标准曲线法测混浊活性蛋白初探

多酚蛋白复合引起的混浊现象是啤酒,果汁需要着重解决的问题之一。本文探讨了标准曲线法测定啤酒,果汁中混浊活性蛋白的可行性。结果表明,PVP的浓度在0.000～0.100g/L范围时,反应产物的浑浊度与PVP浓度成良好的线性关系。     

麦芽蛋白与多酚相关指标对麦汁敏感蛋白和敏感多酚含量的影响

测定30个不同麦芽样品的总氮、可溶性氮、库值、总酚含量以及对应麦汁敏感蛋白及敏感多酚含量,并对结果进行相关性分析发现,麦汁敏感蛋白含量与麦芽可溶性氮呈显著正相关(r=0.686,p0.01),麦汁敏感多酚含量与麦芽总酚呈显著正相关(r=0.646,p0.01),表明麦芽可溶性氮与总酚指标可初步用于评价麦汁中敏感蛋白与敏感多酚含量;其次,选择麦芽可溶性氮与总酚含量差异较大的加麦Metcalfe与澳麦Gairdner、国麦垦七麦芽,按照不同比例进行搭配并制备麦汁,分析发现搭配前后麦汁敏感蛋白及敏感多酚含量呈线性关系,表明可以有选择的使用不同品种麦芽,按特定比例搭配来控制麦汁中敏感蛋白、敏感多酚含量。本研究为从原料角度预测和控制麦汁和啤酒的胶体稳定性提供了支持。     

介绍一种快速测定敏感多酚的新方法

国外开发出单分析仪，用PVPP滴加法测定啤酒浑浊敏感多酚，该法快速、准确。单宁仪可动态反映出啤酒酿造过程中敏感蛋白和敏感多酚的变化趋势。（丹妮）     

饮料中的蛋白-多酚混浊

了解混浊活性（ＨＡ）蛋白和多酚的性质与相互作用,有助于生产出更好的饮料产品,使用更好的分析方法及稳定手段。     

多酚物质对啤酒稳定性的影响

多酚物质对啤酒稳定性的影响主要表现在它的氧化还原性及与蛋白质结合能力上,啤酒的混浊主要为多酚及氧化产物与蛋白质的聚合物;所以多酚是影响啤酒的非生物稳定性的主要物质之一。另一方面多酚物质又是构成啤酒风味的主要物质,它具有氧化还原性直接影响啤酒的风味稳定性。提出了合理控制多酚物质的手段。     

浅谈啤酒中的敏感蛋白和敏感多酚

作者对麦汁、后贮酒、清酒、成品的敏感蛋白和敏感多酚进行了跟踪检测,主要目的是为摸清啤酒中敏感蛋白和敏感多酚的实际情况和变化规律,为以后的工艺改进提供数据基础。     

饮料中的蛋白质—多酚混浊物

引起啤酒、白酒和澄清果汁出现混浊或沉淀的原因很多,最常见的是由蛋白质———多酚的相互作用引起的,但这些饮料一般能稳定存在,并能延缓蛋白质———多酚混浊物形成开始的时间。10多年前已有关于促使蛋白质或多酚成为混浊激活物(ＨＡ)方面的报道(Ａｓａｎｏｅｔａｌ,1982;Ｍｏｌｌ,1987),但近来的研究发现,饮料中两者的比例对混浊的形成数量起着重要的作用(Ｓｉｅｂｅｒｔｅｔａｌ,1996ｃ),这发现使我们能更好地理解一些检测ＨＡ种类的分析方法及其稳定的机制。在鉴别ＨＡ物质的特性方面,我们已经做子大量的工作(Ｍｏｌｌ,1987)。啤酒中的…     

啤酒中的多酚物质及其作用

啤酒中的多酚物质是一类重要化合物，其在啤酒的非生物稳定性、风味、保鲜、色泽、溶氧等方面起重要作用，近年来成为人们研究的热点。随着啤酒生产和市场竞争日趋激烈，生产企业要在竞争中立于不败之地，首要是提高啤酒质量，增强啤酒的稳定性，很多研究结果证实了多酚物质在啤酒中的作用。综述了啤酒中主要多酚物质的作用，检测方法的研究情况等。     

