阳离子淀粉的制备及增强纸张性能的研究

以玉米淀粉、甲基丙烯酰氧基乙基三甲基氯化铵和丙烯酰胺为主要原料,通过自由基共聚反应合成了阳离子淀粉。通过控制淀粉的用量、阳离子单体和丙烯酰胺的配比,合成出一系列阳离子淀粉,利用红外光谱及核磁共振谱对其进行了表征,并使用所合成的阳离子淀粉作为纸张增强剂,研究了共聚阳离子淀粉对纸张的增强作用。     

阳离子淀粉的合成及对纸张的增强作用

以玉米淀粉、甲基丙烯酰氧基乙基三甲基氯化铵(DMC)和丙烯酰胺(AM)为主要原料,采用特殊工艺通过自由基共聚反应合成了阳离子淀粉.通过控制淀粉的用量、阳离子单体和丙烯酰胺的配比,合成出一系列阳离子淀粉,利用红外光谱及核磁共振谱对其进行了表征,并使用所合成的阳离子淀粉作为纸张增强剂,研究了共聚阳离子淀粉对纸张的增强作用.结果表明,阳离子淀粉对纸张的增强作用除与共聚组分淀粉、DMC和AM的配比有关外,还与该阳离子淀粉的分子结构密切相关.     

CMC-PVA共混改性PAE树脂及其对纸张的增强作用

采用羧甲基纤维素-聚乙烯醇（CMC-PVA）改性剂对PAE树脂进行改性,探讨了改性的最佳工艺条件,以及改性后PAE树脂作为增强剂对纸张强度性能的影响,并与阳离子淀粉和CPAM增强剂进行比较,同时,对改性PAE树脂进行红外与热重表征分析。结果表明,与未改性PAE树脂相比,利用CMC-PVA改性剂改性后的PAE树脂对纸张的增强效果更好;在相同用量下,改性PAE树脂具有比CPAM更好的增强效果;在相同使用成本下,改性PAE树脂具有比阳离子淀粉更好的增强效果;改性PAE树脂可取代CPAM、阳离子淀粉用作纸张增强剂。     

乙二醛改性聚乙烯醇纸张增强剂的研究

乙二醛与聚乙烯醇（PVA）反应制备了一种纸张增强剂，讨论了反应时间及m（乙二醛）／m（PVA）的变化对改性PVA水溶液的粘度的影响。应用红外光谱和凝胶渗透色谱（GPC）对改性PVA的结构作了表征，表明乙二醛与PVA发生了一定的交联反应。改性条件为80℃、120min时，制备的产品具有理想的稳定和增强性能。m（乙二醛）／m（PVA）为0．1和改性PVA用量为1．0％时，纸张的耐折度可以提高51％，抗张强度可以提高22％；m（乙二醛）／m（PVA）为0．5时，纸张的撕裂度可提高25％，拉毛速度可提高17％。     

棉纤维阳离子改性及应用探究

以20%盐酸、33%三甲胺和环氧氯丙烷合成了阳离子改性剂,对棉纱进行阳离子改性,用红外光谱对未阳离子改性棉纱和阳离子改性棉纱进行了结构表征。未阳离子改性棉纱和阳离子改性棉纱进行涂料染色,并测试了色纱的K/S值。结果表明：阳离子改性棉纱在1050cm~（-1）处吸收有掩盖,证明有C-N键伸缩振动;当改性剂20g/L、平平...     

改性酚醛树脂在OCC浆中的应用及其增强机理

通过苯酚、甲醛与二乙烯三胺反应,得到阴离子性的酚醛树脂,并将改性的酚醛树脂作为造纸增强剂应用在抄纸过程。结果表明,单独使用改性酚醛树脂时增强效果不显著;改性酚醛树脂和阳离子淀粉共同使用能有效提高纸张的抗张指数和环压指数。通过对改性酚醛树脂和阳离子淀粉用量的优化得到最佳使用条件,即改性酚醛树脂和阳离子淀粉用量分别为0．3％和0．7％,纸张的抗张指数和环压指数分别增加了35．28％和26.50％。由改性酚醛树脂增强机理的试验结果表明,改性酚醛树脂能使浆料在加入阳离子淀粉的情况下分散更均匀;改性酚醛树脂和阳离子淀粉能有效提高纤维之间的结合强度。     

HM－Ⅰ型阳离子淀粉的合成与结构表征

在催化剂存在下，以３－氯－２－羟丙基三乙基氯化胺为醚化剂，采用无盐湿法新工艺合成了ＨＭ－Ⅰ型阳离子淀粉。正交试验结果表明，在温度为９５℃，醚化剂用量为８％。介质ｐＨ值为１１－１１．５条件下，合成的阳离子淀粉取代度较高。通过红外光谱和核磁共振谱对阳离子淀粉进行了结构表征。     

阳离子香豆素的合成及其对高得率浆的返黄抑制作用

以3-氨基酚和乙酰乙酸乙酯为原料,在Lewis酸的催化下,通过Pechmann法合成了 7-氨基-4-甲基香豆素。将阳离子醚化剂2,3-环氧丙基三甲基氯化铵与7-氨基-4-甲基香豆素反应,实现了7-氨基-4-甲基香豆素的阳离子化。通过红外光谱和核磁共振光谱对合成产物的结构进行表征;采用紫外光谱、荧光光谱探讨了其光学性质;采用紫外光加速老化实验检测了合成产物对纸张返黄的抑制效果。结果表明,该阳离子化的7-氨基-4-甲基香豆素的亲水性较好,能在较长时间内抑制纸张返黄。     

GTMAC改性淀粉的合成研究

超声条件下以环氧氯丙烷(EPIC)和三甲胺(TMA)反应制备中间体醚化剂失水甘油基三甲基氯化铵(GTMAC),用制得的醚化剂GTMAC对淀粉进行改性合成季铵盐阳离子淀粉。研究了GTMAC和淀粉的配料比、反应温度、反应pH、反应时间对阳离子淀粉产率的影响。实验得出阳离子淀粉的最佳合成反应条件为:n(GTMAC)∶n(淀粉)=0.6∶1、反应时间4 h、反应温度70℃、反应pH=10,阳离子淀粉产率为88.1%。通过红外光谱对GTMAC和阳离子淀粉进行了结构表征。     

乙二醛改性支链状阳离子聚丙烯酰胺的合成及其对纸张增强性能的研究

以N-羟甲基双丙烯酰胺(NMA)为交联性单体、2-巯基乙醇为链转移剂,以过硫酸铵和亚硫酸氢钠(mAPS∶mNaHSO3=1∶2)组成氧化还原引发体系引发丙烯酰胺(AM)、阳离子单体甲基丙烯酰氧乙基三甲基氯化铵(DMC),进行水溶液自由基共聚合反应,制备了支链状阳离子聚丙烯酰胺(CPAM)。然后用乙二醛对合成的CPAM进行改性,制备了乙二醛改性的阳离子聚丙烯酰胺树脂(GPAM)。结果表明:当丙烯酰胺用量为55%、NMA用量为8%、2-巯基乙醇用量为1.0%、DMC用量为5.5%、引发剂用量为0.5%(wt)、乙二醛用量为30%(wt)、改性温度为60℃、改性时间为140min时,产物的增强效果较好。当用量为0.3%时,纸张的干抗张指数提高了24.6%,湿抗张指数提高了381%。并用红外光谱(FT-IR)和核磁共振氢谱(1H-NMR)对产物的结构进行了表征。     

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.     

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.     

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.     

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.