风味酱中肌苷、肌苷酸的高效液相色谱分析

采用高效液相色谱对风味酱中的肌苷、肌苷酸进行定量分析。Polaris C_(18)-A色谱柱以水(含0.5%H_3PO_4)、异丙醇为流动相,梯度淋洗,检测波长248nm。结果表明,肌苷、肌苷酸分别在2mg/L～32mg/L呈线性关系,样品加样平均回收率分别为92.6%、95.7%,相对平均偏差1.4%～2.0%。     

青海藏系绵羊肉中肌苷酸、肌苷的含量测定

采用高效液相色谱法对藏系绵羊肉中的肌苷、肌苷酸进行定量分析。色谱柱：Kromasil C18 柱(4.6mm× 250mm,5μm);流动相：甲醇-水(95:5,V/V);流速1ml/min;紫外检测波长：254nm。结果表明：肌苷酸、肌苷分别在12.96～207.50mg/L和1.40～22.42mg/L范围内呈线性关系,回收率分别为97.98%、98.26%,该方法可用于动物肌肉组织中的肌苷酸、肌苷含量的测定。     

核苷磷酸化酶酶活力检测方法的建立

建立了一种核苷磷酸化酶酶活的检测方法,解决了工业化磷酸化酶质量无法判定的难题。建立核苷磷酸化酶的反应体系,以10 g/L肌苷、10 g/L三聚磷酸钠为底物,最适反应温度40℃,pH 4.5,反应10 min,使肌苷在磷酸化酶的作用下生成肌苷酸二钠(IMP)。通过高效液相色谱法(HPLC)测定IMP的生成量,液相色谱条件:采用C18色谱柱,以0.02 mol/L磷酸二氢钾∶乙腈为99.5∶0.5(V/V)为流动相,1 mL/min等度洗脱,40℃,紫外检测器(λ=254 nm),进样量2μL。此方法测定结果准确,回收率99.5%,重现性好,RSD0.5%。核苷磷酸化酶酶活检测方法的建立能精准地判定酶液产品指标,准确地计算酶添加量,解决了酶催化反应终点无法判定的问题。     

高效液相色谱法测定呈味核苷酸二钠及其过程产品

建立了一种测定呈味核苷酸二钠及其过程产品肌苷酸、鸟苷酸合成反应液,肌苷酸、鸟苷酸萃取水相、酯相的高效液相色谱法。该方法以乙腈:0.02mol/L KH2PO4(0.5∶99.5v/v)作为流动相,色谱柱为XDB-C18分离柱,采用等度洗脱,检测波长为254nm。实验验证:方法线性良好,重复性、准确性符合检测需要,RSD≤1.85%,加标回收率在99.4%～100.6%之间。综合分析,该方法能更好的指导呈味核苷酸二钠的生产过程、控制产品质量。     

提高离子交换法提取肌苷的收得率

以饲料酵母粉为肌苷发酵主要原料 ,放罐发酵液产肌苷 2 3～ 2 4g/L。通过控制发酵液质量、提高离子交换洗脱流速至 13 0L/min、用碳柱并联的方法使其吸附流速降低至 43L/min ,肌苷提取收得率从月平均 73 %提高到了 79% ,最高批次可达 85 82 %     

高效阴离子交换分离-脉冲安培检测茶叶多糖中的半乳糖、葡萄糖、甘露糖和果糖

建立了高效阴离子交换分离- 脉冲安培检测(HPAE-PAD)同时分离测定茶叶多糖中的半乳糖、葡萄糖、甘露糖和果糖的分析方法。以Metrosep Carb 1(150 × 4.0mm)阴离子交换柱为分离柱,以6.0mmol/L NaOH 溶液将4种单糖从分离柱上洗脱,淋洗液流速为1.0ml/min,总分析时间为45min。在优化的分离条件下4 种单糖的检出限为0.125～2.0mg/L(进样体积20μl,峰高定量)。20mg/L 的半乳糖、葡萄糖、甘露糖和30mg/L 的果糖混标溶液连续7 次进样,峰高的相对标准偏差为5.82%～14.19%,保留时间的相对标准偏差为2.03%～2.26%,样品测定的回收率为91.8%～99.3%。用所建立的方法快速、有效分析了4 种茶叶多糖中的4 种单糖,并得到了满意的检测结果。     

