新型纳米材料在食品安全检测中样品前处理应用的研究进展

在食品安全检测中,样品预处理是衡量污染物定性和定量分析中必不可少的步骤。有效的食品前处理方法具有重要意义。近年来,纳米材料的发展,极大地促进了食品样品预处理方法的创新。如碳纳米管材料、金属有机骨架、磁性金属有机骨架材料等,在食品样品预处理方面,显示出巨大的应用前景。综述了近年来基于新型纳米材料的食品安全筛选预处理方法,讨论了该领域未来的发展前景和面临的挑战。     

微波消解在测定食品中微量元素的应用

总结了食品中微量元素测定时常用的样品处理方法,并重点对微波消解食品时样品的取样量、样品预处理的方法、所用溶剂的种类和数量以及加热时间和压力的选择作了阐述,从而为微波消解食品样品提供了操作依据。     

食品理化检验中样品的预处理方法

<正>为了确保食品理化检验结果的真实、准确、可靠,必须严格按照检验方法选用正确的样品预处理方法。食品理化检验前必须对样品进行预处理,根据检验项目和取样量的不同,预处理方法有很多种。其中湿消化法、干灰化法、微波消解法在食品理化检验中应用比较多,并且被广大检验工作者所熟悉。各种方法都有优点和缺点。下面采用微波消解法检验食品中总砷含量,以及列举食品理化检验所常用的三种样品预处理方法。材料及方法仪器和试剂仪器:WX-400微波快速消解仪、     

色谱法用于食品分析时的样品预处理

食品同其它分析样品一样,是一类不均匀的,由多种复杂化合物组成的混合物质。准确分离和测定食品中某项单一的化学组分一直是食品分析技术中复杂而困难的问题。自色谱分析技术发展以来,色谱分析已成为分离、鉴定食品组成和含量的理想的分析方法,样品预处理简单,甚至可将食品样液直接注入仪器,以获得更合理的结果。我们知道,建立一种由标准溶液反复直接进样而反映数据精密度的分析方法,已经是很常用的技术。本文将通过例举一些样品的分析实例,说明样品预处理同样会对分析结果产生影响,色谱分析中的样品预处理也应该得到     

皮蛋中铅含量测定的样品预处理方法比较

皮蛋是人们喜爱的传统食品,近年来不断有媒体报道,皮蛋中铅含量超过国家标准。铅可对人体多种组织器官产生危害,如果长期食用含铅量过高的食品会引起慢性积累性中毒,因此,检测食品中的铅含量是否符合国家标准直接关系着人体健康。在食品的检验中,样品的预处理是一个很重要的环节。通过实验对皮蛋样品的两种预处理方法进行了比较。     

酶法预处理工艺在镉、砷检测中的应用解析

选择高效、准确的样品消解方法是测定重金属元素含量的关键步骤,直接影响检测结果的准确性和可再现性。本文通过对镉、砷重金属在食品中的存在形态及酶处理工艺进行分析,探讨酶法预处理在镉、砷检测中的应用。认为：镉在食品中主要与蛋白质结合,在叶菜类食品中主要以氯化钠提取态形式存在,在玉米、高粱等作物中主要以酸提取态最多;砷在动物性食品及谷物类中主要以有机态存在,一般用甲醇作为提取剂;蔬菜中砷以无机砷形态存在,以酸作为提取剂;酶法预处理的影响因素包括样品粒度、酶的种类、酶浓度、pH值、温度、液固比和酶处理时间。     

食品中铬（Ⅲ）与铬（Ⅵ）分析方法的探讨

研究了ＩＥ－ＡＡＳ法测定食品中痕量Ｃｒ（Ⅲ）和Ｃｒ（Ⅵ）的方法,讨论了原子化条件,样品预处理方法及Ｃｒ（Ⅲ）和Ｃｒ（Ⅵ）分别测定的条件选择与方法;确定了以酸浸提食品中的各种价态的铬的样品预处理方法;探讨了利用弱碱型阴离子交换树脂选择吸附Ｃｒ（Ⅵ）进而分别测定了Ｃｒ（Ⅲ）和Ｃｒ（Ⅵ）的条件与方法。     

高压脉冲电场对苹果崩塌温度的影响

以苹果为研究对象,进行真空冷冻干燥实验并与高压脉冲电场预处理的样品进行分析对比,研究电场预处理对苹果微观结构及崩塌温度的影响。结果表明:当加热板温度设定为70℃时,未处理的苹果样品出现了较为明显的塌陷以及断裂现象。而经过高压脉冲电场预处理的样品,在缩短了干燥时间、降低了能耗及物料的最终含水率的同时,样品的骨架结构保存完整,没有出现崩塌现象。高压脉冲电场预处理可以提高果蔬的临界崩塌温度约20℃,并使物料的最终含水率达到1.20%,而未经高压脉冲电场预处理样品的最终含水率为7.84%。本文对解决干燥过程中崩塌现象的产生有重要意义。     

磁性固相萃取技术在食品和中药材分析前处理中的应用进展

食品安全和质量控制是关系国计民生的大事, 经常应用于日常生活的中药材的药效物质和安全性也越来越受到重视。食品和中药材真伪鉴定、品质(营养或功效成分)及安全性质量控制分析十分重要, 而分析前预处理是确保分析结果准确无误的关键环节之一。新型前处理技术-磁性固相萃取技术(magnetic solid-phase extraction, MSPE)由于具有萃取时间短、有机溶剂使用量少和操作简便等优点而被越来越多地应用于样品的预处理。本文综述了近年来MSPE在食品和中药材分析预处理中的应用, 分析了其在食品和中药材真伪鉴定、品质及安全性质量控制分析中的应用现状, 并展望了MSPE技术的发展趋势, 以期加速其在食品和中药材分析预处理中的应用。     

食品中限量元素分析样品的预处理技术进展

本文综述了近年来食品中限量元素分析的样品前处理技术,重点对密封罐消解(包括普通电烘箱密封罐消解及微波消解技术)在食品农药限量元素分析中的应用进行了评述;同时对常规样品预处理技术(高温灰化、湿法消化)、低温灰化技术、酸提取技术及分离富集技术应用进行了总结,对食品中限量元素分析预技术发展方向进行了讨论。     

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.     

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.     

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.     

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.