磷脂酶D催化合成磷脂酰丝氨酸的工艺研究

本文研究了磷脂酶D催化合成磷脂酰丝氨酸的工艺,实验结果表明有机相和水相比例、磷脂酰胆碱(PC)浓度、反应温度、水相pH以及反应时间都对磷脂酰丝氨酸的制备有一定的影响。通过正交实验优化利用磷脂酶D催化合成磷脂酰丝氨酸的最佳工艺为:有机相和水相的比例为4/4、PC浓度为75mg/mL、反应温度为40℃、水相pH值为4.0、反应时间为12h,在此工艺条件下磷脂酰丝氨酸得率为:68.9%。     

己烷体系中磷脂酶A1催化卵磷脂乙醇解制备溶血卵磷脂的研究

在己烷体系中,采用磷脂酶A1催化卵磷脂乙醇解制备溶血卵磷脂。首先通过单因素试验分别考察了加酶量、加水量、底物比、温度和溶剂比对卵磷脂乙醇解制备溶血卵磷脂的影响,并在此基础上利用响应面法对反应工艺进行了优化。最终确定最佳工艺条件为:卵磷脂1.5 g,加酶量40μL/g(磷脂酶A1/卵磷脂),加水量25μL/g(水/卵磷脂(PC)),底物比:1∶3(PC/无水乙醇,mol/mol),温度30℃,溶剂比:1∶2(PC/正己烷,W/V),反应时间3.55 h,溶血磷脂转化率达98.3%。结果表明,磷脂酶A1可以催化磷脂酰胆碱乙醇解反应制备溶血磷脂酰胆碱。     

氧化铝吸附提纯大豆卵磷脂的工艺研究

以溶剂粗提后的大豆卵磷脂粗品为原料,采用氧化铝吸附法进行提纯.系统考察了氧化铝用量、乙醇用量、吸附时间和吸附温度等因素对大豆卵磷脂粗品中磷脂酰胆碱(PC)纯度及回收率的影响,得到最佳工艺条件为:大豆卵磷脂粗品与氧化铝质量比为1∶5,大豆卵磷脂粗品与无水乙醇配比为1∶60(m/v),吸附时间60min,吸附温度30℃.在此条件下,PC的纯度和回收率分别为70.23％和83.07％.     

鲢鱼头磷脂的提取工艺优化及乳化性能研究

用乙醇溶液提取鲢鱼头中的磷脂并分析其乳化性能。通过单因素试验和正交试验优化鲢鱼头磷脂的提取条件;利用薄层层析分析鲢鱼头磷脂的组成,气相色谱-质谱联用仪分析鲢鱼头磷脂脂肪酸组成并与大豆卵磷脂比较;分别探究了磷脂质量浓度、离子强度、p H和温度对磷脂乳化特性的影响。结果表明:鲢鱼头磷脂的最优提取条件为乙醇体积分数80%、料液比1∶10、提取温度35℃、提取时间3 h,在此条件下磷脂纯度为74. 45%,磷脂产物提取率为3. 35%。鲢鱼头磷脂PC和PE的含量高于大豆卵磷脂;两者脂肪酸都以多不饱和脂肪酸为主,但鲢鱼头磷脂以C22∶6n-3为主,大豆卵磷脂以C18∶2n-6为主。在试验范围内,磷脂的乳化能力随着其质量浓度的增加而增强,且鲢鱼头磷脂的乳化能力略低于大豆卵磷脂的;无离子环境中两种磷脂的乳化能力较好;鲢鱼头磷脂和大豆卵磷脂皆在pH为7时乳化效果最佳;低温条件下两种磷脂乳化能力较好。总体来看,鲢鱼头磷脂的乳化特性与大豆卵磷脂的接近。     

酶法合成富含二十二碳六烯酸的磷脂酰丝氨酸

通过以鱿鱼卵磷脂和L-丝氨酸为原料,对磷脂酶D催化酰基转移反应制备磷脂酰丝氨酸(phosphatidylserine,PS)的工艺条件进行探索,并进行了优化试验,确定反应的最佳工艺。通过单因素试验法分别探讨有机相种类、反应温度、水相p H、有机相水相体积比、底物质量比、酶量、反应时间等因素对PS合成率的影响,得到初步优化条件。之后,做四因素三水平的正交试验,优化制备PS的工艺条件。最优工艺条件:水相p H4.5、有机相水相体积比5∶6、反应温度40℃、酶量40 U、底物质量比1∶32、反应时间6 h。在该条件下PS合成率为97.65%,DHA含量为33.10%。     

