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     

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     

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     

Variation in gluten protein and peptide concentrations in Belgian barley malt beers

Gluten is the main family of storage proteins found in barley. During malting and brewing, some of the barley malt's proteinaceous material is hydrolysed into peptides or to amino acids. Most of the gluten proteins are removed with the spent grains and with hot‐ and cold‐breaks. However, some gluten proteins and especially gluten‐derived peptides can remain throughout the brewing process and will hamper the gluten‐free (≤20 ppm) status of the beer. In this work, three production batches (a, b and c) of 51 Belgian barley malt beers from 24 breweries were analysed with the sandwich (R7001) and competitive (R7021) Ridascreen gliadin R5‐ELISA to quantify gluten proteins and peptides. Although the majority of the beers contained low‐gluten protein concentrations of ≤20 ppm (a/45, b/47, c/48), only a minority were truly gluten‐free with ≤20 ppm gluten peptides (a/18, b/17, c/15). The grain bill had no influence on the measured gluten concentration, but the use of (combined) clarification techniques and presence of wheat malt in the grist was respectively a positive and negative influence. Ten beers, from four breweries, were gluten free in all analysed samples. These included two wheat beers, reflecting the importance of effective clarification in the management of gluten. These results explore the feasibility of the production of gluten‐free barley malt beers. Copyright © 2018 The Institute of Brewing & Distilling     

‘FREE’ AND ‘BOUND’ β-AMYLASES DURING MALTING OF BARLEY. CHARACTERIZATION BY TWO-DIMENSIONAL IMMUNOELECTROPHORESIS

Major qualitative and quantitative changes in the β-amylases and in other salt soluble barley proteins occurred during the first four days of germination. Two soluble forms of barley β-amylase, ‘free’ β-amylase and β-amylase aggregated with a non-active protein Z, were found in extracts from all stages. A third enzyme form appeared during malting. Immunoelectrophoretic characterization seemed to support the possibility that this enzyme form could be a product of ‘bound’ β-amylase solubilization. All soluble forms of β-amylase and of protein Z in malt were electrophoretically heterogeneous. Two different, immunochemically related forms of protein Z present after malting retained their immunoelectrophoretic properties during brewing and were found to be dominant antigens in beer.     

Fungal Hydrophobins in the Barley‐to‐Beer Chain

Fungal hydrophobins have been shown to induce gushing of beer. In order to study the occurrence and fate of hydrophobins at different stages of the production chain of beer, barley samples artificially infected in the field with Fusarium culmorum, F. graminearum and F. poae were collected during the growing period as well as during various stages of the malting process. In addition, naturally infected malt was brewed in pilot scale and samples were collected throughout the process. The samples were assayed for hydrophobin content using an ELISA method. The results showed that fungi produced hydrophobins that accumulated during barley grain development in the field, but that production was more pronounced during malting. Prolonged storage of barley tended to reduce the ability of fungi to produce hydrophobins in malting. Studies on the fate of hydrophobins during the brewing process revealed that mashing released hydrophobins from the malt into the wort. Some loss of hydrophobins occurred throughout the brewing process with spent grains, cold break (wort boiling) and surplus yeast. In addition, the beer filtration step reduced hydrophobin levels. Despite the substantial loss of hydrophobins during brewing, the level was high enough to induce the gushing detected in the final beer.     

Overcoming technical barriers to brewing with green (non-kilned) malt: a feasibility study

