高效液相色谱法测定发酵液中的四甲基吡嗪

采用高效液相色谱法在Hypersil NH2(300 mm×4.6 mm,5μm)上测定了发酵液中的四甲基吡嗪,流动相为乙腈-水(90︰10,V/V),流速为1 m L/min,紫外检测波长295 nm,柱温35℃。10 min内可以完成色谱检测。该方法的检出限(S/N=3)为0.03μg/L,线性范围0.02~2 g/L;方法回收率为96.7%~98.2%;RSD为0.54%~1.72%。试验结果证明,该方法是测定发酵液中四甲基吡嗪的快速、有效的定量分析方法。     

反相高效液相色谱法测定嗜碱微生物发酵液中的有机酸

建立了采用反相高效液相色谱检测嗜碱微生物Lp3-3发酵液中有机酸的方法。采用Sinochrom ODS-BP色谱柱(250mm×4.6mm,5μm),以2.5mmol/L NH4H2PO4(含1%甲醇)溶液(pH2.5)为流动相,流速为0.5mL/min,柱温30℃,紫外检测器检测波长为210nm。在此色谱条件下,7种有机酸得到很好分离,方法重现性好,精密度高,有机酸浓度在1~500μg/mL范围内,线性相关系数均大于0.999,加标回收率为96%~110%,各有机酸检出限≤0.12μg/mL。运用该方法测定嗜碱微生物Lp3-3发酵液中的有机酸,得到发酵液中主成分乳酸及副产物乙酸、丙酮酸在发酵不同时间的变化趋势。     

高效液相色谱法同时测定右旋糖酐发酵液中的多种糖分

建立了1种同时测定右旋糖酐发酵液中蔗糖、果糖、葡萄糖等3种糖分含量的高效液相色谱定量分析方法。发酵液用流动相乙腈水溶液定容预处理,使其中的产物右旋糖酐析出以消除其对糖分测定的干扰。将预处理液离心,取上清液,在选定的色谱条件下:分离柱为OSMOSIL Sugar-D(4.6 mm I.D.×250 mm,0.46μm)柱,柱温为35℃,80%(V/V)乙腈水溶液为流动相,流速为1.0 m L/min,进样量为20μL,示差折光检测器,温度为40℃,实现了发酵液中蔗糖、果糖、葡萄糖的理想分离。在蔗糖质量浓度为0.1~15.0 g/L,果糖和葡萄糖质量浓度为0.5~25 g/L范围内,对糖分质量浓度与其峰面积进行线性回归分析,其相关系数在0.9994~0.9999之间,平均加标回收率为95.20%~104.00%,相对标准偏差在1.8%~3.2%之间。该方法可直接同时测定右旋糖酐发酵液中蔗糖、果糖、葡萄糖等3种糖分的质量浓度,为右旋糖酐发酵过程提供了一种操作简便、快速、可靠的监测方法。     

亚麻油中TBHQ、BHA和BHT的同时快速检测

建立了高效液相色谱法同时快速测定亚麻油中特丁基对苯二酚(TBHQ)、叔丁基茴香醚(BHA)和2,6-二叔丁基对甲酚(BHT)3种抗氧化剂的方法。采用甲醇(5 m L+5 m L)直接提取亚麻油中的TBHQ、BHA和BHT,C18柱(4.6 mm×250 mm×5μm)进行分离,紫外检测器检测。流动相用甲醇和1%乙酸梯度洗脱,流速为1.0 m L/min,进样量为10μL,检测波长为280 nm。3种抗氧化剂的检出限:TBHQ为0.04μg/m L,BHA为0.01μg/m L,BHT为0.02μg/m L,回收率为91.2%~103.6%;相对标准偏差在2.5%~6.8%之间。     

HPLC 法检测HDBRS-1 菌株发酵液中2- 羟基联苯含量

采用高效液相色谱法测定脱硫菌发酵液中2- 羟基联苯(2-HBP)的含量。以Delta-PakTM C18 (300A,3.9mm× 150mm,5μm)为色谱柱,甲醇:水(7:3,V/V)为流动相,流速1ml/min,用紫外检测器在260nm 处检测2-HBP。结果显示2-HBP 标准品的保留时间为2.6min,线性范围为0～80mg/L,利用该方法测得HDBRS-1 菌株发酵液中,2-HBP 的生成量为6.11mg/L。     

