Malting Barley Varieties Research Articles

The Alleviative Effects of Salicylic Acid on the Activities of Catalase and Superoxide Dismutase in Malting Barley (Hordeum uhulgare L.) Seedling Leaves Stressed by Heavy Metals

AbstractAs toxic divalent heavy metal ions, Zn2+, Cu2+, Mn2+, Cd2+, Hg2+, and Pb2+ exert certain negative effects on plant growth and development, which has been paid huge amount of attention to in the management of heavy metal pollution. As a novel kind of endogenous plant hormone, salicylic acid (SA) is considered to exert beneficial physiological effects on plants. In this paper, the activities of catalase (CAT) and superoxide dismutase (SOD) in seedling leaves of a malting barley variety (called Ganpi No.4) cultured under hydroponic cultivation was measured under different treatments of Zn2+, Cu2+, Mn2+, Cd2+, Hg2+, and Pb2+ and under different treatments of SA alleviation, respectively, and such values were then compared and analyzed. The results showed that all treatments of different ions and the activities of CAT and SOD and all SA‐alleviated treatments and the activities of CAT and SOD exhibited nonlinear relationships. Zn2+, Cu2+, Mn2+ exerted less severe stresses on the activities of CAT and SOD at lower concentrations, and led to significantly inhibitive effects on the activities of CAT and SOD at higher concentrations. And Cd2+, Hg2+, and Pb2+ exerted significantly repressing effects on the activities of CAT and SOD. As for SA's alleviative effects, such effects were salient for most concentrations of Mn2+, Zn2+, and Cu2+ treatments and lower concentrations of Cd2+, Hg2+, and Pb2+ treatments, while were not significant for higher concentrations of Cd2+, Hg2+, and Pb2+ treatments. These data provided theoretical references for studies on physiological mechanism of cereal crops' resistance or tolerance to heavy metal stress as biomarkers.

Recent trends in the use of sprout testing technology in Australia

There are a number of climate risks for grain production in Australia. These include drought, which can lead to delayed planting as well as early harvesting, increases in mean temperatures and also extreme temperature events ranging from heat to frost. Rain at harvest in particular has been a major factor affecting grain quality. This was highlighted by the record wet harvest in eastern and southern Australia in 2010/2011. The current 2011/2012 harvest is proving to be another wet season across the majority of growing regions, including Western Australia this time. This has resulted in a significant increase in weather damage testing at grain receival sites across the country. Up until the past few years, weather damage testing equipment such as Falling Number instruments were stocked in limited numbers by grain handlers. The units were deployed sporadically, often only once every three to four years. There was also a high usage of visual assessment for sprouted grains. This paper describes the changes that have taken place in weather damage testing of wheat and barley in Australia in the past two years. There has been a significant increase in the number of Falling Number instruments utilised for grain receival testing. Work practises have significantly improved in terms of training of receival site staff, as well as regular maintenance and check sample testing programmes. RVA technology is also now used for providing Stirring Number analysis for malting barley varieties.

Effect of batch-to-batch variation on the quality of laboratory and commercially malted Oxbridge barley

The malting performance of two different batches of Oxbridge barley was studied. The study showed that a single 24 h continuous laboratory steep was suitable for steeping the two batches of Oxbridge to provide good quality malt. Although each batch represented the same variety, and was of similar malting quality, they behaved differently in terms of friability scores, filtration rate and predicted spirit yield (PSY) by day 4 of the germination period. Worts prepared from the two malts gave different patterns of filtration rates, showing that each batch of Oxbridge modified at a different rate and in a different way, although they achieved similar final PSY results at the end of the malting period. The two batches of Oxbridge both malted rapidly, but behaved differently in terms of modification pattern, as revealed by the Rapid Visco-Analysis peak viscosities, as well visual germination results. The results of this study confirmed that, given the same malting conditions, batch 1 germinated more rapidly than batch 2, and supports the view that Oxbridge shows some inconsistency as a malting barley variety. The study further showed that the PSY result per se is not necessarily a good indicator of optimum modification of finished malted barley. This study showed that, while a particular barley variety, such as Oxbridge, may be associated with certain qualities and can produce good quality malt when a short steeping cycle is used, other factors are likely to cause batch-to-batch variations from the same barley variety. While the short steeping cycle was very successful in producing high-quality laboratory malt from Oxbridge, and results in a significant reduction of the quantity of water required for steeping, reduces malting time and also saves costs, there is evidence that there may be some additional variability associated with Oxbridge malting barley. Copyright © 2012 The Institute of Brewing & Distilling

