort Key words: Biomelrical analysis. Malt quality. Mashing parameters. added. The use of adjuncts and syrups normally dilutes the metal Metals. level of an all-malt wort. Adjunct worts are less buffered, which results in a greater decrease of the pH value during fermentation. On the other hand, syrups may contain heavy metals and chlorides n addition to carbohydrates and amino acids, the minerals of in abundance. I wort play an important role in fermentation and beer quality For further details, see the review papers "Role of trace metals in (Fig. 1). brewing" (3), "Mineral matter, trace elements, organic and Metals (e.g., magnesium) are components of DNA and RNA as inorganic acids in hopped wort" (10), and "Wort salts in beers well as of coenzymesand cosubstrates. Minerals activate or inhibit brewed using adjuncts" (13). enzymes and influence the transport of carbohydrates and amino An all-malt pale lager wort (12° P) should contain about 550 acids into the cell. Phosphorus is involved in the formation of mg/1. potassium, 30 mg/1. sodium, 35 mg/1. calcium, 100 mg/1. metabolic energy (ATP). Zinc promotes the fermentation rate, magnesium, 0.10 mg/1. copper, 0.10 mg/1. iron, 0.15 mg/1. calcium improves the flocculation. Small amounts of iron, copper, manganese, and 0.15 mg/1. zinc (9,10). and zinc are required to support yeast growth. Gushing is In an earlier paper (2) the effects of barley and malting attributable to heavy metals. Zinc, copper, and iron increase the technology on the wort minerals were presented. In the same head retention of beer. Copper and iron contents in the haze connection, the current report presents a detailed study of the material are 5000 to 50,000 times as high as in the bulk of beer. As influence of mashing conditions, using malts of varied enzyme activators, metals affect the by-product formation, whereas modification. the anions have a direct or indirect influence on beer flavor. Chloride seems to impart fullness and sweetness to beer. Sulfate is TABLE I Properties of Malts 'Presented at the 42nd Annual Meeting, Milwaukee, May 1976 Under- Normally Normally Over- modified Modified Modified modified Malt Malt Malt Malt 1 2 3 4 Fine grind extract, g/lOOgdrywt 80.33 80.8 814 825

Coarse grind extract, g/100 g dry wt 73.7 78.7 794 81.9

Fine-coarse grind extract difference, % 6.6 2.1 2.0 0.6

Conversion time, min 20 10-15 10-15 5-10

Color, EBC 2.5 4.0 3.3 4.2

Protein, g/100 g dry wt 11.5 11.4 11.2 9.9

Soluble nitrogen, mg/100 g dry wt 580 725 693 730

Protein modification, % 31.5 39.8 38.7 46.2

pH,EBC 5.90 5.81 5.87 584

Viscosity, cP 2.00 1.62 1.58 1.49

Hardness, BU 650 365 330 220

Fig. 1. Minerals of wort: influences from barley, malting and mashing, and Extract at 45° C, effects on yeast, fermentation, and beer. Hartong-Kretschmer 28.5 38.6 38.1 46.5 MINERALS OF WORT Vol. 35

