硫辛酸分子印迹膜及其抗氧化效果

以α-硫辛酸(ALA)为模板分子,N-乙烯基己内酰胺(NVCL)为温敏性功能单体,在制备硫辛酸分子印迹聚合物(ALA-MIPs)的基础上,结合膜技术,选用聚丙烯腈(PAN)和聚偏氟乙烯(PVDF)作为成膜材料,以异相粒子填充膜法制备了ALA-MIPs共混膜,通过扫描电镜考察了分子印迹膜(MIM)的微观形貌,研究了机械性能、亲水性、吸水性、ALA的释放特性。结果表明,PVDF膜具有更好的机械性能和疏水性能,PAN膜有较好的ALA释放量,两者都在20℃下存在温敏性释放。通过测定分子印迹膜在植物油中的POV值,发现PAN-MIM膜有更好的抗氧化效果。     

烯唑醇分子印迹固相萃取膜的制备及其应用

以烯唑醇为模板分子,丙烯酰胺(AM)为功能单体,采用原位聚合法制备出对烯唑醇具有高选择性的分子印迹固相萃取膜;通过紫外光谱试验优化了功能单体,考察了不同功能单体与模板分子的结合能力,同时考察了制备印迹膜时致孔剂的选择和分子印迹膜印迹次数对液体通过性的影响;建立了基于分子印迹固相萃取膜-高效液相色谱法测定粮谷中烯唑醇残留的方法。结果表明,与功能单体α-甲基丙烯酸(MAA)相比,丙烯酰胺(AM)与烯唑醇的结合能力更强,以乙腈为制孔剂制备烯唑醇印迹膜,印迹一次印迹膜较稳定,且液体通透性良好。烯唑醇在0.5~15μg/m L浓度范围内有良好的线性关系(r=0.9987),平均回收率在80.34%~87.03%之间,检出限为2.0μg/g。该方法选择性强、灵敏、可靠,适用于粮谷等复杂基质中烯唑醇的残留检测。     

抗氧化剂硫辛酸分子自组装体系及印迹聚合物的制备

采用密度泛函理论,在B3LYP水平下模拟计算以N-异丙基丙烯酰胺（N-isopropyl acrylamide,NIPAM）为 功能单体的硫辛酸分子印迹聚合物（α-lipoic acid molecularly imprinted polymers,ALA-MIPs）自组装体系。在计算 优化的印迹比例下,以乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,采用紫外引发本体聚合法制备了 ALA-MIPs,利用扫描电子显微镜和傅里叶变换红外光谱对其形貌和结构做了表征,并对ALA-MIPs的吸附性能做了 研究。结果表明,计算模拟ALA与NIPAM形成稳定复合物的印迹比例为1∶2,在此印迹比例下制备的ALA-MIPs中 存在两类结合位点,平衡解离常数分别为6.969 7×10－5 mol/L和1.558 5×10－5 mol/L,最大吸附量分别为12.145 mg/g 和104.06 mg/g,并且与非印迹聚合物相比,ALA-MIPs对ALA具有较好的选择吸附性能。     

不同添加剂对酪蛋白可食膜理化性质的影响

酶可催化蛋白质分子内交联,多糖和多酚可与蛋白质发生分子间相互作用,3种添加剂均可改善蛋白质的功能性质。为提高酪蛋白(CA)可食膜的应用范围,研究了谷氨酰胺转氨酶(TG酶)、表没食子儿茶素没食子酸酯(EGCG)和壳聚糖(CS)对酪蛋白可食膜结构及性能的影响。测定膜溶液的粒径和电位,对复合膜机械性能、色泽和水蒸气透过率等指标进行表征。结果表明,TG酶、EGCG和CS对膜结构均影响显著,6组样品中添加EGCG和CS的样品(CAEC组)性能最佳。添加TG酶后,膜的机械性能有所提高,而水阻隔能力下降。添加EGCG后膜颜色变暗,抗拉伸强度提高,而韧性下降。添加CS后膜的抗拉伸强度提升,韧性也下降。同时添加EGCG和CS后,所得薄膜拥有良好的抗拉伸强度、水阻隔能力和较强的自由基清除能力。通过向酪蛋白膜中引入TG酶、EGCG和CS,赋予CA可食膜良好的机械性能和自由基清除能力,提高其水阻隔能力。研究结果对开发新型蛋白基可食膜具有一定意义。     

壳聚糖、纳米壳聚糖对聚乙烯醇膜结构与性能的影响

研究添加同一质量分数壳聚糖(chitosan,CS)、纳米壳聚糖(chitosan nanoparticles,NCS)改性聚乙烯醇(polyvinyl alcohol,PVA)膜的性能,利用色差仪与紫外分光光度计探究其光学性能;利用透气性测试仪与透湿性测试仪测试共混膜透气性能与透湿性能;通过等温吸湿实验研究了PVA膜、PVA/CS共混膜、PVA/NCS共混膜的吸湿性能,并将常见的等温吸湿曲线模型与实验数据进行拟合;采用傅里叶变换红外光谱(Fourier transform infrared spectrometer,FT-IR)、差示扫描量热(differential scanning calorimetry,DSC)仪对3种膜的结构与结晶度进行表征。结果表明:CS的加入会使PVA膜对中波紫外线的屏蔽作用增强,NCS的加入会使屏蔽效果更加明显;CS或NCS的加入会使PVA透气性能减弱,透湿性能增强;3种共混膜的等温吸湿曲线与GAB方程的拟合效果最好(R~20.98);FT-IR结果表明,PVA/CS、PVA/NCS共混均匀且共混材料之间形成分子间氢键;DSC结果表明,加入CS或NCS之后PVA分子的结晶速率变慢,结晶度下降,分子结晶的吸热焓值增加。     

