Immunochemical determination of gluten in malts and beers.

The gluten content in different varieties of barley and malts, and in different types of beers, was determined by a 'sandwich' enzyme immunoassay (RIDASCREEN Gliadin kit). The gluten levels in barley wheat, rye and spelt malts ranged 18.8-45.0, 44.0-68.0, 41.6 and 21.2 g kg-1, respectively. When various types of beer were compared, the gluten concentration increased as follows: alcohol-free beer (<3.0), lager beers (<3.0-8.7 mg l-1), stouts (9.0-15.2 mg l-1) and wheat beers (10.6-41.2 mg l-1). When 10 Czech lager beers were analysed, using both sandwich and competitive ELISA, the results showed that the latter method provided values several times higher than the former. Gluten balance was carried out during the brewing process, starting from the raw materials and terminating at the final beer. Gluten levels decreased due to precipitation during the mashing process, primary and secondary fermentation and, lastly, as a result of adsorption during beer stabilization. The gluten content in beer is, thus, approximately three orders of magnitude lower than in the raw malt.     

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.     

Optimised quantification of the antiyeast activity of different barley malts towards a lager brewing yeast strain

The brewing of beer involves two major biological systems, namely malted barley (malt) and yeast. Both malt and yeast show natural variation and assessing the impact of differing malts on yeast performance is important in the optimisation of the brewing process. Currently, the brewing industry uses well-established tests to assess malt quality, but these frequently fail to predict malt-associated problem fermentations, such as incomplete fermentations, premature yeast flocculation (PYF) and gushing of the final beer product. Antimicrobial compounds, and in particular antiyeast compounds in malt, may be one of the unknown and unmeasured malt factors leading to problem fermentations. In this study, the adaptation of antimicrobial assays for the determination of antiyeast activity in malt is described. Our adapted assay was able to detect differing antiyeast activities in nine malt samples. For this sample set, malts associated with PYF during fermentation and gushing activity in beer showed high antiyeast activity. Both PYF and gushing are malt quality issues associated with fungal infection of barley in the field which may result in elevated antimicrobial activity in the barley grain. Also, two more malts that passed the normal quality control tests were also observed to have high antiyeast activity and such malts must be considered as suspect. Based on our results, this assay is a useful measure of malt quality as it quantifies the antiyeast activity in malt which may adversely impact on brewery fermentation.     

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     

Influence of barley variety and malting process on lipid content of malt

The lipid content of a beer affects its ability to form a stable head of foam and plays an important role in beer staling. The concentration and the quality of lipids in beer depend on their composition in the raw materials and on the brewing process and they may exert considerable influence on beer quality. This paper presents an investigation of the influence of barley variety and malting process on the lipid content of finished malt. Five barley samples, grown in Italy, representing 4 spring barley and 1 winter barley were used. The samples were micro-malted and analysed. The aim of this research was to verify the influence of different barley varieties on the lipid content of malt and also on the changes in fatty acid (FA) profile during the malting process. Lipid content and FA profile were evaluated. Principal component analysis (PCA) was used to establish relationships between the different samples. An evaluation of the correlation between lipid content of barleys and the quality of the resulting malts was also conducted. The data showed that the total lipid content during the malting process decreased significantly as barley was converted into malt. Different barley varieties present different FA contents and different FA patterns. The correlation between the lipid content of barley and the quality of the resulting malt confirmed the negative influence of lipids.     

Fate of enniatins and beauvericin during the malting and brewing process determined by stable isotope dilution assays

The fate of enniatins A, A1, B, B1 and beauvericin during the malting and brewing process was investigated. Three batches of barley grains were used as starting material, one was naturally contaminated, two were artificially inoculated with Fusarium fungi. Samples were taken from each key step of the malting and brewing procedure, the levels of the toxins were determined with stable isotope dilution assays using liquid chromatography–tandem mass spectrometry detection. Significant increases of the toxins were found during germination of two batches of barley grains, resulting in green malts contamination up to a factor of 3.5 compared to grains before germination. Quantitative PCR analyses of fungal DNA revealed in all batches growth of Fusarium avenaceum during germination. After kilning, only 41–72% of the total amounts of the toxins in green malts remained in kilned malts. In subsequent mashing stage, the toxins in kilned malts predominantly were removed with spent grains. In the final beer, only one batch still contained 74 and 14 μg/kg of enniatin B and B1, respectively. Therefore, the carryover of these enniatins from the initial barley to final beer was less than 0.2% with the main amounts remaining in the spent grains and the malt rootlets.     

Impact of colour adjustment on flavour stability of pale lager beers with a range of distinct colouring agents

The impact of colour adjustment on the flavour stability of five pale lager beers with a range of colouring agents such as specialty malts, colouring beer and artificial caramel colourant was investigated. The research focused on determination of the endogenous anti-oxidative potential (EAP) of the beer samples using a novel Electron Spin Resonance (ESR) method. The results were correlated with the concentration levels of a portfolio of compounds formed during beer ageing, which were detected and quantified by GC–MS. The beer samples were also assessed by the ICBD sensory panel. Additionally, the quantification of organic radicals of the specialty malts and the roasted barley were conducted by ESR (whole intact kernel and milling fraction measurement). Based on the results of this holistic approach, a colouring agent was identified that enhanced the flavour stability of pale lagers based on the final beer’s physical-, chemical-, and sensory-properties.     

