ISOELECTROPHORETIC SEPARATION OF COMPLEX NITROGENOUS SUBSTANCES OF BEER AND BREWING MATERIALS

Complex nitrogenous materials extracted from barley, malt, wort and beer have been separated by isoelectrophoresis in thin layers of Sephadex gel. Comparison and interpretation of the different isoelectric profiles has been attempted. A preparative isoelectrophoretic procedure has been developed. The isoelectric species of beer have been isolated in quantities sufficient for certain of their physical and chemical properties to be determined. It is concluded that substances with typical protein-like properties account for only about one-third (by weight) of the total complex-nitrogen fraction of beer. An arbitrary but useful classification of the complex-nitrogen fraction of beer is suggested.     

啤酒和啤酒泡沫中蛋白质组成的差异性比较

利用SDS-PAGE、双向电泳仪、氨基酸分析仪对啤酒和啤酒泡沫中蛋白进行了系统的检测,并探讨了泡沫活性蛋白的组成。结果表明：啤酒和啤酒泡沫蛋白的分子量分布相似,：均由43kD和7-17kD的蛋白组成;在分子量和等电点的分布上啤酒泡沫蛋白的分布要少于啤酒蛋白的分布;双向电泳未能成功检测出单向电泳可测出的在7～10kD间的丰富蛋白分布,但检测到了多个12kD和17kD蛋白;并得出除蛋白质Z、脂转移蛋白外。醇溶蛋白残片也应是泡沫蛋白的一个重要组成。     

ELECTROFOCUSING STUDIES ON THE FORMATION OF BEER HAZE

The composition of protein fractions obtained from beers stored under differing conditions has been studied using a modified system for isoelectric focusing in thin layers of polyacrylamide gel which permitted the numerical evaluation of the focused bands by a scanning densitometer. The incorporation of concentrated urea in the gel enabled beer hazes to be assessed in this manner. The ageing of an unstabilized all-malt beer resulted in an increase in the proportion of acidic material (pl <5.0) although no new protein bands were formed. The derived hazes were enriched with acidic components but contained all except the most basic fractions present in the beer.     

FRACTIONATION OF HIGH MOLECULAR WEIGHT POLYPEPTIDES FROM BEER USING TWO DIMENSIONAL GEL ELECTROPHORESIS

High molecular weight polypeptides from beer were fractionated by a two dimensional gel electrophoretic method comprising isoelectric focusing in the first dimension followed by gradient gel electrophoresis in the second dimension. Silver stained gels revealed a complex pattern of spots which is consistent with individual polypeptide species having both discrete isoelectric points and molecular weights. The pattern of silver stained spots was reproducible both within and between beers and was independent of the sample preparation method or the composition of the sample solubilisation mix. Beers produced from grists containing malt plus 20% wheat flour were shown to contain four polypeptides of approximate molecular weight 30 000, 30 000, 16 000 and 15 000 which were absent from all malt control beers.     

啤酒酵母中还原型谷胱甘肽清除自由基能力的研究

选用啤酒酵母为原料,采用热水浸提提取还原型谷胱甘肽(GSH),经过高速离心分离、阳离子交换树脂纯化、等电点沉淀及真空浓缩干燥制备还原型谷胱甘肽。采用1,1-二苯基-2-苦肼基(DPPH)自由基反应体系,抗氧化性物质抗坏血酸作为参照物,根据DPPH·体系吸光值的变化研究GSH清除自由基的能力,DPPH·反应体系为5mL0.0817mmol/L DPPH·溶液+5mL样品溶液,反应时间30min。考察了不同浓度GSH和抗坏血酸与DPPH·自由基清除率的关系。结果表明,GSH比抗坏血酸抗氧化能力差一些,但GSH清除DPPH自由基能力与其浓度呈明显的量效关系,因此,啤酒酵母GSH有重要的抗氧化开发价值。     

Beer choice and consumption determinants when craft beers are tasted: An exploratory study of consumer preferences

The aim of this paper is to study the emerging craft beer industry from a consumer preference perspective. The craft beer industry is one of the growing segments in the beverage industry and its increasing popularity also affects individuals’ commercial beer preferences and consumption trends, although no empirical study has yet been carried out in Europe on this topic. Our exploratory study is aimed at comparing the “purely” commercial beer consumer profile with that of commercial beer consumers who have already tasted craft beers. It was observed that aroma and perceived quality, as well as the preference for draft beer, drinking beer frequently or by oneself are all factors that explain the propensity of “purely” commercial beer drinkers to taste craft beer. It was also found that beer consumers’ evaluations of characteristics and brands differed depending on whether they had previously tasted craft beer or not. Moreover, craft beer is chosen according to different flavor preferences compared to commercial beer, it is mainly drunk by frequent beer drinkers in pubs and with family members and it is perceived to be of higher quality than commercial beer due to the raw materials used for brewing and its overall quality. These results can help both new entrepreneurs in the craft beer segment as well as big manufacturing firms in trying to better understand this new consumption trend in order to meet the new needs and preferences of beer consumers.     