UPLC-MS/MS分析橘汁发酵液中柠檬苦素的变化趋势

目的:利用超高效液相色谱-质谱检测柑橘果酒发酵工艺中橘汁发酵液的柠檬苦素,分析橘子发酵加工产品中苦味变化趋势。方法:色谱柱Waters ACQUITY BEH C18(50mm×2.5mm,1.9μm);流动相:A为乙腈,B为纯水,A梯度为0～3min(10%～50%),3～4min(50%～10%),4～5min(10%～10%);流速:0.3mL/min;柱温:40℃;进样量:5μL;检测时间:5min;正离子模式质谱检测器:柠檬苦素母离子m/z 471.1,子离子m/z 425.3、161.1。结果:该条件下柠檬苦素检测效果良好,发酵液中柠檬苦素含量随发酵时间变化而变化,保藏时间越长,柠檬苦素含量越低。结论:通过延长橘汁发酵液的贮存时间有利于苦味物质的脱除。     

HPLC-ELSD法测定食品中异麦芽酮糖

建立了一种方便、准确、灵敏的方法以测定食品中异麦芽酮糖含量的高效液相色谱蒸发光散射检测器方法。使用Hypersil APS-2(NH2)(4.6 mm×250 mm,5μm)色谱柱分离,柱温40℃;以乙腈:水=88:12为流动相,流速1 m L/min;ELSD为检测器,雾化器温度50℃;蒸发器80℃;载气(氮气)流速1.6 L/min。结果:检出限为30μg/m L;在80~1200μg/m L内工作曲线线性良好,相关系数r2=0.9991,回收率85.6%~98.1%,精密度2.78%~2.92%。结果表明此方法前处理简单,易于操作,检测限低,在线性范围内线性良好,相关系数高,测量结果精确度高,是检测食品中异麦芽酮糖的有效方法。     

高效液相色谱-蒸发光散射法测定肉制品中山梨糖醇

建立肉制品中山梨糖醇的高效液相色谱-蒸发光散射检测器(high performance liquid chromatographyevaporation light scattering detector,HPLC-ELSD)测定法。采用乙腈-水溶液(7:3,V/V)作为流动相直接超声提取样品,经Agilent ZORBAX NH_2(4.6 mm×250 mm,5μm)色谱柱分离,蒸发光散射检测器检测;优化ELSD检测器参数为飘移管温度90℃,氮气流速2.0L/min。结果表明:山梨糖醇含量在0.2~5.0mg/mL范围内有良好的线性,方法相对标准偏差(relative standard deviation,RSD)在1.28%~2.02%之间,回收率在88.3%~99.0%之间。本方法具有样品前处理简便、方法检出限低、方法重现性好的特点,适用于肉制品中山梨糖醇含量的测定。     

高效液相-阳离子交换色谱法测定藏药安神丸中槟榔碱的含量

目的建立高效液相-阳离子交换色谱法测定藏药安神丸中槟榔碱含量的方法。方法样品用乙醚溶液和碳酸盐缓冲液提取后,用Sepax Polysulfonix-SCX(250 mm×4.6 mm,5μm)强阳离子交换树脂色谱柱分离,以乙腈-0.2%磷酸溶液(pH 3.8,10:90,V:V)作为流动相进行洗脱,0.5 mL/min流速,用紫外检测器于215 nm波长处进行测定。结果氢溴酸槟榔碱在7.028~210.840μg/mL范围内线性关系良好(r~2=0.9998),回归方程为Y=44.5058X-56.3314,加标回收率为95.67%~97.41%,相对标准偏差为1.07%~1.80%(n=3)。结论此方法具有良好的精密度、稳定性及回收率,可用于安神丸中槟榔碱成分的测定。     

高效液相色谱法检测保健食品中的番茄红素

目的建立高效液相色谱法测定保健食品中番茄红素的分析方法。方法用含有0.1%2,6-二叔丁基-4-甲基苯酚抗氧化剂的甲醇:二氯甲烷(10:90,V:V)作为提取溶液。通过Agilent Eclipse XDB-C_(18)(4.6 mm×250mm,5μm)色谱柱;甲醇:乙酸乙酯(85:15,V:V)作为流动相,二极管阵列检测器,检出波长475 nm,色谱柱温25℃,流速1.0 mL/min,进样体积10μL,作为检测条件。结果番茄红素在0~200μg/mL范围内线性良好,相关系数r=0.9995,最低检出限为0.0815μg/mL,平均回收率在89.7%~109.8%之间,RSD为8.4%。结论本方法可以准确、快速地检测保健食品中的番茄红素。     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.