Brewing using enzyme rich ‘green’ (germinated, but not kilned) malt has the potential to unlock considerable energy savings in the malting and brewing chain. This paper examines the major quality issues associated with green malt, by monitoring lipoxygenase (LOX) activity and S-methyl methionine (SMM) levels through a micromalting cycle both with and without rootlets after 48 h of germination. The data suggest that rootlets are a major concern when brewing with green malt and that their influence on wort and beer quality needs to be further investigated. Lipoxygenase activity and nonenal potential were measured following treatment under varying conditions of pH, temperature and pre-treatment. Results indicated that lipoxygenase activity can be controlled to a substantial degree by manipulating these limiting factors, while preserving diastatic enzyme activity. Green malt worts were then prepared from (i) whole green malt immediately post-germination; (ii) heat treated green malt (65°C x 1 h); (iii) re-steeped green malt and (iv) endosperm-rich extracts of green malt after the husk and rootlets had been removed; using laboratory mashing with a ‘LOX-hostile’ mash schedule. Data were compared with mashing of kilned pale malt made from the same green malt, as a reference point. Based on the present data, re-steeping of green malt in combination with a LOX hostile mashing environment (63°C, pH 5.2) could help to control LOX activity and the trans-2-nonenal potential of green malt. The resultant brewing process would need to be optimised to deal with the elevated SMM levels in green malt worts. © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling     

Transfer of Fusarium mycotoxins and ‘masked’ deoxynivalenol (deoxynivalenol-3-glucoside) from field barley through malt to beer

The fate of five Fusarium toxins — deoxynivalenol (DON), sum of 15- and 3-acetyl-deoxynivalenol (ADONs), HT-2 toxin (HT-2) representing the main trichothecenes and zearalenone (ZON) during the malting and brewing processes — was investigated. In addition to these ‘free’ mycotoxins, the occurrence of deoxynivalenol-3-glucoside (DON-3-Glc) was monitored for the first time in a beer production chain (currently, only DON and ZON are regulated). Two batches of barley, naturally infected and artificially inoculated with Fusarium spp. during the time of flowering, were used as a raw material for processing experiments. A highly sensitive procedure employing high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was validated for the analysis of ‘free’ Fusarium mycotoxins and DON-conjugate in all types of matrices. The method was also able to detect nivalenol (NIV), fusarenon-X (FUS-X) and T-2 toxin (T-2); nevertheless, none of these toxins was found in any of the samples. While steeping of barley grains (the first step in the malting process) apparently reduced Fusarium mycotoxin levels to below their quantification limits (5–10 µg kg^?1), their successive accumulation occurred during germination. In malt, the content of monitored mycotoxins was higher compared with the original barley. The most significant increase was found for DON-3-Glc. During the brewing process, significant further increases in levels occurred. Concentrations of this ‘masked’ DON in final beers exceeded ‘free’ DON, while in malt grists this trichothecene was the most abundant, with the DON/DON-3-Glc ratio being approximately 5:1 in both sample series. When calculating mass balance, no significant changes were observed during brewing for ADONs. The content of DON and ZON slightly decreased by a maximum of 30%. Only traces of HT-2 were detected in some processing intermediates (wort after trub removal and green beer).     

Effect of Germination Moisture and Time on Pearl Millet Malt Quality — With Respect to Its Opaque and Lager Beer Brewing Potential

The effect of germination moisture and time on pearl millet malt quality was investigated. Two pearl millet varieties SDMV 89004 and 91018 were germinated at 25°C under three different watering regimes for 5 days. As with sorghum malting, diastatic power, beta‐amylase activity, free α‐amino nitrogen (FAN), hot water extract and malting loss all increased with level of watering. However, pearl millet malt had a much higher level of beta‐amylase and higher FAN than sorghum malt and a similar level of extract. Malting losses were similar or lower than with sorghum. Thus, it appears that pearl millet malt has perhaps even better potential than sorghum malt in lager beer brewing, at least as a barley malt extender, especially in areas where these grains are cultivated and barley cannot be economically cultivated. Also, its increased use in commercial opaque beer brewing, where sorghum malt is currently used, could be beneficial.     

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.     

