棉秆硫酸盐浆打浆及配抄性能的研究

采用PFI磨对棉秆全秆漂白硫酸盐浆进行打浆,分析了纤维长度和纸张强度指标随打浆度的变化。结果表明,打浆初期棉浆的纤维长度下降很快,打浆度超过50°SR后纤维长度下降趋缓。打浆度对棉浆耐破指数和裂断长的影响相近,在60°SR左右耐破指数和裂断长均达到最大值。而耐折度在接近50°SR时达到最大值。打浆度为40°SR时,撕裂指数开始明显降低,耐折度和耐破指数随打浆浓度上升最快,撕裂指数在低浓范围随打浆浓度上升而明显增大。配抄实验表明,棉浆配比20%以下时配抄防水铜版纸是可行的。     

不同打浆度玻璃纤维的形态及其抄片性质

对不同打浆度的玻璃纤维的纤维形态和抄片性能进行研究。实验表明:随着打浆度的增加,玻璃纤维的长度逐渐下降、粗度先增大后减小,在39°SR时达到最大;纤维的扭结和卷曲比例先降低,在49°SR又增大。玻璃纤维抄片的紧度随打浆度增加而大幅增大,当打浆度大于39°SR后,紧度变化不显著。打浆度升高,抄片的抗张强度增大,透气度减小;导热系数先减小后增大,在39°SR时导热系数最小,为0.015 W·(m·K)-1。     

打浆度对宣纸原料纤维形态及成纸性能的影响

本实验分别对宣纸主要原料青檀皮纤维和沙田稻草纤维在不同打浆度下的纤维形态进行测量,并对其手抄片的物理性能进行了研究。结果表明,青檀皮纤维长度比沙田稻草的纤维长度长,随着打浆度的提高,纤维的分丝帚化加剧,细小纤维增多,纤维长度变短。不同打浆度下青檀皮手抄片和沙田稻草手抄片的物理性能变化趋势基本相同,其抗张强度和耐破度随着打浆度的升高,先增加后降低,撕裂度和松厚度则随着打浆度的升高呈现下降的趋势。打浆度在50°SR左右时,手抄片整体物理性能最优。随着打浆度的提高,手抄片墨汁扩散时间不断增加,青檀皮和沙田稻草打浆度相近时,沙田稻草手抄片的墨汁扩散时间更长,且打浆度不同会影响手抄片墨汁扩散的形态。打浆度在50°SR左右时,手抄片墨汁扩散形状接近圆形且适中。     

胶原纤维用于全废纸瓦楞原纸抄造

从胶原纤维打浆度、添加量和废箱纸板浆打浆度3个因素研究了皮胶原纤维配抄瓦楞原纸的可行性。结果表明:胶原纤维打浆度为47°SR,废旧箱纸板浆打浆度为35°SR时,成纸抗张指数、撕裂指数和耐折度均较好,当胶原纤维的添加量为20%时,成纸的环压指数和裂断长达到最佳值,达到了A级瓦楞原纸的物理强度指标。     

卷烟纸用木浆纤维PFI磨浆特性分析

对一种卷烟纸用进口木浆纤维的PFI磨浆特性进行了系统分析,研究了打浆对纸浆物理强度、透气度、不透明度、纤维形态的影响。结果表明:此木浆纤维容易打浆,在7000 r下打浆度即达61.0°SR;随着打浆度的提高,成纸抗张指数随着打浆度的上升呈先快后慢的上升趋势,到了75°SR以后略有下降;撕裂指数则是在打浆度约40°SR之前呈快速上升趋势,之后则呈逐渐下降趋势;耐破指数和撕裂指数变化类似;但转折点变化出现在打浆度约为60°SR时;不透明度在打浆度75°SR之前,变化幅度在90%~95%之间,之后直线下降;透气度则直线下降,在75°SR以上高打浆度下透气度几乎为零;另外,该木浆纤维长度在1 mm左右,除含有纤维细胞外,还具有导管,可以确定其为漂白阔叶木桦木浆。     

