Effects of β‐Glucans and Environmental Factors on the Viscosities of Wort and Beer

This paper reports on the influence of molecular weight and concentration of barley β‐glucans on the rheological properties of wort and beer. Environmental conditions such as pH, maltose level in wort, ethanol content of beer, shearing and shearing temperature were also examined for their effects on wort and beer viscosities. In the range of 50–1000 mg/L, β‐glucans increased solution viscosity linearly with both molecular weights (MW) of 31, 137, 250, 327, and 443 kDa and concentration. The influence of MW on the intrinsic viscosity of β‐glucans followed the Mark‐Houwink relationship. Shearing wort and beer at approximately 13,000 s^?1for 35 s was found to increase the wort viscosity but reduce beer viscosity. Shearing wort at 20°C influenced β‐glucan viscosity more than shearing at 48°C and 76°C whereas the shearing temperature (0, 5 and 10°C) did not effect the viscosity of beer. At lower pHs, shearing was found to reduce the viscosity caused by β‐glucans in wort but had no effect in beer. Higher concentrations of maltose in wort and ethanol in beer also increased the viscosity of β‐glucan polymers. It was found that β‐glucans had higher intrinsic viscosities in beer than in wort (5°C), and lower critical overlap concentrations (C^*) in beer than in wort.     

The Influence of Lactic Acid Bacteria on the Quality of Malt

In this study three strains of lactic acid bacteria were applied during the malting process to evaluate the impact on malt and wort quality. The trials were performed in a micromalting plant simulating an industrial malting programme. The samples were compared to chemically acidified as well as non‐acidified malt. Bacterial cultures were chosen with reference to their enzymatic (proteolytic/amylolytic) activity, or their good acidifying properties. The effects of lactic acid bacteria on wort characteristics were investigated and compared to wort produced from 100% unacidified malt. A chemical food grade lactic acid was also used to acidify the barley for comparison purposes. Characteristics such as pH, extract, colour, viscosity, total soluble nitrogen, free amino nitrogen, apparent fermentability, β‐glucan and lautering performance of the resultant worts were determined. Results showed improved levels of β‐glucanase in the malt although reduced malt friability was observed where LAB was employed. An improved lautering performance, lower wort viscosity and elevated TSN levels were also reported where LAB exhibiting protease activity were applied.     

Malting Behaviour of Barleys Grown in Canada and Spain as Related to Hordein and Enzyme Content

To continue our effort to analyse the genetic (varietal) and environmental (sites and years) effects on malting quality of barley, we have field‐tested four barley varieties, two‐ and six‐rowed, European and North American, in Spain and Canada in 1998 and 1999. The Spanish trials were autumn‐sown whereas the Canadian ones were spring‐sown. Barley grain was analysed for total protein and hordein contents and micromalted. Canadian‐grown barleys had significantly lower contents of grain protein and all‐three hordein fractions than the Spanish ones. They also had lower malt respiratory losses, wort β‐glucan and viscosity but lower fine‐ and coarse‐ground malt extract yield, friability, free amino nitrogen, Kolbach index, α‐amylase and diastatic power. In other words, the Canadian‐grown barleys, despite showing lower protein and hordein contents, produced malt of inferior quality than their Spanish counterparts, which, overall, produced higher quantities of degrading enzymes (amylolytic, proteolytic and cytolytic) during germination, thus being able to attain higher extract yield levels.     

Refining the Prediction of Potential Malt Fermentability by Including an Assessment of Limit Dextrinase Thermostability and Additional Measures of Malt Modification,Using Two Different Methods for Multivariate Model Development