重组核苷磷酸转移酶产生菌培养条件优化

5’-肌苷酸是一种重要的食品增鲜剂。核苷磷酸转移酶能够高选择性地使肌苷5’-位羟基磷酸酯化生成5’-肌苷酸,该反应不需要ATP,具有反应条件温和、反应速度快、位置特异性强、转化率高、环境友好等特点。以实验室前期构建的携带有来自Escherichia blattae磷酸转移酶(AP/PTase)编码基因的重组大肠杆菌E.coli BL21(DE3)/pET28b-AP/PT为菌株,研究了培养基成分对细胞生长和产酶的影响,确定了最优培养基为:甘油7.5 g/L,蛋白胨12.5 g/L,酵母粉10g/L,NaCl 10 g/L,ZnCl2 0.1 g/L,初始pH值7.0。在该条件下,核苷磷酸转移酶酶活达到143.8U/L,比优化前提高了1.0倍。利用该条件下培养获得的菌体为生物催化剂,反应1 h,5′-肌苷酸的摩尔收率达到83.3%,表明该核苷磷酸转移酶对肌苷具有良好的活性。     

高效液相法测定调味品中5’-鸟苷酸二钠和5’-肌苷酸二钠

采用Inertsil ODS-3色谱柱(250mm×4.6mm,5μm);以0.02moL/L磷酸二氢钾溶液(pH4.5)为流动相,流速1.0mL/min,柱温25℃,检测波长250nm,同时分离了样品中5'-鸟苷酸二钠和5'-肌苷酸二钠。结果显示:在选定色谱条件下5'-鸟苷酸二钠和5'-肌苷酸二钠线性关系良好,加样平均回收率为98.6%～100.3%;相对标准偏差0.77%～1.67%。该方法精密度好,结果准确可靠,适合于调味品中5'-鸟苷酸二钠和5'-肌苷酸二钠的定量分析。     

毛细管区带电泳-间接紫外检测法测定饮用水中5种阴离子

目的建立毛细管区带电泳-间接紫外检测法测定饮用水中5种阴离子的新方法。方法样品无需滤膜过滤可直接进样。用未涂覆熔融石英毛细管(75μm×80 cm,有效长度为70 cm)作为分离柱。以20 mmol/L邻苯二甲酸、100 mmol/L二乙醇胺和0.5 mmol/L十六烷基三甲基溴化铵为分离缓冲体系。结果 Cl~-、NO_3~-、SO_4~(2-)、F~-和H_2PO_4~-这5种阴离子的校正峰面积与质量浓度分别在0.5～100.0、0.2～20.0、0.5～100.0、0.2～4.0和0.2～5.0 mg/L范围内呈线性相关,相关系数分别为0.998 8、0.999 9、0.999 7、0.999 7、0.999 8。检出限均为0.05 mg/L,定量限均为0.15 mg/L,方法精密度均小于5%(n=6)。低、中和高质量浓度加标回收率在81.6%～108.6%之间,相对标准偏差在0.6%～3.7%之间(n=6)。用本法分析了7份饮用水样品,并与离子色谱法的结果相比较,除矿泉水中Cl~-结果偏低外,其余基本吻合。结论本方法简单,所用试剂环保,为饮用水中5种阴离子的常规检测提供了一种新方法,但不适合测定水样中低浓度的Cl~-。     

离子色谱-直接紫外检测法测定食品接触材料中的六价铬迁移量

目的建立一种离子色谱-直接紫外检测法测定食品接触材料中六价铬迁移量的新方法。方法样品经碱性食品模拟物(碳酸钠-盐酸,pH=8.5)浸泡后,使用氯化铵-氨水溶液为淋洗液,IonPacA S7(4 mm×250 mm)阴离子分析柱分离,以紫外检测器在350 nm波长直接检测。结果本方法在0.001～0.5 mg/L范围内线性关系良好,线性方程为y=10.8554x+0.00472,r=0.999 9,检出限为0.000 3 mg/L,定量限为0.001 mg/L,样品加标回收率为88%～113%,相对标准偏差(n=6)为1.9%～9.0%。结论本方法具有灵敏度高、准确性好、检出限低、操作简便易行等特点,适用于日常样品检测。     

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