Wheat Variety and Barley Malt Properties: Influence on Haze Intensity and Foam Stability of Wheat Beer

Laboratory wheat beers were brewed with different wheat varieties of different protein content (8.7–14.4%) and with five different barley malts, varying in degree of modification (soluble protein: 3.9–6.9%). In a first series of experiments, it was investigated whether wheat positively influences the foam stability, a major characteristic of wheat beers. NIBEM and Rudin (CO₂) foam analyses revealed that the effect of wheat on foam stability depended on the barley malt used for brewing. When using malt with high foaming potential, wheat exerts a negative influence. However, wheat added to over‐modified malt with less foam promoting factors, ameliorates beer foaming characteristics proving that wheat contains foam active compounds. In addition, Rudin (N₂) values suggested that wheat positively influences foam stability by decreasing liquid drainage, probably caused by a higher beer viscosity and/or a finer foam bubble size distribution. Furthermore, the haze in wheat beers, which is another important quality characteristic of these beers, was investigated. Permanent haze readings of the 40% wheat beers were lower than 1.5 EBC haze units. For 20% wheat beers, an inverse relation between the permanent haze (9.4–19.3 EBC haze units) and the protein content of the wheat was established. The barley malt used for brewing also influenced permanent haze readings. A positive correlation between the modification degree of the malt and the permanent haze intensity was found. It was concluded that the choice of raw materials for wheat beer brewing considerably influences the visual properties of the beer.     

Fungal Hydrophobins as Predictors of the Gushing Activity of Malt

Fungal infection of barley and malt, particularly by strains of the genus Fusarium, is known to be a direct cause of beer gushing. We have shown previously that small fungal proteins, hydrophobins, isolated from strains of the genera Fusarium, Nigrospora and Trichoderma act as gushing factors in beer. A hydrophobin concentration as low as 0.003 ppm was sufficient to induce gushing. The gushing‐inducing abilities of the isolated hydrophobins varied probably due to their structural differences. The hydrophobins did not affect beer foam stability. A correlation was observed between the hydrophobin level analyzed by the hydrophobin ELISA developed and the gushing potential of malt. The risk of gushing was found to increase with hydrophobin concentrations above 250 μg/g malt. The levels of hydrophobin and the Fusarium mycotoxin deoxynivalenol (DON) in malts were not correlated which indicated that the formation of those two fungal metabolites may not be linked. Furthermore, we did not observe a correlation between the DON content and the gushing potential of the malt studied. Our observations suggest that the accuracy of predicting gushing could be improved by measuring the amount of the actual gushing factors, hydrophobins, in barley or malt.     

Effect of Carbonyl Sulphide (COS), Ethyl Formate (EF) and Carbon Disulphide (CS2) on the Malting Quality of Barley and the Flavour Profile of Beer

New fumigants are needed to control grain insects because methyl bromide is being phased out as an ozone‐depleting substance under the Montreal Protocol and because resistance to phosphine is increasing. Alternative fumigants also provide one strategy to manage resistance. To assess the effect of candidate fumigants on barley quality, malting and brewing trials were conducted with malting barley (Schooner), 9.4% moisture content, fumigated with carbonyl sulphide (COS), ethyl formate (EF) and carbon disulphide (CS₂) at concentrations of 20, 90 and 36 mg/L respectively for 7 days at 20°C in riveted steel silos containing 33 t of barley. The appropriate industry body, the Malting and Brewing Industry Barley Technical Committee (MBIBTC) set the quality parameters to be evaluated and allocated work to the appropriate quality laboratories. Germination of fumigated barley was not affected by the fumigants. Residues of COS, EF and CS₂ in outloading barley samples were 0.085 ± 0.0052, 0.4 ± 0.1 and 2.22 ± 0.07 mg/kg respectively, which were below the experimental permits of maximum residue levels (MRL). Residues of COS, EF and CS₂ in malt, wort and beer were indistinguishable from those in unfumigated (or non‐fumigated) barley. Ethyl formate and CS₂ affected wort in increasing the apparent attenuation limit (AAL) and CS₂ affected barley colour. Sulphur volatiles in the trial beer made from EF and CS₂ (unlike COS) fumigated barley decreased significantly. Beer from COS, EF and CS₂ fumigated barley had a somewhat higher 24‐hour chill haze level (0.62–0.84) than beer from the untreated barley (0.53). The total alcohols and isoamyl acetate increased in beer made from EF fumigated barley. Carbonyl sulphide, EF and CS₂, however, had no effect on beer flavour or quality.     

