Effect of ultrasonication on fermentation kinetics of beer using six‐row barley cultivated in Korea

The effect of a ‘bath type’ ultrasound on the fermentation of beer made from Korean six‐row barley was studied. Beer samples were treated in an ultrasonication bath for 4 days during primary fermentation. The frequency of the ultrasound was 40 kHz, and the input power was adjusted to 120, 160 and 200 W. Ultrasonic treatment was performed for 2, 6 and 12 h for each input power. The physicochemical and sensory properties, as well as the quality of the beers were measured. Ultrasonication enhanced ethanol production by 13.18% at 160 W. Copyright © 2015 The Institute of Brewing & Distilling     

Characteristics of beer produced from Korean six‐row barley with the addition of adjuncts

In this study, the effect of the addition of various amounts of adjuncts (rice, wheat, corn and potato at 10 and 20%) on the fermentation period of beer produced from Korean six‐row barley was examined. Korean six‐row barley is not suitable for brewing because of its relatively high protein/starch ratio. However, this can be offset by partially replacing the barley with adjuncts. Adjunct‐added samples were analysed and compared with the control sample made from 100% six‐row barley. All adjunct‐added samples showed changes in final beer properties (e.g. lower specific gravity, higher alcohol content, beer colour), because the initial free amino nitrogen (FAN) content was decreased and the reducing sugar content was increased. However, potato‐added samples showed a higher initial FAN level, resulting in the highest alcohol content. In addition, the colour of the potato‐added samples was darker, while the colours of the other samples were lighter. Consequently, the addition of adjuncts at a level of up to 20% had an impact on some of the quality properties of the samples in terms of fermentation period, suggesting the possibility of using Korean six‐row barley with adjuncts in brewing. Copyright © 2016 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。     

果酿啤酒的酿造工艺和品质研究进展

果酿啤酒的品质受众多因素影响,特别是水果特性差异和产品质量标准缺失使得果酿啤酒的酿造工艺存在较大差别,产品质量难以稳定。为进一步提升果酿啤酒品质,该文对近年来果酿啤酒的研究现状进行综述,探讨水果榨汁处理、灭菌方式,发酵过程中原麦汁浓度、主发酵温度、果汁添加量及添加阶段、酵母菌种选择等因素对果酿啤酒品质的影响,分析果酿啤酒的风味成分及风味劣变、活性成分及抗氧化活性,并对果酿啤酒的发展趋势及品质提升进行展望,以期实现不同果酿啤酒的精准调控,为实际生产中果酿啤酒的酿造提供借鉴。     

啤酒大麦、麦芽中多酚类化合物HPLC指纹图谱分析技术研究

以10个进口和8个国产啤酒大麦品种及其相对应的麦芽为样本,采用高效液相色谱（HPLC）建立大麦和麦芽中14种多酚类物质的指纹图谱,并分别进行相似度分析、聚类分析（CA）和主成分分析（PCA）。结果表明,进口大麦样品的相似度（0.938～0.989）高于国产大麦样品（0.911～0.937）,而进口大麦麦芽的相似度（0.892～0.967）普遍低于国产大麦麦芽的相似度（0.956～0.981）;CA（判别距离＜5）结果和PCA结果一致,8个国产大麦和1个进口大麦样品B2聚为一类,8个国产麦芽和3个进口麦芽样品M2、M3、M4聚为一类,说明通过大麦、麦芽多酚类物质的HPLC指纹图谱技术能基本区分国产和进口大麦品质的差异。     

添加小麦芽对啤酒发酵中化学物质变化的影响

目的:通过配制不同配比的混合麦芽发酵啤酒,运用化学方法分析啤酒发酵过程中主要化学物质变化的影响来探讨混合麦芽用于啤酒发酵对啤酒品质的影响。方法:采用刚果红法、高效液相色谱法、气相色谱法等常用化学方法测定啤酒中β-葡聚糖、阿拉伯木聚糖、有机酸和挥发性物质的含量。结果:随小麦芽添加量增加啤酒中粘度升高;挥发性物质中醇类先升高后降低,酚类物质、多种有机酸的含量提高;感官评价评分在小麦添加量为50%达到最大值。结论:添加小麦芽可改变啤酒中化学成分的组成,显著提高啤酒的品质。      

Fed‐batch fermentation with glucose syrup as an adjunct for high‐ethanol beer brewing

