毛细管电泳仪在掺假牛乳检测中的应用

应用高效毛细管电泳方法对牛乳蛋白、大豆分离蛋白、明胶和乳清蛋白进行检测.选择未涂层的熔融石英毛细管,采用浓度为0.1mol/L的磷酸盐缓冲体系,在紫外检测波长214nm,分离电压26 kV条件下测出5种乳蛋白在不同线性范围内的线性相关系数均大于0.997,各乳蛋白的迁移时间和峰面积的相对标准偏差(RSD)分别小于0 .33%和4.65%,牛乳样品加标回收率范围为86%～102%;通过对比大豆分离蛋白、明胶、乳清蛋白及乳蛋白的电泳图语,定性并定量出不同蛋白质特征峰,方法重现性较好,可以作为牛奶质量的监控快速检测方法.     

电子鼻技术结合化学计量学快速鉴别掺假茶籽油

目的:建立茶籽油掺假的快速定性和定量检测方法。方法:采用电子鼻技术结合化学计量学，基于单因素方差分析筛选差异变量，通过主成分分析(PCA)和判别分析(DA)建立茶籽油掺假类型鉴别的定性模型；通过正交偏最小二乘法(OPLS)建立了茶籽油掺假类型和掺假度鉴别的定量模型。结果:模型的R²均高达0.98,RMSEE均低于0.005,RMSECV均低于0.01,具有较高性能指标。通过外部验证，DA模型对不同掺假类型的茶油样品定性识别率高达100%,OPLS模型具有良好的准确性。结论:电子鼻技术结合化学计量学能够实现茶籽油掺假的快速、无损鉴定。     

基于高光谱成像快速检测牛肉糜中大豆分离蛋白掺入量

采用近红外高光谱成像技术(900~1700 nm)结合化学计量学算法快速定量预测牛肉糜中大豆分离蛋白掺入量。首先按照2%~30%(w/w),掺入间隔1%的浓度梯度,制备不同大豆分离蛋白掺入浓度的牛肉糜样品,然后采集样品的高光谱图像并提取光谱数据,最后运用偏最小二乘回归(Partial least squares regression,PLSR)和多元线性回归(Multiple linear regression,MLR)算法建立预测模型。为了减少模型的高维共线性问题,采用回归系数法(Regression coefficients,RC)和连续投影算法(Successive projection algorithm,SPA)筛选最优波长,优化全波段预测模型。结果显示基于RC法筛选的22个最优波长构建的RC-PLSR模型和RC-MLR模型预测效果优于基于SPA法筛选的21个最优波长构建的SPA-PLSR模型和SPA-MLR模型。其中,RC-PLSR模型预测效果最接近全波段PLSR模型,r_P为0.95,RMSEP为2.73%,RPD为3.32。试验结果表明近红外高光谱成像技术结合化学计量学方法可快速预测牛肉糜中大豆分离蛋白的掺入量。     

聚丙烯酰胺凝胶电泳法快速检测植物源性食品中的蛋白成分

目的建立十二烷基磺酸钠-聚丙烯酰胺凝胶电泳法(sodium dodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE)鉴定核桃、杏仁、花生、大豆中的蛋白成分,并分析植物蛋白饮料中蛋白质的来源。方法采用一步法植物活性蛋白质提取试剂盒分别提取预处理后的核桃、杏仁、花生、大豆等样品中的蛋白质成分,计算蛋白质的相对分子量,之后分别进行SDS-PAGE检测得到这几种蛋白成分的特征条带,并对不同样品中蛋白成分的电泳图谱进行比对。结果每一物种都有相对应的蛋白指纹图谱,不同种类的核桃含有相同的蛋白质亚基,具有高同源性,但核桃与花生、黄豆和杏仁含有不同种类大小的蛋白,具有高特异性。结论本方法快速、准确、灵敏,可有效分析植物蛋白饮料中各类蛋白质的来源,对食品中植物源性成分的鉴定具有重要意义。     

酪蛋白沉淀检测方法及其在牛乳经济掺假鉴定中的应用

试验表明酪蛋白等电点沉淀检验方法的最适检测条件为:10%乙酸溶液,磁力搅拌,pH4.4～4.8,3000 r/min离心15 min,102℃直接干燥法。通过检测,生牛乳、银桥纯牛奶、市售便宜奶粉、乳清粉、食用明胶、三聚氰胺、大豆分离蛋白粉的酪蛋白质量分数(g/g蛋白质)分别为79.8%、78.7%、0、0、0、0和90.3%。结果表明,本检测方法能够很好的检测正常牛乳的酪蛋白含量,并能对市售便宜奶粉、乳清粉、食用明胶和三聚氰胺进行经济掺假鉴定,结合对产品豆腥味的感官评价和对假酪蛋白色泽偏暗的颜色测定的方法,可以对大豆分离蛋白粉进行掺假鉴定,验证了纯牛乳制品掺假检验的定量指标:酪蛋白质量分数(g/g蛋白质)≥73%。     