化学催化制备富含共轭亚油酸的改性磷脂

在无溶剂体系中,使大豆卵磷脂与共轭亚油酸乙酯发生酯交换反应,以制备富含共轭亚油酸(CLA)的改性磷脂。研究了催化剂种类、催化剂用量(基于磷脂的质量)、反应时间、反应温度、物料比(大豆卵磷脂与共轭亚油酸乙酯的质量比)对改性磷脂制备的影响,并通过气相色谱对改性磷脂的脂肪酸组成进行定量分析。结果得出优化的制备条件为:甲醇钠(30%甲醇溶液)为催化剂,催化剂用量2.0%,反应时间8 h,反应温度130℃,物料比1:5。在此条件下,产物改性磷脂中CLA含量可达29.18%。     

直链淀粉/大豆卵磷脂包合物的制备及其性质研究

目的:为了制备直链淀粉-大豆卵磷脂包合物并优化包合工艺以及对制得的直链淀粉包结络合大豆卵磷脂样品的结构性质进行分析研究。方法:本文以木薯淀粉为原料,加入普鲁兰酶酶解制备直链淀粉;在酶解后的淀粉中加入大豆卵磷脂溶液,制备直链淀粉-大豆卵磷脂包合物;通过单因素实验考察大豆卵磷脂的添加量、反应时间、反应温度对直链淀粉包结络合大豆卵磷脂反应效率的影响,采用X-射线衍射(XRD)、傅立叶变换红外光谱(FT-IR)、~(13)C固体核磁共振谱(~(13)C CP/MAS NMR)和差示扫描量热法(DSC)表征其结构。结果:直链淀粉-大豆卵磷脂包合工艺的最佳条件为:每克木薯干基淀粉添加0.16 g大豆卵磷脂,反应时间2 h,反应温度60℃。在最佳条件下得到包合物中大豆卵磷脂的含量为116.28 mg/g,包合率达到63.02%。XRD、FT-IR、DSC结果表明直链淀粉与大豆卵磷脂发生了包结络合作用,~(13)C CP/MAS NMR结果表明是与大豆卵磷脂上的脂肪酸烃基发生了包结络合,大豆卵磷脂分子的其他基团位于直链淀粉螺旋空腔的外部。     

大豆卵磷脂的酶法改性研究

利用实验室自制的液态磷脂酶A2，水解大豆卵磷脂得到溶血卵磷脂。设计了正交实验研究该磷脂酶A2在水浴中静止水解大豆卵磷脂的最佳工艺条件：底物浓度为4％，反应温度30℃，起始pH值7．5，Ca^2＋浓度0．10％，反应时间13h。在最佳条件下，得到的产物经酸碱滴定法及HPLC检测，大豆卵磷脂的转化率为86．30％。     

脂肪酶催化大豆卵磷脂和亚油酸酯交换反应的研究

采用Lipozyme TL IM酶催化大豆卵磷脂(90%)和亚油酸(95%)进行酯交换反应,以制备富含亚油酸的卵磷脂.探讨了大豆卵磷脂质量浓度(甲苯为溶剂)、底物摩尔比(n(亚油酸):n(大豆卵磷脂))、酶添加量(以底物总质量为基准)、水分添加量(以酶质量为基准)、反应时间、反应温度对酯交换反应的影响.优化后的反应条件为:大豆卵磷脂质量浓度0.25g/ml,底物摩尔比6:1,酶添加量20%,水分添加量3%,反应时间60h,反应温度65℃.在最优反应条件下最终获得82.85%亚油酸含量的卵磷脂产品.     

响应面优化脂肪酶催化酸解合成共轭亚油酸磷脂

采用商业化脂肪酶Lipozyme RM IM作为生物催化剂,催化共轭亚油酸(CLA,80％)和大豆磷脂( PC90)酸解反应合成富含CLA的结构磷脂.利用响应面分析方法研究了在正己烷溶剂体系中,底物摩尔比、酶用量、反应温度和反应时间对产物中CLA含量的影响.通过分析验证得到最佳反应条件为∶CLA与大豆磷脂的摩尔比6∶1,酶用量30％(以底物总质量计),反应温度48℃,反应时间64 h.在最佳反应条件下,产物中CLA的含量为24.18％.     

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.     

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.     

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