介绍一种快速测定啤酒浑浊敏感蛋白的方法

介绍了一种新兴的啤酒浑浊敏感蛋白的方法，该法快速、准确，弥补了国内无浑浊敏感蛋白测定的技术空白。     

Analysis of cooling curve to determine the end point of freezing

The cooling curve method used for the measurement of freezing point of food is further analyzed to explore whether it can be used to identify the end point of freezing or glass transition. In this method, slope of the cooling curve is determined and plotted as a function of time to identify the end point of freezing (T′_m). Initially, the slope is decreased and then reached a minimum value, which is identified as the nucleation of ice. Then the slope is increased until the end point of freezing. The end point of freezing is identified when the slope starts to decrease from its highest value or plateau. Sucrose solutions and starch gels were used to measure its T′_m in identifying validity of the proposed method. The measured values of T′_m by the proposed method is very close to the literature values.     

茶多酚苹果酒的发酵新工艺中试研究

以浓缩苹果汁为原料,采用固定化酵母发酵技术,加入茶多酚作为抗氧化剂,进行苹果酒中试发酵试验,通过测定发酵过程中的酒精度、酸度、透光率、残糖等理化指标的变化情况,考察中试后发酵速度和发酵效果的变化。结果表明:当发酵体积扩大50倍后,苹果酒发酵效果与小试样小体积状态下的发酵效果无显著差异,总的变化趋势趋于一致。     

A highly sensitive method to determine the washing resistance of artificial hair colours

Citation: IFSCC Magazine, 11 (2008) (2) 139–142 Abstract: Due to the improved performance of modern hair colorants, the high natural variability in hair qualities and the individual influences of manual product applications, colour care effects of cosmetic treatments are very difficult to detect. A new, highly sensitive test method to study the colour fading behaviour of human hair was established for a large variety of cosmetic treatments. This method is based on an automatic multistage application of standard wool tissues combined with automatic colour evaluation by means of CIE L × a × b × measurements (DIN 5033). The delta E values are the main interest because they include all information regarding the L (black vs. white), a (red‐green) and b (blue‐yellow) axes defined in the Hunter Lab colour space. For validation of this new method, different permanent and non‐permanent hair colour shades were applied to undamaged light brown Caucasian hair strands. The hair strands were washed manually stepwise 30 times and the colour loss compared with the results obtained on wool tissues using an automatic application system. For most of the investigated hair colours, a coefficient of determination of r2 > 0.99 was achieved. Modern permanent hair colours show a high resistance to cosmetic treatments. Over 90% of the initial colour result was retained after 30 product applications. Shampoo and conditioner formulations induce different degrees of colour loss in hair. In basic formulas significant influences of single surfactants could be detected. The new method using wool tissues correlates very well with that using manually washed Caucasian hair strands. This automatic method is very time‐effective and offers an excellent reproducibility with a high sensitivity for assessing product influences on artificial hair colours. Keywords: Color fading, color protection, color retention, hair color resistance, hair wash simulation Paper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands     

标准女体胸围曲线研究

采用法国力克公司生产的非接触式智能三维人体测量仪,测量18例22～25岁体型接近160/84A的健康女性人体,并截取过乳头部位的胸围曲线,以5°定1个点,借助MatLab7.0编程计算,得到18例女体胸围曲线上的平均点坐标,即标准女体胸围点坐标.在此基础上,运用origin软件对标准女体胸围点坐标进行曲线方程拟合,在确...     

ROC curve analysis to determine effects of repetition on the criteria for same-different and A Not-A tests

Judges performed over 2000 same-different tests followed by over 2000 A Not-A tests, to distinguish between ‘threshold’ sodium chloride solutions and purified water. Fitting ROC curves to the data indicated that three out of four judges used a τ-strategy for the same-different test. The hypothesis that judges might, with experience, start to categorize the stimuli and switch to a β-strategy was generally not confirmed. On changing to the A Not-A method, half the judges appeared to continue initially to use the τ-strategy. The hypothesis that judges might make comparisons with the preceding stimulus rather than the standard stimulus, because of prior extensive experience with the same-different test, was generally not confirmed. Yet, in all cases there were exceptions.     