Indian black rice: A brewing raw material with novel functionality

Indian black rice (Chakhao Poireiton) is a pigmented variety, rich in anthocyanins and other phytonutrients. With growing interest in the use of local raw materials in brewing, it was of interest to develop protocols for malting and brewing with Chakhao Poireiton to see whether the antioxidant capacity of anthocyanins could be delivered into finished beer. Protocols for brewing with 100% malted rice were developed and the performance of Indian black rice compared with that of an Italian white rice cultivar suited to brewing. The apparent fermentabilities of rice worts were 69.5% (black) and 67.3% (white), yielding beers of 3.28 and 3.19% ABV respectively. Black rice worts were deficient in free amino nitrogen (83.5 mg/L relative to 137 mg/L for white rice) and would need nitrogen supplementation to avoid issues with fermentation, e.g. elevated diacetyl. Black rice beer had an orange-red hue as a result of extraction of anthocyanin pigments (2.84 mg/L). The oxidative stability of 100% rice beers was measured using electron spin resonance spectroscopy and both samples were found to be unusually stable. Interestingly, when rice beers were blended with a control barley malt derived lager in varying proportions (10, 25, 50%), the oxidative stability was improved, relative to the control lager, particularly so in the case of black rice beer, which contained an antioxidant capacity over and above that of the white rice beer. Future studies are required to determine whether the noted oxidative stability of 100% rice malt beers results in a more flavour-stable beer. © 2019 The Institute of Brewing & Distilling     

Malting for Brewhouse Performance*

In many instances brewhouse performance cannot be predicted from a finished malt specification. This is particularly so for factors such as lautering, yeast performance, filtration and head character. There are two aspects involved in improving the brewing performance of malt. Firstly, an understanding of the malt characteristics affecting particular aspects of the brewing process and secondly an understanding of how the malting process affects or can be controlled to optimise these characteristics and thus their performance. In this work the relationship between barley variety, steeping pattern, malt quality and brewing performance is investigated. Six different barley varieties were micromalted in a Seeger micromalting unit under four different steeping regimes. Sub-samples were taken at intervals during steeping for enzyme analysis and measurement of water distribution. Following steeping, the samples were germinated and kilned using standard micromalting conditions. Finished malts were analysed by standard EBC methods for routine malt quality parameters including apparent attenuation limit. Worts were tested for total β-glucan content, β-glucan molecular weight distribution, filter plugging potential and carbohydrate levels. A sub set of malt samples were then micro-brewed and tested for β-glucan molecular weight (MW) distribution, beer filterability and foam stability.     

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.     

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     

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     

MALT PROCESSING STABILITY OF BARLEY CULTIVARS — A STATISTICAL ANALYSIS

This paper presents a simple statistical analysis of malting process stability of barley cultivars grown for three years in the Mississippi Valley Six-rowed Uniform Barley Nursery and in the Western United States Two-rowed Uniform Barley Nursery. The effects of variety, location, and year on barley and malt quality were investigated. First, the Duncan Multiple Range Test was used to determine whether there were any varietal, location and year differences in barley and malt properties. The effects of variety, location, and year on various characteristics were further studied by comparing differences between extremes for the two-rowed and six-rowed barleys. Second, correlations between various properties were determined by calculating simple correlation coefficients. Barley nitrogen is the single most important parameter which affects extensively the processing characteristics of barley in malting and brewing, so the partial correlation coefficients, independent of total barley nitrogen, also were calculated. Third, the effects of variety, location, year, variety × location, variety × year, and location × year, were tested with variety × location × year as the estimate of error for each of the barley and malting properties. The stability model was designed to evaluate stability of all barley and malt properties. Based on the principle of regression analysis, the stability was measured by regression coefficient and the varietal mean of each barley and malting property. Stability (over years and locations) for kernel weight was significantly higher in the new than in the old cultivars. Improvements in stabilities of total extract and fine-coarse grind extract were greater and more consistent for the six-rowed than for the two-rowed barley malts. This reflects, presumably, the generally more satisfactory total extract and fine-coarse grind extract in the two-rowed barley malts than in the six-rowed barley malts.     

MALTING AND BREWING WITH BARLEYS HAVING BLUE ALEURONES

Blue aleurones in barley are associated with elevated levels of polyphenolic materials such as anthocyanins and anthocyanidins. A rapid method has been developed for assessing the anthocyanin content of barleys, malts and worts. Malts were prepared from a range of barleys, some of which had intensely blue aleurones, while others were only slightly blue or showed no visible pigmentation. The malting quality of barley was not affected by aleurone colour and ales and lagers of sound flavour as well as acceptable analytical parameters were brewed from malts having pronounced blue aleurones. In some cases sweet worts prepared from blue aleurone malts had a slight pinkish tinge, but this disappeared during wort boiling, and beer colours were normal. Levels of anthocyanins in barley correlated with those in malt and in wort. However, the concentration of anthocyanins was unrelated to the amount of anthocyanogens or total polyphenols. High anthocyanin levels in either barley or beer had no deleterious effects on beer flavour or the rate of haze development.     