新世纪中国啤酒工业发展展望

中国是世界啤酒第二大国，由于啤酒企业重组，大集团垄断地位加强，这些集团的产量已占全国总量的55．8％，预计到2010年，中国啤酒企业将从500多家降至不到100家，有10余家大集团垄断中国啤酒产量的80％。当前，啤酒企业应以开发纯生啤酒为契机，迎来新一轮装备、管理、技术的改造和发展，使企业素质达到现代化标准。啤酒是世界性饮料，啤酒饮料化是当前啤酒风格发展的大趋势，这是新世纪啤酒发展的一个特点。在新世纪，要以质量竞争为首要竞争，并且，应加速发展啤酒大麦，加强麦芽厂大型化，推广使用国产大麦。（丹妮）     

多元统计分析技术在市售纯生啤酒一致性研究中的应用

目的 研究不同品牌和不同工厂市售纯生啤酒特征和产品质量一致性。方法 以国内3个品牌共计9个工厂1年内生产的不同批次纯生啤酒为研究对象,采用气相色谱法测定啤酒的风味代谢产物并由国家级专业评酒委员进行样品感官评价分析,以多元统计分析方法中的主成分分析(principal component analysis,PCA)、聚类分析(cluster analysis, CA)研究不同品牌纯生啤酒一年内生产的不同批次之间的产品特质和一致性。结果 研究结果显示3个品牌之间风味代谢物差异不大,感官评价分析差异较大,B品牌一致性最差,A品牌次之,C品牌最好。B品牌出现日光臭比率为19.4%,出现均值0.18以上纸板味的比率为48.4%,缺陷量级为专业级国家评委可感知,普通消费者难以察觉,国内纯生啤酒风味评价良好。结论 多元统计分析方法可用于产品质量一致性评价,不论是生产过程中的麦汁、发酵液等半成品还是啤酒成品控制中都能够发挥一定作用,这些工具的运用可提升啤酒企业的产品质量一致性。     

调配型黑啤酒的研制

以淡色啤酒为基酒,使用黑啤酒浓缩液、焦香浓缩液和焦糖色等物料,通过色度测试、口味测试和小型试酿,得出最优的配方。使用浓缩液方法生产黑啤酒,选择在过滤阶段完成,可达到精简工艺,便于设备清洗和酵母管理等效果,且生产成本较传统酿造法低,该法可行性高、经济效益明显,符合低碳、环保生产发展。     

模糊数学结合响应面法优化啤酒鱼的煮制工艺

为实现广西阳朔地方特色菜啤酒鱼的标准化加工,对啤酒鱼加工过程中煮制工艺参数进行优化。以罗非鱼为原料,通过模糊数学感官综合评价法,对啤酒鱼嫩度、弹性、组织状态、气味、滋味进行感官的权重分析;利用Box-Behnken响应面优化设计研究啤酒添加量、煮制时间、加热功率对啤酒鱼感官评分的影响;分别使用气相色谱-离子迁移谱（gas chromatography-ion mobility spectrum, GC-IMS）和质构仪对用最优参数煮制的啤酒鱼进行挥发性风味物质测定及质构剖面分析（texture profile analysis, TPA）。结果表明:嫩度和滋味是影响啤酒鱼模糊数学感官综合评价值的重要指标,工艺参数对啤酒鱼综合评价值的影响强弱顺序为煮制时间>啤酒添加量>加热功率。啤酒鱼最佳煮制工艺参数为:啤酒添加量66%,煮制时间33 min,加热功率500 W,预测值7.89,实际综合评价值为7.91。啤酒鱼的啤酒风味主要由乙醇、2, 3-戊二酮等醇、酮类物质组成;啤酒的添加使鱼肉的硬度、咀嚼性降低。本研究可为啤酒鱼的工业化生产工艺提供一定的理论支持。     

低醇啤酒专用糖浆的生产及应用

采用啤酒专用糖浆代替玉米和大米作辅料，可使啤酒生产工艺简化，啤酒质量得到提高。低醇啤酒专用糖浆的发酵度比普通麦汁和低聚麦芽糖浆的发酵度低，且含有较低的麦芽糖和葡萄糖。采用二次液化法可生产出低发酵度的低醇啤酒专用糖浆，并用其可生产出合格的低醇啤酒。（孙悟）     

新氮源啤酒酿造新技术的研究

研究以大豆蛋白为原料,通过新型的双酶(碱性酶和酸性酶)联合酶解工艺的研究,自主研制开发出适合啤酒酿造的小分子大豆蛋白多肽新氮源,采用新氮源替代部分麦芽,研制开发出新氮源啤酒酿造新技术,在保证啤酒口味和质量的前提下,降低麦芽使用量至30%,降低了啤酒的生产成本,提高了生产效率。     

Inhibition of Aldose Reductase Activity by Extracts from Hops

The inhibitory effect of beer on aldose reductase was investigated. Components present in beer strongly inhibited aldose reductase. Inhibition activity was observed primarily in the methanol‐soluble fraction of the beer and active components were identified to be of hop origin. Further, a component was identified as iso‐α‐acids, which are well known as main bitter components of beer. The inhibition rate of iso‐α‐acids was similar to quercetin, which is known to be a strong inhibitor of aldose reductase activity.     