Development of long-term and reliable in vitro plant regeneration systems for elite malting barley varieties: Optimizing media formulation and explant selection

The response to in vitro tissue culture of five important Mexican malting barley cultivars namely ‘Armida’, ‘Esmeralda’, ‘Adabella’, ‘Esperanza’ and ‘Alina’, was evaluated. Callus induction and plant regeneration were evaluated in shoot apices and immature barley embryos harvested eight, 12, 16, 20 and 24 days after pollination. These explants were cultured on 22 media formulations that included Murashige and Skoog (MS) and Chu (N6) media amended with two carbon sources and different concentrations of 2,4-Dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (Dicamba), 6-benzyladenine (BA), casein hydrolyzate and L-proline. No regenerable callus lines could be recovered from the experiments using shoot apices as the starting material. Conversely, immature embryos harvested at 12 to 16 days after pollination (1.0 to 1.5 mm long) and cultured on formulations containing the basal MS medium supplemented with 2 mg L -1 of 2,4-D or Dicamba resulted in the production of nodular and friable embryogenic calli with regenerative capacity in all barley cultivars. A medium containing MS, Dicamba and maltose generated the highest percentage of embryogenic calli formation (2.1 in ‘Adabella’ vs. 23.4 in ‘Alina’ cultivar) with the maximal regenerative potential (7.2 in ‘Armida’ vs. 9.1 recovered plants per gram FW callus in ‘Esperanza’ cultivar). Using this medium, ‘Esmeralda’ embryogenic callus lines have been maintained for more than five years without loss of regenerability or the capacity for producing normal plants. Key words: Barley, somatic embryogenesis, plant regeneration, immature embryos.

Comparative analysis of Australian and Canadian barleys for seed dormancy and malting quality

The association between high malting quality and pre-harvest sprouting (PHS) susceptibility is a key challenge when developing new malting barley varieties. A new malting barley variety Baudin has successfully combined high malting quality and PHS tolerance. A doubled haploid population was developed for mapping PHS tolerance and seed dormancy from a cross of Baudin × AC Metcalfe using 233 molecular markers. Three QTLs were mapped for seed dormancy based on the standard germination test at 24, 48 and 72 h. One major QTL was mapped to the long arm of chromosome 5H controlling seed dormancy and PHS tolerance from Baudin. Two other minor QTLs were identified from Baudin on chromosomes 3 and 7H. QTL/QTL interaction was detected for seed dormancy between chromosomes 3 and 5H. The PHS tolerance allele of the 5H QTL from Baudin contributes to higher malt yield without significant impact on diastatic power, beta-glucan content and wort viscosity. QTL from Baudin provide new sources to integrate PHS tolerance and high malting quality.

