木质素模型化合物在Co-salen型仿酶降解体系中的结构变化

用由Co-8alen、吡啶、H2O2、O2组成的Co-salen型仿酶体系对β-O-4型木质素模型化合物--愈创木基丙三醇-β-愈创木基醚进行仿酶降解,并用GC-MS等方法分析β-O-4型木质素模型化合物在降解过程中的结构变化,并在此基础上初步探讨了Co-salen型仿酶体系对木质素的降解机理.结果表明:Co-saJen型仿酶体系埘β-O-4型木质索模型化合物有较强的降觯能力,降解后产生一系列含羟基、醛基和羧基的芳香族低分子化合物,根据反应产物的结构可以说明β-O-4型木质素模型化合物的主要降解途径为β-O-4醚键、Cα-Cβ键、烷基-芳基键的断裂和苯环开环反应等.     

臭氧氧化后麦草碱木质素磺化反应性能的研究

首次对O3/H2O2氧化降解木质素产物进行改性研究,测定了不同氧化反应条件下的碱木质素磺化改性后的物化性能.在O3用量5%、温度20℃、pH值11.68、H2O2的用量2.5%的氧化反应后的氧化木质素,经高温磺化后,磺酸基含量最大;此时,木质素产品的表面活性也较好;在H2O2用量为10%、pH值7.08、温度20℃、O3用量5%的O3/H2O2氧化反应条件下,氧化木质素经过高温磺化后,分散性能大大改善.     

β_2-(TBA)_6SiW_(11)O_(39)Co的合成及光催化性能研究

制备了β_2-(TBA)_6[SiW_(11)O_(39)Co(H2O)]·x H2O多酸电荷转移配合物,用IR、UV、XRD等方法进行了表征。以β2-(TBA)6[SiW11O39Co(H2O)]·x H2O作为光催化反应的催化剂,分别催化降解龙胆紫和亚甲基蓝染料溶液。实验结果表明:初始质量浓度为15mg/L的龙胆紫溶液,加入80 mg/Lβ2-(TBA)6[SiW11O39Co(H2O)]·x H2O,pH=5时,在太阳光下照射140 min,脱色率达85.16%;初始质量浓度为15 mg/L的亚甲基蓝溶液,加入160 mg/Lβ2-(TBA)6[SiW11O39Co(H2O)]·x H2O,pH=4时,在太阳光下照射140 min,脱色率达72.77%。     

硅胶负载邻菲罗啉亚铁类Fenton降解水中罗丹明B

采用H2O2为氧化剂,自制硅胶负载邻菲罗啉铁(Ⅱ)配合物[Phen-Fe(Ⅱ)]为催化剂,对罗丹明B(Rh B)进行催化氧化降解.研究了催化剂质量比和用量、H2O2用量、反应温度和反应初始p H等因素对降解率的影响,并对Rh B的降解产物进行了初步分析.结果表明,对于20 mg/L Rh B溶液,当Phen-Fe(Ⅱ)催化剂质量比为1∶1,用量为3 g/L,H2O2用量为0.6 g/L,在40℃和初始p H=11.0的条件下降解6 h,其降解率可达70%.研究表明,Phen-Fe(Ⅱ)具有良好的催化效果.     

碳纤维负载钴酞菁降解染料的研究

采用碳纤维负载钴酞菁和苯磺酸钠制备出对活性染料具有高效降解的新型催化功能纤维(CoPc-CF),讨论了温度、pH对CoPc-CF/H2O2体系催化氧化染料性能的影响,并研究了在无机盐(NaCl、Na2SO4)和异丙醇存在下对染料催化降解速率的影响,以及不同活性染料对其催化降解性能的影响。结果表明:提高温度,能明显促进染料的氧化降解;CoPc-CF/H2O2体系在中性和弱碱性中都具有较好的催化降解性能;NaCl和Na2SO4的存在对CoPc-CF/H2O2体系的催化氧化没有影响,而异丙醇的加入有明显地抑制作用;CoPc-CF/H2O2体系对不同活性染料催化氧化速率有很大的影响。     