大豆黄浆水中乳清蛋白和低聚糖制备研究进展

大豆黄浆水是豆腐和大豆分离蛋白生产过程中排放的高浓度废水,其BOD5(生物需氧量)、COD值(化学需氧量)远远高于国家规定的排放标准,由于大豆黄浆水中含有多种生理活性物质,具有很好的商业开发价值,为此文中阐述了大豆黄浆水中乳清蛋白和低聚糖的制备和检测方法.     

MALDI-TOF质谱法分析与鉴定羊乳中的磷酸肽

基于基质辅助激光解吸电离-飞行时间质谱(MALDI-TOF MS)技术建立一种羊乳中磷酸化肽段的检测方法。以商品化二氧化钛(Ti O2)为富集材料用于羊乳中低丰度磷酸肽的富集,并优化了商品化Ti O2富集羊乳中磷酸肽的最佳吸附洗脱条件,得到的结果为,孵育缓冲液为乙腈∶水(50∶50,体积比)+1%三氟乙酸,洗脱液为氨水15%。接着探讨了脱脂对检测结果的影响,结果表明,通过MALDI-TOF MS分析实际乳磷酸肽时,需要对乳类样品进行脱脂才能更完整的鉴定磷酸肽,从羊乳中鉴定出八个磷酸化肽段通过Mascot数据库检索。本研究为乳类磷酸肽指纹图谱的建立提供了理论基础,指纹图谱的建立能够应用于掺假乳的快速鉴定。     

鲜奶掺假检验方法研究进展

鲜奶掺假事件时有发生,综述鲜奶中常见掺假物质及其检测方法,对方法的优缺点进行简要的分析,并着重介绍一种叫做非线性化学指纹图谱的方法,以期为有关管理部门和生产厂家进行产品全程质量控制和原料收购时的质量把关提供技术参考。     

基于指纹图谱和化学计量分析的鳕鱼肝油软胶囊掺假植物油鉴定

目的 建立一种基于脂肪酸气相色谱(gas chromatography, GC) 指纹图谱技术结合化学计量分析的鳕鱼肝油软胶囊中掺假植物油的鉴定方法。方法 采用GC法测定不同来源鳕鱼肝油软胶囊脂肪酸指纹图谱, 经拟合后构建对照指纹图谱, 并进行样品相似度评价。模拟制备鳕鱼肝油软胶囊中掺入不同种类、不同比例植物油的掺假样品, 以其中14个共有脂肪酸峰的相对峰面积作为数据源, 输入SIMCA-P数据分析软件进行主成分分析(principal component analysis, PCA)及掺假模型建立。结果 获得鳕鱼肝油软胶囊GC对照指纹图谱及三维掺假识别模型, 44批样品经相似度评价发现有2批拟似掺假植物油, 将拟似样品色谱数据标准化后导入SIMCA-P软件, 显示2批样品均掺了大豆油, 掺假比例约为15%和35%。结论 脂肪酸GC指纹图谱结合化学计量分析为鳕鱼肝油软胶囊中掺假植物油的鉴定提供一种可靠准确的检测手段, 可快速有效识别鳕鱼肝油掺假行为。     

基于非线性化学指纹图谱的羊乳广谱掺假检测研究

目前羊乳中发现的掺假物质种类繁多,而检测方法多为针对单一掺假物质的检测。本研究基于非线性指纹图谱技术构建非特异性的广谱掺假物质判定方法。本研究在测定32个纯山羊乳样品及添加5%、1%和0.1%不同浓度氯化钠、大豆蛋白胨、尿素和蔗糖羊乳样品的非线性指纹图谱基础上,对纯山羊乳与掺假羊乳的指纹图谱进行直观的比较和相似度比较。添加0.5%以上氯化钠或尿素的掺假样品和5%以上大豆蛋白胨或蔗糖的掺假样品与纯生鲜羊乳的指纹图谱明显不同,可判定为掺假羊乳。以纯羊乳样品最低相似度值为临界值,则含0.5%和1%蔗糖的掺假样品相似度值在临界值上下,其余掺假样品的相似度值均小于临界值83.4%。故对生鲜乳中添加以上四种掺假物质浓度大于5%的掺假行为通过指纹图谱的直观比较和相似度值比较均可判定为掺假,该方法可用于生鲜羊乳的掺假检测,一次检测即可排除多种掺假物质的存在。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.