共轭亚油酸异构体生理功能的差异

介绍了共轭亚油酸不同异构体在降低机体脂肪积累、抗肿瘤、抗动脉粥样硬化以及免疫调节方面的研究,讨论了不同共轭亚油酸异构体,尤其是顺9,反11-共轭亚油酸(c9,t11-CLA)和反10,顺12-共轭亚油酸(t10,c12-CLA)在生理功能上的差异,以期更有效地利用不同CLA异构体实现特有的生理功能。     

c9t11- 和t10c12- 共轭亚油酸抗癌和影响脂质代谢的异同

共轭亚油酸(CLA)是一组位置和构象异构体的总称,异构体c9t11-CLA 和t10c12-CLA 或二者的协同作用赋予了CLA 的许多生理功能,比如抗癌、降低体脂含量、预防糖尿病的发生、降低血脂抑制动脉粥样硬化等;异构体c9t11-CLA 和t10c12-CLA 在结构及来源上存在一定差别--由于双键位置的不同,t10c12-CLA 异构体比c9t11-CLA 异构体更容易氧化;而在生理功能上二者也有差异-- c9t11-CLA 异构体的主要作用是抗癌,而 t10c12-CLA 则是降低体脂、血脂等,大量单一异构体的体外实验研究表明二者在抗癌及脂肪代谢的调节上作用机制也不尽相同。     

瘤胃细菌生物合成共轭亚油酸的累积特性

为了解瘤胃细菌生物合成共轭亚油酸(CLA)的特性,通过毛细管电泳(CE)分析,发现瘤胃细菌生物合成CLA的主要异构体有c9,t11-CLA、t10,c12-CLA和t9,t11-CLA 3种。在厌氧和有氧条件下,瘤胃细菌均能合成CLA,且氧气有利于CLA的累积,随反应时间的延长,CLA的量呈现先增加后减少的变化趋势。结果表明瘤胃细菌参与了反刍动物体内CLA异构体的生物合成与代谢,瘤胃细菌生物合成CLA异构体的特异性还有待更深入的研究。     

响应面优化法尿素包合法分离共轭亚油酸2种异构体

目的优化尿素包合法,对共轭亚油酸2种主要异构体c9, t11-CLA和t10, c12-CLA进行分离(2种异构体比例近1:1)。方法在单因素实验基础上,以温度、尿素与油比例、乙醇与油比例3个因素为自变量,以t10, c12-CLA/c9, t11-CLA为响应值,利用响应面法优化了共轭亚油酸异构体的分离。结果优化后的实验条件为:在乙醇作溶剂的情况下,将共轭亚油酸、尿素和乙醇按1:2.5:5(V:V:V)配比,置于75℃水浴锅中水浴溶解,室温下搅拌冷却结晶。所得样品中t10,c12-CLA与c9,t11-CLA的比值高达2.47,且共轭亚油酸总量为97.3%。结论优化后的尿素包合法可有效分离CLA的2种异构体,提高t10, c12-CLA比例。     

新型食品营养强化剂-共轭亚油酸

共轭亚油酸 (Conjgatedlinoleicacid ,CLA)是一类含有共轭双键的亚油酸的异构体 ,由于具有特殊的脂肪链结构使得其具有多种生理功能。c9t11和t10cl2异构体是共轭亚油酸的主要活性异构体。本文对共轭亚油酸的生理功能、代谢、安全性等进行综述。     

西北牧区牧民自制酸奶中c9,t11-CLA含量的研究

共轭亚油酸（CLA）是亚油酸的一组几何和位置异构体,具有多种生理功能。反刍动物肉、乳制品是c9,t11-CLA丰富的天然来源。本研究用气相色谱法测定青海、甘南、天祝和肃北4个不同牧区牧民自制酸奶中c9,t11-CLA的含量,并与市售酸奶和牦牛乳中的含量进行对比。结果表明：采用该方法使牧区酸奶中c9,t11-CLA得到很好的分离,测得青海、甘南、天祝和肃北牧区酸奶中c9,t11-CLA的含量分别为1．007、0．782、0,987、1．196rag／ml酸奶;牧区自制酸奶中c9,t110CLA的含量与市售酸奶中的含量差异不显著（p〉0．05）：但含量极显著低于牦牛乳（p〈0．01）。     

优化乳杆菌高产共轭亚油酸的研究进展

共轭亚油酸(CLA)是亚油酸(LA)的一组位置和空间异构体的总称,其中具有生理活性的异构体是c9,t11-CLA和t10,c12-CLA,它们具有丰富的营养价值和医药价值。在乳球菌属和链球菌属等乳酸菌、丙酸杆菌、瘤胃细菌以及其它菌属中,分离纯化得到的亚油酸异构酶,可催化LA异构化为CLA,利用酶法合成CLA可以有效弥补传统化学合成法的缺陷。本文概述了近年来国内外利用紫外、微波、等离子体诱变、离子注入等物理或化学方法诱变、改造亚油酸异构酶,优化产酶条件和酶学特性,还阐述利用定点突变、基因敲除等基因工程方法,对生产菌株进行改造和培养条件优化,提高CLA产量的相关研究,为进一步筛选出高产共轭亚油酸菌株和CLA的产业化应用提供理论依据。     

一种共轭化植物油的光化学制备方法

对共轭化植物油的光化学制备方法进行了研究,考察了引发剂DPIS用量、溶剂种类、植物油质量浓度、温度等因素对共轭化反应的影响。结果表明:在玉米油40 g,环己烷300 mL,72℃,引发剂用量0.2%条件下,玉米油可在30 min内被完全共轭化。利用核磁共振氢谱和气相色谱分析了光化学共轭化玉米油中脂肪酸的组成,其共轭亚油酸(CLA)异构体主要为t9,t11-CLA(含量39.10%),与碱法共轭产品中CLA主要为c9,t11-CLA和t10,c12-CLA有明显区别。     

酶法拆分制备共轭亚油酸功能单体

研究利用Lipase AYS催化甲醇和共轭亚油酸(CLA)进行酯化反应,以期对共轭亚油酸异构体进行拆分制备共轭亚油酸功能单体。通过考察酯化反应的影响因素,确定了最优反应条件为:Lipase AYS加酶量180 U/g,反应温度40℃,CLA与甲醇摩尔比1∶1,缓冲液p H 6.5。在最优条件下反应8 h,总酯化率为49.5%,分离产物可以得到甲酯相与脂肪酸相,甲酯相中c9,t11-CLA甲酯的拆分效率达到86.2%,脂肪酸相中t10,c12-CLA的拆分效率达到80.0%,两者回收率分别为72.4%和54.2%。     

共轭亚油酸生理功能及其合成方法

共轭亚油酸（CLA）为亚油酸（LA）的异构体,具有抗癌、降脂、调节免疫、抗粥样硬化等重要的生理功能,目前共轭亚油酸（CLA）的生产大都是利用碱催化亚油酸异构而成,但其异构体繁多。利用微生物转化生产的共轭亚油酸（CLA）,异构体较少,与天然食品中的CLA异构体组成相似,具有很好的商业前景。     

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