Prediction of malt fermentability (apparent attenuation limit — AAL) by measurement of the diastatic power enzymes (DPE), α‐amylase, total limit dextrinase, total β‐amylase, β‐amylase thermostability, and the Kolbach index (KI or free amino nitrogen — FAN) is superior to the conventional use of diastatic power (DP) alone. The thermostability of β‐amylase is known to be an important factor in determining fermentability, thus the thermostability of the other relatively thermolabile enzyme, limit dextrinase, was investigated to determine if it was also useful in predicting fermentability. To facilitate this aim, methods were developed for a rapid and cost efficient assay of both β‐amylase and limit dextrinase thermostability. Internationally important Australian and international malting varieties were compared for their total limit dextrinase and β‐amylase activity and thermostability. Interestingly, the level of limit dextrinase thermostability was observed to be inversely correlated with total limit dextrinase activity. The prediction of malt fermentability was achieved by both forward step‐wise multi‐linear regression (MLR) and the partial least squares (PLS) multivariate model development methods. Both methods produced similar identifications of the parameters predicting wort fermentability at similar levels of predictive power. Both models were substantially better at predicting fermentability than the traditional use of DP on its own. The emphasis of this study was on the identification of predictive factors that can be consistently used in models to predict fermentability, because the model parameter estimates will subtly vary depending on mashing conditions, yeast strain/fermentation conditions and malt source. The application of these multivariate model development methods (PLS and MLR) enabled the identification of further potential fermentability predicting factors. The analyses divided the predictive parameters into those defined by DP enzymes and those associated with modification (KI, FAN, fine/coarse difference, wort β‐glucan and friability). Surprisingly, limit dextrinase thermostability was not a substantial predictor of fermentability, presumably due to its negative correlation with total limit dextrinase activity. The application of these insights in the malting and brewing industries is expected to result in substantial improvements in brewing consistency and enable more specific quality targets for barley breeder's progeny selection cut‐off limits to be more precisely defined.     

Barley for Brewing: Characteristic Changes during Malting,Brewing and Applications of its By‐Products

ABSTRACT: Barley is the basic raw material for brewing. Its chemical composition, brewing, and technological indices are highly determinative for the beer quality and the economical efficiency of the brewing process. Barley is rich in protein, carbohydrates, dietary fibers, minerals, and vitamins. The presence of nonstarch polysaccharides as mixed linkage (1‐3),(1‐4)‐β‐d ‐glucans and arabinoxylans together with the enzymes are responsible for barley modification. Malting is a complex process that involves many enzymes; important ones are α‐amylase, β‐amylase, α‐glucosidase, and limit dextrinase. During the process of malting and brewing, the by‐products left after separation of the wort are rich in protein, fibers, arabinoxylans, and β‐glucan. This review summarizes and integrates barley grain with respect to nutritional, functional, and compositional changes that take place during malting and brewing. It also explores in‐depth the several by‐products obtained after brewing and their potential for various food applications. Barley brewing by‐products offer an opportunity for cereal‐based baked and extruded products with acceptable sensory and nutritional characteristics.     

Effect of malting regimen on diastatic power,cold and hot water extracts of malts from sorghum

In this study, sorghum grains were malted using different malting regimens and the malt qualities were analysed for cold water extract (CWE), hot water extract (HWE) and diastatic power (DP). Results showed that malting regimen produced sorghum malts with peak CWE, HWE and DP within the pre-determined limits of malting regimen. From this, predictive models of sorghum malt quality were developed and tested. Whilst steeping duration interacts significantly with the germination period to cause variations in CWE and HWE, only the germination period significantly influenced the DP of sorghum malts. However, the kilning temperature showed no significant impact on the parameters studied. Besides CWE, HWE and DP correlating positively with each other, the developed predictive models were significant (P < 0.05) and satisfy the quality of fit (R² > 0.70) of the proposed models. The result demonstrated that wort for different purposes can be obtained by varying the malting operational conditions in the predictive model, thus saving time, resources, preliminary studies and research designs. Besides the promotion of a cheaper local alternative material for industrial wort production and brewing purpose, this research provides valuable insight on the brilliant prospect of variable malting regimen in predicting and adjusting the quality characteristics of sorghum malt and wort. Future studies are required to develop models for wort produced from peak CWE, HWE and DP, for predicting wort quality characteristics.     

Effects of Pulses of Higher Temperature on the Development of Enzyme Activity During Malting

The increase of temperature at the beginning, in the middle and at the end of malting has been evaluated in terms of quality parameters (malting losses, index of acrospire development, friability, HWE, viscosity, SNR) and enzyme (β‐glucanase and α‐amylase) development, in a good quality malting barley (Otis) and a higher protein‐higher β‐glucan content barley used for feed (Extra). A shift from 15 to 20°C at the beginning of malting was shown to increase acrospire development, friability, HWE and SNR and to reduce viscosity, without significantly affecting malting losses. This effect was related to higher β‐glucanase and α‐amylase activities within each variety. However, the same enzyme activities were not directly related to a better malting quality when the two genotypes were compared. This confirms previous indications that diversity in malting performance between genotypes cannot simply be traced back to differences in enzyme activities; but, indeed, it suggests that, for a defined barley lot, changes in the levels of enzyme activities following different malting procedures may have a direct effect on malt quality.     

