一种检测麦芽中泡沫蛋白的方法

建立了从麦芽中提取泡沫蛋白的便捷方法.并利用考马斯亮蓝定量蛋白法(Bradford法)和SDS-PAGE电泳技术,能够准确直观地检测到麦芽中泡沫蛋白的含量、组分和各组分的相对含量及其变化情况,为评估大麦和麦芽质量以及预测啤酒泡沫的品质提供了方法.     

四种大麦间泡沫蛋白质含量差异的比较

本实验建立了从麦芽中提取泡沫蛋白的便捷方法,并利用考马斯亮蓝法(Bradford 法)和SDS-PAGE 电泳技术进行定量分析,直观地检测和比较了四种大麦和麦芽中泡沫蛋白质的含量、组分和各组分的相对含量及其变化情况,可为评估大麦和麦芽质量以及预测啤酒泡沫的品质提供借鉴。     

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。     

基于竞争性等位基因特异性PCR技术对啤酒花进行纯度检测

基于已知数据库中啤酒花的基因组信息和测序信息设计引物,筛选出了可以区分7个啤酒花品种的8个多态性良好的单核苷酸多态性(single nucleotide polymorphisms,SNP)位点。并基于竞争性等位基因特异性PCR(Kompetitive allele specific PCR,KASP)技术,利用筛选到的特异SNP标记对8份预混样品与2份企业送检样品进行了检测。结果表明,该技术能对混杂程度低至5%的啤酒花样品进行有效鉴定,可以满足企业对实际啤酒花样品进行检测评价的要求。研究结果完善了啤酒花的SNP数据库,为啤酒企业对于原料质量的把控提供有效的技术手段。     

一种检测麦芽蛋白质溶解度的新方法

麦芽库值是反映大麦蛋白质溶解的重要指标,只有溶解适度的麦芽才能酿制出高品质的啤酒,因此麦芽蛋白质溶解度的检测尤为重要.EDTA是一种良好的金属离子螯合剂,本文分别用不同浓度的EDTA水溶液培养大麦,利用EDTA、金属离子和蛋白酶活性之间的关系,分析EDTA对蛋白酶活力和麦芽中各组分蛋白含量的影响、各蛋白组分之间的转化及其与麦芽库值的相关性,并以此为据建立检测麦芽蛋白质溶解度的新方法.     

以未发芽大麦替代麦芽酿造啤酒及其麦香改善研究

本文研究了利用酶制剂Ondea Pro进行大麦啤酒的生产,对其麦汁糖谱、氨基酸谱、蛋白质区分、α-氨基氮和大麦啤酒理化成分及风味物质等指标进行了检测,特别是对麦香物质呋喃酮、2-乙酰吡咯、2-乙酰-1-吡咯啉、麦芽酚、2-甲基吡嗪、乙基吡嗪、乙酰呋喃和甲基糠醛等化合物进行了分析,并邀请专业品酒委员进行了感官品评。研究结果发现,利用Ondea Pro酶生产的麦汁,能够满足酵母发酵需求,然而大麦啤酒存在明显的麦香缺陷。通过额外添加不同比例的焦香麦芽,分析大麦啤酒中主要麦香物质的变化规律,结合感官品评,结果表明添加1%的焦香麦芽酿造而成的大麦啤酒,其主要麦香物质和品评口感与麦芽啤酒接近。添加少量焦香麦芽生产的大麦啤酒市场潜力具大,极具推广价值。     

HPLC法测定啤酒原料中的脱氧雪腐镰刀菌烯醇毒素

建立了一种利用多功能净化柱-高效液相色谱检测啤酒大麦和麦芽中脱氧雪腐镰刀菌烯醇毒素（DON）含量的方法。把该方法和GC／ECD方法进行了对比,线形回归分析表明两种方法的检测结果接近。分析了10种国产、进口的大麦和麦芽,大麦和麦芽中DON最高污染水平分别为1．23μg／g、0．24μg／g。该方法可应用于啤酒酿造原料中DON污染情况的检测分析。     

利用HPLC测定麦芽及大麦中的麦角固醇含量

大麦和麦芽中的麦角固醇是霉菌的感染指标。本研究测定了捷克不同种类大麦和麦芽中的麦角固醇水平。用改进的高效液相色谱(HPLC)分析了124个大麦和麦芽样品,并用统计方法进行处理。麦角固醇的分离是通过提取和皂化,利用带有二极管阵列检测的HPLC定量测定。大麦的麦角固醇含量在最小检测限(LOD)和36.6 mg/kg之间,麦芽在LOD和131.1mg/kg之间。推测麦角固醇可能和微生物侵染大麦时产生的代谢产物有关,因此大麦经常有很高的喷涌值。然而,我们发现麦角固醇含量和啤酒喷涌程度没有关联。     