Pilot‐scale brewing using self‐cloning bottom‐fermenting yeast with high SSU1 expression

A pilot‐scale fermentation was performed using SSU1‐overexpressing bottom‐fermenting yeast strains constructed by ‘self‐cloning’. In these strains, the gene SSU1, encoding a plasma membrane protein that excretes sulphite, was highly expressed. The rate of fermentation of the two SSU1‐overexpressing strains tested showed some reduction during the mid‐fermentation phase as compared with the parental strain. These differences, however, did not affect overall fermentation and the final apparent extracts had decreased to a level normally obtained during brewing. The concentration of hydrogen sulphide in the wort remained low during fermentation in the case of the two self‐cloning strains compared with the parent. The concentration of 2‐mercapto‐3‐methyl‐1‐butanol, a sulphur compound that causes an ‘onion‐like’ off‐flavour, was also reduced in the case of the self‐cloning strains, a result confirmed by sensory evaluation of the beer immediately after bottling. Furthermore, with these strains the anti‐oxidation potential of bottled beer, as measured by electron spin resonance, was improved and the concentration of trans‐2‐nonenal in bottled beer after 7 days of accelerated aging at 37°C was decreased. These observations, together with the lower stale flavour score determined by sensory evaluation of bottled beer after a month of aging at 25°C, indicated that the flavour stability of the beer had been successfully improved. Copyright © 2013 The Institute of Brewing & Distilling     

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.     

A fundamental study on the relationship between barley cultivar and hordeins in single cultivar beers

The hordein proteins found in beer are not suitable for gluten‐sensitive consumers. Hordeins are storage proteins found in barley and have limited solubility in water. It is not currently known if the nitrogen concentration of barley directly impacts on the hordeins present in beer. In this study a controlled malting on eight barley cultivars was performed and a single cultivar model beer was produced from each. The single cultivar model beers were then examined for differences in content of hordeins. The quality of barley and malt was assessed and the parameters measured were compared with the beer hordeins using a Pearson correlation matrix. The results showed significant differences in the content of beer hordeins, depending on the barley malt used. Correlations between results showed a positive relationship to malt nitrogen and a negative relationship to friability. The results suggest it may be possible to optimize the choice of the barley cultivar and the malting conditions in order to produce a beer low in hordeins. Copyright © 2016 The Institute of Brewing & Distilling     

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     

An early development of the nonenal potential in the malting process

The scarce knowledge of the significance of enzymatic oxidation of polyunsaturated fatty acids throughout the malting process led the authors to conduct studies on the monitoring of a set of selected parameters involved in the reaction. Lipoxygenase (LOX) activity, the nonenal potential, the temperature and the moisture content were assessed for the top and bottom malt layers in various stages of an industrial kilning process. Significant differences were obtained between the lower and upper malt bed, suggesting that the moisture content and temperature gradient play a key role on the production of E-2-nonenal during the early stages of kilning. The residual nonenal potential already present in the finished malt (malt-RNP) may account for approximately 25% of the total nonenal potential in the mash, depending on the residual LOX activity. LOX showed a good degree of relationship with the nonenal potential for micro-malts (r=0.79, p<0.05), whereas for commercial malts no correlation was found. These results suggest that the malt-RNP plays a prominent role for commercial malts, probably owing to the great heterogeneity observed for the malt bed in the industrial kiln. On the other hand, a major role of LOX during mashing was observed for micro-malts, emphasizing that the intrinsic properties of the barley and malt may be overwhelmed by technological factors. Therefore, kilning programmes should be adopted in order to minimize formation of malt-RNP during the drying phase of the malting process.     

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     

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     

MALTING CHARACTERISTICS OF FINGER MILLET,SORGHUM AND BARLEY*

The malting characteristics of the finger millet variety Imele (FI), sorghum varieties Andivo (SA) and Ingumba (SI) and the barley variety Research (BR) were compared in relation to the brewing of traditional African opaque beer as well as conventional lager beer. The investigations include (a) the effect of steeping and germination conditions, (b) the influence of gibberellic acid and kilning temperature on the activity of important brewing enzymes and (c) an appraisal of the brewing potential of the worts obtained. FI, SA and SI malts were considered unsuitable as barley malt extenders for conventional lager beers, but FI and possibly SI malts would be suitable for tropical lager beer manufacture.     

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.