EXPERIMENTAL asterisks (**) denote "significant" and "highly significant" values, respectively. The term "malt modification" (in Figs. 3, 5, 7,9, and The investigations were carried out with four malts of varying 11) includes the four malt qualities. The terms "mashing modification degrees (Table I). Malt 1 is undermodified; the values temperature" (Fig. 2), "pH in mashing" (Fig. 4), "mash for fine-coarse grind extract difference, viscosity, and hardness are concentration" (Fig. 6), and "mashing time" (Figs. Sand 10) include high, and the values of soluble nitrogen, protein modification, and a varying number of cases; the number of calculated cases is set in extract at 45°C are low. Malts 2 and 3 are normally modified. They parentheses behind the corresponding mashing factor in Figs. 3. 5, reflect normal cytolytic, amylolytic, and proteolyticactivities. Malt 7, 9, and 11. 4 is overmodified; the values for fine-coarse grind extract RESULTS difference, viscosity, and hardness are low, whereas those for soluble nitrogen, protein modification, and extract at 45° C are Mashing Temperature high. For this study, 50-g grist samples were mashed with 350 ml The malts were coarsely ground and 50-g grist samples were distilled water for 30 min at the following temperatures: 20°, 25°, mashed with varying amounts of distilled water. Glass beakers and 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, and 80°C. glass stirrers were used for mashing. At the end, the mash was filled An increase in the mashing temperature from 20° to 80° C shows up to a weight of 450 g. The worts were centrifuged (not filtered) for the following effects (Fig. 2): a stepwise increase in potassium until 30 min at 4000 rpm. The metals were determined in the unboiled 55° C; a slight increase in sodium until 55° C; a decrease in calcium, worts by atomic absorption spectrophotometry (12). especially above 70°C; a strong increase in magnesium until 60°C, The results were calculated biometrically. A program was used and a decrease above 65° C; a slight increase in copper, especially in from Reiner of the Technical University Munich/Germany (2-4V), the mashes at higher temperatures (70° to 80°C); and a stepwise for the analysis of variance. An analysis of variance was made, and decrease in iron, manganese, and zinc. the components of variance were estimated on the basis of mean For the calculation of the components of variance, only the squares (SQ X DF). The total of the components of variance was values for mashing temperatures between 45° and 75°C were 100%. For example, the sum of the components of variance, considered. A comparison of the relative importance of mashing mashing temperature, and malt modification, and the interaction temperature and malt modification shows that the former factor of both factors will be 100%. This type of biometrical calculation has a greater effect on copper, iron, manganese, and zinc, while the shows which component of variance (e.g., mashing temperature or latter is more important for potassium, sodium, calcium, and malt modification, or the interaction of both factors) magnesium (Fig. 3). is—relatively—the most important. The significance of the biometrical results for each sample was pH in Mashing examined on the basis of the F-test. A single asterisk (*) and double For the hydrogen ion concentration study, 50-g grist samples

POTASSIUM (mg/l) SODIUM (mg/l) CALCIUM (mg/l) MAGNESIUM (mg/l) 250 270 290 310 330 350 370 3.9 4.3 4,7 5,1 22 26 30 30 34 38 42 46 50 54

20 ~1 1 O 30 o ] *""* 40 1 a. 1 z> 50 < CE 60 1 n z 70 UJ p— 80

COPPER (mg/l) IRON (mg/l) MANGANESE (mg/l) ZINC (mg/l) 0,35 0.43 0,51 0.59 0.04 0.08 0,12 0,16 Q20 0,17 0.25 0.33 0.41 0.49 0.57 0.40 0.50 0.60 0.70 0.80 0,90 1,00

Z 20

Fig. 2. Mashing temperature and mineral content of wort (average values of four differently modified malts). No. 1 ASBC JOURNAL were mashed with 350 ml liquid for30minat45°C,20minat62°C, amounts of sodium and copper are obtained in a pH range from 5.5 and 40 min at 70°C. In the final worts, the pH values and the metals to 5.7. were determined. The amounts of acids and alkalis used and the The relative effects of pH in mashing and malt modification were resulting pH values are given in Table II. evaluated (taking into account only the values between pH 6.0 and A lowering of pH leads to a higher solubilization of potassium, pH 5.2). Calcium, magnesium, iron, manganese, and zinc are more calcium, magnesium, iron, manganese, and zinc (Fig. 4). High affected by hydrogen ion concentration, and potassium and sodium

MASHING TEMPERATURE* MASHING MALT MALT TEMPERATURE(7) MODIFICATION (4) MODIFICATION T POTASSIUM *•* SODIUM =• CALCIUM I** n MAGNESIUM i** **- COPPER

IRON D

MANGANESE ZINC ID 20 40 60 80 100% 0 20 40 60 80 100% 0 20 40 60% Fig. 3. Relative effects of mashing temperature and malt modification on the minerals of wort.

POTASSIUM(mg/I) SODIUM (mg/l) CALCIUM (mg/l) MAGNESIUM ( mg/l) 350 370 390 410 3,8 4.2 4.6 11 19 27 35 43 51 50 60 70 80 90 100 110 120 i i I \ \ I I 1 6,35 6.2 n ' 5,9-6.0 5,7-5,9 i o 5'5'5'7 i z 5.4-5,6 - 5.2-5,5 x i 5.0-5.4

COPPER(mg/l) IRON (mg/l) MANGANESE ( mg/l) ' ZINC (mg/l) 0.28 0.32 0.36 0,40 0,05 009 0.13 0.20 0.30 0.40 0,50 0,60 0.70 0.80 Q.30 0.50 0,70 0.90 1.10 J.30 i i i i i I I I I I ' I T I