原料大麦和麦芽中霉菌污染的检测

目前,国内大多数啤酒厂尚未开展对原料的微生物检测,随着啤酒生产的发展,对这方面的工作应加以重视并逐步建立相应检测制度。 1 原料大麦和麦芽中霉菌污染的危害 大麦上霉菌的数量不多时,对啤酒酿造没有影响。如果收获或贮存时水分较高,这些微生物会迅速繁殖,产生严重的后果。首先,霉菌会使贮存的大麦颗粒发热,如灰绿曲霉、亮白曲霉和黄曲霉,能使贮存大麦的温度升高到55℃,能在此温度下维持数星期。这样,为耐热的细菌生长繁殖提供了条件,严重时可     

麦芽品种多重荧光SSR标记指纹数据库的构建

为提高麦芽品种及纯度的鉴定效率,降低检测成本,利用SSR(simple sequence repeats,简单重复序列)荧光标记对24个麦芽品种进行核心引物筛选、多重PCR和指纹数据分析,构建适合麦芽品种鉴定的多重荧光检测体系。首先从前期筛选的多态性引物中选择12对引物进行组合设计,通过优化引物浓度、退火温度进行多重PCR体系构建,3个引物组合扩增成功。按照最少引物鉴定最多品种的指纹图谱构建原则,将引物HVM68、EBmag0007和Bmac755确定为品种区分的核心引物,每对引物平均产生8. 3个等位基因。利用3对核心引物构建麦芽品种指纹数据库,通过指纹编码可实现全部24个麦芽品种的快速区分。该研究建立了一种准确、快速、高通量的麦芽品种鉴定检测方法,为啤酒企业在麦芽采购和酿造配方研究上提供技术支持和质量保障。     

A genome-wide association study for left-sided displacement of the abomasum using a high-density single nucleotide polymorphism array

Left-sided displacement of the abomasum (LDA) is a frequent disease in dairy cattle causing significant financial losses for dairy farmers. Heritability (h²) of this complex disease was estimated at up to 0.5 in German Holstein (GH) cattle. Using the Bovine High Density BeadChip (Illumina Inc., San Diego, CA) comprising 588,753 single nucleotide polymorphisms (SNP) after quality control for 126 LDA cases and 280 population-based controls, we used a mixed linear model analysis in a genome-wide association study (GWAS). We identified 6 genomic regions for LDA on bovine chromosomes 2, 8, 13, 20, 24, and X that were significantly associated with LDA. Each of these regions was covered by 4 to 12 LDA-associated SNP. Single SNP within these regions explained up to 7.3% of the phenotypic variance. An independent sample of 1,554 GH cows, including 539 controls and 1,015 cases, were genotyped for 8 SNP highly associated with LDA on Bos taurus autosomes (BTA) 2, 8, 13, and 24, as well as 6 SNP located in previously identified LDA regions on BTA1, 5, 11, and 27 using competitive allele-specific PCR genotyping technology (KASP). The analysis using the KASP genotypes confirmed LDA-associated loci on BTA2, 8, 13, and 27. These genomic regions may contribute to the susceptibility to LDA in Holstein cows and may harbor functional variants for LDA.     

A Method to Detect Anti‐metabolic Factors in Fermentations

Premature yeast flocculation (PYF) has been described as the rapid settling of yeast cells during fermentation despite the presence of sufficient nutrients. PYF can cause negative impacts on beer quality and thus can be quite costly to brewers and maltsters. To investigate the causative agent of PYF, small‐scale fermentations were undertaken in both test tubes and cuvettes (15 and 3.5 mL respectively) using worts prepared from PYF‐positive and PYF‐negative malt samples. Fermentations were carried out using six malts, for up to seven days. Turbidity and extract values were monitored for all samples. The small scale (test tube) assay exhibited clear yeast cell flocculation differences between malts. In the cuvette assay the wort fermented, but the yeast cells settled out of suspension rapidly. While this property made the cuvette assay unsuitable for detecting PYF malt, it did allow for measurement of impaired sugar uptake by the yeast independent of yeast in suspension effects. All wort samples fermented in the cuvette assay showed a similar decline in apparent extract (p > 0.05), indicating that (at least in the samples studied) premature yeast flocculation was not caused by a decline in yeast activity. We believe the simple cuvette assay reported here could have application in the measurement of anti‐metabolic factors in fermenting media.     