Comparison of beer quality attributes between beers brewed with 100% barley malt and 100% barley raw material

BACKGROUND: Brewing with 100% barley using the Ondea^® Pro exogenous brewing enzyme product was compared to brewing with 100% barley. The use of barley, rather than malt, in the brewing process and the consequences for selected beer quality attributes (foam formation, colloidal stability and filterability, sensory differences, protein content and composition) was considered. RESULTS: The quality attributes of barley, malt, kettle‐full‐wort, cold wort, unfiltered beer and filtered beer were assessed. A particular focus was given to monitoring changes in the barley protein composition during the brewing process and how the exogenous OndeaPro^® enzymes influenced wort protein composition. All analyses were based on standard brewing methods described in ASBC, EBC or MEBAK. To monitor the protein changes two‐dimensional polyacrylamide gel electrophoresis was used. CONCLUSION: It was shown that by brewing beer with 100% barley and an appropriate addition of exogenous Ondea^® Pro enzymes it was possible to efficiently brew beer of a satisfactory quality. The production of beers brewed with 100% barley resulted in good process efficiency (lautering and filtration) and to a final product whose sensory quality was described as light, with little body and mouthfeel, very good foam stability and similar organoleptic qualities compared to conventional malt beer. In spite of the sensory evaluation differences could still be seen in protein content and composition. Copyright © 2011 Society of Chemical Industry     

Effect of varying starch properties and mashing conditions on wort sugar profiles

The aim of this research was to investigate the relationship between starch composition in barley and its malted counterpart alongside malt enzyme activity and determine how these factors contribute to the fermentable sugar profile of wort. Two Australian malting barley varieties, Commander and Gairdner, were sourced from eight growing locations alongside a commercial sample of each. For barley and malt, total starch and gelatinisation temperature were taken, and for malt, α‐ and β‐amylase activities were measured. Samples were mashed using two mashing profiles (infusion and Congress) and the subsequent wort sugar composition and other quality measures (colour, original gravity, soluble nitrogen) were tested. Variety had no significant (<0.05) effect on any barley, malt, enzyme or wort characteristics. However, growing location impacted gelatinisation temperature, colour, malt protein content and original gravity. The gelatinisation temperature in malt samples was higher, by ~0.8°C, than in the equivalent barley sample. Several malt samples, even with protein contents <12.0%, had gelatinisation temperature >65°C. The fermentable sugars measured in the malt prior to mashing showed a higher proportion of maltose than glucose or maltotriose. In addition, there were significant differences in the amount of sugar produced by each mashing method with the high temperature infusion producing a higher amount of sugar and proportionally more maltose. There is scope for further research on the effect of genetics and growing environment on gelatinisation temperature, mash performance and fermentable sugar development. Routinely measuring gelatinisation temperature and providing this information on malt specification sheets could help brewers optimise performance. © 2019 The Institute of Brewing & Distilling     

Differences in protein content and foaming properties of cloudy beers based on wheat malt content

To investigate differences in protein content, all barley malt beer, wheat/barley malt beer and all wheat malt beer were brewed, and the protein during mashing, wort, fermentation and beer determined. It was shown that protein was mainly extracted during mashing and the protein rest phase, decreased in the early stages of fermentation and remained almost steady during wort boiling and cooling, in the middle and late stages of fermentation. By separating beer foam from beer, similar protein bands of 51.7, 40.0, 27.3, 14.8, 6.5 and < 6.5 kDa appeared in the three beers, defoamed beers and beer foams using the sodium dodecyl sulphate polyacrylamide gel electrophoresis. Quantitatively, protein bands of 6.5–14.8 and <6.5 kDa had the highest contents in the three beers. Unique bands at 34, 29.2, 23.0, 19.7 and 17.7 kDa were found in beer, defoamed beer and beer foam from wheat beer and all‐wheat malt beer, respectively. Wheat beer foam showed the best foam stability and the protein in all barley malt beer showed the best migration to the foam. The beer foam properties were influenced by not only protein content but also protein characteristics and/or origin. It is suggested that the barley malt contributed the beer foam ‘skeleton protein’ while protein components from wheat malt kept the foam stable. © 2018 The Institute of Brewing & Distilling     

