3种海洋鱼油脂肪酸组成及其位置分布

采用米黑根毛霉源固定化脂肪酶(Lipozyme RM IM)对常见的海洋鱼油甘三脂进行水解,分析了凤尾鱼、金枪鱼、三文鱼甘三酯中脂肪酸的组成及位置分布。采用硅胶色谱柱分离3种海洋鱼油甘三脂,利用Lipozyme RM IM的sn-1,3特异性,将酯化在sn-1,3位上的脂肪酸(EFA)水解成游离脂肪酸(FFA),然后通过薄层层析(TLC)分离得到sn-2-单甘酯,再甲酯化后利用气相色谱(GC)测定sn-2位脂肪酸组成,并按照脂肪酸的不饱和程度和n-3,6-多不饱和脂肪酸归类分析海洋鱼油甘三酯中各类脂肪酸位置分布的特点。结果表明:3种海洋鱼油(凤尾鱼油、金枪鱼油、三文鱼油)中不饱和脂肪酸含量达到60%以上,其中单不饱和脂肪酸(MUFA)占24.67%~33.51%,多不饱和脂肪酸(PUFA)占26.89%~36.15%,而且一半以上PUFA分布在sn-2位,有利于其吸收和提高其耐氧化性;而SFA和MUFA倾向于分布在sn-1,3位上。n-3与n-6PUFAs之间的比例均10,均符合FAO/WHO推荐摄入的标准(4),是理想的n-3PUFA天然营养补充剂。     

酶法全酯化合成富含EPA/DHA甘油酯工艺研究

以富含EPA/DHA的脂肪酸为底物,采用两步酶法合成富含EPA和DHA的甘油酯。首先,以T1脂肪酶为催化剂催化富含EPA/DHA的脂肪酸和甘油反应;在最优条件为:反应温度40℃,水分添加量为底物混合物的3%、甘油与脂肪酸摩尔比3∶1和酶添加量50 U/g底物混合物时,富含EPA/DHA的脂肪酸的转化率达到62%以上,此时产物中甘油三酯、甘油二酯、甘油单酯的质量分数分别为10.52%、38.15%、25.64%。将游离酶催化酯化反应产物中的油相回收,利用自制的固定化CALB(LipozymeCALB L固定于环氧树脂ECR8285上)为催化剂,在真空条件下继续催化未反应的脂肪酸与偏甘油酯(甘油单酯和甘油二酯)继续酯化反应12 h,此时产物中甘油三酯、甘油二酯和甘油单酯的质量分数分别达到38.34%、51.02%、10.63%,没有检测到脂肪酸的存在。     

高酸值米糠油酶法酯化脱酸工艺研究

采用油酸单甘酯作为酯化剂,对固定化脂肪酶Lipozyme RMIM催化高酸值米糠油酯化脱酸工艺进行了研究。确定的最佳工艺条件为:游离脂肪酸(FFA)与单甘酯(MG)摩尔比为2∶1,脂肪酶添加量4%(以底物总质量计),反应温度60℃。在最佳工艺条件下反应6 h,FFA含量由原来的19.75%降到1.83%,而TAG和DAG的含量分别增加了20.91%和7.08%。     

两步酶法合成富含EPA/DHA甘油酯的研究

采用两步酶法合成富含EPA/DHA的甘油酯。首先利用游离脂肪酶催化富含EPA/DHA的脂肪酸与甘油进行酯化反应,在水添加量为底物混合物质量的3%、脂肪酸与甘油摩尔比1∶3和酶添加量为底物混合物质量的1%时,酯化反应达到平衡时富含EPA/DHA脂肪酸的酯化率可以达到67%左右。再将游离脂肪酶催化酯化反应产物中的油相回收,利用Novozym 435为催化剂,在真空状态下继续进行酯化反应6 h,富含EPA/DHA脂肪酸的酯化率可以达到96.4%,甘油酯的组成为甘油三酯52.07%、甘油二酯41.9%。     

基于人乳脂肪组成的酶法人乳脂肪替代物的构建

为了开发新型高相似性人乳脂肪替代物,依据中国人乳脂肪的脂肪酸组成和甘油三酯结构,以巴沙鱼油、樟树籽仁油、亚麻籽油、微生物油(富含ARA)及DHA藻油(质量比为153.81∶15.16∶62.33∶7.89∶10.81)为原料油脂,以固定化脂肪酶Lipozyme RM为催化剂,在60℃下酯交换反应8 h制备人乳脂肪替代物,测定其脂肪酸、sn-2位脂肪酸及甘油三酯组成及含量,分析其红外光谱图、熔融性质、结晶性质及流变学性能。结果表明,构建的人乳脂肪替代物中链脂肪酸含量为12%、亚油酸和亚麻酸总含量为19.53%且比例约为1∶1.5,ARA含量为1.17%,DHA含量为1.11%,其sn-2位富含棕榈酸(43.10%),结构甘油三酯含量高(58.75%),无反式脂肪酸生成,熔融温度低于人体温度且在20℃下仍能保持18.7%的固体脂肪含量,结晶形态细腻且流变性能优异。制备的人乳脂肪替代物具有应用于婴幼儿配方奶粉、婴幼儿米糊和婴幼儿饼干等各种婴幼儿食品的潜力。     

