HPLC法测定梵净山不同品种茶叶氨基酸含量比较分析

以梵净山绿茶、红茶、翠峰和白茶为原料,采用反向高效液相色谱法分析不同品种茶叶中水解和游离氨基酸含量。该方法色谱条件为:Agiln100高效液相色谱系统Agilcnt Hypcrsil ODS柱(5μm,40 mm×250 mm);流动相A (pH 7.2) 27.6 mm/L醋酸钠-三乙胺-四氢呋喃(500:0.11:2.5,V/V);流动相B (pH 7.2) 80.9 mmol/L醋酸钠一甲醇-乙睛(1:2:2,V/V);采用梯度洗脱,洗脱程序为0 min,8%B;17 min,50%B;20 min,100%B;24 min,0%B;流速1.0mL/min;柱温40℃;紫外检测器(VWD)检测波长338 nm,脯氨酸以262 nm检测;氨基酸含量以外标法定量测定。结果表明,4种茶叶的游离氨基酸含量显示,必需氨基酸含量最高的是白茶中Phe*(0.131 g/100 g),非必需氨基酸含量最高的是白茶中Asp (0.435 g/100 g),半必需氨基酸含量最高的为白茶中Arg (1.148 g/100 g)。4种茶叶中游离氨基酸必需氨基酸、半必需氨基酸和非必需氨基酸含量最高的均为白茶;另外,4种茶叶水解氨基酸含量显示,必需氨基酸含量最高为翠峰茶中Lys*(1.908 g/100 g),非必需氨基酸含量最高为绿茶中Glu (4.190 g/100 g),半必需氨基酸含量最高为白茶中Arg (2.290 g/100g)。不同茶叶品种其游离氨基酸和水解氨基酸含量不同,值得被开发利用。     

HPLC-ELSD测定茶梗中茶氨酸的含量

采用蒸发光散射检测器(ELSD)测定茶叶下脚料茶梗中茶氨酸的含量。以AE.LichromC18(250mm×4.6mm,5μm)为色谱柱,含0.1%三氟乙酸的乙腈-含0.1%三氟乙酸的水(体积比为2:98)为流动相,流速0.5mL/min,漂移管的温度54℃,载气(N2)1.46×105Pa。茶氨酸在2.55～20.43μg范围内有良好线性关系,平均回收率为98.5%,RSD=2.30%,茶梗中茶氨酸的含量为6.59～17.04mg/g。该方法简单,快速,分离度好,下脚料茶梗仍具有较大的开发利用价值。     

柱前衍生法测定茶叶中L-茶氨酸的含量

本文研究了柱前衍生测定茶叶中L-茶氨酸含量的方法。茶叶中的L-茶氨酸用热水提取后,经2,4-二硝基氟苯衍生后上高效液相色谱法测定。色谱条件为:色谱柱(Kromasil C18柱4.6 mm×250 mm,5μm);流动相:乙腈︰磷酸盐溶液(pH=6.5)=15︰85梯度洗脱;检测波长:360 nm;流速:1.0 mL/min;柱温:35℃;进样:5μL。本方法检出限4 mg/kg,在1.0~50.0μg/mL呈现良好的线性关系(r=0.999 9),衍生后的样品室温25℃放置6天内稳定,重现性试验相对标准偏差0.16%(n=6),回收率为96.4%~102.2%。本高效液相色谱法可以准确地测定茶叶中L-茶氨酸的含量。     

茶氨酸的HPLC快速检测

建立了未衍生化高效液相色谱法(HPLC)快速检测茶叶及绿茶提取物中茶氨酸含量的方法。采用Zorbax SB-AQ色谱柱(250mm×4.6mm,5μm),乙腈:0.1%磷酸溶液=5:95(体积比)为流动相,流速1mL/m in,进样量10μL,柱温25℃,检测波长196nm。结果表明茶氨酸在0.02mg/mL 0.20 mg/mL浓度范围内线性关系良好,相关系数r=0.9998,加样回收率为98.59%(n=5)。本方法检测快速,定量准确,可用于茶叶及绿茶提取物中茶氨酸含量的测定。     

高效液相色谱法测定发芽麦粒中γ-氨基丁酸(GABA)含量

建立了一种测定发芽麦粒中γ-氨基丁酸(GABA)含量的HPLC方法,并对四川10个小麦品种中GABA含量差异及其发芽培养期间变化规律进行了分析。采用FDNB(2,4-二硝基氟苯)为柱前衍生剂,色谱条件为:色谱柱Luna C18_((2))(150 mm×4.60 mm,5μm),乙腈-0.02 mmol/L乙酸铵混合溶液为流动相(V:V=15:85),柱温30℃,流速1.0 mL/min,测定波长320 nm。结果表明,在0.025 5~0.127 6μg范围内,呈良好的线性关系,最低检出限1.081×10~(-5)μg/mL,方法的平均加标回收率为97%。采用建立的方法测定不同小麦品种在萌发12 h后的GABA含量在0.238~5.26 mg/100 g之间,不同品种间GABA的含量差异显著,在萌发的0~12 h内,GABA含量呈现先上升后下降的趋势,在8 h时含量达到最高。     

