| | Presented at the 18th North American Barley Researchers Workshop, July 17-20, 2005, Red Deer, Alberta, Canada
The differences in fermentable carbohydrates of major Canadian malting barley varieties and their effects on fermentation
The fermentable carbohydrates of the major Canadian malting barley varieties were monitored during malting and brewing processes. It was observed that the fermentable carbohydrate compositions of the congress wort were varietal dependent, while the fermentable carbohydrate compositions of the finished wort were both varietal and mashing condition dependent. The overall malt modification affected malt carbohydrate composition, and malt’s brewing performance and final beer quality.
Yueshu Li (1), Rob McCaig (1), Ken Sawatzky (1), Aleks Egi (1) and Michael Edney (2)
(1) Canadian Malting Barley Technical Centre, Winnipeg, R3C 3G7 Canada
(2) Grain Research Laboratory of the Canadian Grain Commission
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NanoMash: A novel procedure for research mashing of limited-quantity barley malts
The ASBC Malt-4 extract analysis method (Congress Mash) provides a standard set of conditions for generating an unhopped wort commonly used to evaluate the malting quality performance of experimental malts. However, the method requires specialized instrumentation and relatively large quantities of malt. These requirements prevent researchers without access to the specialized instrumentation and particularly those with limited sample availability from generating Congress worts for malting quality analysis and other research uses. Use of a commercially available device allows agitation of small volume samples through orbital mixing while heating or cooling them using a Peltier temperature controlled block. Controlling the device to follow the Congress mash temperature profile offers the possibility of conducting a mashing cycle at a significantly reduced scale. Adaptation of standard ASBC wort analysis methodology to microtiter plate and other reduced-scale methodology allows provision of several key parameters for worts generated from size-limited samples. While not intended to supplant standard ASBC methodology, this small-scale mashing protocol significantly lowers the sample requirements and extends the potential for malt analysis to research programs where it may not have been previously feasible.
Laurie A. Marinac and Mark R. Schmitt*
*Corresponding author: markschmitt@wisc.edu
USDA Agricultural Research Service, Cereal Crops Research Unit, 501 Walnut St., Madison, WI 53726
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Comparison of hull peeling resistance of barley and malt in western Canadian two-row barley lines
Hull peeling resistance in barley and malt is desired by the malting and brewing industry. A group of 15 two-row malting barley (Hordeum vulgare L.) lines and one feed cultivar were used to compare these traits in Canadian two-row barley and determine their relationship to other agronomic traits, including grain yield, kernel plumpness, test weight and kernel weight. Barley samples from standard yield test plots at two sites in each of Manitoba and Saskatchewan during 1999 and 2000 were evaluated for % hull peeling on a weight basis direct from the plot combine (RPWB) and after inducing peeling with an air-blast de-huller (APWB). Micromalted samples were evaluated for % hull peeling of the malt “as is” (RPWM) and after air-blast de-hulling (APWM). Analyses of variance over years and locations indicated that hull peeling of barley and malt were strongly influenced by environmental factors, particularly year. However, the single largest source of variance for RPWM and APWM was the genotypic component, indicating that heritability and response to selection would be higher in malt than barley. Genotypic effects were lowest for RPWB, but still highly significant (P<0.001). Genotype-by-environment interactions were also highly significant, but lower in magnitude. Manley, Stein and CDC Dolly were consistently lower in all hull peeling traits, while TR251, CDC Unity, AC Oxbow and AC Bountiful were significantly higher with TR244 always being the highest. The relative ranking of the barley lines varied somewhat with CDC Unity, AC Bountiful and Merit ranking higher for susceptibility to hull peeling as malt than barley, while AC Metcalfe, Harrington and TR253 were ranked less susceptible as malt. Among hull peeling traits, the highest correlation of 0.95 (P<0.001) was between RPWM and APWM, indicating that RPWM would be adequate for determining hull peeling in malt. The correlation between RPWB and APWB was also high at 0.92 (P<0.001), but RPWB was more variable due to its relatively low values averaging about 1.0% overall compared with 36.8% for APWB. Other correlations among hull peeling traits ranged from 0.82 to 0.92. There were moderate negative correlations between test weight and the hull peeling traits, ranging from -0.55 (P<0.05) to -0.69 (P<0.01). Kernel plumpness, kernel weight and yield were not significantly correlated with any of the hull peeling traits. In conclusion, it should be possible to develop two-row malting barley cultivars with acceptable kernel characteristics and improved resistance to hull peeling of both barley and malt.
W.G. Legge (1), J.S. Noll (2), and B.G. Rossnagel (3)
Corresponding author: blegge@agr.gc.ca
(1) Agriculture and Agri-Food Canada, Research Centre, P.O. Box 1000A, R.R. #3, Brandon, Manitoba R7A 5Y3;
(2) Agriculture and Agri-Food Canada, Cereal Research Centre, 195 Dafoe Road, Winnipeg, Manitoba R3T 2M9;
(3) Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, Saskatchewan S7N 5A8.