To produce a beer with a high ethanol content, preliminary research on fed‐batch fermentation profiles with glucose syrup as an adjunct during the primary fermentation period was conducted. The ethanol concentration of the beer was elevated by feeding a glucose syrup into the fermentors at a later stage of primary fermentation. Fermentation trials were carried out using a typical lager strain, SC‐9, with a pitching rate at 7.0 × 10⁶ cells/mL. An all‐malt wort (12.5°P) was employed and the primary fermentation temperature was 14 °C. Glucose syrup was supplemented when the concentration of residual reducing sugars was decreased to ~10 g/L. Results showed that the supplemented glucose was consumed rapidly and that the ethanol concentration in the final beer was raised to 67.9 g/L. Additional growth of yeast was observed after feeding accompanied by a low yield of ethanol (~0.46 g/g). Formation of diacetyl was enhanced by yeast growth and two additional peaks were obtained after feeding. The peak value of the diacetyl concentration was 1.90 mg/L. The fed‐batch fermentation resulted in a beer with an overproduction of higher alcohols and esters, indicating that brewing under these experimental conditions led to an unbalanced flavour profile. Results of optimization demonstrated that the optimal conditions were found to be 15°P for initial wort extract, 10 °C for fermentation temperature and 20 × 10⁶ cells/mL for yeast pitching rate, leading to total higher alcohols of 173.8 mg/L, total esters of 22.8 mg/L and an acetaldehyde concentration of 40.5 mg/L. A 12 day maturation and fermentation temperature of 8 °C was needed to reduce the acetaldehyde to 14.3 mg/L. Copyright © 2014 The Institute of Brewing & Distilling     

基于主成分分析、神经网络对啤酒感官评价的预测

该研究运用主成分分析(PCA)结合误差反向传播(BP)神经网络对啤酒感官评价进行了预测。把啤酒中11种理化及风味指标进行主成分分析,以除去数据之间的线性相关性,提取后的理化及风味指标做为输入数据,感官评价得分作为输出数据,运用BP神经网络建立啤酒感官评价预测的模型。使用此模型对50种啤酒的感官得分进行预测,预测最大相对误差为2.68%。结果表明,主成分分析和神经网络相结合的这种方法能够准确预测啤酒感官评价得分。     

Evaluation of mepiquat in malted barley and beer using LC‐MS/MS

Following recent studies that showed that the agrochemical mepiquat (1,1‐dimethylpiperidinium) forms during the roasting of coffee beans and barley, this work investigates the presence of mepiquat in malted barley and commercially available beers. Liquid chromatography–tandem mass spectrometry was used to develop a sensitive and precise analytical method, with detection limits of 0.031 ng/g in malted barley and 0.014 ng/g in beer. Mepiquat was detected in nine out of 10 malted barley samples, with all results under the Canadian maximum residue limit (100 ng/g). The data suggest a relationship between perceived malted barley colour and mepiquat concentration. The concentration of mepiquat in the beers analysed was also below the maximum residue limits in Canada (100 ng/g) and in the EU (600 ng/g), suggesting that mepiquat is not a regulatory concern in finished beers. Copyright © 2015 The Institute of Brewing & Distilling     

青岛啤酒酵母与高浓酵母筛选高浓酿造酵母融合亲株

以青岛啤酒酵母和高浓精酵母为供试菌株,筛选出生长良好的酵母,为选育具有青岛啤酒风味的高浓酵母做准备.比较了7株酵母不同糖类发酵、离子抗性、二氧化碳减重、发酵液风味品评等指标.结果表明:T1、T2和T3是传统的青岛啤酒发酵菌株,其发酵液口味符合青岛啤酒口味要求,且对Cu2+均不耐受;而G4和G6发酵减重试验和风味物质分析中的乙醛含量指标的评价均优于G5和G7菌株,且它们的发酵液的风味也接近青啤口味.因此,选择T1、T2、T3和G4、G6作100L酿造试验,进一步确定融合亲株.     

高压蒸汽提取啤酒废酵母还原型谷胱甘肽的工艺优化

为了得到高压蒸汽提取废酵母中还原型谷胱甘肽的最佳工艺条件,利用Box-Behnken的中心组合设计及响应面法（RSM）探讨了表压、提取时间、液料比和提取次数四因素的优化组合。通过建立二次回归模型,确定其最佳提取工艺条件为:表压1.1MPa,提取时间15min,液料比10∶1,提取次数1次,在此条件下得率最大为4.63mg/g。结果表明高压蒸汽提取技术是提高啤酒废酵母还原型谷胱甘肽得率的有效途径之一。      

Multivariate analysis for the safety assessment of genetically modified rices in the anti‐nutrients and phenolic compounds