X 6.35 a. 6.2 5.9-6.0 1 5.7-5.9 5.5-5.7 | 5,4-5.6 1 5.2-5.5 1 5.0-5.4

Fig. 4. pH in mashing and mineral content of wort (average values of four differently modified malts). MINERALS OF WORT Vol. 35 pH IN MASHING* MALT MALT pH IN MASHING (6) MODIFICATION (4) MODIFICATION

POTASSIUM 1 1 I

SODIUM I

CALCIUM ]** I

MAGNESIUM |

COPPER 1 | J

IRON 1 1 j^. .,., MANGANESE | ] I

te&- •¥ ZINC 1 J J 0 20 40 60 80 100% 0 20 40 60 80 100% 0 20 40 60%

Fig. 5. Relative effects of pH in mashing and malt modification on the minerals of wort.

POTASSIUM (mg/1) SODIUM(mg/l) CALCIUM(mg/l) MAGNESIUM (mg/l) 375 385 395 405 415 3.5 4.5 5.5 16 18 20 63 67 71 75 79 i i i i i i i i i i i i i i i i 1*3 n n 1+4 p-i i ?1+5 I 1 f- 1+6 < I 1 * 1+7 1 1 1 z UJ o z. COPPER (mg/ ) RON (mg/l) MAN(3ANESE(mg/l) ZINC(mg/l) o 0.15 0.17 0.19 0.21 0.10 0,12 0.14 0,17 0.19 0.21 0,23 0.27 0,29 0.31 0,33 o i i i i i i i i i i i i i i i oo 1+3 p < n 2 1+4 i i 1+5 1+6 1 h 1 1+7 i i 1 1+3= 50g MALT+150ml H20

1+7 « 50g MALT+ 350ml H20

Fig. 6. Mash concentration and mineral content of wort (average values of four differently modified malts). No. ASBC JOURNAL MASH CONCENTRATION MASH MALT MALT CONCENTRATION (4) MODIFICATION MODIFICATION POTASSIUM 1 1 SODIUM 1 CALCIUM ^ 1 MAGNESIUM 1 1 COPPER 1 IRON _J 1 &• MANGANESE 1 1 & ZINC 1 J 0 20 40 60 80 100% 0 20 40 60 80 100% 20 40 60%

Fig. 7. Relative effects of mash concentration and malt modification on the minerals of wort.

POTASSIUM(mg/l) SODIUM (mg/l) CALCIUM (mg/l) MAGNESIUM (mg/l) 350 370 390 410 430 4,3 4.7 19 21 23 25 52 60 68 76 84 i i i I i i i i i i i i i ^ 5 n n uj 15 ^- i I 1 30 2 60 i | - 120 _i o LJ o ID <£> h- :OPPER(mg/l) IRON (mg/l) I^lANGANESE(mg/l) ZINC(mg/l) < 0,17 0.19 0,21 0.09 0.13 0.17 0.21 0.16 0,24 0 32 0,40 0.23 0.27 0.31 0,35 0.39 LU i i 1 1 1 1 i i i i i i i i i 2 ~ 5 n 1 I ^ 15 1 i x 30 -r- I < 60 : 120 ^^•i J

Fig. 8. Mashing time (at 65°C) and mineral content of wort (average values of four differently modified malts). MINERALS OF WORT Vol. 35 MASHING TIME(AT65°C)* MASHING MALT MALT TIME(5)AT65°C MODIFICATION^) MODIFICATION I *•* 1 ^JJ, POTASSIUM 1 SODIUM 1 I *-* *•* CALCIUM |

MAGNESIUM

IE-*

COPPER 1

IRON I**

!•* MANGANESE 1 •

t ZINC ** , , , 1 " 0 20 40 60 80 100% 0 20 40 60 80 100% 20 40%

Fig. 9. Relative effects of mashing time (at 65°C) and malt modification on the minerals of wort.

