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     

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     

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.     

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.     

影响啤酒过滤性能的酶制剂

总结了整个啤酒酿造过程中各个工艺因素对啤酒过滤的影响，并提出相应的工艺控制措施，特别侧重于各项新技术、新工艺（如用低发芽率麦芽、小麦芽酿酒、露天罐技术及酒龄缩短等）采用后给啤酒过滤造成不利影响的情况下，采取相应的工艺措施来提高啤酒的过滤性能。     

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

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

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.     

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.     

无定形碳处理等离子工艺

100年前啤酒由外国传入中国后,中国由不谙啤酒生产技术发展至现在成为全球第二大啤酒生产国,预计21世纪,中国将跃居为全球第一大啤酒生产王国;此外,由于市场竞争激烈,啤酒酿造商必须改良现有的生产配方和技术,共同努力,在市场上争一席之地,为中国成为全球第一大啤酒生产王国奠定良好的基础,为此,编者组织这个啤酒专辑,以馈企业和读者。     

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.     

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.     

Phenolic Substances in Beer: Structural Diversity,Reactive Potential and Relevance for Brewing Process and Beer Quality

For the past 100 years, polyphenol research has played a central role in brewing science. The class of phenolic substances comprises simple compounds built of 1 phenolic group as well as monomeric and oligomeric flavonoid compounds. As potential anti‐ or prooxidants, flavor precursors, flavoring agents and as interaction partners with other beer constituents, they influence important beer quality characteristics: flavor, color, colloidal, and flavor stability. The reactive potential of polyphenols is defined by their basic chemical structure, hydroxylation and substitution patterns and degree of polymerization. The quantitative and qualitative profile of phenolic substances in beer is determined by raw material choice. During the malting and brewing process, phenolic compounds undergo changes as they are extracted or enzymatically released, are subjected to heat‐induced chemical reactions or are precipitated with or adsorbed to hot and cold trub, yeast cells and stabilization agents. This review presents the current state of knowledge of the composition of phenolic compounds in beer and brewing raw materials with a special focus on their fate from raw materials throughout the malting and brewing process to the final beer. Due to high‐performance analytical techniques, new insights have been gained on the structure and function of phenolic substance groups, which have hitherto received little attention. This paper presents important information and current studies on the potential of phenolics to interact with other beer constituents and thus influence quality parameters. The structural features which determine the reactive potential of phenolic substances are discussed.     

Investigation of Protein Composition of Barley by Gel Electrophoresis and MALDI Mass Spectrometry with Regard to the Malting and Brewing Process

The protein composition of barley partly determines its quality in terms of malting and brewing. For this reason, the water‐soluble proteins of two different barley cultivars were investigated by gel electrophoresis and matrix‐assisted laser desorption/ionization mass spectrometry. Mass spectra were obtained directly from barley extracts by using three matrices. According to the quality of the measured spectra, it was possible to establish which matrix was the most suitable for the analysis of water‐soluble proteins from barley. We found that the protein patterns did not differ significantly between Jersey and Tolar varieties. However, our results showed the influence of the malting process on the posttranslational modification of some water‐soluble barley proteins. These proteins also survive the brewing process and they are very important for the formation and stability of beer foam. Several barley proteins were also identified by proteomic analysis.     

Brewing Beer with Sorghum

Research reports on extracts, proteins, total nitrogen and free amino nitrogen content of sorghum malt and worts obtained from mashes indicate that sorghum is potentially an alternative substrate for conventional beer brewing in the tropics. Remarkable variations in biochemical characteristics among different sorghum cultivars affect their optimal malting conditions. Factors such as temperature and time of steeping and germinating of grains with their intrinsic enzymic activities, and kilning temperature determine the quality of malt. Further works on mashing, viscosity and fermentability of worts as well as the character of the resulting beers, such as alcoholic content, colour, taste and specific gravity tend to confirm the status of sorghum as a credible substitute for barley in beer brewing. This review reports on progress made in the use of sorghum for brewing beer.     