Dextrin as the main turbidity components in wort produced from major malting barley cultivars of Jiangsu province in China

As wort is the sweet starter liquid for beer, its quality needs to be strictly controlled. It is generally accepted that wort turbidity is of importance in terms of the brewing process and the resulting beer quality. This study investigated the major ingredients of wort turbidity using the malting barley cultivar Dan'er, grown in Jiangsu province, China. It was found that dextrins of low molecular weight constituted the vast majority of the polysaccharides causing wort turbidity. To solve the turbidity problem with the Dan'er malt, the present study supplemented 80 U g^?1 of β‐amylase, and as an activator, an extra 50 mg  L^?1 of Ca²⁺ to the malting process of Dan'er barley. The turbidity of the resulting congress wort of the Dan'er malt declined to <5.0 EBC units, which then met the quality guidelines of the brewery. The results of the present study may also help in developing new turbidity detection methods and yield breeding clues for quality improvement of the barley cultivars in the Jiangsu province of China. Copyright © 2016 The Institute of Brewing & Distilling     

Relationship between Kolbach index and other quality parameters of wheat malt

In order to determine suitable Kolbach indices in wheat malting, the relationships between the Kolbach index and other quality parameters in wheat malt were studied. Eight white wheat malts with different Kolbach indices (31.4, 33.1, 37.0, 37.6, 39.5, 40.7, 42.8 and 45.5%) from the same wheat variety were prepared. The increase ratio of the ALSP (albumins and other soluble proteins) and the decrease ratio of the glutenins were found to have a significant positive correlation with the Kolbach index, and the corresponding r‐values were 0.883 and 0.975 (p < 0.01). The ALSP of the wheat malts had a positive correlation with chromaticity, extract, free amino nitrogen (FAN), viscosity, acidity, xylan glycosidase activity, endo‐β‐1,4‐xylanase activity and malting loss (p < 0.05). When the Kolbach indices were 31.4, 33.1, 37.0, 37.6 and 39.5%, there was a positive correlation between the soluble xylan and the viscosity, and the r‐value was 0.888 (p < 0.05). Comparing the malts, it could be concluded that, for this particular wheat variety, when the Kolbach index was 39.5%, the wheat malts exhibited the best characteristics; the extract was 81.98%, the FAN content was 166.03 mg per 100 mg, the saccharifying power was 496.72 WK, the viscosity was 1.61 cP, and the saccharification time was 6 min. Copyright © 2012 The Institute of Brewing & Distilling     

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.     

Current Developments in Malting and Brewing Trials with Sorghum in Nigeria: A Review

Initially, large‐scale lager beer brewing with sorghum malts proved highly intractable due to a number of biochemical problems including: high malting losses estimated at 10–30% as against 8–10% for barley; high gelatinisation temperatures which limited starch solubilisation/ hydrolysis by the amylolytic enzymes during mashing; low extract yield/low diastatic power (DP) due to inadequate hydrolytic enzyme activities especially β‐amylase; low free α‐amino nitrogen (FAN) due to inadequate proteolysis limiting yeast growth during fermentation; high wort viscosities/beer filtration problems due to low endo‐β‐1,3; 1–4‐glucanase activities on the endosperm cell walls causing the release of some β‐glucans. Strident research efforts using improved Nigerian sorghum malt varieties (SK5912, KSV8 and ICSV400) have reported some encouraging results. The knowledge of the biochemical integrity of the endo‐β‐glucanases of the sorghum malt is helping to elucidate their mode of activity in the depolymerisation of the β‐glucans. This is bound to ensure process efficiency in sorghum beer brewing, reduce beer production costs and ultimately, produce a Pilsner‐type of lager beer with 100% sorghum malt.     