分子印迹技术在天然活性成分分离纯化中的研究进展

分子印迹聚合物对模板分子具有特异识别能力和选择性,被广泛应用于环境、医药、生物及食品等领域。本文从印迹分离材料不同使用形式的角度出发,分别讨论了分子印迹整体柱,印迹微球和印迹膜等印迹材料在天然活性成分分离方面的研究进展。通过分析说明了分子印迹聚合物材料对天然活性成分具有特异识别功能和选择性,分离工艺简单、快速、印迹材料可重复使用等优势,具有潜在应用价值。同时指出分子印迹微球和分子印迹膜作为分离材料在天然活性成分分离中更具有良好的应用前景,值得深入研究。     

分子印迹固相萃取膜-高效液相色谱法检测粮谷中腈菌唑残留

以腈菌唑为模板分子,丙烯酰胺(AM)为功能单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,模板分子与功能单体最佳浓度配比为1∶2,制备出对腈菌唑具有高选择性的分子印迹固相萃取膜。通过紫外光谱试验考察了制备印迹膜时致孔剂的选择和分子印迹膜印迹次数对液体通过性的影响。建立了基于分子印迹固相萃取膜-高效液相色谱法测定粮谷中腈菌唑残留的方法。样品经乙腈提取,固相萃取膜净化,经C18柱分离,紫外检测210 nm。结果表明,腈菌唑在0.3~20μg/m L浓度范围内有良好的线性关系(r=0.999 4),平均回收率在80.2%~86.0%之间,相对标准偏差(RSD)≤3.3%(n=5),检出限为1.2μg/g。该方法选择性强、灵敏、可靠,适用于粮谷等复杂基质中腈菌唑的残留检测。     

双通道尼泊金乙酯分子印迹传感器的研制与应用

以尼泊金乙酯(EP)为模板分子,邻苯二胺(o-PD)为功能单体,利用循环伏安法在玻碳电极(GCE)表面制备分子印迹膜,对分子印迹聚合条件进行了优化,并进一步在双通道丝网印刷碳电极(SPCE)表面进行电聚合,制得双通道尼泊金乙酯分子印迹膜电极(EP-MIP/SPCE)。利用循环伏安法、方波伏安法和电流-时间曲线法对分子印迹传感器的电化学性能进行评价。EP在双通道EP-MIP/SPCE上的氧化电流与EP在低浓度区(3.2×10~(-7) mol/L~3.2×10~(-6) mol/L)和高浓度区(2.7×10~(-5) mol/L~5.6×10~(-4) mol/L)分别呈良好的线性关系,检出限为9.7×10~(-8) mol/L。运用建立的方法对市售酱油中的EP进行了测定,加标回收率为97.2%~106.6%,实验结果表明,该双通道分子印迹传感器可对酱油等食品样品中的尼泊金酯类进行快速测定。     

基于纳米金信号放大的分子印迹膜-SPR传感器检测奶制品中的三聚氰胺

采用分子印迹和SPR信号放大技术,构建一种以嵌有纳米金的分子印迹膜为识别元件,用于检测奶制品三聚氰胺的分子印迹膜-表面等离子体共振传感器(MIM-SPR)。首先利用表面热引发聚合的方法在SPR金片表面合成嵌有纳米金的分子印迹膜,再对MIM-SPR传感器的吸附响应性、选择性、再生性及精准度进行评价。该传感器的响应值与三聚氰胺在1×10-2~2μg/m L浓度范围内线性关系良好,R2=0.998。加标浓度在0.5~1.5μg/m L范围内的回收率为86.43%~107.11%,RSD小于6.0%(n=5)。结果表明该方法操作简单、选择性和再生性好、精准度高,可用于奶制品三聚氰胺残留量的测定。     

莲子钻芯粉淀粉理化性质及成膜特性研究

以莲子钻芯粉为原料，采用碱浸法提取淀粉，并与玉米淀粉(CS)、马铃薯淀粉(PS)和大米淀粉(RS)为参照，开展了莲子钻芯粉淀粉(LCPS)的理化性质和成膜特性研究。结果表明，LCPS直链淀粉质量分数最高(34.12%),透明度较低(8.67%);其糊化最终黏度和糊化终止温度显著高于CS、PS和RS(P<0.05),分别为6 852 cP和86.1℃;LCPS颗粒平均粒径为13.77μm,大小分布较CS、PS和RS更均匀，大多数呈椭圆形，少数呈圆形，属于A型晶体结构；LCPS具有较优的成膜特性，其膜的抗张强度(6.60 MPa)和水蒸气透过性[1.80×10^-10g/(m?s?Pa)]显著高于CS、PS和RS(P<0.05),透光率较低(53.54%)。本研究为LCPS的开发利用及其在生物基可降解膜研发中的潜在作用提供了理论参考。     

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.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

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.     

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.     

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.     

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.     

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.     

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.