A safety assessment of genetically modified (GM) rice Agb0102 (resveratrol synthesis) and Agb0103 (drought‐tolerant) were conducted by comparing with their non‐GM comparators. Phytic acid, trypsin inhibitors and phenolic acids of the rices were analysed to identify the biological equivalences and the impacts of the environment. The analytical tools were principal component analysis (PCA), Pearson's correlation analysis and hierarchical clustering analysis (HCA). The PCA results of phytic acid and trypsin inhibitors revealed no clear separation among rices due to breeding conditions, environmental conditions or among various cultivars. The total, bound, free and ester forms of phenolic acids were not separated in the environmental conditions and different cultivars. The HCA analysis showed strong relationship between GM rice and non‐GM rice. The concentrations of anti‐nutrient and phenolic compounds of the GM rices were not different from those of non‐GM comparators and that various chemometric tools were useful to describe the separation of GM and non‐GM groups.     

Investigation of mashing regimes for low‐alcohol beer production

Low‐alcohol beer can be obtained by physical and biological methods. The group of biological methods includes modification of the mashing regimes and changes in the fermentation process. The aim of the present work was to study two mashing regimes for low‐alcohol beer production. The increase in the mashing duration at 50 °C led to a linear increase in the extract and the concentration of reducing and fermentable sugars in the wort. It was found that the rate of formation of reducing sugars was higher than that of the formation of fermentable sugars, which can be used for the optimization of the mashing process. The introduction of a pause at 77 °C did not lead to a substantial increase in the concentration of fermentable extract, but did lead to an increase in the total and non‐fermentable extract. The available nitrogen content in the laboratory wort was in the range of 120–150 mg/dm³. As a result of conducting fermentation processes with the top‐fermenting yeast strain Saccharomyces cerevisiae S‐33, it was found that the combination of a small amount of fermentable sugars and a low fermentation temperature led to a beer being obtained that met the requirements for a low‐alcohol beverage. Copyright © 2016 The Institute of Brewing & Distilling     

不同奶啤风味成分分析

采用气相色谱-质谱联用（GC-MS）技术和高效液相色谱（HPLC）法测定4种奶啤主要风味成分及有机酸,并结合各物质的香气活性值（OAV）进行主成分分析（PCA）和香气轮分析。结果表明,奶啤中共鉴定出58种风味成分,其中醇类11种、酯类23种、酸类6种、醛和酮7种、其他类物质共11种。其中天润奶啤中醇类物质相对含量较高,达到34.92%,酯类和酸类含量最低,分别为11.32%和28.41%,金河、西域春、海伦司奶啤中三种酯类和酸类含量最高,酯类含量分别为25.39%、23.61%、30.62%,酸类含量分别为43.62%、43.91%、40.59%。主要挥发性物质为乙醇、苯乙醇、乙酸苯乙酯、正癸酸。奶啤中含草酸、柠檬酸、苹果酸、富马酸和乳酸5种有机酸,柠檬酸含量最高,且柠檬酸和乳酸为主要呈香物质。     

High‐pressure homogenization: a non‐thermal process applied for inactivation of spoilage microorganisms in beer

The inactivation of spoilage microorganisms in beer using high‐pressure homogenization (HPH) was studied with the aim of evaluating the possibility of changing the conventional pasteurization process using this particular process. The homogenization pressure required for the inactivation of lactic acid bacteria, acetic bacteria and yeasts was investigated. For the most resistant microorganisms, the pressure inactivation kinetics and the effects of multiple process passes, initial temperature of the beer and the CO₂ concentration were studied. The results indicated that Lactobacillus delbrueckii was the most resistant microorganism tested, requiring 250 MPa to reach a six decimal reduction. Additionally, results showed that L. delbrueckii inactivation followed a second‐order kinetic process. A multi‐pass process and the use of a high initial beer temperature increased inactivation by HPH with L. delbrueckii, allowing the use of 150 MPa to achieve a five log cycle of inactivation. In contrast, a high CO₂ concentration reduced the efficacy of the HPH process. The results that were obtained are useful for high‐pressure homogenization applications in breweries and help to elucidate the effect of this new technology in a beverage that is both alcoholic and carbonated. Copyright © 2013 The Institute of Brewing & Distilling     

