正交试验优化染料木素-锌配合物合成工艺

以天然活性成分染料木素为配体,与锌金属离子配位,合成染料木素-锌配合物。以配合物产率为考察指标,采用单因素试验和L_9(3~4)正交试验设计确定染料木素-锌配合物的最佳合成工艺条件,同时采用紫外光谱法和红外光谱法对染料木素-锌配合物进行了结构表征。结果表明,合成工艺中各因素的影响次序为反应pH反应温度反应时间,染料木素-锌配合物的最优合成工艺条件为反应pH 9.0、反应温度60℃、反应时间6 h,此条件下配合物的产率达39.67%。结构表征结果初步显示染料木素是通过4位羰基和5位羟基与锌金属离子进行配位的。筛选的合成工艺可有效提高染料木素-锌配合物的产率。     

芹菜素-铜(Ⅱ)配合物研制及其清除自由基活性

黄酮类化合物是一类天然的抗氧化剂,有着广泛的药理活性,但大部分黄酮的生物活性与生物利用率都比较低,而大量的研究发现黄酮类金属配合物能提升黄酮稳定性、水溶性及清除自由基能力。实验在乙醇-水混合溶剂中合成了芹菜素-铜(Ⅱ)配合物[Cu(AP)_2(H_2O)]·H_2O(AP=芹菜素阴离子),采用元素分析、红外光谱、紫外可见光谱、热重分析、电导率测定、铜(Ⅱ)滴定等方法确定其组成及结构,推断出芹菜素与铜(Ⅱ)的配位点为4-羰基及5-羟基,配位比为2:1,配合物分子为一变形的四方锥结构。同时着重分别通过NBT光照还原、Fenton反应和抗脂质过氧化方法研究了该配合物对超氧阴离子自由基、羟基自由基及过氧自由基的清除作用。结果表明,相对于芹菜素,配合物具有较强的清除自由基能力。     

聚丙烯酸与锌配合物鞣剂合成条件的研究

本文以丙烯酸和氯化锌为原料，采用溶液聚合的方法，对丙烯酸单体进行聚合，然后再与锌离子配合，生成一种配合物鞣剂。实验中运用正交试验的方法，对合成条件进行了优选，研究并讨论了合成路线、单体浓度、引发剂用量、反应时同、稳定剂用量等因素对合成反应的影响，从而得出了合成聚丙烯酸与锌配合物鞣剂的最佳合成条件．     

聚丙烯酸与锌配合物鞣剂合成条件的研究

本文以丙烯酸和氯化锌为原料,采用溶液聚合的方法,对丙烯酸单体进行聚合,然后再与锌离子配合,生成一种配合物鞣剂.实验中运用正交试验的方法,对合成条件进行了优选,研究并讨论了合成路线、单体浓度、引发剂用量、反应时间、稳定剂用量等因素对合成反应的影响,从而得出了合成聚丙烯酸与锌配合物鞣剂的最佳合成条件.     

木犀草素-锡(Ⅱ)配合物合成的工艺研究

探究了木犀草素与锡(Ⅱ)配合物的最佳合成条件,制备木犀草素-锡(Ⅱ)配合物以作进一步的活性研究.以木犀草素与锡(Ⅱ)配位反应生成的配合物在乙醇溶液中吸光度大小为指标,在单因素实验的基础上,利用正交实验法探讨了配位反应溶液pH、原料物质的量比、反应液温度以及反应时间的影响,并探究配合物的UV-Vis特征.结果表明,最佳的合成条件为溶液pH4.5,木犀草素与氯化亚锡的物质的量比为1∶2.5,反应液温度为35℃,反应时间为5h.反应溶液pH对配合物的生成影响最显著,反应时间次之,原料物质的量比较小,温度影响最小.在最佳工艺条件下制备了木犀草素-锡(Ⅱ)配合物,产率为75.14％.     

