流动注射分光光度法测定啤酒及海产品中的甲醛

研究建立流动注射分光光度法可简单、快速检测啤酒及海产品中甲醛的含量。在以醋酸铵为缓冲溶液的介质(pH7)中,甲醛、醋酸铵以及乙酰乙酸甲酯混合后在60℃条件下反应3min生成有色物质,在375nm波长处有最大吸收。探讨最佳的实验条件,在最佳条件下,方法的检出限为3.2×10-6mol/L,且甲醛标准溶液的浓度在0.8×10-5～8.0×10-5mol/L之间符合朗伯比尔定律。应用所建立的方法分别测定4种海产品和3种啤酒中甲醛的含量,加标回收率分别在84.5%～107.4%和94.6%～114.6%之间。     

热脱附-气相色谱/质谱联用分析初榨橄榄油挥发性风味成分

以橄榄油为原料,分别采用液液萃取法、顶空法、固相微萃取法、热脱附法提取橄榄油风味成分,使用气相色谱-质谱法(GC-MS)结合Massworks~(TM)质谱解析软件鉴定分析,并针对最佳提取方法进行工艺优化。结果表明,热脱附法因操作简单、重复性好、无需溶剂及样品检测非破坏性等优点,适宜橄榄油风味成分的检出。最佳萃取条件为:吸附温度40℃;吸附时间2 h;一级解吸温度180℃;一级解吸时间5 min;二级解吸温度280℃;二级解吸时间8 min;冷阱温度-30℃。橄榄油风味成分共鉴定出26种,有醇类、醛类、酯类、酮类、烃类,不同国家的初榨橄榄油挥发性组分存在差异;同一国家的初榨橄榄油挥发性组分存在差异;同一国家不同等级橄榄油挥发性组分存在差异。     

流动注射分析法测定啤酒中甲醛含量的研究

针对啤酒中甲醛检测方法操作烦琐,不适合在线检测的情况,建立了在线流动注射分光光度法直接测定啤酒中甲醛的方法。此方法快速,简便,精密度高,在0．2～10mg·L^-1范围内甲醛浓度与峰高成良好线性关系,相关系数r=0．9991,检出限为0．068mg／L,相对标准偏差（RSD）为0．67％,结果令人满意。     

用热脱附方法分析哈密瓜香气成分

为探究哈密瓜主要香气成分,该文采用热脱附方法对哈密瓜果肉、哈密瓜果汁的香气进行富集,经气相色谱质谱法(GC-MSD)联机进行检索分析.结果显示,哈密瓜果肉、哈密瓜果汁香气成分和含量存在一定的差异,并从中检测出56种香气成分,其中哈密瓜肉香气成分有31种,哈密瓜汁的香气成分有46种,共同香气物质为乙酸甲酯、乙酸乙酯、丙酸...     

Perception of Beer Flavour Associates with Thermal Taster Status

Beer flavour, and thus much of the consumer experience of beer, is determined by the sensations elicited when it is taken into the mouth. Thus, individual differences in the perception of these oral sensations may contribute to the variation in consumer behaviour. A new taste phenotype shown to associate with the intensity of oral sensations elicited by simple solutions is thermal taster status (TTS). Thermal tasters (TTs) perceive ‘phantom’ tastes with thermal stimulation of the tongue, while thermal non‐tasters (TnTs) do not. Here, we investigate the effect of TTS on the perceived intensity of bitterness, sourness, sweetness, fullness, carbonation and overall flavour intensity elicited by seven beers representing classic styles — wheat beer, brown ale, pale ale, low‐alcohol lager, standard lager, high‐alcohol lager and stout. A strong trend was observed for TTs (n = 20) to rate attributes higher than TnTs (n = 20) for all beers except the stout, with these differences significant in many instances (ANOVA or binomial analysis). It is concluded that TTS may be an important determinant of individual differences in the perception of beer flavour, but beer liking and preference are more complex phenomena than can be accounted for by this phenotype alone.     

Thermal Resistance of Saccharomyces cerevisiae in Pilsen Beer

The thermal resistance of S. cerevisiae (CMOJ896) was determined in Pilsen beer (pH = 4.28 ± 0.05; extract of original wort (EOW %) = 11.30 ± 0.08; percentage of alcohol by volume (% at 20°C) = 4.97 ± 0.05; total nitrogen content (mg/L) = 590 ± 37; bitterness units (BU) = 20.5 ± 1.3; carbonation of the beer (Vol. CO₂) = 2.89 ± 0.09; color (SRCM) = 3.3 ± 0.4). The flask method was used for an initial population of 1 × 10⁴ cells/mL. Decimal reduction times of D_47°C = 3.16 min, D_48°C = 2.65 min, D_49°C = 1.74 min and D_50°C = 0.68 min were obtained at the temperatures studied. Values of D_60°C = 0.01 min and z = 4.6° were obtained for this microorganism.     