The impact of barley nitrogen fertilization rate on barley brewing using a commercial enzyme (Ondea Pro)

Two Australian (Buloke and Commander) and two Canadian (CDC Meredith and Bentley) barley varieties were grown under four levels of nitrogen fertilization (0, 20, 40 and 80 kg ha^?1). Barley samples were assessed by barley brewing with the Ondea Pro enzyme cocktail for mashing analysis and were compared with typical malt brewing quality specifications. The study observed that increased nitrogen fertilization resulted in increased barley kernel nitrogen content which significantly impacted a range of wort quality parameters including increased soluble nitrogen, free amino nitrogen and barley beta‐amylase level, but also reduced extract, barley Kolbach index, β‐glucan and colour. Increased grain nitrogen had relatively little effect on apparent attenuation limit, lautering and barley limit dextrinase level. Knowledge of the effects of interactions between barley of different qualities (e.g. nitrogen content) and the Ondea Pro enzymes on wort quality will result in enhanced barley to directly and efficiently brew good quality beer, to better satisfy the quality expectations of brewers. Copyright © 2018 The Institute of Brewing & Distilling     

Lofty Nijo: A High Quality Malting Barley Variety Released from an Australian‐Japanese Collaboration

A new malting barley variety, Lofty Nijo, was bred in Australia through a collaborative breeding program between a Japanese brewing company and Adelaide University. The variety is early flowering and maturing, with similar yield potential to Schooner except in lower rainfall areas, and is not zinc efficient. It produces plump grains with low screenings similar to Schooner and more uniform and plumper grains than Franklin. Lofty Nijo has a well‐balanced malting quality profile. It shows high values in malt extract, diastatic power, apparent attenuation limit and Hartong index (VZ45) and low values in wort beta‐glucan and viscosity. The Kolbach index of this variety is lower than Schooner and Sloop, however, it is higher than Franklin. A pilot‐scale brewing trial indicated that Lofty Nijo is as suitable for Japanese brewing as the world's leading varieties, such as Franklin. Lofty Nijo should therefore offer a premium malting barley variety in Australia for export markets. The breeding, agronomic performance and quality profile of the variety is described in this paper.     

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.     

Image analysis and quality attributes of malting barley grain dried with infrared radiation and in a spouted bed

The impact of drying two spring barley cultivars (Mauritia and Prestige) in a spouted‐bed and in infrared radiation (IR) dryers on grain dimensions, colour, pigment content, vitality and malt quality was investigated. The results indicate that the investigated drying methods led to kernel dimension changes. Kernel shrinkage was typical of spouted bed drying, while kernel expansion was observed after IR drying at the intensity of 900 W m^?2. An increase in the intensity of yellowness (b*) on the surface of dried grain and a decrease in the yellowness intensity of kernel cross‐section were also observed. The aforementioned changes were associated with the decomposition of carotenoids (endosperm colour) and reduction of soluble proanthocyanidin and total phenolic compounds (surface colour). The drying processes also lowered germination energy and capacity, in addition to susceptibility to moisture diffusion into the endosperm. These adverse results were cultivar dependent and affected the quality of malt and wort only to a limited extent. The main changes were an increase in the Kolbach index in malt from Mauritia cv., and a fluctuation of the diastatic power of malt that did not exceed ±3%. Generally, drying of barley grain in spouted bed should be conducted at an inlet air temperature of 40 °C and using an IR drier at a radiation intensity of 600 W m^?2.     

Isolation,structural features and rheological properties of water‐extractable β‐glucans from different Greek barley cultivars

β‐Glucans were isolated from six Greek barley cultivars (Persefoni, Kos, Thessaloniki, Athinaida, Dimitra and Triptolemos) by water extraction at 47 °C, enzymatic removal of starch and protein and subsequent precipitation of the water‐soluble β‐glucans with 37% (w/v) ammonium sulfate saturation. The purity of barley β‐glucans was high (>93% dry basis) with some small contamination by protein (<3.84%). The molecular size of the β‐glucan isolates was determined by high‐performance size‐exclusion chromatography (HPSEC); the weight‐average molecular weights and the intrinsic viscosities ranged between 0.45 × 10⁶ and 1.32 × 10⁶ and 2.77 and 4.11 dl g^?1, respectively. Structural features of barley β‐glucans were revealed by ¹³C NMR spectroscopy and high‐performance anion‐exchange chromatography (HPAEC) of the oligomers released by the hydrolytic action of lichenase. Lichenase degradation showed that β‐glucans from all barley cultivars consisted of blocks of cellotriosyl and cellotetraosyl units, accounting for 90.6–92.3% of the total oligomers released, with a molar proportion of these units between 2.31 and 2.77. Rheological measurements of aqueous solutions/dispersions of β‐glucans showed the behaviour of non‐interacting polysaccharides and a transition from the typical viscoelastic response to gel‐like properties after a time period that depended on the molecular size of the polysaccharide. The lowest molecular size β‐glucans from the Triptolemos cultivar showed shorter gelation times than their higher molecular weight counterparts. The effect of sugar incorporation (glucose, fructose, sucrose, xylose and ribose), at a concentration of 30% (w/v), to the β‐glucans gels (6% w/v) on compression parameters seemed to be related to the type of sugar used; the pentose sugars substantially reduced gel firming. Copyright © 2004 Society of Chemical Industry     

