Barley Grain Non‐specific Lipid‐Transfer Proteins (ns‐LTPs) in Beer Production and Quality

Plant non‐specific lipid‐transfer proteins (ns‐LTPs) are known for their ability to transfer various lipids between membranes in vitro. These ubiquitous basic proteins, that all share alpha structure stabilized by four disulphide bridges, are characterized by the presence of a hydrophobic cavity able to accommodate lipid molecules. According to molecular mass, this multigene family is subdivided into two subfamilies, ns‐LTP1 (9 kDa) and ns‐LTP2 (7 kDa); both located in the aleurone layer of the cereal grain endosperm. Ns‐LTP1 is a prominent protein in barley grain, malt and beer. Numerous studies performed on its structure and function confirm its important role in grain protection, as well as brewing technology. As the major beer protein crucial for many aspects of brewing, ns‐LTP1 can affect beer production and quality. Comparatively, there is less data available on the less abundant ns‐LTP2. In this review, the focus is on recent progress on the structure, biological and technological function of barley grain ns‐LTP1 and ns‐LTP2, with an emphasis on their importance in brewing.     

Effects of Lipid‐Transfer Protein from Malting Barley Grain on Brewers Yeast Fermentation

A lipid‐transfer protein (LTP), which belongs to a family of pathogenesis‐related (PR) proteins, was isolated from malting barley grain. This LTP significantly decreased fermentation and respiration of brewers yeast (Saccharomyces cerevisiae) and caused the leakage of cell constituents. These effects were dose dependent tending to saturation at higher concentrations (～ 200 μg/mg yeast dry weight cells). It was found that LTP survives the thermal treatment during the mashing process. Despite yeast fermentation inhibition in vitro, this LTP did not appear to cause impairment of yeast fermentation capability in the brewing process.     

Antimicrobial Activity of Malting Barley Grain Thaumatin‐Like Protein Isoforms,S and R

Two basic proteins were isolated to homogeneity from malting barley (Hordeum vulgare L.) grain. Proteins were identified as members of a Thaumatin‐Like Protein (TLP) family, by Western blot. Isoforms, assigned as TLP‐S and TLP‐R, have slightly different mobility at about 22 and 27 kDa in nonreducing and reducing conditions, and pI values of 9.5 and 9.4, respectively. The antifungal potency of malting barley grain TLPs isoforms was examined on Micrococcus lysodeikticus, Saccharomyces cerevisiae, Candida albicans and plant pathogen Fusarium sporotrichioides growth in vitro. It was found that that IC₅₀ value for TLP‐S was two fold higher. Antibacterial and antifungal activities of both isoforms were completely abolished by divalent (Ca²⁺, Mn²⁺, Mg²⁺) and monovalent (K⁺) cations, at concentrations approximating physiological ionic strength and higher. Glucanase activity was not observed; neither TLP‐S nor TLP‐R digested glucan. On the basis of these results, the importance of TLP for barley grain protection against fungal diseases has been discussed together with the mechanism of antimicrobial action.     

Utilization of the Linear Mode of MALDI‐TOF Mass Spectrometry in the Study of Glycation During the Malting Process

The process of glycation during the malting process was monitored by the linear mode of matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐TOF MS). Water‐soluble proteins were investigated and two hulled barley varieties, Jersey and Tolar, were compared to the hulless line KM 1910. The crude extracts of the proteins obtained from the grain, the malt, and aliquots collected every 24 h during the malting process, were mixed with the matrix (2,6‐dihydroxyacetophenone) and analyzed by mass spectrometry. The protein composition of the barley changed during the malting process. The protein patterns did not differ significantly between the three varieties of the barley grains. However, significant differences between the malts were evident. Results showed the influence of the malting process on the glycation of certain water‐soluble barley proteins, nonspecific lipid transfer protein 1 (LTP1) and protein Z, of which the glycated forms survived the brewing process. These major barley proteins are very important for the formation and stability of beer foam and glycation may prevent their precipitation. Analysis results indicated that slight glycation of the proteins had occurred on the second day of malting. The linear mode of MALDI‐TOF mass spectrometry was used as a fast and simple method for monitoring the patterns of low‐molecular weight barley proteins with regard to barley variety discrimination. This procedure also enables the selection of barley varieties suitable for the malting industry.     