DHA单细胞油脂的脂肪酸分布及甘油三酯组成分析

测定了DHA单细胞油脂的总脂肪酸组成,采用脂肪酶Lipozyme 435醇解DHA单细胞油脂获得2-单甘酯(2-MAG),结合薄层色谱法和气相色谱法,分析其脂肪酸分布,并选择超高效液相色谱(UPLC)串联四级杆飞行时间质谱(Q-TOF-MS/MS)在电喷雾离子化(ESI)模式下对DHA单细胞油脂的甘油三酯进行了分离鉴定。结果表明:DHA单细胞油脂中含量较高的脂肪酸是DHA(51.37%)、棕榈酸(31.13%)和DPA(10.78%);sn-2位DHA和DPA含量分别为72.65%和18.21%,sn-1,3位棕榈酸含量为43.61%;DHA和DPA平均分布在甘油三酯的sn-1,3位和sn-2位,棕榈酸主要分布在sn-1,3位。DHA单细胞油脂中含量较高的甘油三酯是22∶6-22∶5-16∶0(12.76%),22∶5-16∶0-16∶0(8.93%),22∶6-22∶6-22∶6(8.78%),22∶6-22∶6-22∶5(6.62%),16∶0-16∶0-16∶0(6.61%),占总甘油酯的43.7%。     

酶法醇解-气相色谱法分析中长碳链甘油三酯sn-2脂肪酸

建立了一种测定中长碳链甘油三酯sn-2脂肪酸的分析方法。将中长碳链甘油三酯利用Novozym435酶法醇解得到2-单甘酯,采用BSTFA-TMCS(体积比99∶1)硅烷化衍生后通过气相色谱仪分析测定sn-2脂肪酸。最优测定条件为:200 mg油脂样品,脂肪酶添加量88 mg,反应温度30℃,反应时间2 h,硅烷化试剂添加量200μL,HP-5MS毛细管气相色谱柱(60 m×0.25 mm×0.25μm),柱温从100℃以5℃/min升温至180℃,再以1℃/min升温至230℃,再以5℃/min升温至300℃。该方法用于分析中长碳链甘油三酯样品准确可靠,重复性良好,RSD小于1.5%,分析长链甘油三酯样品时,结果与猪胰脂肪酶法、Novozym435法结果一致,RSD均小于5%。     

超临界CO2体系下酶法制备中碳链甘三酯的研究

中碳链甘三酯作为一种低能量的油脂因其特殊的生理功能和代谢途径得到了广泛的应用,本文以甘油和辛酸、癸酸混合物为原料,研究在超临界CO_2体系下酶法制备中碳链甘三酯的工艺条件,并对酯化产物进行分析。通过脂肪酶的比较,得出脂肪酶Novozyme 435优于Lipozyme RM IM,因此,选用脂肪酶Novozyme435为催化剂,以中碳链甘三酯得率为指标,通过响应面法对工艺条件进行优化,得出最佳反应条件为:反应压力9.1 MPa、反应温度90℃、酶添加量4.2%、底物摩尔比3∶1和反应时间10.2 h。在此反应条件下中碳链甘三酯的得率为95.1%,酯化率为98.62%。该方法有效的提高了脂肪酸的利用率及MCT得率,所得酯化产物色泽较浅。     

酶法合成1-油酸-2-棕榈酸-3-亚油酸甘油三酯结构脂的研究

在Lipozyme RM IM脂肪酶的催化作用下,将分提后的棕榈硬脂与油酸和亚油酸反应,通过酶法酸解合成富含1-油酸-2-棕榈酸-3-亚油酸甘油三酯(OPL)的结构脂,通过单因素实验对酶法合成反应条件进行了优化。结果表明,合成OPL结构脂的最优反应条件为:棕榈硬脂、油酸、亚油酸摩尔比1∶7∶7,酶添加量8%,反应温度60℃,反应时间6 h。在最优条件下,进行50倍放大实验,合成产物中OPL和sn-2位棕榈酸的含量分别为48.37%和84.70%。     

褐点石斑鱼鱼肉及其副产物的脂肪酸分析

为了评估褐点石斑鱼的脂肪酸组成特点,采用固相萃取和气相色谱技术对鱼肉、头、皮和内脏的脂质含量、总脂及各脂类脂肪酸组成,甘油三酯(triacylglycerols, TAG)和磷脂(phospholipids, PL)中脂肪酸的位置分布进行了较全面的分析。石斑鱼鱼头和内脏中含有丰富的糖脂(saccharolipids, SL)和PL。在各组织总脂中,必需脂肪酸的含量占总脂肪酸的24.17%～24.51%,二十二碳六烯酸(docosahexaenoic acid, DHA)及二十碳五烯酸(eicosapentaenoic acid, EPA)的含量为12.42%～13.73%,动脉粥状硬化指数、血栓形成指数和n-6/n-3的比例处于较低水平。多不饱和脂肪酸(polyunsaturated fatty acids, PUFA),尤其是DHA+EPA(28.43%～37.37%)在PL中的比例要远高于在其它脂类中的占比。饱和脂肪酸主要分布在TAG和PL的sn-2位,单不饱和脂肪酸主要分布在TAG的sn-1,3位和PL的sn-2位,PUFA倾向于分布在TAG的sn-1,3位和PL的sn-1位;T...     

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.     

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.     

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.     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.