采用固相微萃取-气相色谱-质谱法分析啤酒中醛类化合物

建立了顶空固相微萃取-气相色谱-质谱(HS-SPME-GC-MS)结合邻-五氟苄基羟胺(PFBHA)衍生以测定啤酒中与老化味相关的13种醛类化合物的方法。样品前处理不同于文献报道的方法,衍生试剂直接加入到啤酒样品中,然后插入SPME装置,一步完成衍生和萃取过程。经优化的固相微萃取条件为:65μmPDMS/DVB萃取头,萃取温度50℃,萃取时间60min。GC-MS分析采用选择离子模式(SIM)并以内标法定量,所建方法的定量重复性较好,样品重复测定的RSD在2.5%-19.5%;回收率在55.3%-108.8%。在测定新鲜和老化啤酒时,显示出该方法具有较好的适用性。     

大豆酶解产物复合含氮糖浆用于啤酒发酵的研究

本文主要对大豆蛋白水解产物用于部分替代麦汁进行啤酒发酵的可行性进行了实验研究,并对发酵液的理化指标进行了检测分析.实验证明酵母在添加了大豆蛋白酶解液中的发酵液里可以正常发酵,所得啤酒各项指标均符合国家标准.     

超高效液相色谱-串联质谱法测定啤酒中的真菌毒素

建立啤酒样品中脱氧雪腐镰刀菌烯醇、3-乙酰基脱氧雪腐镰刀菌烯醇、15-乙酰基脱氧雪腐镰刀菌烯醇、玉米赤霉烯酮、去环氧脱氧雪腐镰刀菌烯醇、脱氧雪腐镰刀菌烯醇-3-葡萄糖苷、雪腐镰刀菌烯醇等7种真菌毒素的超高效液相色谱-串联质谱测定方法。啤酒样品经过Mycosep226多功能净化柱净化后,取净化液吹干浓缩后,经Acquity UPLC BEH C18色谱柱（100 mm×2.1 mm,1.7μm）分离,在负离子模式下,用电喷雾电离串联质谱以多反应监测模式（MRM）进行检测分析,同位素内标法进行定量。结果表明,7种真菌毒素在2～1000μg/L浓度范围内线性关系良好（r＞0.999）,最低检出浓度为0.03μg/L,在20μg/L、200μg/L、500μg/L 3个加标水平下进行了验证试验,平均回收率为82.7%～115%,相对标准偏差为1.94%～9.87%。该方法简便、快速、准确,满足实验要求,可用于啤酒样品中真菌毒素的多残留的检测分析。     

A Preference Study for No Alcohol Beer in Italy Using Quantitative Concept Analysis

The aim of this paper is to understand the consumer's attitude towards alcohol free beers in Italy by using a quantitative concept analysis. The method uses conjoint analysis with consumers of Italian beer, living in different geographical areas. Results show that packaging (RI = 56.24%) is the main attribute considered, followed by price, flavour, claims and colour. As far as part‐worths are concerned, glass and twist‐off caps are the utilities that most increase the preference. They are followed by malty and fruity characters, a price of less than 0.80 Euros, a remarkable body and intended for young adults. In contrast, plastics, a price of over 1.25 Euros, organic raw materials and imports showed the greatest negative impact on preference. These findings can be used as a base for new product development and for media communication purposes.     

Brewing Beer with Enzymes and Starch Analysis

The method of HPLC carbohydrate analysis allows a stepwise and controlled alteration of the mashing technology. Our aim was to find a method for altering a given mashing technology by increasing the amount of digested corn grits by 40% using reduced mashing time and an up-to-date technology with simultaneous application of brewing-enzymes. In the course of these experiments, by means of the HPLC method, the critical stages of carbohydrate decomposition could be revealed; after systematic application of industrial enzyme products under HPLC control the process has been short-cut and, on the basis of analytical data, the entire mashing technology has been simplified and rationalized. As result of industrial-scale experiments mashing time, including the cooking process of the surrogates, was cut down to 5.5 h. The wort produced by means of the elaborated well-controllable combined infusion-decotion mashing process has an attenuation of 85-87% and shows the same carbohydrate composition, organoleptic properties and characteristics observed for the original wort. The results are also supported by tests of significance.     

啤酒及其泡沫中蛋白质组分的比较分析

将数种国内知名啤酒的泡沫和酒液分离,分别测定它们的总蛋白质和高分子蛋白质(HMWP)质量浓度.结果显示,泡沫具有富集蛋白质的功能,且泡沫中HMWP含量的增加尤为明显;与啤酒原液中的HMWP相比,泡沫中的HMWP含量与泡持值具有更高的相关性;不同的啤酒样品的HMWP在泡沫中的富集能力存在明显的差异,由此从啤酒蛋白的层面提出一项啤酒的质量判定标准.     