Assessment of Enzymatic Endosperm Modification of Malting Barley Using Individual Grain Analyses

Enzymatic modification of the endosperm of malting barley is a main feature of the malting process. Uneven enzymatic modification of the endosperm (heterogeneity) can cause brewhouse problems. Although there is a general correlation between endosperm modification, beta‐glucan breakdown and endo‐beta‐glucanase development, it is based on average results from sample analyses and may conceal heterogeneity. The primary aim of this work was to use individual grain analyses to investigate factors that control endosperm modification and beta‐glucan breakdown. In terms of beta‐glucan breakdown and physical modification, the barley variety Chariot malted faster than Decanter. However, both varieties showed similar distribution of endo‐beta‐glucanase in individual grains during malting. Further work on individual grains showed that the correlation between beta‐glucan breakdown and endo‐beta‐glucanase activity was not significant. Surprisingly beta‐glucan breakdown did not always correlate with the physical modification of the endosperm. Both these findings suggest that sample analyses of beta‐glucan levels and malt beta‐glucanase activities are not reliable indicators of the degrees of which malt samples are modified during malting. Since the distribution of beta‐glucan in individual grains of the unmalted barley varieties was similar, the total beta‐glucan levels of the original barley did not determine the rate at which beta‐glucan was broken‐down during malting. Although protein studies are at a preliminary stage, the rate of protein breakdown was not correlated with the rate at which beta‐glucan was broken down in the malting grain. It is possible that the physico‐chemical properties of endosperm storage proteins may limit the rate of beta‐glucan breakdown during malting.     

The Measurement of Structural Characteristics of Barley for Shochu Using Single‐Kernel Characterization System 4100 Crush‐Response Profiles

The selection of grain that is optimum for barley Shochu is not straightforward. Usually malting barley is used, but not all malting barley samples perform well in Shochu production. In addition there is a genotype × environment effect, so that a given variety may perform satisfactorily in one environment but not another. Therefore a method for testing samples for Shochu is required. This group has previously reported on the evaluation of barley for Shochu production using the Single Kernel Characterization System (SKCS) and demonstrated a significant correlation between the SKCS Hardness Index and pearling performance. The Hardness Index values are multivariate statistical predictions derived from an incremental change analysis of the crush‐response profiles. In the present study, a detailed analysis was performed of the averaged SKCS Crush‐Response Profiles of barley, obtained when measuring the SKCS Hardness Index. It was concluded that the morphological differences between averaged barley SKCS Crush‐Response Profiles appear to allow barley varieties to be classified into four distinct classes. In addition, the elastic response to the crushing on the SKCS device of the aleurone layers of barley kernels yields a useful predictor of pearling quality/performance.     

Potential of Hull‐less Barley Malt for Use in Malt and Grain Whisky Production

Hull‐less (or husk‐less) barley is possibly one of the most important developments in barley in recent years. This study looked at the potential of hull‐less barley for use by the Scotch whisky industry. By modifying the malting conditions for hull‐less barley, it was possible to provide good alcohol yield as well as significant improvements in processing characteristics. The biochemistry controlling the germination of hull‐less barley was consistent with established knowledge about ‘normal’ hulled barley except that care is needed to ensure the consistency of feedstock, particularly since hull‐less barley may be prone to embryo damage during harvesting in the field. Our results indicated that the new batches of hull‐less barley studied, produced malt that gave much improved mash filtration rates in comparison with previous batches of material. These experiments demonstrated that by changing the malting conditions, to give a much shorter steeping cycle (8 h), it is possible to reduce water usage substantially in the malting industry, since only one ‘wet’ cycle was used, and also reduce germination times since optimum alcohol yield was achieved on day 4 germination rather than day 5 for conventional husked barley. This could save costs in terms of water, energy and time for the malting industry. The study also confirmed the potential of hull‐less barley for providing significant benefits for Scotch whisky distillers, both in terms of higher alcohol yields, and increased throughput, by showing that it is possible to overcome some of the filtration issues that have been previously associated with hull‐less barley. This study indicated that the new material was better suited than previous batches to both malt and grain distilling, both in terms of enzyme development and potential distillery performance, and further showed that viscosity problems associated with grain distillery co‐products can be significantly reduced when using hull‐less barley malt in the grain distillery. These would be substantial potential benefits for the Scotch whisky distilling industry.     

