A Review: Biological and Technological Functions of Barley Seed Pathogenesis‐Related Proteins (PRs)

The mature barley seed proteome is dominated by proteins involved in stress responses, including the Pathogenesis‐Related proteins (PRs). PRs are currently classified into 17 families. The biochemistry of the PRs families, whose members are constitutively present in barley seed, is surveyed in this paper. These proteins are assumed to protect dormant and germinating seeds against pathogenic microorganisms and pests. The current knowledge on PRs structural and functional properties is summarized in an attempt to illustrate their importance in barley seed innate resistance. At the same time, a platform to understand PRs technological function in cereal foods and in beverage processing and quality is provided.     

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.     

A study on malt modification,used as a tool to reduce levels of beer hordeins

Storage proteins from barley, wheat and rye are toxic to gluten sensitive consumers. These consumers include those suffering from coeliac disease, which account for up to 1% of the global population, and non‐coeliac gluten sensitivity that may affect even greater numbers of the population. Codex Alimentarius has published guidelines and limits of gluten in gluten‐free foods, which are applied in Europe, and similar guidelines apply in the rest of the world. The storage proteins present in barley are hordeins. These proteins are broken down and used by the plant as a source of amino acids during germination and growth of the barley embryo. The objective of this study was to extend the germination stage of the malting process and look at the effect on beer hordeins. Standard MEBAK methods were used to develop an extended malting process and produce three different malts, germinated for 3, 5 or 7 days. The quality of malt was assessed and model beers were produced from each malt to test the effect of modification on levels of beer hordeins. Malt germinated for 7 days produced beer 18 mg/kg hordeins corresponding to a reduction of 44% compared with the beer made from malt germinated for 3 days characterized by a hordein content equal to 32 mg/kg. The malting loss was increased during the 7 days of germination but otherwise all malts were of high quality. The results showed that malting conditions have a significant impact on beer hordeins. Copyright © 2018 The Institute of Brewing & Distilling     

啤酒酵母凝集性的探讨

从啤酒酵母的凝集特性、作用机理及主要影响因素,分析了啤酒酵母凝集性对啤酒生产工艺过程及啤酒质量的影响,介绍了啤酒酵母凝集性的测定方法.     

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     

对影响啤酒泡沫因素的探讨

啤酒泡沫被誉为"啤酒之花",是啤酒区别于其它饮品的主要特征之一.良好的泡沫性能是优质啤酒的一个显著标志.对影响啤酒泡沫性能的因素进行了研究,并对改善啤酒泡沫性能的工艺措施进行了探讨.     

啤酒中蛋白质及其测定方法研究进展

啤酒中蛋白质对啤酒品质的各方面有着很大的影响,尤其是对啤酒泡沫和浑浊的形成.本文在叙述啤酒泡沫和浑浊蛋白质性质的基础上探讨了啤酒中蛋白质的测定方法,给酿造者提供选择合适的方法来测定和控制啤酒中的蛋白质,以此来提高啤酒的品质.     

小黑麦啤酒糖化工艺的探讨

首次采用了小麦与黑麦属间异源多倍体杂交品种——小黑麦作为酿造啤酒原料。与传统啤酒大麦原料相比 ,小黑麦不仅淀粉酶活性及蛋白质含量高 ,八种必需氨基酸平衡 ,而且产量高 ,种植费用低 ,可降低原料价格。本试验对小黑麦糖化工艺进行了探讨 ,确定糖化主要技术参数 ,麦汁质量符合酿造啤酒标准。     

Construction of a novel beer proteome map and its use in beer quality control

Beer proteins were analysed by two-dimensional gel electrophoresis (2DE). The protein species associated with major spots on 2DE gels were identified by mass spectrometry followed by a database search to construct a comprehensive beer proteome map. As a result, 85 out of 199 protein spots examined were positively identified and categorised into 12 protein species. A total of 11 beer samples were brewed from the malt of eight cultivars having different levels of protein modification. This experiment was designed to demonstrate the influences of barley cultivar and malt modification on beer protein composition and beer quality characters. The beers produced from these brewing trails were subsequently analysed by 2DE and their proteomes were compared. Cultivars and malt modification affected the concentration of several proteins in beer. Beer protein concentration was associated with differences in the desirable beer quality trait, foam stability. In addition, expression of yeast derived proteins were observed that may also influence beer quality. Overall, the application of a comprehensive beer proteome map provides a strong platform for detection and potential manipulation of beer quality related proteins.     

啤酒泡沫中发泡蛋白的研究进展

大量研究表明，啤酒泡沫产生的关键因素是啤酒中所含的发泡蛋白，发泡蛋白的性质和数量很大程度上决定着啤酒泡沫的质量。通过对发泡蛋白定义、特性和与泡沫质量的关系，以及泡沫质量测定方法、改进措施等方面的介绍，说明了发泡蛋白对啤酒泡沫质量的决定性作用及研究发泡蛋白的现实意义。     

酿造单宁在啤酒糖化过程中的应用研究

在糖化阶段分别加入两种不同的酿造单宁,研究两种单宁对啤酒质量的影响。实验证明,单宁沉降啤酒中敏感蛋白的效果非常显著,明显降低高分子蛋白质的含量,有效地提高了啤酒的非生物稳定性;对发酵过程中酵母的繁殖和啤酒的口感无不良影响。     

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.     