SODIUM POTASSIUM(mg/l) (mg/l) CALCIUM (mg/l) MAGNESIUM (mg/l) 240 280 320 360 400 4.2 4.6 26 28 30 36 44 52 60 68 76 LO LU

± 15 z 30 o 60 S> 12° vT

(— <

LU COPPER (mg/l) IRON(mg/l) MANGANESE (mg/l) ZINC(mg/l) H- 0.20 0.22 0.24 0,15 0.17 0.19 0,21 0.40 0,44 0.48 0.50 0,52 0.54 0,56 0.58 0,60 o 5 I 15 c/) 30 60 120 F Fig. 10. Mashing time (at 45°C) and mineral content of wort (average values of four differently modified malts). No. 1 ASBC JOURNAL MASHING TIME(ATA5°C)x MASHING MALT MALT TIME(5) ATA5°C MODIFICATIO_ N MODIFICATION POTASSIUM 1 SODIUM -I** CALCIUM *# MAGNESIUM 1 ## COPPER 1 IRON 1 If- MANGANESE D* I** ZINC ] 0 20 40 60 80 1000/. 0 20 40 60 80 100% 0 20 40"/o

Fig. 11. Relative effects of mashing time (at 45°C) and malt modification on the minerals of wort.

TABLE II of 45°C. The mashing time varied between 5, 15, 30, 60, and 120 pH in Mashing min. An extension of the mashing time (at 65°C) from 5 to 120 min Step Distilled Water + Addition pH Value of Wort leads to an increase in potassium, magnesium, and (partly) copper, ml and a stepwise decrease in sodium, calcium, iron, manganese, and zinc (Fig. 8). 1 340 + 10ml n/10 NaOH 6.35 Potassium, magnesium, and iron are more influenced by 2 345 + 5 ml n/ 10 NaOH 6.2 mashing time (at 65°C), whereas sodium, calcium, copper, 3 350 5.9 - 6.0 manganese, and zinc depend more on malt modification (Fig. 9). 4 345 + 5mln/10HCl 5.7 -5.9 The experiment with mashing time at 45° C yielded—with the 5 340 + 10 ml n/IO HC1 5.5 - 5.7 exception of sodium—similar results (Fig. 10): a stepwise increase 6 335 + 15 ml n/10 HC1 5.4 - 5.6 in potassium, magnesium, and copper, and a stepwise decrease in 7 330 + 20 ml n/10 HC1 5.2 - 5.5 calcium, iron, manganese, and zinc. 8 325 + 25 ml n/10 HC1 5.0 - 5.4 The analysis of variance shows that mashing time (at 45° C) has a greater effect on potassium and magnesium; whereas malt modification has more influence on sodium, calcium, copper, iron, more by malt modification (Fig. 5). manganese, and zinc (Fig. 11). Finally, the relative importance of malt modification and Mash Concentration mashing conditions was assessed. The term "malt modification" Mash concentration varied between 1+3 (i.e., 50 g grist and 150 included undermodified malt, overmodified malt, and the two ml distilled water) and 1+7 (i.e., 50 g grist and 350 ml water). The normally modified samples. The term "mashing conditions" malts were mashed at 45°, 62°, and 70° C. included mashing temperature, pH in mashing, mashing A dilution of the mash concentration leads to a higher concentration, and mashing time at 65°C and at 45°C. From this solubilization of potassium, sodium, calcium, magnesium, evaluation, it can be seen that potassium, sodium, calcium, and manganese, and zinc. Much copper is already solubilized in steps copper are mainly influenced by malt modification, and iron is 1+4, and most of the iron in steps 1+7 (Fig. 6). more affected by mashing conditions; whereas magnesium, For the calculation of the components of variance, only the data manganese, and zinc depend on both variables (Fig. 12). for the mash concentrations 1+4 through 1+7 were used. The biometrical evaluation shows that seven of eight metals are more DISCUSSION influenced by malt modification, whereas iron depends neither on mash concentration nor on malt modification (Fig. 7). Variations in the pH and in mashing temperature have more effect on the solubility of the metals than do mash concentration Mashing Time and mashing time. In the last experiment, mashing time was determined. For this Potassium is more solubilized in a range in which a-amylase purpose, two model systems were chosen: one experiment was activity is optimal. The sodium level shows a certain correlation carried out with a temperature of 65°C, and one with a temperature with the formation of lower nitrogen compounds. Calcium and MINERALS OF WORT Vol. 35 The amount of metals extracted from malt varies with the MAINLY INFLUENCED BY MINERALS mashing conditions as well as with the chemical and physical properties of the malt. OF MALT MASHING WORT A short germinated and undermodified malt has a different grist MODIFICATION