The Variation of β‐amylase Activity and Protein Fractions in Barley Grains as Affected by Genotypes and Post‐anthesis Temperatures

The variation of β‐amylase activity and protein fractions in barley grains was evaluated using 148 barley genotypes grown in the field and two cultivars under in vitro culture with two temperature treatments during grain development. The results showed that there was significant genotypic variation in β‐amylase activity and protein fraction content. Regression analysis indicated that β‐amylase activity was positively correlated with total protein and the level of each of the protein fractions, with the correlation coefficient between β‐amylase activity and hordein content being the highest. Furthermore, higher post‐anthesis temperatures (32/26°C, day/night) significantly enhanced β‐amylase activity and protein fraction content, presumably as a result of reduced starch content. Albumin and glutelin were the least and most affected, respectively, in comparison with the plants under lower temperature (22/16°C). Temperature post‐anthesis also influenced the morphology of the starch A granule and the number of B granules, suggesting the altered starch structure may also be a reason for deteriorated malting quality under high temperatures.     

The influence of steep regime and germination period on the malting properties of some hull‐less barley lines

Following field trials in 2008 and 2010, six lines, derived by mutation in the hull‐less barley cultivar Penthouse, were selected to provide a range in grain β‐glucan content. These lines, along with Penthouse and the hulled, malting variety Optic, were then malted, using four different steeping regimes, with samples kilned after 3, 4 and 5 days of germination. The longest steep regime provided samples with optimum modification after 5 days of germination. Samples from the other steep regimes were under‐modified to varying degrees. In particular, the steeps with a single immersion gave poorly modified samples with low extracts and alcohol yields. One line, with low grain β‐glucan, gave higher alcohol yields than either Penthouse or Optic, following a regime comprising two short immersions and a single air‐rest, but there was no clear association, within the lines, between β‐glucan content and malting properties. Copyright © 2012 The Institute of Brewing & Distilling     

Breeding of lipoxygenase‐1‐less malting barley variety ‘Satuiku 2 go’

The lipoxygenase‐1‐less (LOX‐less) trait has positive effects on beer quality, in particular, improvement of flavour stability related to the reduction of beer‐deteriorating substances such as trans‐2‐nonenal. ‘Ryohfu’ is the only spring‐sown malting barley variety grown in Hokkaido, located in the northern part of Japan, and has been used in the Japanese brewing industry for over 20 years. ‘Satuiku 2 go’ was developed as the first LOX‐less malting barley variety in Japan by successive back‐crossing with molecular marker‐assisted selection to introduce the LOX‐less trait into the recurrent parent ‘Ryohfu’. The agronomic performance and general malt quality of ‘Satuiku 2 go’ were almost equivalent to those of ‘Ryohfu’. Wort and beer analyses at the pilot‐scale brewing trial indicated that the LOX‐less trait had little effect on the general characteristics. In contrast, the beers made from ‘Satuiku 2 go’ malt exhibited reduced levels of trans‐2‐nonenal and trihydroxyoctadecenoic acid. The sensory evaluation demonstrated the superiority of ‘Satuiku 2 go’ beers stored under differing conditions in terms of staleness. It can be concluded that the LOX‐less trait was effective in different genetic backgrounds of the recurrent parents used for the development of LOX‐less malting barley varieties. Copyright © 2018 The Institute of Brewing & Distilling     

Antioxidant and anti‐hypertensive activity of anthocyanin‐rich extracts from hulless pigmented barley cultivars

Anthocyanin‐rich acetone extracts of barley grain of four hulless pigmented genotypes were investigated to determine their potential as functional food ingredients. The purple barley cultivar contained 11 anthocyanins, whereas only one anthocyanin, peonidin derivative, was observed in blue, black and yellow barley. The total anthocyanin content of pigmented barley genotypes ranged from 3.2 to 678.5 mg kg^?1 in whole grain and from 4.5 to 1654.6 mg kg^?1 in bran. The purple barley bran extract gave the highest DPPH radical scavenging capacity, superoxide radical scavenging capacity and total antioxidant activity. The half maximal inhibitory concentration (IC₅₀) of angiotensin I‐converting enzyme (ACE) of anthocyanin‐rich extract of purple barley grain and bran was 8.77 and 4.54 mg mL^?1, respectively. Purple barley appears to have great potential uses for the promotion of human health and development of nutraceuticals and functional foods.     

Indigenous Microbial Community of Barley Greatly Influences Grain Germination and Malt Quality

The present study was carried out to investigate the impacts of bacterial and fungal communities on grain germination and on the malting properties of good‐quality two‐row barley. In order to suppress the growth of bacterial and/or fungal communities, various antibiotics were added to the first steeping water of barley. This study was also designed to explore the dynamics of the bacterial community in the malting process after antimicrobial treatments by polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE). The diverse microbial community played an active role in the malting ecosystem. Even previously undescribed bacterial species were found in the malting ecosystem. Suppression of the bacterial community mainly consisting of Gram‐negative bacteria was advantageous with respect to grain germination and wort separation. In addition, more extract was obtained after antibacterial treatments. The fungal community significantly contributed to the production of microbial β‐glucanases and xylanases, and was also involved in proteolysis. An improved understanding of the complex microbial community and its role in malting enables a more controlled process management and the production of high quality malt with tailored properties.     