橙皮苷-锌金属配合物合成工艺的正交试验优化研究

以橙皮苷和氯化锌配合物为原料合成橙皮苷-锌配合物。以产率为考察指标,通过单因素和L9(34)正交试验设计确定了合成橙皮苷-锌配合物的最佳反应条件。结果表明,各因素影响次序:橙皮苷用量反应p H反应温度反应时间。橙皮苷与氯化锌用量比为4∶1,反应p H 10.0,反应温度45℃,反应时间45 min,此条件下配合物产率达59.41%。傅里叶红外光谱仪对橙皮苷及其配合物进行了结构表征。     

芹菜素席夫碱金属配合物的合成及抗氧化活性研究

芹菜素(AP)是一种天然的抗氧化剂,具有多种生物活性,但是存在药效低、开发利用低等问题。为了提高芹菜素的开发应用和药效,本研究对芹菜素进行结构修饰,制备了芹菜素席夫碱金属衍生物,并采用紫外(UV),红外(UV),差热-热重分析(DSC-DTG)等波谱分析方法表征化合物。采用水杨酸法和邻苯三酚-NBT法评价芹菜素和其衍生物的体外清除羟基自由基(·OH)和超氧自由基(O2-·)活性。通过表征,合成了两种新的芹菜素席夫碱金属配合物,即[Co(C22H16O4N)2(H2O)2]·8H2O和[Zn(C22H16O4N)2(H2O)2]·4H2O配合物,AP、[Co L2]和[Zn L2]清除·OH自由基的IC50为880.65±46.52μg/m L,517.12±16.36μg/m L,633.62±18.95μg/m L;清除O2-·自由基的IC50为116.30±3.94μg/m L,61.13±0.05μg/m L,48.56±0.32μg/m L,合成的配合物相对芹菜素抗氧化活性增强,有望开发出一种新型抗氧化性食品添加剂,为芹菜素的开发及抗氧化剂的研究提供理论研究基础。     

美味牛肝菌多糖锌配合物的制备

研究美味牛肝菌多糖锌配合物的最佳制备工艺条件.用火焰原子吸收分光光度计(FAAS)测得配合物中锌元素含量.结果表明:最佳合成工艺条件为硫酸锌浓度0.45 mol/L,多糖浓度0.9 g/mL,反应温度90℃、反应时间4 h,制备的牛肝菌多糖锌配合物中锌含量为2.643 2 μg/g.     

超声辅助低共熔溶剂提取芹菜叶中的芹菜素及其抗氧化性分析

以芹菜叶粉末为原料,芹菜素含量为指标,优化超声辅助低共熔溶剂提取芹菜叶中芹菜素的提取工艺。用筛选的最优低共熔溶剂进行单因素试验,考察含水量、液料比、超声时间、提取温度对芹菜素含量的影响。在单因素的基础上,利用Box-Behnken响应面优化提取条件。AB-8型大孔树脂纯化提取液后,利用紫外可见光谱和液质联用对芹菜素纯化物进行分析和验证。最后,研究了芹菜素纯化物的抗氧化性。结果表明:低共熔溶剂(氯化胆碱/乙醇)比80%乙醇提取芹菜素的效率高17.78%。最优提取条件为:液料比40:1;含水量24%;超声时间14 min;提取温度42℃。此条件下得到的芹菜素含量为16.87 mg/g。芹菜素纯化物对DPPH、ABTS自由基具有良好的清除能力,对OH自由基清除效果更好,其IC50分别为82.44、148.92和8.69μg/mL,但均低于抗坏血酸和芹菜素标准品的清除能力。该绿色环保的低共熔溶剂能高效提取芹菜叶中芹菜素,且能够保持良好的抗氧化活性。     

多肽-锌配合物的生物功能活性及安全性

多肽-锌配合物是一种具有多种生物功能活性的新型有机金属化合物,该配合物主要来源于三个方面：一是通过人工制备的多肽与Zn2+的配合作用合成多肽-锌配合物,二是通过动植物蛋白质酶解获取的多肽与Zn2+的配合作用合成多肽-锌配合物,三是从动植物组织中直接提取多肽-锌配合物。由于构成多肽-锌配合物的配基多肽的不同而具有不同的组成和结构,从而体现出不同的生物功能活性,包括抗菌抑菌、生理机能调节和免疫调节、抗氧化作用等。本文就国内外对多肽-锌配合物的生物功能活性及安全性的研究现状、最新研究进展及未来研究方向等方面进行综合阐述。提出今后应加强对其毒理学特性和应用安全性方面的研究,以推进多肽-锌配合物的实际应用和产业化开发。     

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.