胶原纤维的预处理及其在瓦楞原纸中的应用

从胶原纤维预处理、添加量和打浆度三个因素研究了皮革固体废弃物——胶原纤维配抄瓦楞原纸的可行性。结果表明:胶原纤维预处理最佳条件为CaO用量3%,处理温度60℃,处理时间3h,液比1∶5;胶原纤维打浆度为47°SR,废旧箱板纸浆打浆度为35°SR时,抄造的瓦楞原纸抗张指数、撕裂指数均最好;当胶原纤维的添加量为20%时,瓦楞原纸的环压指数和裂断长同时达到最佳值,并且达到A级瓦楞原纸物理指标。     

打浆度和纤维配比对液体包装纸板面层纤维基片性能的影响

利用液体包装纸板的实际生产工艺,探讨了不同打浆度和纤维配比对液体包装纸板面层纤维基片抗张指数、撕裂指数、耐破指数、挺度、松厚度和内结合强度的影响,并通过压痕测试研究了其在加工应用上的适应性。结果表明,在改善液体包装纸板面层纤维基片强度性能上,优化打浆工艺比增加针叶木浆配比效果更好,针叶木浆/阔叶木浆配比为1∶1,打浆度22°SR时撕裂指数最大为13.4 mN·m~2/g;打浆度25°SR时挺度最大为85.9 mN·m;打浆度29°SR时耐破指数和抗张指数最大分别为5.82 kPa·m~2/g和68.2 N·m/g,此条件下压痕测试数据和效果表现佳。     

胶原纤维配抄制鞋纸板工艺的初步研究

制鞋纸板是一种新型的制鞋材料。本文研究了胶原纤维代替部分植物纤维抄造制鞋纸板的工艺。实验从纤维的打浆度、配比等方面讨论了影响制鞋纸板的生产工艺,通过分析纸板的物理性能得出了最佳的工艺条件。结果表明,针叶木打浆度42°SR,胶原纤维打浆度59°SR,配比40%为制鞋纸板的最佳生产条件。最佳工艺抄造两层复合纸板的性能指标为:紧度0.533g/cm3;环压强度9.730N.m/g;挺度44.93mN.m;抗张强度347.99kN/m;层间剥离强度0.838kN/m.     

打浆方式对生活用纸未起皱原纸性能的影响

采用了针叶浆、阔叶浆分别打浆和混合打浆的打浆方式,将分别打浆情况下制备的不同打浆度的针、阔浆料混合至相同的打浆度21°SR,得到不同组合的浆料,然后与针、阔混合打浆至21°SR的浆料对比,研究了不同打浆方式下浆料的湿部化学及抄纸后纸张的强度、吸水性、柔软度、掉毛量的变化。研究结果表明不同打浆方式下,浆料的pH、Zeta电位及电导率未发生明显变化;采用针、阔分别打浆的打浆方式,针叶木浆打浆度为24°SR、阔叶木浆打浆度为20°SR时,纸张强度最高,达到43.36N.m/g,且掉毛量最少,仅16.20%,吸水性和柔软度适中;针叶木浆打浆度为31°SR、阔叶木浆未打浆的情况下,纸张吸水性和柔软度较好,达到21.0mm、153m N,但强度较差且掉毛量较多。采用针、阔混合打浆的打浆方式,纸张强度略低,为42.07N.m/g,掉毛量稍多,为18.54%,但吸水性和柔软度较差。     

打浆度对超高压绝缘纸老化性能的影响

选用俄罗斯云杉进行硫酸盐法蒸煮并纯化制备绝缘浆,进一步得到不同打浆度绝缘纸,对比其不同老化时间下纤维特性及绝缘纸机械和电气性能差异,研究打浆度对绝缘纸老化性能的影响。结果表明,随着打浆度升高,纤维长度和孔隙率降低,细小纤维含量增加,纤维分丝帚化率和弯曲扭结率增大;老化后纤维长度显著降低,低打浆度折断纤维和细小纤维含量越大。随着老化时间延长,不同打浆度绝缘纸性能差距增大;随老化时间延长,高打浆度绝缘纸机械性能和电气性能降低幅度更小,性能更稳定。当打浆度提高到83 °SR时,热压后绝缘纸的抗张强度达到17.5 kN/m,老化30天后纤维聚合度仍能保持在500左右,且打浆度为83 °SR油纸绝缘材料击穿强度远大于其他较低打浆度油纸绝缘材料,介电常数和介质损耗均低于其他较低打浆度油纸绝缘材料。     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.