Effects of Grain and Malt â‐Glucan on Distilling Quality in a Population of Hull‐less Barley

A population of barley lines, derived by mutation in the hull‐less variety, Penthouse, was included in a replicated trial, along with Penthouse and the hulled malting cultivar, Optic. Samples were assessed for a range of grain quality traits, then malted, with germination for either 4 or 5 days, prior to kilning. Most lines had grain β‐glucan contents lower than that of Penthouse, but there was no significant correlation between grain and malt β‐glucan content. Malt β‐glucan levels were indicative of differences in cell wall breakdown between 4 and 5 days germination, but negative associations with distilling parameters Extract and Alcohol Yield, were not statistically significant. It was concluded that the lines differed in the rate and extent of cell wall breakdown and that grain shape may influence modification in distal parts of the grain. However, a malting regime, optimised to suit Optic may be less suited to discriminating between hull‐less lines of reasonable quality.     

Relationship Between Quality Parameters and SKCS Hardness Index in Malting Barley

To make an efficient and laborsaving quality selection in a malting barley breeding program, the relationship between malting quality parameters and the hardness index (HI) measured by Single Kernel Characterization System (SKCS) 4100 was studied with barley genetic resources and a group of descendant lines from “Yon Rkei 1363” that possess the high lysine allele lys1 and a very high diastatic power (DP). There was a highly significant correlation between the grain HI and the malt extract both in the genetic resources (r = ?0.48^**) and in the lys1 parent‐derived lines (r = ?0.50^**). Malt HI showed a highly significant correlation with malt extract (r = ?0.70^** in genetic resources, r = ?0.57^** in the lys1 parent‐derived lines) and malt total protein (r = 0.73^**, 0.84^**, respectively). For the selection of very high DP lines from the lys1 parent‐derived group, high grain HI selection was effective as all the very high DP lines had much harder grain characteristics. Therefore SKCS was regarded as a useful tool for quality selection in malting barley breeding.     

BRAZILIAN HULL-LESS AND MALTING BARLEY GENOTYPES: I. CHEMICAL COMPOSITION AND PARTIAL CHARACTERIZATION

Barley represents an important source of total dietary fiber (TDF) and β‐glucans. The chemical composition and partial characterization of two Brazilian barley experimental lines, hull‐less and malting, are reported. The range in diameter of the A‐ and B‐type granules was similar in both barley lines, 15 to 28 µm and 8 to 10 µm, respectively. Higher values for total starch, damage starch, ash, TDF and insoluble dietary fiber (IDF) were observed in the malting line while β‐glucan content was similar in both samples. The malting barley line had higher values of total isolated starch, as well as residual protein and total lipids in starch. The starch from the hull‐less barley line had lower swelling power and higher solubility than malting barley.     

A Reappraisal of the Differences Between Scandinavian and Spanish Barleys: Effect of β‐Glucan Content and Degradation on Malt Extract Yield in the cv. Scarlett

Forty one samples of the malting barley cultivar Scarlett were collected from both Scandinavia (15 from Finland and 10 from Denmark) and the Iberian Peninsula (15 from Spain and 1 from Portugal), during the harvest years of 1998 and 1999. These samples were subjected to grain analyses, comprising protein content, hordein fractions by high performance liquid chromatography (HPLC) and β‐glucan content. The samples were micro‐malted and the malts were analysed to determine different patterns in the influence of grain composition on malt extract development linked to the two contrasting environments. The most obvious difference found between the Scandinavian and Iberian barleys was the effect of the total and insoluble barley β‐glucans. They were an effective barrier of malt extract in the North, but appeared to increase extract in the South. A conclusion was that the positive effect of β‐glucans in the Iberian barleys was a consequence of their greater capacity to synthesise and release β‐glucan hydrolases during germination.     