高效液相色谱法分析沙棘中类胡萝卜素的含量

目的 建立沙棘中β-胡萝卜素、玉米黄素、β-隐黄质、叶黄素等4种类胡萝卜素的高效液相色谱分析方法,并用于分析我国不同产地和不同品种沙棘中4种类胡萝卜素的赋存状态及含量差异,以及不同采摘时期类胡萝卜素的变化规律。方法 沙棘鲜果经冷冻干燥预处理,取适量沙棘粉进行皂化,再用正己烷提取, 二氯甲烷-乙腈-甲醇（2:3:5,V:V:V）复溶, 经YMC Carotenoid 色谱柱(150 mm×4.6 mm,3.0 μm)分离,以二氯甲烷-乙腈-甲醇（2:3:5,V:V:V）为流动相,等度洗脱,DAD检测器检测,外标法定量。采集新疆、四川、吉林、山西和河北等地的19个沙棘样本,并以新疆阿勒泰地区深秋红品种为代表,从9月初至12月底分9期采样,对样本中4种类胡萝卜素的含量进行分析。结果 β-胡萝卜素、玉米黄素、β-隐黄质、叶黄素等4种类胡萝卜素在1.0~200 g/mL的浓度范围内具有良好的线性关系,相关系数(r2)大于0.99, 方法检出限为2.0 mg/100 g, 定量限为6.0 mg/100 g。加标回收率为88.1%~92.7%, RSD为1.36%~8.36% (n=6)。19个沙棘样品中类胡萝卜素的总含量介于1468.4~6999.1 mg/kg之间,平均含量为3287.9 mg/kg。β-胡萝卜素、玉米黄质、β-隐黄质、叶黄素的平均含量分别为581.3、1789.4、102.0、815.3 mg/kg。结论 本研究建立的分析方法准确、可靠,对19个沙棘样本进行分析,结果表明不同品种沙棘中4种类胡萝卜素的含量差异较大,对不同采摘时期的样本进行分析,结果表明11月中旬采摘的沙棘果类胡萝卜素的含量最高。     

不同茶叶中表没食子儿茶素没食子酸酯的含量测定

目的建立反相高效液相色谱法检测茶叶中表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)的含量,并对比不同茶叶中EGCG的含量。方法对不同产地茶叶样品用70%甲醇提取10 min,提取后冷却至室温,提取溶液经过离心;采用反相色谱柱Agilent SB-C_(18)(4.6 mm×250 mm,5μm)检测,以流动相A(90mL乙腈:20 mL乙酸:2 mL乙二胺四乙酸二钠:888 mL水)、流动相B(800 mL乙腈:20 mL乙酸:2 mL乙二胺四乙酸二钠:178 mL水)梯度洗脱,流速1.0 mL/min,柱温35℃,检测波长278 nm。结果 EGCG在78.0~468.0μg/mL的范围内与峰面积积分值呈良好的线性关系(r~2=1.0000),平均加标回收率为95.6%,RSD为1.29%。结论该方法简单、灵敏、稳定、可靠,可用于不同茶叶EGCG的含量测定。实验同时发现,不同茶叶由于产地和工艺不同,EGCG含量差异较为明显。     

陕西省不同产地绿茶中6种活性成分含量的比较

目的：采用高效液相色谱法HPLC,对陕西不同产区(安康、汉中和商洛)绿茶中茶氨酸(theanine)、没食子酸(gallic acid,GA)、咖啡碱(caffeine,CAF)、表没食子儿茶素(epicatechin gallate,EGC)、表儿茶素没食子酸(epicatechin gallate,ECG)及表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)的含量进行分析比较。方法：绿茶经热水提取后采用HPLC测定上述6种活性成分的含量,色谱柱(250mm×4.6mm,5μm),流动相为0.05%三氟乙酸溶液(A)、乙腈(B)梯度洗脱,流速为1mL/min,柱温25℃,检测波长：190nm和280nm。结果：3个产区中6种组分的含量在0.325～47.061mg/g之间,产区间各组分含量存在显著性差异(P＜0.05),其中汉中绿茶中GA的平均含量最高,安康绿茶中茶氨酸、CAF、ECG、EGC、EGCG的平均含量最高。     

青藏地区青稞中VE 的高效液相色谱测定

采用高效液相色谱法对青藏高原的16 种不同地区和品种的青稞中δ-VE、γ- VE 和α- VE 同时进行了含量的测定,为青稞的质量评价和综合利用提供依据。采用Symmetry C18(4.6mm × 250mm,5μm)色谱柱;甲醇:水=98:2(V/V)为流动相;检测波长295nm;柱温25℃;流速1ml/min。结果表明,青藏地区的青稞中VE 总含量在0.3～0.8mg/100g,其中青海地区青稞中VE 的平均总含量比西藏地区低约10%。     

液相色谱法测定核桃乳中糠氨酸含量

目的建立液相色谱法测定核桃乳中糠氨酸含量的检测方法。方法样品经酸水解、乙酸铵缓冲溶液定容后,经反相C18色谱柱分离,以甲醇/三氟乙酸溶液为流动相,流速为1.0mL/min,梯度洗脱,在紫外检测器波长为280 nm下检测。结果糠氨酸浓度在2～50μg/L的范围内线性关系良好,相关系数均大于0.999。糠氨酸在2.00、5.00和10.00mg/100g蛋白质添加水平的回收率为88.82%～91.95%,相对标准偏差(relative standard deviation, RSD)小于3.55%(n=6),方法检出限为1.0 mg/100 g蛋白质。结论该方法操作过程简单、方法准确、可靠、重现性好、回收率较高,适合于核桃乳中糠氨酸含量的分析检测。     

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.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press