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Elimination of barley colour defects in Australia
Grain colour defects including staining and black point have been a problem for Australian barley growers for a number of years, resulting in thousands of tonnes of malting barley being downgraded each year. Over the last decade, research has been conducted investigating many aspects of these disorders, including objective assessment, biochemical evaluation, crop management, storage effects and resistance breeding. A number of breeding lines have been identified with resistances to both forms of colour defects. The black point tissue has been extracted with high levels of phenolic acids (namely ferulic and coumaric acids) being present suggesting the dark pigmentation may be a large polyphenolic compound. Black pointed grain also has an impact on germination rate. Markers for black point resistance coincide with markers for dormancy and pre-harvest sprouting amylase. The effects on fungal contamination results in a dark staining on the grain. A number of factors impact of the degree of staining including pre-harvest rainfall, timing of the rainfall event and pre-existing level of resistance. Husk content also appears to have an impact on the final appearance of the grain. Markers for husk content also coincide with genetic regions for dormancy and pre-harvest sprouting. The improvement of grain quality at intake can be delivered through two options; 1. the development of barley varieties with resistance to these grain defects as resistance to black point and staining has been shown to be heritable and 2. optimising early harvest strategies and cool-air drying on-farm.
Glen Fox (1), Maria Sulman (1) and Kevin Young (2)
Corresponding author: glen.fox@dpi.qld.gov.au
(1) Department of Primary Industries & Fisheries, Toowoomba, Qld 4350, Australia
(2) GxE Crop Research, PO Box 1704, Esperance, WA 6450, Australia
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Characterization of barley tissue-ubiquitous beta-amylase2
There are two barley β-amylases genes, encoding important starch degrading enzymes. The endosperm-specific β-amylase (Bmy1), the more abundant isozyme in cereal seeds, has been thoroughly characterized. The lesser abundant β-amylase2 (Bmy2), has not been biochemically characterized from any cereal seeds. Characterization of Bmy2 from two commonly grown barley (Hordeum vulgare L.) cultivars, ‘Morex’ and ‘Steptoe’, was a major objective of this study. The bmy2 cDNAs were sequence, expressed in Escherichia coli, and the recombinant enzymes (rBmy2) characterized. The relative hydrolysis rates of various a-D-glucans and the pH activity optima of ‘Morex’ and ‘Steptoe’ rBmy2s were the same and not significantly different from barley rBmy1. The ‘Morex’ rBmy2 was 7oC more thermostable than the ‘Steptoe’ rBmy2, determined by differences in their T50 values, and is more thermostable than any reported wild type β-amylase1. Three amino acid differences were identified between the two Bmy2 sequences and the contributions to enzyme thermostability evaluated by site-directed mutagenesis. Examination of mutant enzymes with one amino acid substitution revealed that each of the three residues contributed ~3oC to the thermostability of the ‘Morex’ wild type rBmy2. Mutant enzymes with two amino acid substitutions contributed ~5.6oC and the triple amino acid mutant enzyme contributed ~8.7oC to thermostability. To date, no quantitative trait loci (QTL) for malting quality traits have been associated with the bmy2 locus. Should an association be discovered, the ‘Morex’ bmy2 allele, containing D238, M337 and Q362, provides a discrete signature of a thermostable β-amylase2 that could be targeted for marker assisted selection.
Suzanne E. Clark (1), Patrick M. Hayes (2), and Cynthia A. Henson (1,3)
Corresponding author: cahenson@wisc.edu
(1) Dept. of Agronomy, University of Wisconsin-Madison,
(2) Dept. of Crop and Soil Science, Oregon State University, and
(3) UDA-ARS Cereal Crops Research Unit, Madison, WI
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Barley seed osmolyte concentration as an indicator of preharvest sprouting
This study was conducted to test the hypothesis that barley seed osmolyte concentrations can be used as an indicator of preharvest sprouting (PHS). Osmolyte concentrations from the 2002 Minnesota and North Dakota crops were compared to pearling and other techniques for assessment of PHS. Approximately 30% of the seed evaluated were sprouted. Samples were evaluated for osmolyte concentrations, pearling, and Stirring Number, while smaller subsets were evaluated using other methodologies. Osmolyte concentrations correlated well with pearling (r=0.822, P<0.0001) and fluorescein dibutyrate staining (r=0.835, P<0.0001). a-Amylase activity correlated less positively with osmolyte concentration (r=0.650, P<0.0001). Stirring Number, Falling Number, germination, and accelerated aging had weak negative correlations with osmolyte concentration. It is concluded that seed osmolyte concentration, a relatively simple assay, is a good indicator of PHS in barley as assessed by the pearling method or fluorescein dibutyrate staining.