BRAZILIAN HULL-LESS AND MALTING BARLEY GENOTYPES: II. THERMAL AND RHEOLOGICAL PROPERTIES OF STARCH

Thermal and rheological properties of starch isolated from two Brazilian barley experimental lines, malting and hull‐less, are reported. Gelatinization's thermal properties were T_o 53.3 and 58C, T_p 59.4 and 62.7C, and ΔH 6 and 6.8 J/g for the malting and hull‐less starch, respectively. A trend to slightly higher retrogradation rates were obtained for the malting (73.3%) compared with the hull‐less (72.1%) starch, while lower hot‐paste peak and final viscosity were observed in the former (125 and 114 RVU versus 169 and 179 RVU, respectively). Changes in storage (G′) and loss (G″) moduli during heating and cooling showed higher values for the starch from the hull‐less line. During heating, G′was higher than G″and developed at higher temperatures. A trimodal distribution pattern of G″was observed in the starch from the hull‐less barley line. Two G′peaks at 75 and 87.5C were 6.2 and 2.4 times higher, respectively, in the starch from the hull‐less line than that from the malting line.     

Multivariate analysis for feasibility of Korean six‐row barleys for beer brewing

The feasibility of using six‐row barley, which is produced more often than two‐row barley (malting barley) in Korea, for beer brewing was studied. Beer was brewed from one variety of two‐row barley (Jinyang, malting barley) and four varieties of six‐row barley (Jasujungchal and Hinchalssal which are unhulled; Dahyang and Samgwangchal which are hulled). Using principal component analysis of the material properties in malting, mashing and fermentation, and the sensory properties of beer, the barley was categorized into three groups: group 1 (Jinyang and Dahyang), group 2 (Samgwangchal and Hinchalssal) and group 3 (Jasujungchal). Group 1 was distinctive for extract (dry basis), Brix and carbonation; group 2 was characterized by alcohol, foam stability and sour odour; and group 3 was characterized by malt protein and sour taste. The brewing qualities of group 1 were superior to those of the other groups. Among the Korean six‐row barley varieties, Dahyang was found to be the most suitable for beer production. Copyright © 2014 The Institute of Brewing & Distilling     

A rapid identification of barley varieties using DNA‐AFLP

Barley (Hordeum vulgare L.) is one of the most ancient crops in the world, and is mainly used in feed, as a grain and as industrial material for beer, medicine and health protection. Its purity can affect beer taste and quality, thus it is important to set up rapid and accurate identification methods for the malting industry. In this study, 27 domestic and imported malt barley varieties were studied. Three pair primers of EcoR I + 3/Mse I + 3 were selected from 64 different primer combinations for DNA–AFLP (amplified fragment length polymorphisms) and an AFLP fingerprinting map of the 27 domestic and imported malt barley varieties was constructed, with the primer combination of E‐AGG/M‐CAA amplification after polyacrylamide gel electrophoresis. With this fingerprinting map, it was possible to distinguish all of the 27 malt barley varieties with 10 specific loci. This could be useful for the identification of malt barley varieties in the beer industry. Copyright © 2015 The Institute of Brewing & Distilling     

Prediction of protein supply to ruminants from concentrates: comparison of the NRC‐2001 model with the DVE/OEB system

The objective of this study was to compare the DVE/OEB system (DVE = truly absorbed protein in the small intestine; OEB = degraded protein balance) and the NRC‐2001 model in the prediction of supply of protein to dairy cows from 46 selected concentrates: malting‐type barley (cv Harrington), feed‐type barley (cv Valier), field tick beans (Vicia faba), white albus lupins (Lupinus albus), whole soybeans and horse beans (Vicia faba cv Alfred). The two barleys were processed by coarse (roller miller, 0.533 mm gap) and fine (hammer mill, 2 mm screen) processing. The field tick beans and white albus lupins were dry roasted at various conditions at the University of Melbourne. The soybeans and horse beans were pressure‐toasted at 100, 118 and 136 °C for 3, 7, 15 and 30 min at Wageningen Feed Processing Centre. Comparisons were made in terms of (1) ruminally synthesized microbial protein, (2) truly absorbed protein in the small intestine and (3) degraded protein balance, based on 46 samples. The results showed that the predicted values from the DVE/OEB system and the NRC‐2001 model had significant correlations. However, using the DVE/OEB system, the overall average microbial protein supply based on available energy was 10% lower and the truly absorbed protein in the small intestine was 8% lower than that predicted by the NRC‐2001 model. A difference was also found in the prediction of the degraded protein balances, which was 16% higher than that estimated from the NRC‐2001 model. These differences are due to factors used in calculations in the two models, although both are based on similar principles. This indicates that further refinement is needed for a modern protein evaluation and prediction system. Copyright © 2004 Society of Chemical Industry