125th Anniversary Review: The science of the tropical cereals sorghum,maize and rice in relation to lager beer brewing

Mainstream lager beer brewing using the tropical cereals sorghum, maize and rice, either as malt or as raw grain plus commercial enzymes, is becoming widespread. This review examines the differences in composition between these tropical cereals and barley and their impact on brewing processes and beer quality. All of these cereals have a starch gelatinization temperature some 10 °C higher than barley. The sorghum prolamin proteins are particularly resistant to proteolysis owing to disulphide cross‐linking involving γ‐kafirin. Unlike barley, the major endosperm cell wall components in sorghum and maize are arabinoxylans, which persist during malting. The rice cell walls also seem to contain pectic substances. Notably, certain sorghum varieties, the tannin‐type sorghums, contain considerable levels of condensed tannins (proanthocyanidins), which can substantially inhibit amylases, and probably also other brewing enzymes. Tropical cereal malts exhibit a similar complement of enzymic activities to barley malt, with the notable exception of β‐amylase, which is much lower and essentially is absent in their raw grain. Concerning beer flavour, it is probable that condensed tannins, where present in sorghum, could contribute to bitterness and astringency. The compound 2‐acetyl‐1‐pyrroline, responsible for the popcorn aroma of maize and also the major aroma compound in rice, presumably affects beer flavour. However, much more research is needed into tropical cereals and beer flavour. Other future directions should include improving hydrolysis of prolamins into free amino nitrogen, possibly using prolyl carboxypeptidases and investigating tropical cereal lines with useful novel traits such as high amylopectin, high protein digestibility and low phytate. Copyright © 2013 The Institute of Brewing & Distilling     

Protein changes during malting and brewing with focus on haze and foam formation: a review

Beer is a complex mixture of over 450 constituents and, in addition, it contains macromolecules such as proteins, nucleic acids, polysaccharides, and lipids. In beer, several different protein groups, originating from barley, barley malt, and yeast, are known to influence beer quality. Some of them play a role in foam formation and mouthfeel, and others are known to form haze and have to be precipitated to guarantee haze stability, since turbidity gives a first visual impression of the quality of beer to the consumer. These proteins are derived from the malt used and are influenced, modified, and aggregated throughout the whole malting and brewing process. During malting, barley storage proteins are partially degraded by proteinases into amino acids and peptides that are critical for obtaining high-quality malt and therefore high-quality wort and beer. During mashing, proteins are solubilized and transferred into the produced wort. Throughout wort boiling proteins are glycated and coagulated being possible to separate those coagulated proteins from the wort as hot trub. In fermentation and maturation process, proteins aggregate as well, because of low pH, and can be separated. The understanding of beer protein also requires knowledge about the barley cultivar characteristics on barley/malt proteins, hordeins, protein Z, and LTP1. This review summarizes the protein composition and functions and the changes of malt proteins in beer during the malting and brewing process. Also methods for protein identification are described.     