Association Mapping of Malting Quality Quantitative Trait Loci in Winter Barley: Positive Signals from Small Germplasm Arrays

Malting quality comprises one of the most economically relevant set of traits in barley (Hordeum vulgare L.). It is a complex phenotype, expensive and diffi cult to measure, that would benefi t from a marker-assisted selection strategy. Malting quality is a target of the U.S. Barley Coordinated Agricultural Project (CAP) and development of winter habit malting barley varieties is a key objective of the U.S. barley research community. The objective of this work was to detect quantitative trait loci (QTL) for malting quality traits in a winter breeding program that is a component of the U.S. Barley CAP. We studied the association between fi ve malting quality traits and 3072 single nucleotide polymorphisms (SNPs) from the barley oligonucleotide pool assay (BOPA) 1 and 2, assayed in advanced inbred lines from the Oregon State University (OSU) breeding program from three germplasm arrays (CAP I, CAP II, and CAP III). After comparing 16 models we selected a structured association model with posterior probabilities inferred from software STRUCTURE (QK) approach to use on all germplasm arrays. Most of the markertrait associations are germplasm- and environment-specifi c and close to previously mapped genes and QTL relevant for malt and beer quality. We found alleles fi xed by random genetic drift, novel unmasked alleles, and genetic-background interaction. In a relatively small population size study we provide strong evidence for detecting true QTL.

Dry Matter Digestion Kinetics of Two Varieties of Barley Grain Sown with Different Seeding and Nitrogen Fertilization Rates in Four Different Sites Across Canada

Our objective was to determine the differences in the rate and extent of dry matter digestion between barley subjected to differing agronomic variables. Two malting barley varieties, Copeland and Metcalfe were seeded at rates of 200 and 400 plants/m 2 . Each of these varieties received nitrogen fertilizer at rates of 0, 30, 60 and 120 kg/ha, resulting in a total of 20 different barley grain samples. Samples were ground through a 6mm screen and approximately 3 g of each weighed into 50 μm Dacron bags and sealed. The bags were incubated in three ruminally cannulated Holstein cattle for periods of 0, 3, 6 and 24 h. Using the data obtained from these incubations, rates of digestion were able to be predicted. The soluble fraction ranged from 0.229-0.327, the slowly degradable fraction ranged from 0.461-0.656, and the undegradable fraction ranged from 0.038-0.299. The rates of digestion ranged from 0.127-0.165 h -1 and the effective degradability ranged from 0.527-0.757. At the Canora location, the Copeland samples which received 120 kg/ha of nitrogen fertilizer had a significantly lower (p = 0.013) soluble fraction than the rest of the samples at that location. A significant interaction (p = 0.009) was seen between the seeding rate and nitrogen fertilizer application with samples from the Canora location, as well as significant differences (p = 0.029) between nitrogen application rates in samples from the Indian head location. The rate of digestion of samples from the Indian head location differed (p = 0.020) between the two seeding rates, with samples seeded at 200 seed/m 2 having a slightly higher rate of degradation. Differences in the effective degradability were seen between the different nitrogen application rates with samples from both the Canora and Indian head locations, as well as an (p = 0.004) interaction between the seeding rate and nitrogen fertilizer application rate. Although there was not a clear correlation between the different variables, both nitrogen application and seeding rate did have a significant effect on the rates and extent of digestion across each of the four locations. (Key

NIR and Planting Breeding—A Long and Productive Partnership

For over 60 years, the Department of Employment, Economic Development and Innovation (formally the Department of Primary Industries & Fisheries) has released high quality Prime Hard wheat and malting barley varieties to the grain farmers in Queensland and New South Wales. This profile outlines the work carried out in this area at the Queensland Grain Research Laboratory.

The Oxalic Acid Content in Selected Barley Varieties Grown in Poland, as well as in their Malts and Worts

The purpose of this work was to try to answer the question “What factors influence the oxalic acid content in barley, malt and wort?” Samples of three malting barley varieties (Prestige, Sebastian and Jersey, registered and grown in Poland) were investigated for their oxalic acid content. Laboratory scale malting and kilning of these samples and investigation of their oxalic acid content were conducted. Furthermore, the oxalic acid content was analysed in worts obtained from these malts. Tested barley samples, originating from various regions of Poland, showed different oxalic acid contents, ranging from 17.2 to 66.8 mg/kg d.m. basis. A higher temperature of germination (an increase from 14°C to 18°C with the same length of time) resulted in a decrease in oxalic acid content in the resultant worts. In most cases a positive linear correlation was found between the oxalic acid content in the malts and worts, and the initial barley samples. Oxalic acid content in barley appears to depend on the growth region rather than on the variety, but the data was not sufficient to draw any firm conclusions on this subject.