Development of a sensitive picrate method to determine total cyanide and acetone cyanohydrin contents of gari from cassava

The sensitivity of the normal picrate method for determination of total cyanide in cassava was increased tenfold using a small 1 cm² picrate paper, eluted using 0.5 mL instead of 5 mL of water as in the normal method. The absorbance was measured in a 2 mm cuvette in the spectrophotometer. The sensitive method was calibrated against the normal picrate method. The total cyanide content in mg HCN equivalents/kg sample = ppm, is calculated from the absorbance (A) by the equation ppm = A × 45.7 which is applicable from 0.1 to 50 ppm. A new method to determine acetone cyanohydrin was developed based on irreversible denaturation of linamarase in 0.1 M HCl at 30 °C for 1 h. Five gari samples from Mozambique gave a mean total cyanide content of 12 ppm (range 6–15 ppm) and mean acetone cyanohydrin content of 11 ppm (range 5–14 ppm). Acetone cyanohydrin liberates cyanide quantitatively in the human intestine.     

正交试验优化红芸豆多酚超声辅助提取工艺

研究红芸豆中多酚的超声辅助提取工艺。在单因素试验基础上,采用正交试验优化提取工艺。结果表明:红云豆多酚超声辅助提取最佳工艺条件为料液比1∶80 (g/m L)、超声功率280 W、提取温度60℃、乙醇浓度30%和提取时间25 min。该工艺条件下,红芸豆中多酚提取率为3.870 mg/g。     

Development of a novel pomegranate standard and new method for the quantitative measurement of pomegranate polyphenols

BACKGROUND: The Folin–Ciocalteu method is routinely used to calculate total polyphenol concentrations (TPP) in food products. However, the use of inappropriate standards such as gallic acid (GA) may give inaccurate estimates of TPP content. A method for the production of a pomegranate (Punica granatum L. ‘Wonderful’) standard was developed and validated to avoid this problem. The PPS was produced by solid phase (C18) isolation of polyphenols from POMx powder (a nutritional supplement) and used for TPP analysis. RESULTS: TPP content of POMx was > 90% using PPS, whereas the GA standard underestimated TPP by up to 30%. Compositional analysis confirmed a balance of about 9% non‐polyphenolic compounds. Mass spectrometry analysis corroborated polyphenol composition and confirmed pomegranate‐specific peaks, i.e., punicalagin and punicalin. CONCLUSION: Results support the use of pomegranate‐specific standards to accurately determine TPP. Copyright © 2008 Society of Chemical Industry     

水样亚硝酸盐标准曲线斜率质控图的应用分析

目的 利用质控图对水样亚硝酸盐标准曲线的斜率准确性进行判断。方法 运用X-S控制图, 即平均值-标准偏差控制图对曲线的斜率加以监控, 运用Westgard多质控规则对各个点或相邻点进行独立或联合的数据分析, 确定曲线斜率的有效性。结果 通过回收率和相对偏差的对比, 质控图直接观察法能够弥补加标回收法的不足。曲线斜率为0.2249时, 位于警告限与失控限之间, 说明此数据无效, 重新制作曲线。结论 运用质控规则对曲线斜率数据的准确性进行监控, 能起到有效的指导作用。     

Study on standard curve of lower leg cross section at top of men's socks

袜口处标准腿截面曲线形态是研究袜口压力舒适性的前提和基础,也是袜口优化设计的关键.通过三维人体扫描仪对人体内侧脚踝点水平向上6 cm处腿部形态进行扫描,应用MatLab软件,将腿截面曲线按照直角坐标系每5°为1个点等分为72个点,并在此基础上定义点坐标值,将得到的所有腿截面曲线X和Y分别取平均值,得到袜口处标准腿截面曲线72个点坐标.运用SPSS曲线拟合得到袜口处腿截面曲线的二次方程,曲线方程的建立为袜口处压力数学模型的构建提供了基础数据.对袜口处标准腿截面曲线周长进行了求解,结论为男短袜原始袜口围度的改良设计以及袜口面料弹性伸长率的选取提供了理论参考.