A Survey of Barley,Malt and Beer Contamination with Ochratoxin A in Turkey

The presence of ochratoxin A (OTA) was investigated in barley, malt and beer samples using an ELISA method (RIDASCREEN). The lower detection limit of this OTA test was 0.08 μg/L for beer and 0.4 μg/kg for barley and malt. In 26 out of 29 barley samples the OTA content was between 0.53–12 μg/kg. OTA was between 0.5–6.6 μg/kg in 23 out of 24 malt samples. Only one malt sample had no detectable OTA using RIDASCREEN. The OTA content was between 0.1–8.10 μg/L in 42 out of 150 beer samples (28%) and in 108 beer samples OTA was not found at detectable levels (72%). Only one beer sample contained more than 5 μg/L OTA.     

Effect of different analysis conditions on Rapid Visco Analyser malt viscograms in relation to malt of varying fermentability

Malt fermentability is a difficult and time consuming trait to measure. The Rapid Visco Analyser (RVA) was assessed as an alternative rapid method to indicate potential fermentability. This study evaluated changes in rheological profiles under different operational conditions and compared these changes with reference to malt fermentability from a limited number of samples. Viscosity measurements of samples were also made using different RVA (models 3D+ and 4) analysis conditions including a brewhouse time–temperature profile, heating/cooling rate, particle size and enzyme activity. Rheological measurements using the RVA‐3D + gave similar results compared with the RVA‐4, indicating adequate sensitivity of the RVA 3D+ for discriminatory purposes. Use of a time–temperature profile of a commercial brewery mashing process was unsuitable. When malt enzymes were inactivated with silver nitrate, differences in viscosities were observed. However, this eliminated the ability to discriminate on fermentability. Increasing or decreasing the heating rate influenced the time available for enzyme action, which affected the degree of discrimination. This also provided some insight into physical and biochemical processes affected by differences in particle size. RVA has the potential to be used as a tool to discriminate between poor and good fermentability barley malts. RVA conditions when using the ‘Kilned Malt’ method with an appropriate mashing malt–water ratio provided a fast and reliable indication of malt performance prior to conducting lengthy fermentability tests. Copyright © 2014 The Institute of Brewing & Distilling     

TP-M13-SSR技术在麦芽品种鉴定中的应用

利用TP-M13-SSR标记技术构建麦芽品种指纹图谱,从163?对简单序列重复（simple sequence repeat,SSR）引物中筛选到4?对多态性丰富的SSR引物,每对引物的等位基因为3～10?个不等,平均每个引物产生6.75?个等位基因。在大批量引物筛选的情况下,M13通用引物可大大降低SSR引物进行荧光标记的合成成本。利用4?对SSR引物进行麦芽品种DNA指纹图谱构建,得到23?个麦芽品种的指纹图谱及指纹数据库。该法检测成本低,方法准确可靠,可实现国内主要麦芽品种的鉴定,为啤酒企业在麦芽采购环节提供技术支持。     

Fundamental study on the influence of Fusarium infection on quality and ultrastructure of barley malt

Barley infection with Fusarium species has been a long standing problem for the malting and brewing industries. In this study, we evaluate the impact of Fusarium culmorum infected raw barley on the final malt quality. Barley grains were infected for 5 days at optimum fungal growth conditions. Grains were fully characterized and compared to standard barley grains. Due to fungal infection, germinative energy of infected barley grains decreased by 45%; its water sensitivity increased dramatically, and grains accumulated 199 μg/kg of deoxynivalenol (DON). Barley grains were subsequently malted for 8 days, fully characterized and compared to standard malt grains. Fungal growth behavior was evaluated during malting using a PCR-based assay and mycotoxins were measured using HPLC. Fungal biomass increased in grains, during all stages of malting. Infected malt accumulated 8-times its DON concentration during malting. Kernel ultrastructure was evaluated using scanning electron and confocal laser scanning microscopy. Infected malt grains were characterized by extreme structural proteolytic, (hemi)-cellulolytic and starch deterioration with increased friability and fragmentation. Infected grains had higher protease and β-glucanase activities, lower amylase activity, a greater proportion of free amino and soluble nitrogen, and a lower β-glucan content. Malt loss was over 27% higher in infected malt in comparison to the control. The results of this study revealed that 20% F. culmorum infected barley kernels lead to a significant reduction in malt quality as well as mycotoxin formation.     