Reduced Phytate Barley Malt to Improve Fermentation Efficiency

ABSTRACT J. Inst. Brew. 117(3), 401–410, 2011 Brewery fermentations require continuous yeast growth to effi-ciently convert fermentable sugars to ethanol. Yeast growth is dependent on an adequate supply of nutrients, including miner-als. Minerals are generally assured in the brewery with addition of nutrient supplements but reduced phytate barley malts could reduce the need for supplements. The present study used bulked segregant analysis to determine effects of the reduced phytate trait in barley on field performance, barley quality, malting qual-ity and brewing performance. Two bulks from a doubled haploid population, along with a series of normal and reduced phytate controls, were grown at 3 to 5 western Canadian sites in 2006, 2007 and 2008. The normal and reduced phytate barley bulks had similar yields, but the reduced phytate barley had signifi-cantly lower test weight. Rates of endosperm modification were similar between the two phytate types, although, reduced phytate malt was significantly more friable. Malt extract and α-amylase levels were significantly lower in the reduced phytate bulk. Zinc and magnesium levels were significantly higher in reduced phy-tate worts and these worts produced better yeast growth as indi-cated by greater amino acid use during fermentation. Brewing performance tended to be better with reduced phytate worts, but not consistently so, likely due to the lower levels of malt extract and α-amylase. Results supported the incorporation of the re-duced phytate trait into malting barley varieties, but with atten-tion to breeding for improved test weight and levels of α-amylase.

Transcriptome analysis of a barley breeding program examines gene expression diversity and reveals target genes for malting quality improvement

BackgroundAdvanced cycle breeding utilizes crosses among elite lines and is a successful method to develop new inbreds. However, it results in a reduction in genetic diversity within the breeding population. The development of malting barley varieties requires the adherence to a narrow malting quality profile and thus the use of advanced cycle breeding strategies. Although attention has been focused on diversity in gene expression and its association with genetic diversity, there are no studies performed in a single breeding program examining the implications that consecutive cycles of breeding have on gene expression variation and identifying the variability still available for future improvement.ResultsFifteen lines representing the historically important six-rowed malting barley breeding program of the University of Minnesota were genotyped with 1,524 SNPs, phenotypically examined for six malting quality traits, and analyzed for transcript accumulation during germination using the Barley1 GeneChip array. Significant correlation was detected between genetic and transcript-level variation. We observed a reduction in both genetic and gene expression diversity through the breeding process, although the expression of many genes have not been fixed. A high number of quality-related genes whose expression was fixed during the breeding process was identified, indicating that much of the diversity reduction was associated with the improvement of the complex phenotype "malting quality", the main goal of the University of Minnesota breeding program. We also identified 49 differentially expressed genes between the most recent lines of the program that were correlated with one or more of the six primary malting quality traits. These genes constitute potential targets for the improvement of malting quality within the breeding program.ConclusionsThe present study shows the repercussion of advanced cycle breeding on gene expression diversity within an important barley breeding program. A reduction in gene expression diversity was detected, although there is diversity still present after forty years of breeding that can exploited for future crop improvement. In addition, the identification of candidate genes for enhancing malting quality may be used to optimize the selection of targets for further improvements in this economically important phenotype.

Assessment of genetic diversity by simple sequence repeat markers among forty elite varieties in the germplasm for malting barley breeding.