Cynthia A. Henson* (1,2), Stanley H. Duke 2(,) Paul Schwarz (3), Rich Horsley (3), and Charles Karpelenia (1)
*Corresponding author: cahenson@wisc.edu
(1) USDA-ARS Cereal Crops Research Unit, Madison, WI 53706,
(2) Department of Agronomy, University of Wisconsin, Madison, WI 53706,
(3) Department of Plant Sciences, North Dakota State University, Fargo ND 58105
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Osmolyte concentration as an indicator of malt quality
This study was conducted to test the hypothesis that malt osmolyte concentrations can be used as an indicator of barley malt quality. Seeds of four 6-row and four 2-row genotypes were steeped for six days at 20oC for 6 days. At intervals of 24 h over the steeping regime green malt from each cultivar was removed and tested for osmolyte concentration, malt extract (ME), diastatic power (DP), α-amylase activity, soluble/total protein (S/T), and β-glucan concentration. Osmolyte concentrations increased most rapidly in days 1 through 3 of germination. After 4 days osmolyte concentrations began to plateau. Significant positive correlations were found for malt extract and osmolyte concentrations in days 1 through 4 and day 6 (r=0.740 to 0.942, P<0.0001). Days 2 and 3 osmolyte concentrations correlated well with ME for all days (r=0.740 to 0.942, P<0.0001) and α-amylase activity for day 2 (r=0.771, P<0.0001). Day 2 osmolyte concentration correlated well with days 2 through 6 for β-glucan concentration (r= -0.702 to -0.830, P<0.0001). No significant correlations were found for DP and osmolyte concentrations on any day. These data indicate that osmolyte concentrations at early time points in steeping are good indicators of several measures of malt quality at later time points in steeping.
Cynthia A. Henson* (1,2), Stanley H. Duke (2), and Charles Karpelenia (1)
*Corresponding author: cahenson@wisc.edu
(1) USDA-ARS Cereal Crops Research Unit, Madison, WI 53706,
(2) Department of Agronomy, University of Wisconsin, Madison, WI 53706
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Relationships among malt fermentability and malt quality parameters under the influence of barley beta-amylase heat stable allele
Starch hydrolysis during germination is achieved by the action of four major enzymes, α- and β-amylase, limit dextrinase and α-glucosidase. This hydrolysis produces fermentable sugars required for yeast nutrition in brewing. Fermentability is a critical quality parameter for brewing that affects the level of alcohol produced by yeast, and is typically assessed in malt extracts by determining the change in specific gravity after small scale fermentation, referred to as apparent attenuation limit. Diastatic power is a measure of the capacity of the malt to degrade starch into fermentable sugars and is primarily determined by β-amylase activity. Although diastatic power is a reasonable predictor of fermentability, it does not always accurately estimate the level of fermentable sugar generated during mashing or the subsequent fermentability of the resultant wort. β-amylase is one of the major proteins found in the starchy endosperm, which rapidly loses activity at mashing temperatures above 55oC. Two alleles with different β-amylase enzyme thermostability are distinguished with the insertion/deletion of a palindromic 126-pb sequence in intron III of β-amy1 gene. Increased thermostability results in more efficient starch degradation. Barley cultivars with high thermostability β-amylase allele will achieve high levels of fermentability without a good malt modification. On the other hand, barley cultivars with low thermostability β-amylase allele will achieve high levels of fermentability if they achieve high levels of malt modification. The objective of this study was to determine the influence of heat stable β-amylase allele in the relationship between fermentability and quality parameters. We characterized 40 commercial malting barley varieties from different countries. The malt quality data used in the correlations studies come from the average of the results obtained by 50 laboratories. The quality malt parameters analyzed were: Fine Grind Extract, Total Nitrogen, Hartong 45, Diastatic Power, Wort Viscosity, Alpha-Amylase, Friability, Free Amino Nitrogen, Final Attenuation Apparent and Soluble β-Glucans. Significant correlations were obtained from the statistical point of view, but values of R square explained less than 20 % of the variability among the parameters. In general, barley varieties that present high thermostability β-amylase allele showed better qualitative levels of fermentability and malt modification than the varieties with low thermostability β-amylase allele. From these results we conclude that the fermentability is not easily predicted from quality parameters, therefore the use of β-amy1 allele in barley breeding program is necessary to improve fermentability levels in malting barley grains. More studies are needed to understand all the properties that influence malt fermentability and how they interact.
Blanca Gómez* (1), Héctor Acevedo (2), and Ana Clara López (3)
*Corresponding author: bgomez@latu.org.uy
(1) Malting Unit, Cereal Department, Laboratorio Tecnológico del Uruguay, Av. Italia 6201 CP 11500, Montevideo, Uruguay
(2) Quality Laboratory, Malteria Oriental S.A. Abrevadero 5525, Montevideo, Uruguay
(3) Biotechnology Department, Laboratorio Tecnológico del Uruguay, Av. Italia 6201 CP 11500, Montevideo, Uruguay.
The above posters were presented at the 18th North American Barley Researchers Workshop, July 17-20, 2005, Red Deer, Alberta, Canada |
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