辣根过氧化物酶催化淀粉接枝丙烯酸/丙烯酸甲酯

以辣根过氧化物酶(HRP)/乙酰丙酮(ACAC)/过氧化氢(H2O2)为引发剂,催化淀粉接枝丙烯酸/丙烯酸甲酯。采用裂解-气相色谱/质谱联用仪、热重分析、凝胶渗透色谱法表征了接枝淀粉的结构,并测试浆液的粘附性能。结果表明:在HRP酶催化作用下,丙烯酸与丙烯酸甲酯以交替共聚形式接枝至淀粉主链;大量支链小分子提高了接枝淀粉相对分子质量;接枝产物有较好的热稳定性;接枝淀粉浆液对纯棉及涤棉粗纱的粘附性能较原淀粉均有所改善。     

辣根过氧化物酶催化淀粉接枝丙烯酸甲酯浆料制备及其上浆性能

为改善淀粉浆液对涤棉混纺纱的黏附性和浆膜的力学性能,采用辣根过氧化物酶(HRP)/乙酰丙酮(ACAC)/过氧化氢(H2O2)引发体系,催化酸解淀粉接枝丙烯酸甲酯。通过傅里叶红外光谱、扫描电子显微镜和X射线衍射对接枝淀粉进行表征,并分析其流变特性。结果表明,在HRP酶催化作用下丙烯酸甲酯与未糊化酸解淀粉发生接枝共聚反应,且对酸解淀粉结晶度影响不大;淀粉接枝改性后浆液黏度增大,黏弹性增加,呈现更具弹性的流体特征;相比于酸解淀粉,含有柔性接枝支链的淀粉浆液对涤/棉黏附性有明显提高,浆膜断裂伸长率和断裂强度均有增加,力学性能得到改善。     

HRP催化没食子酸与对氨基苯磺酸共聚物的制备及性能研究

没食子酸(GA)与对氨基苯磺酸(SAA)在HRP/H2O2催化下进行自由基共聚反应,合成了GA-SAA共聚物,研究了单体物质的量比对GA-SAA共聚物应用性能的影响。当GA与SAA的物质的量比为1:1、pH为8.0及在35℃下反应4h得到的GA-SAA共聚物的应用性能最好。用FTIR、1H-NMR对产物结构进行了表征,将产品用于主鞣时,成革收缩温度可以达到76℃,用于复鞣时成革丰满柔软,均匀度好且粒面平细。     

微波辐射淀粉接枝共聚物研究

以玉米淀粉为主要原料,以N,N'-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂.以丙烯酸为淀粉接枝单体对微波辐射合成淀粉接枝共聚物反应条件进行优化研究,并对共聚物结构进行了分析.研究结果表明:在m(淀粉):m(丙烯酸)=1:5,pH 6.8,初始聚合温度35℃～40℃时.合适的接枝共聚反应条件为:引发剂和交联剂用量(与单体质量百分比)分别为O.1%和0.008%.微波功率280 W,时间180 s,此时合成的树脂吸水率为772.9 g/g.通过红外扫描可知共聚物存在着羧基、酰胺基等特征性亲水性基团.     

淀粉氧化降解条件与淀粉/丙烯酸类单体接枝共聚反应的关系

以氧化剂 (NH4) 2 S2 O8为淀粉降解试剂 ,研究了降解条件与淀粉 /丙烯酸类单体接枝共聚反应的关系。结果表明 :当氧化剂 (NH4) 2 S2 O8用量为 1 .0 g、降解反应温度为 95℃、降解时间为 0 .5h时 ,共聚物的接枝率、接枝效率和单体转化率较高 ,应用于皮革复鞣试验 ,其应用效果最好 ;同时利用FI-IR、XRD和DSC对产品结构进行了表征     

壳聚糖/AM/DM接枝共聚物对纸张的增强效果

采用硫酸亚铁(FeSO4)+过氧化氢(H2O2)氧化还原体系引发制备壳聚糖(CS)和丙烯酰胺(AM)及甲基丙烯酸二甲基氨基乙酯(DM)三元接枝共聚物,讨论了反应条件对接枝共聚物在纸张上增强效果的影响。其最佳合成条件为:m(FeSO4)=0.05%,m(FeSO4):m(H2O2)=0.05:1.8,m(CS)=1%,m(AM)=5%,m(DM)=0.3%,反应体系pH值为4～6。当接枝共聚物用量为0.4%时,与同等条件下壳聚糖-AM接枝共聚物相比,可使纸张的抗张强度和耐破度分别提高15%和18.68%。     

辣根过氧化物酶在纤维材料生物整理中的应用研究进展

针对化学法整理纤维材料存在能耗高、纤维损伤大的缺陷,提出借助酶法在温和条件下对纤维材料进行生物整理加工。介绍了辣根过氧化物酶/双氧水/β-二酮类引发剂乙酰丙酮(HRP/H₂O₂/ACAC)三元催化体系的氧化机制,综述了该体系在淀粉、黄麻和丝蛋白生物改性中的应用,包括:通过酶促反应使丙烯酸甲酯与淀粉接枝共聚,提高淀粉浆料对疏水性纤维的成膜性;通过催化黄麻与丙烯酰胺或甲基丙烯酸六氟丁酯接枝,实现黄麻亲水或疏水化整理;通过酶促反应使丝素与丙烯酸接枝共聚,提升丝素材料的仿生矿化效果;通过催化丝胶与甲基丙烯酸甲酯接枝共聚,改善丝胶基生物材料的成型性。指出HRP在纤维整理及生物材料制备中具有潜在的应用前景。     

过氧化物酶在蔗汁澄清工艺中除酚脱色的研究

本文研究了pH值、温度、H2O2用量及辣根过氧化物酶(HRP)用量等因素对辣根过氧化物酶催化H2O2氧化多元酚类的影响,并分别用HRP处理亚硫酸法糖厂的混合汁、清汁、糖浆,考察其对糖汁的除酚脱色效果。试验结果表明,HRP催化H2O2氧化处理糖汁具有明显的除酚脱色作用。     

玉米淀粉接枝丙烯酰胺合成

以Ce4 +为引发剂 ,研究了玉米淀粉 丙烯酰胺接枝共聚物形成的条件 .结果表明 ,引发剂用量、单体用量、反应温度及反应时间对合成产物的接枝率和单体聚合率有很大的影响 ,当淀粉用量为 5 .0 g ,引发剂用量为 1.0mL ,温度为 6 0℃ ,单体用量为 8.0 g时 ,单体聚合率最大 .另外 ,还研究了淀粉用量 ,Ce4 +-S2 O2 +8复合引发剂对玉米淀粉与丙烯酰胺接枝共聚的影响     

丙烯酸接枝淀粉的制备及其印花性能

采用丙烯酸(AA)单体对酸解玉米淀粉进行接枝,讨论了丙烯酸单体与玉米淀粉剩基（AGU）配比、丙烯酸单体pH值、引发剂用量、反应时间及温度对接枝产物接枝率、抱水性及PVID值的影响,并用红外光谱（FTIR）对接枝产物进行表征。试验得出丙烯接枝酸解玉米淀粉优化工艺为：n(AA):n(AGU)=2:1,丙烯酸单体pH值为6、引发剂n(H2O2)/n(FeSO4)=1.98,n(H2O2)=0.529mmol,接枝反应温度为50℃及时间为3h。所得接枝产物接枝率为5.14%,羧基含量为4.02%;接枝产物的抱水性为10.5mm,PVID值为0.34,各项性能与海藻酸钠相近,可作印花原糊用。     

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.