The genetic diversity and relationship among 40 elite barley varieties were analyzed based on simple sequence repeat (SSR) genotyping data. The amplified fragments from SSR primers were highly polymorphic in the barley accessions investigated. A total of 85 alleles were detected at 35 SSR loci, and allelic variations existed at 29 SSR loci. The allele number per locus ranged from 1 to 5 with an average of 2.4 alleles per locus detected from the 40 barley accessions. A cluster analysis based on the genetic similarity coefficients was conducted and the 40 varieties were classified into two groups. Seven malting barley varieties from China fell into the same subgroup. It was found that the genetic diversity within the Chinese malting barley varieties was narrower than that in other barley germplasm sources, suggesting the importance and feasibility of introducing elite genotypes from different origins for malting barley breeding in China.

Coincident quantitative trait loci effects for dormancy, water sensitivity and malting quality traits in the BCD47×Baronesse barley mapping population

A degree of seed dormancy (SD) is required for malting barley varieties in Uruguay, and many other parts of the world, in order to prevent pre-harvest sprouting. Water sensitivity (WS) (a decrease in germination under excess water) is a related trait that can create problems at the malthouse. Both traits are affected by environmental conditions during grain filling. We used a population of 100 doubled haploid lines derived from the cross BCD47 × Baronesse to map quantitative trait loci (QTL) affecting SD, WS, and malting quality traits. Preliminary experiments revealed that BCD47 has low SD and Baronesse has high SD. WS for these accessions was not known before this research. A major SD QTL – detected in four experiments – is on chromosome 5H, with BCD47 contributing the low dormancy allele. Four other regions with QTL effects for SD were mapped, but these QTL were significant in data from only one or two environments. Four regions were detected with QTL effects for WS, but only two – in 5H coincident with the SD QTL, and 3H – were significant in more than one environment. SD and WS were affected by the average temperature at the end of the grain-filling period, with higher temperatures associated with lower values for SD. At the same region on 5H where SD and WS QTL were detected, we found significant QTL for malt extract, α-amylase activity, β-glucans, FAN, Kolbach index, wort turbidity and protein content, with BCD47 contributing favourable alleles for all traits. These results underscore the importance of environmental effects on both SD and WS as well as the difficulties of combining good malting quality with adequate levels of SD and WS.

Structural and functional characterization of a winter malting barley

The development of winter malting barley (Hordeum vulgare L.) varieties is emerging as a worldwide priority due to the numerous advantages of these varieties over spring types. However, the complexity of both malting quality and winter hardiness phenotypes makes simultaneous improvement a challenge. To obtain an understanding of the relationship between loci controlling winter hardiness and malt quality and to assess the potential for breeding winter malting barley varieties, we structurally and functionally characterized the six-row accession "88Ab536", a cold-tolerant line with superior malting quality characteristics that derives from the cross of NE76129/Morex//Morex. We used 4,596 SNPs to construct the haplotype structure of 88Ab536 on which malting quality and winter hardiness loci reported in the literature were aligned. The genomic regions determining malting quality and winter hardiness traits have been defined in this founder germplasm, which will assist breeders in targeting regions for marker-assisted selection. The Barley1 GeneChip array was used to functionally characterize 88Ab536 during malting. Its gene expression profile was similar to that of the archetypical malting variety Morex, which is consistent with their similar malting quality characteristics. The characterization of 88Ab536 has increased our understanding of the genetic relationships of malting quality and winter hardiness, and will provide a genetic foundation for further development of more cold-tolerant varieties that have malt quality characteristics that meet or exceed current benchmarks.

Porovnanie vybraných ukazovateľov technologickej kvality starších a súčasných odrôd sladovníckeho jačmeňa.