啤酒中有机酸含量的RP-HPLC检测条件优化及其酿造过程中动态分析

该研究对反相高效液相色谱（RP-HPLC）法测定啤酒中有机酸含量的方法进行优化,最终确定了RP-HPLC法测定啤酒中草酸、乳酸、酒石酸、乙酸、苹果酸、α-酮戊二酸、抗坏血酸、柠檬酸、琥珀酸9种有机酸的检测条件,并结合发酵机理对啤酒酿造过程中的有机酸含量动态变化进行分析。结果表明,RP-HPLC优化条件为：检测波长215 nm、流动相缓冲液0.10 mol/L KH2PO4、pH值3.0、流速0.6 mL/min。有机酸在质量浓度0.2～400.0 mg/L范围内线性关系良好（R2均＞0.99）,加标回收率79.3%～110.0%,精密度试验结果相对标准偏差（RSD）为0.3%～11.5%,表明该方法精密度高、准确性良好。在啤酒酿造过程中有机酸总量及乙酸、琥珀酸、苹果酸、乳酸、柠檬酸、α-酮戊二酸含量呈现先增长后平稳的趋势,草酸、抗坏血酸、酒石酸含量变化相对平稳。     

Sensory and compositional attributes of melting‐ and non‐melting‐flesh peaches for the fresh market

A study was conducted to determine differences in sensory and compositional characteristics of melting‐flesh (MF) and non‐melting flesh (NMF) fresh market peach genotypes. Sensory results showed that the NMF fruit (‘Oro A’ and FL 86‐28C) were ‘harder’, less ‘juicy’ and more ‘rubbery’ than their MF (FL 90‐20 and ‘TropicBeauty’) counterparts. A principal component analysis of the sensory data showed a clear distinction between the textural aspects of MF and NMF fruit, but not between their flavour aspects. Likewise, chemical analysis showed that while differences in pH, titratable acidity, and soluble solids were detected among the four genotypes, no consistent grouping could be made based on the MF/NMF nature of the fruit. © 1999 Society of Chemical Industry     

Screening of new strains of Saccharomycodes ludwigii and Zygosaccharomyces rouxii to produce low‐alcohol beer

Low‐alcohol beer (0.5–1.2% v/v ethanol) is a less common brewing industry output than standard beer but there is an increasing interest in this product, as evidenced by increased attention to health and safety and government policies on alcohol and diet. The main challenge in the production of low‐alcohol beer is the achievement of a product as similar as possible to regular beer, particularly concerning the content of the volatile compounds. These compounds can be lost during the physical removal of alcohol by dialysis, reverse osmosis and vacuum rectification. Consequently, an alternative technique is the use of biological methods, which involve the employment of non‐conventional yeasts. In this paper, 11 non‐conventional yeast strains were tested for low‐alcohol beer production. The strains used belonged to two different species: Saccharomycodes ludwigii and Zygosaccharomyces rouxii. The beer samples produced by these strains were analysed for their ethanol content and main volatile compounds. The S. ludwigii strains were more suitable for brewing low‐alcohol beer, especially strain DBVPG 3010, which also showed a higher content of esters and a lower amount of diacetyl compared with previous reports. The Z. rouxii strains produced an ethanol and diacetyl content above the taste threshold. This screening project can be considered as a first step towards the production of low‐alcohol beer by means of new selected non‐conventional yeasts. Copyright © 2015 The Institute of Brewing & Distilling     

基于顶空-气相色谱-离子迁移谱法分析不同类型精酿啤酒的挥发性香气成分

目的 基于顶空-气相色谱-离子迁移谱法(headspace-gas chromatography-ion mobility spectrometry,HS-GC-IMS)建立一种快速、准确的精酿啤酒挥发性香气检测方法。方法 采用HS-GC-IMS对不同来源及类型的精酿啤酒中挥发性组分进行分析,通过指纹图谱比较挥发性组分差异,结合主成分分析(principal component analysis, PCA)实现不同类型精酿啤酒区分。结果 所检样品中共定性出54种挥发性香气成分;指纹图谱显示,不同来源及类型的精酿啤酒中挥发性香气成分含量差异显著,其中自制的4种啤酒中风味物质具有各自的特征风味物质成分,如自制白啤中的香茅醛、2-庚酮、癸酸乙酯,自制黄啤中的己醛,自制印度淡色艾尔啤酒中的异丁酸异丁酯、异丁酸-2-甲基丁酯、壬醛、α-水芹烯,自制玫瑰啤酒中的乙酸己酯、壬酸乙酯、2-甲基丁酸乙酯、3-甲基丁酸乙酯等;采用PCA可以实现对不同来源、不同类型啤酒的准确区分。结论 HS-GC-IMS可快速检测啤酒中的挥发性香气成分,其结果直观、准确,为啤酒类型分析及质量控制提供方法和技术支持。