基于ANSYS的平板塑件注塑模具热应力分析

以平板塑件的注塑模具为研究对象,运用ANSYS对其进行瞬态热分析,模拟注塑过程中各时刻模具的温度分布情况,并在模具温度最大时刻进行稳态静力分析,找出应力集中区域,为模具的疲劳设计提供一定的依据。     

基于气相色谱-质谱联用与偏最小二乘-判别分析的啤酒爽口性评价

目的：建立一种偏最小二乘-判别分析（partial least squares-discrimination analysis,PLS-DA）评价啤酒爽口性的方法。方法：基于顶空固相微萃取（headspace solid-phase microextraction,HS-SPME）结合气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用检测啤酒中爽口性相关指标转化为数据矩阵,利用SIMCA-P软件进行PLS-DA。结果：不同爽口性的啤酒在得分图中能够明显区分。根据载荷图显示爽口性较差的样品集DA（1）中敏感特征变量为辛酸乙酯、癸酸乙酯及乙酸异戊酯等酯类化合物。选取50 个样本为校准集,建立PLS-DA模型,4 个爽口性不同的啤酒样本模型的回归相关系数分别为0.861、0.798、0.765、0.812,样品辨别率为92%。利用建立的PLS-DA模型对27 个未知样品进行预测,不同爽口性样品的预测均方根误差分别为0.183、0.321、0.523、0.323,准确识别率为74.07%。结论：HS-SPME-GC-MS结合PLS-DA法是一种简单、快速、有效评价啤酒爽口性的方法。     

低产高级醇啤酒酵母在啤酒中试中的应用发酵分析

对选育到的低产高级醇啤酒酵母MS-11进行应用发酵研究分析。结果表明,对比出发菌株SC-2和工业生产菌株DAB,MS-11菌株在保持原啤酒风味的基础上,不仅提高发酵速度,缩短发酵时间5d,降低能耗近10％,增加设备周转率20％左右,降低生产成本;而且生产的成品啤酒防老化效果好。     

Analysis of Isinglass Residues in Beer

A method has been developed for the detection of trace quantities of residual isinglass present in fined beers. Isinglass residues in beer are concentrated by means of an antibody raised using isinglass as an antigen. The separated isinglass is hydrolysed to its constituent acids and quantified by measuring the content of hydroxyproline. The limit of quantification of this method, that is the concentration of isinglass in beer which can be distinguished from background levels of hydroxyproline, is 0.17 mg of isinglass/litre of beer (on an isinglass dry weight basis). This method has been used to quantify the concentration of isinglass residues which could be present in brewery and cask conditioned beers, and also to determine whether there is likely to be stratification of isinglass residues in casks.     

利用基体辅助激光解吸/电离飞行时间质谱分析水温对奶粉蛋白质的影响

利用基体辅助激光解吸/电离飞行时间质谱法(matrix-assisted laser desorption/ionization mass spectrometry,MALDI-TOF-MS)分析不同水温冲调下奶粉中部分蛋白质相对含量的变化,从而获得其蛋白质成分的变化规律。实验选取11个目标离子峰,对样品进行15次平行测定,每个目标离子峰每次测得的m/z值相差均不超过3,相对误差不超过0.19%,相对标准偏差不超过0.19%。最终数据为15个平行实验结果的切尾平均值。结果表明,随着水温的升高,奶粉中蛋白质逐渐发生热变性;当水温高于70℃时,奶粉蛋白变性程度开始显著增加。推荐以40℃左右水冲调奶粉为宜。     

啤酒中硅的ICP—AES测定

硅钼蓝化学法测定Ｓｉ繁杂费时，湿法消解时，硅又易形成沉淀。我们用ＩＣＰ－ＡＥＳ地啤酒中的Ｓｉ进行直接稀释测定，回收率１０２－１０８％。     

Analysis of Protein and Total Usable Nitrogen in Beer and Wine Using a Microwell Ninhydrin Assay

In this study we present a ninhydrin based microwell assay that can be utilized in place of the traditional Kjeldahl method for the determination of the protein content of beer or wine. In addition, the assay is ideal for the determination of free amino acids in beer (FAN), a term understood and used by brewers, and yeast assimilable nitrogen (YAN) used by enologists. The assay only measures alpha amino acids and ammonia so other nitrogen sources are not detected, resulting in a 30% reduction in total protein of a variety of beers compared to the Kjeldahl method, which measures nitrogen from all sources. The results also showed that only 25% of the total “protein” in beer is actually derived from peptides larger than 3,500 Kd. Analysis of beer or wine with the microwell assay for total usable nitrogen was compared to the standard FAN and YAN methods and conditions were determined for maximal efficiency and precision. Superior results were obtained with low reaction volumes and a stable sodium acetate buffered ninhydrin reagent at pH 5.5. As an alternative, for use with cuvettes, a reduced volume FAN assay using the same pH 5.5 sodium acetate buffered ninhydrin reagent gave comparable results. The assay is economical, rapid, accurate and applicable to large numbers of samples.