Subor v minulosti pestovaných, ako aj neskor registrovaných genotypov sladovnickeho jacmeňa, bol podrobený analýze z hľadiska vybraných ukazovateľov technologickej kvality. Hodnotila sa hmotnosť 1000 zŕn a obsah bielkovin a skrobu pocas vegetacných obdobi v rokoch 2004 a 2005. Suchý rocnik 2004 vplýval na zniženie HTZ pri vacsine novsich ako aj starsich genotypov. Na obsah skrobu v sledovanom subore nemal vplyv rocnik, dokonca sa neprejavil ani vplyv genotypu. Vplyv rocnika na obsah bielkovin bol v sledovanom subore statisticky nepreukazný. Hmotnosť 1000 zŕn novsich genotypov sa v sledovanom subore zvýsila v porovnani so starsimi o 1 % a obsah bielkovin v zrne novsich genotypov bol v priemere nižsi o 1 %, v porovnani so starsimi genotypmi. Napriek tomu niektore starsie genotypy dosahovali vyssiu HTZ v obidvoch rocnikoch, v porovnani so sucasnými odrodami a analýza obsahu skrobu ukazala, že z hľadiska obsahu skrobu boli starsie genotypy porovnateľne s novsimi odrodami. Na zaklade sledovaných ukazovateľov technologickej kvality zrna dosahovala napr. odroda Slovenský kvalitný, registrovana v roku 1946, najlepsie výsledky.

MALDI‐TOF mass spectrometry of hordeins: rapid approach for identification of malting barley varieties

A procedure for identification of malting barley varieties using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of ethanol-soluble barley proteins (hordeins) is described. The hordeins were first extracted from milled barley grains by several extraction protocols (using different extraction agents and conditions). Hordein extracts were then analyzed directly via MALDI-TOF MS without any preliminary purification or separation step, and the protein profiles of analyzed hordein extracts were compared in order to find out the most suitable extraction procedure for mass spectrometric analysis. The optimized procedure was successfully applied to identification of 13 malting barley varieties. Our results revealed that the proposed mass spectrometry-based approach provides characteristic mass patterns of extracted hordeins, which can be advantageously used for barley variety identification.

Amino acid substitutions of the limit dextrinase gene in barley are associated with enzyme thermostability

Limit dextrinase (LD) is a key enzyme in determining the malting quality. A survey of 60 barley varieties showed a wide range of variation for the enzyme activity and thermostability. Galleon showed low enzyme activity and high thermostability while Maud showed high activity and low thermostability. Alignment of the LD amino acid sequences of Galleon and Maud identified seven amino acid substitutions Lys/Arg-102, Thr/Ala-233, Ser/Gly-235, Gly/Ala-298, Cys/Arg-415, Ala/Ser-885 and Gly/Cys-888. Genetic diversity of LD was investigated using single strand conformation polymorphism based on the amino acid substitutions. Only limited genetic variation was detected in the current malting barley varieties, although wide variation was observed in the wider barley germplasm. The Thr/Ala-233 and Ala/Ser-885 substitutions were associated with enzyme thermostability (P < 0.0001), but no polymorphism was associated with the enzyme activity. This result was confirmed from further sequence analysis. The results will provide a tool for understanding and selection of high LD thermostability.

Variety and N Management Effects on Grain Yield and Quality of Winter Barley

Winter malting barley (Hordeum vulgare L.) is a potential alternative crop for the dryland region of the Pacific Northwest. Nitrogen fertilization can increase grain yield but may also increase lodging and grain protein and reduce test weight. The objectives of this research were to determine the effect of N application rate and timing on grain yield and quality of winter feed and malting barley varieties. Field trials were conducted at Pendleton, OR (17 inches annual precipitation) and Moro, OR (12 inches annual precipitation). Nitrogen was applied at 0, 50, 100, or 150 lb N per acre in the fall and at 0 or 50 lb N per acre in the spring at Pendleton and at 0, 30, 60, or 90 lb N per acre in the fall and at 0 or 30 lb N per acre in the spring at Moro. Nitrogen fertilization increased grain yields at Pendleton to a maximum of 5,800 lb/acre in 2001 and 5,200 lb/acre in 2002 and at Moro to a maximum of 3,000 lb/acre. Nitrogen fertilization increased grain protein and reduced test weights. Yields of the advanced lines of malting barley were about 90% of the yields of feed type barley varieties. Spring N applications did not increase grain yield or protein more than fall N applications.