The influence of LOX‐less barley malt on the flavour stability of wort and beer

The aim of this study was to investigate the influence of lipoxygenase‐less (LOX‐less) barley malt on the quality of wort and beer, with the main focus on beer flavour stability. In the current study, pilot‐scale (1000 L) brewing trials were conducted with a control barley malt AC Metcalfe and a LOX‐less barley malt, PolarStar. The results clearly indicated that the LOX‐less barley malt showed less nonenal potential than the control, although LOX activities in both barley malts were relatively low. The beer brewed from the LOX‐less barley malt contained much lower concentrations of trans‐2‐nonenal (T2N) and gamma‐nonalactone, especially after the (forced or natural) aging of the beer, compared with the beer brewed under the same conditions using the control malt. The sensory panel evaluation indicated similar results in the general flavour profile. The freshness scores of beer brewed from the LOX‐less malt were higher than those from the control malt, and this was more pronounced after forced aging. In addition, the beer brewed from LOX‐less malt had a much better foam stability, almost 30 s (NIBEM test). These results confirm that the use of the LOX‐less barley malt was beneficial to beer flavour stability and foam stability. Copyright © 2014 The Institute of Brewing & Distilling     

The influence of unmalted barley on the oxidative stability of wort and beer

The aim of this study was to investigate the influences of unmalted barley on the brewing process and the quality of the resulting beer‐like beverages, with the main focus on the oxidative stability, using traditional beer analyses, GC‐MS for the determination of aging compounds and electron paramagnetic resonance spectroscopy to determine free radical activity. For the investigation, brews with different barley proportions and 75% barley brews with a colour malt addition, to compensate for a lower colour using barley, were produced. In general, it can be said that beers with a proportion of up to 50% barley achieved a comparable or higher extract yield and final attenuation owing to the combined effectiveness of the malt and microbial enzymes. Although all analytical values were within the normal range according to Methodensammlung der Mitteleuropäischen Brautechnischen Analysenkommission (MEBAK), a slight decrease in total polyphenols and free amino nitrogen content was observed. Also in response to higher barley portions, an increase of higher molecular weight proteins and β‐glucan was detected. Barley is not exposed to heat and oxidative stress in the malting plant, which explains the lower values of the thiobarbituric acid index and colour as an indicator of Maillard reaction products in the resulting wort and beer. Additionally, the results demonstrate a slower increase of aging compounds during beer storage with increasing barley proportions. Furthermore, it was observed that higher barley proportions led to a better oxidative stability indicated by a lower radical generation (T₄₅₀‐value) in wort and an increasing beverage antioxidant index/endogenous antioxidative potential (BAX/EAP value) in the final beverage. The case of ‘barley beers’ showed that the positive effect of barley on the oxidative beer stability was greater than the negative effect of the addition of colour malt, to adjust the colour of a 100% malt beer. In sensory comparison with beer produced with 100% malt, the beers brewed with a barley proportion up to 50% showed a slight flavour preference and up to a 75% equivalent evaluation. Copyright © 2012 The Institute of Brewing & Distilling     

Brewing with 100% Oat Malt

Oats are a cereal with beneficial nutritional properties and also unrealized brewing potential. Furthermore, oats can be tolerated by the majority of people who suffer from celiac disease. Malting of oats produced a malt, which was found suitable for brewing a 100% oat malt beer. The mashing regime, designed by using mathematical modelling, was successfully transferred to a pilot scale plant. The improved lautering performance of oat malt was due to its higher husk content, which also led to a lower extract content in oat wort when compared to barley wort. The protein profile of oat wort, as measured by using Lab‐on‐a‐Chip analysis, revealed that there was no significant difference in the protein profile between oat and barley wort. The fermentation of oat and barley worts followed the same trend; differences could only be seen in the higher pH and lower alcohol content of the oat beer. The flavour analysis of oat beer revealed some special characteristics such as a strong berry flavour and a lower amount of staling compounds when forced aged. This study revealed that it was possible to brew a 100% oat malt beer and that the produced beer was comparable to a barley malt beer.     