Relationships between the index of protein modification (Kolbach index) and hydrolytic enzyme production in a wheat malt

In this study, the relationships between protein degradation, enzyme activities and quality of EBC (European Brewery Convention) wort were investigated. The Kolbach index of wheat malt at 37.6–42.7% was found to be suitable for acquiring higher enzyme activities. A globulin increase was the main factor that promoted the activities of the degradation enzymes. Strong synergistic activity was observed among the polysaccharide degradation activities of enzymes [α‐amylase, β‐amylase, β‐glucanase, β‐d ‐xylosidase and β‐(1,4)‐endoxylanase]. Increased protease production improved the Kolbach index of a wheat malt, that is, promoted the degradation of gliadins into albumins and globulins. Increased albumins and globulins resulted in increased enzyme activity for polysaccharide degradation. Increased enzyme activities demonstrated synergistic actions that ultimately promoted the quality indices of an EBC wort, including extract yield, α‐amino nitrogen, acidity and chromaticity. Copyright © 2014 The Institute of Brewing & Distilling     

Effects of Wheat Protein Content on Endosperm Composites and Malt Quality

In this study, the malting performance of six traditional Chinese wheat varieties was evaluated. The effects of protein content on wheat endosperm composition and the malt quality were studied. The β‐glucan in the malt showed a positive correlation (r = 0.806, P<0.1) with the protein content of the wheat. With an increase in protein content, there was a significant linear decrease in extract (r = ?0.923, P<0.01) and Kolbach Index (r = ?0.850, P<0.05), but diastatic power, soluble protein and FAN gave a peak value at 16.0% protein content. Because of the suitable protein and starch content, the malt qualities of wheat W‐3 were satisfactory. Extract was 81.7%, saccharification time was 6.5 min, diastatic power was 484.07WK, FAN was 136.58 mg/100 g, the Kolbach index was 40.0% and viscosity was 1.77 cP.     

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Varieties of a cereal may have a considerable influence on malting qualities owing to variations in the physicochemical properties of the grains. This research was aimed at assessing the influence of five teff varieties on malt quality attributes. The teff samples were malted using previously optimized malting conditions and mashed with the congress mashing procedure. In this research, the Kuncho teff variety was malted in a one year period after harvesting, whereas the other four varieties were malted after three years of storage. Alpha‐ and β‐amylase, and limit dextrinase activity, were in the ranges 14–68, 10–440 and 375–1072 U/kg, respectively. Extracts ranged from 54% for Dessie to 74% for Ivory teff. Free amino nitrogen, protein content, soluble nitrogen, Kolbach index, viscosity and wort colour were in the ranges 160–364 mg/L, 8.6–13.6%, 532–1048 mg/100 g, 24–50%, 1.441–1.629 mPa s and 5.9–9.0 EBC units, respectively. High‐performance liquid chromatographic analysis for individual fermentable sugars revealed that the highest value in all varieties was recorded for glucose followed by maltose. The concentration of glucose ranged from 9.49 g/L in Brown teff, to 19.42 g/L in Ivory teff, whereas maltose ranged from 2.95 g/L in Dessie teff to 16.1 g/L in Kuncho teff. All of the malt quality attributes considered in this study were markedly influenced (p < 0.05) by the type of teff cultivar. It was concluded that the use of different teff varieties yielded malts with significantly different malt quality attributes. Copyright © 2013 The Institute of Brewing & Distilling