Composition and molecular structure of polysaccharides released from barley endosperm cell walls by sequential extraction with water, malt enzymes, and alkali

Isolated and purified endosperm cell walls (CW), used in this study, were derived from a Canadian malting barley variety, AC Metcalfe, grown in three different environments in Canada in 2003, and varying in grain protein and β-glucan contents, as well as in grain hardness. The CW were initially extracted with water at 45 °C and subsequently digested with barley malt crude enzyme extract resulting in two fractions designated CW-WE45 and CW-MD, respectively. The remaining non-digested cell wall material (CW ND) was further fractionated by sequential extraction with water at 95 °C (CW ND-WE95), saturated barium hydroxide (CW ND-BaE), and 1 N sodium hydroxide (CW ND-NaE) at 25 °C. Composition and molecular structure analyses were carried out for all fractions including the remaining cell wall residue (CW RES). Extraction of CW with water followed by digestion with malt crude enzyme extract solubilized the majority of β-glucans (∼55–70%) and glucomannans (∼60–80%) but only a small portion of arabinoxylans (∼20–30%) present in the intact CW. The CW-WE45 and CW ND-WE95 fractions consisted mostly of β-glucans exhibiting high average molecular weights ( M w) (2–3 × 10 6), whereas the CW ND-BaE consisted mainly of arabinoxylans with M w about 1–1.5 × 10 6. The CW ND-NaE contained almost equal amounts of β-glucans and arabinoxylans and a small amount of glucomannans, whereas the CW RES contained approximately equal proportions of β-glucans, arabinoxylans and glucomannans. β-Glucans in CW ND-WE95, CW ND-NaE, and CW RES exhibited a higher ratio of 3- O-β- d-cellobiosyl- d-glucose to 3- O-β- d-cellotriosyl- d-glucose (DP3/DP4) compared to β-glucans in CW-WE45 and CW-MD. β-Glucans in CW ND-NaE showed the highest level of long cellulosic oligosaccharides with DP ≥ 5, whereas those in the CW RES had the highest DP3/DP4 ratio. The CW-MD was fractionated by ultrafiltration into high (CW-MD HMW) and low-molecular weight (CW-MD LMW) sub-fractions, with weight-average M w of ∼150–350 × 10 3 and <10 × 10 3, respectively, as confirmed by size-exclusion chromatography. The monosaccharide composition of the sub-fractions indicated a more extended enzymic degradation of β-glucans and glucomannans than arabinoxylans. Some differences in composition and molecular structure of the cell wall constituents among the three barley samples were related to their solubility and enzymic digestibility.

Evaluation of antioxidant activities and total phenolic contents of typical malting barley varieties

Fourteen typical malting barley varieties from China were evaluated for their DPPH radical, ABTS radical cation and superoxide anion radical scavenging activities, reducing power, metal chelating activities, and total phenolic contents (TPC). All barley samples exhibited significant antioxidant activities determined by different assays, and contained significant levels of phenolic compounds. Gan4 and Wupi1 barley exhibited the highest DPPH radical scavenging activity, ABTS radical cation scavenging activity and reducing power. Gan4 and Humai16 barley showed the highest TPC, whereas the highest superoxide anion radical scavenging activity and metal chelating activity were found in Huaimai19 and Ken3 barley, respectively. The Pearson correlation analysis revealed that the TPC showed strong correlations with DPPH radical scavenging activity, ABTS radical cation scavenging activity, and reducing power ( P < 0.01), whereas its correlations with superoxide anion radical scavenging activity and metal chelating activity were poor ( P > 0.05). Moreover, DPPH radical scavenging activity, ABTS radical cation scavenging activity and reducing power were well positively correlated with each other ( P < 0.01). Principal component analysis (PCA) was applied to understand the interrelationships among the measured antioxidant activity evaluation indices, and to gain an overview of the similarities and differences among the 14 barley varieties.