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     

Hyd5 gene-based detection of the major gushing-inducing Fusarium spp. in a loop-mediated isothermal amplification (LAMP) assay

Fusarium graminearum and the closely related F. culmorum were found to be associated with over foaming of bottled beer (gushing) when contaminated brewing malt is used. The presence of highly surface active hydrophobins produced by these fungi upon growth on wheat or barley in the field or during malting may affect bubble formation and stability in gushing beers and other carbonated beverages. Aiming for a method for the rapid and user friendly analysis of unmalted and malted cereals during quality control in the brewing industry, a loop-mediated isothermal amplification (LAMP) assay for the detection of Fusarium spp. capable of producing the gushing inducing hydrophobin Hyd5p was set up. A set of primers was designed towards a 221 bp region within the hyd5 gene of F. culmorum. The LAMP product was verified by sequencing a 150 bp portion. Testing specificity with purified DNA from 99 different fungal species as well as barley and wheat showed that DNA synthesis only occurred during LAMP when DNA of the closely related species F. graminearum, F. culmorum, F. cerealis and F. lunulosporum were used as template. In-tube indirect detection of DNA amplification was applied using manganese-quenched calcein as fluorescence indicator for pyrophosphate produced during DNA synthesis. The assay had a detection limit of 0.74 pg of purified target DNA which corresponds 20 copy numbers per reaction within 30 minutes using a simple heating block. Analysis of Fusarium infected cereals revealed that the assay was able to detect F. graminearum at a level of 0.5% of infected grains in uninfected barley by analysis of surface washings without further sample preparation. Results show that the hyd5 based LAMP assay can be a rapid, useful and sensitive tool for quality control in the brewing and malting industry.     

Production of a Novel Proanthocyanidin-free Barley Line With High Quality

A proanthocyanidin-free (ant-free) barley with improved quality, Mokkei 92–130, was bred from the cross between Ant 13–347, an ant-free mutant and Haruna Nijo, a Japanese malting barley variety. The malting and brewing quality of the line are described in this paper, while its agronomic performance will be summarised elsewhere. Mokkei 92–130 achieved high levels in some malting quality character including hot water extract, diastatic power and apparent attenuation limit, which were significantly low in most of the ant-free lines and varieties previously reported. Cell wall degradation was also improved. Overall malting quality was found to be satisfactory in Mokkei 92–130. Pilot-scale brewing trials showed that Mokkei 92–130 had superior colloidal stability (less haze formed) in its final beer compared with the normal counterparts. Beer brewed with ant-free barley at a pilot-scale performed as well as the standard production in sensory evaluations soon after bottling, although it was rated poorer than the control after one month storage at ambient temperature.     

BACTERIAL EXPRESSION OF THE BIFUNCTIONAL α-AMYLASE/SUBTILISIN INHIBITOR FROM BARLEY

The bifunctional α-amylase/subtilisin Inhibitor (BASI) is an endogenous inhibitor of the high pl cereal α-amylases encoded by the amyl genes. Evaluation of the potential role of this protein in malting and brewing would be greatly assisted by the availability of large quantities of the protein. We have produced the protein by expression of the barley gene in bacteria. The barley gene was cloned into a pMAL vector and expressed as a fusion protein. The purified fusion protein was successfully cleaved with a specific protease to release the native BASI protein. The BASI produced by bacterial expression will be a useful source of the protein for studies of interactions with barley α-amylases and studies of the influence of this protein on malting and brewing.     

蛋白质组学技术在鉴定啤酒浑浊蛋白中的初步研究

啤酒中包含多种大麦蛋白,制麦和酿造过程中受到化学方式或酶的修饰,影响最终的啤酒浑浊稳定性。从啤酒中分离出的浑浊活性蛋白主要来自大麦储藏蛋白或大麦醇溶蛋白（Hordeum vulgare L.）,这些蛋白有富含脯氨酸,由许多不同分子量的片段组成。尽管对啤酒浑浊的研究时间较长,但是对于其特性方面的有待进一步确认。