反吹-气相色谱法快速检测啤酒中的主要风味物质

采用反吹技术改进了气相色谱检测啤酒中乙醛、高级醇、高级酯等10种主要风味物质的方法。用配备毛细管色谱柱、氢火焰离子化检测器及微板流控装置的气相色谱仪,对啤酒直接进样,建立了一种快速分析的气相色谱分析方法。结果表明,采用内标法定量,啤酒中10种主要的风味物质具有良好的线性关系（R2＞0.999）。对同一啤酒五次进样,测得的相对标准偏差为0.13%～2.77%。对啤酒加标回收,回收率达到96%～104%。采用反吹技术可以省去复杂的样品前处理,有效降低样品基质的影响,缩短样品的分析时间,提高效率,减少材料消耗。该方法以期能快速检测生产过程中啤酒的风味物质含量,有针对性控制啤酒的生产工艺,提高啤酒的质量。     

Brewing with 100% Oat Malt

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

小麦面筋蛋白质酶解产物用作啤酒发泡蛋白的研究

为改善啤酒的泡沫性能,作者分别采用木瓜蛋白酶、胃蛋白酶以及碱性蛋白酶对小麦面筋蛋白进行适度酶解改性,并对其产物用作啤酒发泡蛋白的可行性进行了研究.结果表明,经适度酶解作用后,小麦面筋蛋白在pH 4.5条件下溶解性和泡沫性能得到显著改善(P<0.05),且小麦面筋蛋白酶解产物在啤酒环境中热稳定性较好,经30 min的热处理,含100 mg/L小麦面筋蛋白酶解产物的啤酒浊度与加热前相比增加不显著(p>0.05).小麦面筋蛋白胃蛋白酶酶解产物和碱性蛋白酶酶解产物对啤酒初始泡持性的改善效果都较好,但胃蛋白酶酶解产物对酵母蛋白酶A作用较敏感,对纯生啤酒货架期内泡持性的改善效果不太理想,而碱性蛋白酶酶解产物可明显改善纯生啤酒货架期内的泡沫稳定性.     

玉米淀粉辅料在啤酒生产中的应用

以玉米淀粉为辅料进行啤酒生产的研究结果表明,用量适当,不仅啤酒的成本降低,而且啤酒的发酵度、色度、总酸和非生物稳定性都较原工艺有一定的提高,泡持性有所降低,有利于生产淡爽型啤酒。     

LOW MOLECULAR WEIGHT NITROGENOUS COMPONENTS AND THEIR INFLUENCE ON THE STABILITY OF BEER FOAM

Addition of low molecular weight nitrogenous components, nucleoside (adenosine), nucleotide (AMP), amino acids (glutamic acid, glycine, proline and asparagine) and a tripeptide (glycylglycylglycine) had no effect on the head retention value of beer. Under such conditions of artificial manipulation of the content of low molecular weight beer nitrogenous components no correlation between the nitrogen molecular weight ratio of beer and beer head retention value was observed. Collapsed beer foam was collected and separated into soluble and precipitated fractions. Analysis of collapsed beer foam demonstrated that high molecular weight polypeptide material and isomerised α acids are concentrated in beer foam and are constituents of beer foam precipitate material. Beer foam precipitate material may be stabilised by ionic interactions between polypeptide material and isomerised α acids. Further analysis of beer and collapsed beer foam demonstrated that purine nucleosides are not concentrated in beer foam. Similarly, under conditions simulating beer dispense, amino acids are not concentrated in beer foam. Under strongly selective foaming conditions, such as those encountered in a foam tower, the hydrophobic amino acids, valine, isoleucine, leucine and phenylalanine are concentrated in beer foam.     

The impact of sulphur dioxide and oxygen on the behaviour of 2-furaldehyde in beer: an industrial approach

2‐Furaldehyde is often used as an analytical indicator of beer flavour deterioration. Although 2‐furaldehyde itself has a flavour threshold far above levels generally present in beer, it can be used as a good marker of heat damage of beer. A reversed‐phase liquid chromatographic assay, using ultraviolet‐visible detection, was applied to investigate the behaviour of 2‐furaldehyde throughout the brewing process and during extended storage of beer. The impact of storage temperature, sulphur dioxide and oxygen content on the level of 2‐furaldehyde was studied. It was found that the concentration of 2‐furaldehyde markedly increases during wort boiling and is rapidly reduced by yeast during the first hours of fermentation, emphasising the yeast reducing capacity as a determinant factor for the 2‐furaldehyde content found in the final beer. The results obtained suggest that sulphur dioxide and oxygen content play a key role on the 2‐furaldehyde content in packaged beer. 2‐Furaldehyde increase during ageing is oxygen dependent and sulphur dioxide retards its development by possibly protecting beer against the occurrence of oxidative reactions.