Optimised quantification of the antiyeast activity of different barley malts towards a lager brewing yeast strain

The brewing of beer involves two major biological systems, namely malted barley (malt) and yeast. Both malt and yeast show natural variation and assessing the impact of differing malts on yeast performance is important in the optimisation of the brewing process. Currently, the brewing industry uses well-established tests to assess malt quality, but these frequently fail to predict malt-associated problem fermentations, such as incomplete fermentations, premature yeast flocculation (PYF) and gushing of the final beer product. Antimicrobial compounds, and in particular antiyeast compounds in malt, may be one of the unknown and unmeasured malt factors leading to problem fermentations. In this study, the adaptation of antimicrobial assays for the determination of antiyeast activity in malt is described. Our adapted assay was able to detect differing antiyeast activities in nine malt samples. For this sample set, malts associated with PYF during fermentation and gushing activity in beer showed high antiyeast activity. Both PYF and gushing are malt quality issues associated with fungal infection of barley in the field which may result in elevated antimicrobial activity in the barley grain. Also, two more malts that passed the normal quality control tests were also observed to have high antiyeast activity and such malts must be considered as suspect. Based on our results, this assay is a useful measure of malt quality as it quantifies the antiyeast activity in malt which may adversely impact on brewery fermentation.     

Near‐Infrared Spectroscopy for Proficient Quality Evaluation of the Malt and Maize Used for Beer Production

Moisture and total nitrogen content are considered very important factors that influence barley malt quality, as well as moisture and lipid content for maize quality. In the present study, the feasibility of using Near‐Infrared (NIR) spectroscopy to measure the moisture, total nitrogen and lipid content of the whole malt grains and maize grits was examined. The NIR spectra of the following samples were examined: 295 malt whole grains for moisture, 281 malt whole grains for total nitrogen, 128 maize grits for moisture and 102 maize grits for total lipids. Validation was carried out both by means of cross‐validation and test set validation. Coefficients of determination (R²) were higher than 93% for both malt and maize moisture and higher than 71 and 80 for malt total nitrogen and maize total lipids, respectively. The Root Mean Square Error (RMSE) values (both in Cross Validation (RMSECV) and in Prediction through external validation (RMSEP)) ranged from 0.127 to 0.165% for both malt and maize moisture, whereas they ranged from 0.043 to 0.053% for malt total nitrogen and from 0.065 to 0.079% for maize total lipids. Repeatability (r₉₅) ranged from 0.105 to 0.222% and from 0.012 to 0.155% for malt moisture and total nitrogen content, respectively, and from 0.086 to 0.192% and from 0.020 to 0.171% for maize moisture and total lipid content, respectively. The findings showed that NIR spectroscopy has potential for the rapid prediction of quality of whole malt grains and maize grits for brewing.     

EXTRACTION AND ASSAY OF PROTEOLYTIC ACTIVITIES IN SORGHUM MALT

A method has been developed to assay the proteinase and carboxypeptidase activities in sorghum malt. The method specifically addresses two problems encountered with some other assays for malt proteolytic activity; that of enzyme inextractability and the use of alien substrates. It was found that as with barley malt proteolytic enzymes, a high proportion of sorghum malt proteolytic activity was inextractable with sodium chloride solution. Systematic investigation into the extraction of proteolytic enzymes from sorghum malt led to the development of a novel extractant viz. 0.6 M Lithium iodide LiI plus 3.33 mM dithiothreitol. This extractant appears to solubilize a significantly higher proportion of the malt proteolytic activities with a single extraction than previously used buffers. Assay is carried out Using purified Kafirin, the sorghum prolamin storage protein, as substrate. Proteinase is measured in terms of total nitrogen solubilized and carboxypeptidase as free α-amino nitrogen solubilized.     

Barley and Malt Proteins and Proteinases: I. Highly Degradable Barley Protein Fraction (HDBPF), a Suitable Substrate for Malt Endoprotease Assay

Barley grain proteins were extracted and fractionated, based on their solubility, to investigate their proteolytic digestibility and suitability to be used as a substrate for the assay of malt proteinases. The fraction extracted with alkaline buffer (Tris‐HCl or Tris‐glycine pH 8.8–9.5), at the end of the sequence, exhibited remarkably high degradability by malt proteases compared to other fractions or any known protein substrate. Gel filtration chromatographic analysis of this fraction revealed that it is composed of three different molecular weight components. Further investigation, after proteolytic treatment, demonstrated that the third and the low molecular weight component is the highly degradable protein(s) (HDP). We designated the whole fraction, the mixture of the three components, as the highly degradable barley protein fraction (HDBPF) and used it (and recommend it) as the substrate for the assay of malt endoproteases activity.