基于Py-GC/MS技术的Pd/C催化乙醇木质素热解油特性研究

以毛竹为原料,结合Py-GC/MS热裂解技术,研究不同球磨处理过程中Pd/C催化剂加入对乙醇木质素热裂解油组成的影响作用。实验结果表明:乙醇木质素提取过程加入Pd/C催化剂对木质素得率产生明显影响作用。球磨3d,2%Pd/C催化剂对乙醇木质素的得率提升作用最大,其得率为43.81%。乙醇木质素热裂解产物主要为酚类物质,愈创木酚和苯酚类物质含量较高。球磨处理程度和Pd/C催化剂加入量对单酚产物组成产生影响,其中,Pd/C催化剂用量增加导致2-甲氧基苯酚得率增加。     

不同氧化剂对禾草类碱木质素结构变化的影响

研究了禾草类碱木质素在O2、H2O2、O3、O2/H2O2、O3/H2O2等不同氧化剂氧化时其结构的变化规律,为更好地利用禾草类碱木质素提供理论依据和工艺方法。研究结果表明,以O2/H2O2氧化禾草类碱木质素时,高用碱量可促进木质素高分子组分氧化降解,分子质量均一化,酚羟基和羧基增加较多,脱甲氧基反应也较强烈;低用碱量时,木质素氧化降解少,并伴有缩合反应;H2O2可促进碱木质素氧化降解,促进酚羟基、羧基的产生和脱甲氧基反应;在O3氧化适宜条件下,添加H2O2可使O3氧化反应缓和,木质素分子发生缩合并均一化,生成较多的酚羟基、羧基和羰基。     

重组漆酶降解黄曲霉毒素B1分子对接分析及产物结构解析

以重组漆酶lac3基因同源性最高的3KW7作为模板进行同源模建,采用分子对接预测漆酶与黄曲霉毒素B1（aflatoxin B1,AFB1）的结合模式,结果显示漆酶与AFB1可以相互作用,氢键是其关键作用力,漆酶可用于黄曲霉毒素的降解。随后,通过实际的降解实验进行验证,响应面优化获得AFB1降解率最优的条件为底物AFB1 1 μg、孵育时间15 h、孵育温度34 ℃、酶活力2 U,降解率可达91.08%。在此条件下利用超高效液相色谱-飞行时间串联质谱分析AFB1降解产物结构,发现4 个主要降解产物,根据其二级质谱信息和精确分子质量,推测出降解产物的分子式分别为C16H22O4、C14H16N2O2、C7H12N6O和C24H30O6。     

ZnSn（OH）6/Zn2SnO4复合粉体的制备及其光催化性能的研究

以Zn(NO3)2·6H2O和SnCl·5H42O为原料,NaOH为沉淀剂,采用水热法制备了ZnSn(OH)6/Zn2SnO4复合材料,样品的组成和带隙能分别采用X射线粉末衍射(XRD)和紫外-可见漫反射能谱(DRS)进行了表征;探讨了水热反应温度和p H对产物成分的影响,得出ZnSn(OH)6/Zn2SnO4复合材料的最佳制备条件:水热反应温度180℃,p H=10;并以亚甲基蓝为降解对象,研究了ZnSn(OH)6/Zn2SnO4复合材料的光催化性能,结果表明,在15 W紫外灯(λ=365 nm)下照射150 min后,亚甲基蓝的降解脱色率可达99.2%.     

Fe_2O_3/膨润土光催化Fenton降解造纸法烟草废水

以膨润土作为载体,制备Fe2O3/膨润土光催化剂,利用Fe2O3/膨润土光催化Fenton深度处理造纸法烟草薄片废水,单因素考察p H值、H2O2用量、催化剂用量、反应时间等因素对降解效果的影响,并对降解动力学和反应机理进行分析。结果表明:在初始p H 3.0,H2O2用量2.5 mg·L-1,催化剂用量1750 mg·L-1,反应时间180 min的条件下,废水CODCr去除率达到80.78%;动力学研究表明,该废水催化降解反应符合一级动力学模型,Fe2O3/膨润土光催化剂具有较高的稳定性和较好的可重复实用性。     

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.     

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.     

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.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

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.