Influence of barley variety, timing of nitrogen fertilisation and sunn pest infestation on malting and brewing

BACKGROUND: This paper presents a multivariate approach to investigate the influence of barley variety, timing of nitrogen fertilisation and sunn pest infestation on malting and brewing. Four spring and two winter barley varieties were grown in one location in southern Europe. Moreover, one of the spring varieties was infested with sunn pest, in order to study the effects of this pest on malting quality, and subjected to different nitrogen fertilisation timing regimes. The samples were micromalted, mashed, brewed and analysed. RESULTS: The data showed that even though the two winter barleys seemed to be the best regarding their physical appearance (sieving fraction I + II > 82%), this superiority was not confirmed in the malt samples, which showed low values of Hartong extract (27.1%) and high values of pH (6.07–6.11) and β‐glucan content (12.5–13.2 g kg^?1), resulting in low‐quality beers. The barley sample subjected to postponed fertilisation had a total nitrogen content (19.5 g kg^?1 dry matter) exceeding the specification for malting barley and gave a beer with a low content of free amino nitrogen (47 mg L^?1) and high values of viscosity (1.99 cP) and β‐glucan content (533 mg L^?1). The beer obtained from the barley sample subjected to pest attack had good quality parameters. CONCLUSION: All spring barleys gave well‐modified malts and consequently beers of higher quality than the winter barleys. Moreover, postponed fertilisation was negatively related to the quality of the final beer, and sunn pest infestation did not induce important economic losses in the beer production chain. Copyright © 2010 Society of Chemical Industry     

Determination of Prolamins in Beers by ELISA and SDS‐PAGE

Coeliac disease is triggered by exposure to the prolamin protein fraction of wheat, barley, or rye. The prolamin content of five lager beers and one wheat beer were analyzed by sodium dodecyl sulfate—polyacrylamide gel electrophoresis (SDS‐PAGE) and immunoblotting and seven lager beers and three wheat beers were analyzed by enzyme‐linked immunosorbent assay (ELISA). Most of the lager beers were made from barley and some had varying amounts of rice or corn as adjuncts. One of the beers was “gluten‐free”, having been produced from corn and buckwheat without barley. The lager beer samples were gel‐filtered before ELISA or SDS‐PAGE analysis. Prolamin proteins were found in all but one beer which was made of corn, rice and barley and which was not the “gluten‐free” beer. ELISA analysis was done using a commercially available gluten assay kit. For lager beers, a barley prolamin standard for ELISA was propanol‐extracted from barley malt instead of using the prolamin standard of the gluten assay kit. As expected, the wheat beers contained much higher amounts of prolamins than the lager beers. The samples were studied by SDS‐PAGE to identify different prolamin fractions. Proteins having a relative molecular mass in the range of 8000–17,000 and 38,000 and above were detected in immunoblotting by the prolamin sensitive antibody in the lager beers.     

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.     

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     

青稞精酿啤酒酿造工艺优化

以大麦芽、青稞为原料，制备青稞精酿啤酒，以感官评分为响应值，通过单因素试验和响应面法对青稞精酿啤酒酿造工艺进行优化，并对青稞精酿啤酒的基本指标和生物活性物质进行分析。结果表明，青稞精酿啤酒的最佳酿造工艺条件为：酒花添加量2 g/L，初始麦汁浓度14 °P，主发酵温度12 ℃。在此优化条件下，青稞精酿啤酒的感官评分为86.7分，外观鲜亮金黄，泡沫细腻，香气丰富，杀口力强。青稞精酿啤酒的酒精度为5.28%vol，β-葡聚糖、总黄酮和γ-氨基丁酸含量分别为（124.26±9.74）mg/L、（138.65±2.07）mg/L和（81.79±6.37）mg/L。     

LOW PROANTHOCYANIDIN MALTS FOR PRODUCTION OF CHILLED AND FILTERED OR FINED BEER

Malts which conform to most commercial specifications can be prepared from Galant barley, which is low in anthocyanogens. However, the malting performance of this variety is only medium and considerable care is required during kilning in order to avoid excessive colour development. Beers brewed from Galant malt have greatly improved chill haze stability, although flavour stability is not significantly affected. Fining and filtration studies on rough beer and forcing tests for the development of non-biological haze in finished beer indicate that the use of Galant malt greatly reduces the extent of precipitation of particulate matter during brewing, conditioning and subsequent storage. This can result in considerable savings in the use of finings, and in longer filter runs since levels of addition of body feed can be reduced. It is suggested that the use of low anthocyanogen malts could, with some beers, reduce the necessity for chilling prior to and during filtration.