The Role of Malt and Hop Polyphenols in Beer Quality,Flavour and Haze Stability

Pilot‐scale brewing trials of a 12°P pale lager beer were conducted to look at the effect of a modified dose of hop and malt polyphenols on haze, flavour quality, and stability. Results confirmed that malt polyphenols, and particularly hop polyphenols, in the course of wort boiling, improved reducing activity values and the carbonyl content in fresh and stored beers. Hop polyphenols significantly increased reducing activity and decreased the formation of carbonyls (TBA value) in fresh and stored beer. Reduced content of malt polyphenols, combined with the use of hop CO₂ extract, caused an increase in the TBA value in beer. PVPP stabilized beers tended to be lower in reducing activity. Both malt and hop polyphenols affected the intensity of “harsh taste” in fresh beers and a significant influence from PVPP stabilization of beer was not observed. The staling degree of forced‐aged beers depended on the polyphenol content in the brewhouse. Both hop and malt polyphenols had a positive impact on flavour stability. PVPP treatment of beer had a positive effect on the flavour stability of heat‐aged beers. Polyphenols, especially hop polyphenols, slowed down flavour deterioration during the nine month storage period, but the primary effect was seen during the first four months of storage. Storage trials did not show any unambiguous effects for PVPP stabilization on beer flavour stability. Results confirmed the negative impact of malt and hop polyphenols on haze stability, and PVPP stabilization minimized differences in shelf life prediction values between beers prepared with the modified dose of polyphenols.     

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     

PROANTHOCYANIDIN-FREE BARLEY—MALTING AND BREWING

Colloidal haze in beer is due to the precipitation of proteins by proanthocyanidins. Carlsberg Research Center reported in 1977 that the use of barley mutants which block the biosynthesis of catechins and proanthocyanidins in the grain prevents the formation of haze in beer. The results from ten years of malting and brewing research with proanthocyanidin-free barley and malt are reviewed.     

THE INTRINSIC INFLUENCE OF CATECHINS AND PROCYANIDINS ON BEER HAZE FORMATION

Different concentrations of catechins and procyanidins were added to an all-malt Pilsner beer brewed from proanthocyanidin-free malt (ant 13·13 × Rupal) and tannin-free hop extract in order to evaluate their intrinsic role in beer haze formation, i.e. in the absence of malt and/or hop flavanoids. The molar tanning capacities of flavanoids depend upon their degree of polymerisation. Procyanidin B6 was much more haze active than procyanidin B3. Both immediate haze and formation of haze after 150 days of storage at room temperature was in general linearily related to the added concentration of phenolics.     

Amylase modification induced by the germination process in organic barley

Eleven barley landraces (Hordeum vulgare L.) grown under the same climatic and soil conditions according to the same organic protocol and corresponding malt samples were considered in this study. In order to assess the modification induced by the mashing process on barley samples cultivated under the same conditions, the enzymatic activity of alpha and beta-amylase was determined in all samples. In addition, the modification induced by the germination process on the protein pattern was also investigated by SDS–PAGE. Barley samples resulted different both in protein content and in amylase quality and quantity; these differences, evidently related to genetic factors, also were found in malt samples. Although two bands at 41–42 kDa and 55–58 kDa were found in the Betamyl extracts analysed by SDS–PAGE, only the 55–58 kDa had discriminating ability, and for this reason, it could be considered in order to evaluate barley suitability for beer production.     

Malted and unmalted oats in brewing

Using oats as a raw material in brewing has recently become the focus of increased interest. This is due to research findings that have shown that oats can be consumed safely by coeliac sufferers. It is also a response to consumer demand for products with novel sensory properties. In this study, beer was produced entirely from oat malt, from barley malt and from oat and barley malts mixed with various quantities of unmalted oats. Compared with barley wort, wort made from malted oats provided a lower extract content and had a higher protein content, but a lower free amino nitrogen content (FAN). The oat wort also showed increased viscosity and haze. The addition of unmalted oats during wort production produced significant changes in the physico‐chemical parameters of both oat and barley worts and beers. Unmalted oats caused an increase in wort viscosity and haze, and a reduction in total soluble nitrogen and FAN. Unmalted oats also contributed to lowering the concentration of higher alcohols and esters. Beer made from 100% oat and barley malts exhibited a similar alcohol content. The use of an oat adjunct in both cases resulted in a lower ethanol content. The introduction of enzyme preparations during the production of wort with oat adjunct had many benefits: increased extract content and FAN; a higher volume of wort; and a lower viscosity that led to faster wort filtration. This research suggests that the use of enzymes is necessary to make production using a high proportion of oats in the grist profitable. Copyright © 2014 The Institute of Brewing & Distilling