啤酒糖化生产过程预测统计数学模型的研究

本文对啤酒生产糖化过程预测统计数学模型的建立进行了研究。首先采用正交拟因子试验设计法,对不同质量的麦芽确定对麦芽汁质量具有显著影响的因素,并得出了二次煮出糖化法最佳工艺条件。在此基础上建立了麦芽汁主要质量指标与不同质量的麦芽和其它影响因素之间关系的预测统计数学模型。通过实验验证,模型的预测精度较高。     

Proteins and amino acids in beers,their contents and relationships with other analytical data

Fluorometry, ion-exchange chromatography, electrophoretic separations and Fourier transform–infrared (FT–IR) spectra were used to determine and characterize amino acids and proteins in 15 different beer samples. Proteins precipitated by ammonium sulfate yielded complex electrophoretic patterns. The major bands corresponded to 45–40 kDa as determined by a two-dimensional gel electrophoresis (2-DE). Proteins and some amino acids are partially responsible for nutritional value and stability of beer. Therefore, electrophoretic analysis revealed that protein characterization of beer during all technological stages might be useful in its quality. FT–IR protein spectra showed the presence of I, II and III amide bands. Protein distribution and amino acid composition of beer differ significantly, depending on the raw materials and enzymatic reactions used in beer technology. Concentrations of histamine (3.02–3.23 mg/l), proline (1.60–3.13 mg/l) and tyramine (3.61–7.4 mg/l) increased during beer fermentation. Statistically significant change was registered in the protein content of the final product, which was less than that in wort (p<0.005). Levels of tyramine and proline, which were higher than in wort (p<0.025) showed significant changes. This investigation shows that, in Israeli, Mexican and Brazilian beers, the contents of protein and amino acids are in accordance with the international standards.     

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。     

奶啤的研究进展

奶啤是一种以牛乳作为主要原料，经过乳酸菌和酵母菌发酵后所得到的一种含二氧化碳的低醇发酵型乳酸菌饮品。该文系统的介绍了奶啤的发展历程、风味变化、原料组成、发酵过程和工艺流程中的质量控制的现状，对奶啤的未来进行了展望，为奶啤产业的深入研究提供理论参考。     

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     

Use of Glucose-Galactose Concentrates in Beer Production

Three kinds of demineralized and non-demineralized glucose-galaktose concentrates obtained from whey or partially refined lactose, were substituted for barley malt in brewers wort. Demineralized concentrates can be substituted for up to 50% of the malt extract in wort without negatively affecting the technological process of beer production or the quality of the final product. Beer produced with concentrates added showed high quality, flavour and smell, being in most cases quantitatively superior to the control beer. Substitution for the extract by non-demineralized concentrate showed that while a 10% substitution did not negatively affect the quality of beer, increased proportions of 25 and 50 per cent produced a salty taste.     

A Discussion of Polyphenols in Beer Physical and Flavour Stability

Generally referred to as polyphenols (PPs), beer flavonoids such as the flavan‐3‐ols and their condensed products, the proantho‐cyanidins, represent a class of readily oxidizable compounds capable of hindering or preventing the oxidation of other molecules present in beer. Flavan‐3‐ol and proanthocyanidin capacity to improve oxidative stability has been well established in other food systems, and thus these antioxidants have recently gained significant consideration as potential beer flavour modifiers and/or stabilizers. The duality of their presence in beer is that PPs complex with proteins in the beer matrix to form temporary and permanent hazes. Undesirable physical instability caused by PP‐protein interactions can be resolved via use of adsorptive resins such as polyvinylpyrrolidine. While there is no doubt that polyphenol removal increases beer shelf stability in terms of haze formation, the impact of polyphenol removal on beer flavour remains unresolved. This review discusses the sources, content and impact of polyphenol presence and removal on beer physical and flavour stability.     

中国啤酒低碳技术领域专利发展态势分析

为了明确中国啤酒低碳技术领域专利的发展态势,使相关的企业、科研院所从整体上把握该领域专利发展的脉络,进一步为未来专利申请布局及市场战略的制定提供参考与支持。基于M-Trends平台,对中国专利数据库中1986-01-2012-08啤酒领域公开的专利进行检索。并从专利申请数量类型、发展态势、技术生命周期、集中程度、主要国家和地区、主要申请人以及主要技术领域等方面对检索的结果进行分析。结果表明：在啤酒低碳技术领域,我国正处于快速成长期、专利申请量快速增加、集中程度日益提高,低碳技术在啤酒领域所占地位持续加强、专利结构、技术分布相对合理,国际竞争者在我国的专利布局还处于初级阶段。但仍存在发展滞后,低碳技术在啤酒领域整体比重较小,单位专利科研投入相对较少,还未形成全产业链的专利布局等问题。