CONDITIONS composition in husks, grits, and flour than a longer germinated and overmodified malt. In a cereal grain, there is a general transfer of POTASSIUM mineral elements from the storage tissues to the developing seedling. Minerals are more concentrated in the germ end than in • SODIUM the central section, whereas the distal section has intermediate CALCIUM • amounts (7). Rootlets and shoots contain substantially more potassium, phosphorus, iron, zinc, manganese, and copper than MAGNESIUM • kilned malt. Calcium is transported to rootlets but not to shoots (7), • • and it is more uniformly distributed throughout the kernel than is COPPER magnesium (8). High-protein fractions are substantially richer in IRON • minerals than low-protein fractions. In differently modified malts, the development of rootlets and MANGANESE • acrospires and the extent of metal transport from the central and distal sections to the germ end are variable. It can thus be expected ZINC • • 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 Fig. 12. Malt modification and mashing conditions as main factors malts greatly varied (Table 1). As a consequence, the brewer must influencing minerals in wort—a statistical summary. carefully consider both malt modification and mashing conditions in order to achieve a desired metal level in the wort. magnesium are more solubilized in a range in which /3-amylase Acknowledgment activity is optimal and in which amino acids are formed. Copper, iron, manganese, and zinc levels exhibit a relationship with the This work received financial support from the Deutsche Gesellschaft zur formation of soluble nitrogen. Foerderung der Brauwissenschaft. The decrease in metal concentration during mashing is due to the formation of insoluble phosphates (e.g., with calcium and Literature Cited magnesium), the formation of salts with the acidic groups of proteins, and the mechanical adsorption on spent grains and trub I. HOPKINS, R. H.,and AMPHLETT, P. H.Z. Gesamte lirauw.62: 129 (1,11,14). The insoluble material is precipitated and thus prevented (1939). from getting into the wort. 2. HOPULELE, T., and PIENDL, A. Amer. Soc. Brew. Chem., Proc. 1973, p. 75. The brewhouse yield of minerals is about 100% for potassium 3. HUDSON, J. R. J. Inst. Brew. 65: 321 (1959). and sodium (11), about 95% for chloride, 84% for sulfuric acid, and 4. JACOBSEN, T., and LIE, S. J. Inst. Brew. 81: 10 (1975). 63% for phosphoric acid (5). More than 50% of other minerals is 5. KOLBACH, P., and RINKE. W. Monatsschr. Brau. 16: II (1963). lost, and the loss is particularly high for trace elements (5,11). 6. LIE, S., HAUKELI, A. D., and JACOBSEN, T. Ear. Brew. Com-., The metal content of wort is mainly governed by a partition Proc. Congr. 15th, Nice, 1975, p. 601. between the sequestering agents in wort and the metal binders in the 7. LIU, D. J., POMERANZ, Y., and ROBBINS, G. S. Cereal Chem. 52: insoluble matter of the mash (6). Amino acids (such as histidine and 678 (1975). cysteine), polyphenols (tannins), and phytic acid are strong metal 8. LIU, D. J.. ROBBINS, G. S., and POMERANZ. Y. Cereal Chem.51: 309(1974). binders. Naturally occurring chelators in wort are sulfur-, nitrogen- 9. MAENDL, B. Brauwissenschaft 27: 177 (1974). or oxygen-compounds, containing reactive groups such as 10. MAENDL, B. European Brewery Convention, Monograph-I, Wort carboxyl, sulfhydryl, o-diphenyl, and amine (4). Svmposium, p. 233. Zeist (1974). The binding capacity of a metal chelator is highly pH-dependent, 11. MAENDL, B. Brauwell 115: 1565 (1975). due to competition between the hydrogen and metal ions in 12. MAENDL, B., WULLINGER, F.. HOPULELE. T.. and PIENDL, A. solution (6). Usually, a decrease in pH leads to an increase in free Brauwissenschaft 25: 277 (1972). metal ions, since the stability constant of the metal binder 13. RUD1N, A. D. European Brewery Convention, Monograph-I, Wort decreases. The precipitation of nitrogenous components at elevated Symposium, p. 239. Zeist (1974). temperatures removes sequestering agents from the wort (6), 14. STONE, I. Wallerstein Lab. Commun. 25: 329 (1962). leading to a greater loss of minerals. [Received May 10, 1976.]