高岭土分散液流变性的初步研究

对2种高岭土(MMO1和Premium)的流变性进行了研究,探讨了固含量、分散剂用量以及pH值对颜料分散液高剪切黏度的影响。结果表明,MMO1的最佳分散剂用量为0.15%,Premium的最佳分散剂用量为0.10%;要获得较好的高剪切特性,MMO1分散液pH值应调至8.0以上,但不应太高,Premium分散液pH值也应调至8.6左右较好。MMO1的固含量控制在68%左右较合适。而Premium固含量对高剪切黏度的影响较MMO1的明显,其分散液固含量一般控制在69%~70%。     

二氧化钛对涂料流变性的影响

颜料是涂料的重要组成部分,影响到涂料的流变特性和产品质量。金红石型二氧化钛折射系数高、白度高和化学稳定性好,能提高纸张不透明度和涂层遮盖性。本文以金红石型二氧化钛部分取代瓷土,研究了其对涂料流变性和涂布纸光学性能的影响。研究发现：随着涂料配方中二氧化钛用量的增加,涂料的低剪切黏度和高剪切黏度增加,导致涂料高剪切力条件下的流变性变差。二氧化钛对涂料保水性影响不大。二氧化钛会吸收紫外光,降低了荧光增白剂的应用效果;但能增加成纸的不透明度。     

超细滑石粉在轻量涂布纸中的应用研究

测试了超细滑石粉颜料的基本理化性能,试验了超细滑石粉替代高岭土对轻量涂布纸涂料性能及成纸性能的影响。结果表明,随着超细滑石粉用量的增加,轻量涂布纸涂料的低剪切黏度小幅度增加,但高剪切黏度呈降低趋势;轻量涂布纸白度、平滑度、不透明度、光泽度、表面粗糙度、印刷光泽度等性能指标基本接近,印刷表面强度明显提高。     

滑石颜料高剪切流变性能的研究

使用毛细管高剪切黏度仪研究了滑石颜料分散体系的高剪切黏度性能,以及pH值、固含量、不同分散剂和润湿剂、不同粒径分布对滑石分散体系高剪切黏度的影响。同时还研究了滑石与GCC及高岭土混合浆料的高剪切黏度性能。结果表明,滑石含量越高、粒度越细,其分散浆料的高剪切黏度值越大。同时发现,滑石高剪切黏度受分散剂和润湿剂的影响不大。提高pH值有利于降低滑石分散体系的高剪切黏度。滑石与GCC混合浆料的高剪切黏度随着GCC粒度的变细而降低。当滑石与GCC的体系中加入高岭土后,混合浆料的高剪切黏度大幅增大,且随着GCC粒度的变细而增大。     

滑石粉在涂布白纸板面涂涂料中的应用研究

采用滑石粉取代涂布白纸板面涂涂料中的高岭土,对比分析滑石粉不同用量对涂料流变性能及涂布白纸板成纸性能的影响。结果表明,随着滑石粉取代量的不断增加,虽然涂料的低剪切黏度有小幅度增加,但涂料的高剪切黏度却呈降低趋势;滑石粉取代高岭土后,对涂布白纸板的白度、平滑度以及表面吸水性能未产生明显影响,但明显提高了涂布白纸板印刷光泽度与光泽度的差值和印刷表面强度。在纸机试验条件下,以滑石粉取代高岭土用于涂布白纸板面涂时也明显提高印刷光泽度与光泽度的差值和印刷表面强度。     

聚乳酸接枝马来酸酐/淀粉共混物对涂料流变性及纸张性能的影响

将聚乳酸接枝马来酸酐与淀粉共混物作为胶黏剂用于造纸涂料中,研究了改性聚乳酸不同用量对涂料流变性以及对涂布纸白度、表面强度、油墨吸收性能的影响;同时与涂料中常用的合成胶乳丁苯胶乳作比较。结果发现:改性聚乳酸用量的增加可以显著降低涂料低剪切黏度和高剪切黏度,改善涂料流变性;同时,随着改性聚乳酸用量增加,涂布纸白度、表面强度和油墨吸收性提高;另外,改性聚乳酸/淀粉共混物作为胶黏剂使用与丁苯胶乳对涂布纸性能影响相差不大,可替代丁苯胶乳或与之配合使用,获得更好的涂布纸性能。     

涂布滑石粉也可有好的流变性

薄片状颜料能改善用于轮转凹版印刷LWC纸涂料的覆盖性和适印性，但是高径厚比、窄粒径分布的颜料能增加颜料分散液和涂料的高剪切黏度和不希望有的剪切增稠的流变特性。这些性质可以降低颜料分散液的可过筛性和轮转凹版印刷用LWC纸涂料的可过筛性和可运行性。一个高径厚比颜料含量高的涂料配方的主要影响因素就是高剪切黏度。本文介绍了相对于传统的滑石粉，一种新型滑石粉如何在较高固含量和较低化学助剂用量下改善颜料分散液的可过筛性和流变性。中试涂布试验结果表明片状颜料和这种新型滑石粉组成的涂料，改善了轮转凹版印刷涂布纸涂料的保水质和涂布运行性。虽然在较低的滑石粉固含量时两种产品的涂层结构有一定差异，但在较高固含量时，这两种滑石粉提供了相似的轮转凹版印刷LWC纸性质。应用：合适的矿石和颜料处理技术可以在优化颜料分散时，使其对设备和化学助剂的要求最小化，同时改善颜料分散液和涂料的性质。性能的改善和较低的成本使造纸生产厂商控制涂布颜料的使用时更具灵活性。     

颜料悬浮液固含量对低剪切黏度的影响

分析了不同种类颜料悬浮液固含量对低剪切黏度的影响。结果表明,尽管颜料悬浮液固含量与黏度平方根倒数的线性关系相当好,但对于相当一部分颜料,由此得到的黏浓度数据偏差仍然不可接受;而且根据测算,在黏浓度点附近,固含量的微小波动会造成低剪切黏度很大的变化,导致黏浓度的测定结果不可靠。在给定固含量条件下测定黏度,控制黏度在较低范围可以获得很好的测定精度。     

PCC对涂料流变性和涂布纸性能的影响

研究了PCC对涂料流变特性、涂布纸性能的影响,比较了PCC和高岭土对涂布纸性能的影响.研究发现,随着PCC在涂料配比中用量的增加,涂料低剪切黏度降低,导致涂料保水性变差,不利于涂料固含量增加;涂料高剪切黏度增加.会对涂布机的运行性能产生负面影响.但是,PCC有利于增加L*值和a*值,降低b*值,能提高涂布纸的白度和不透明度,减少荧光增白剂用量.PCC有利于增加涂层表面强度.随着PCC用量的增加,油墨吸收性增加.与高岭土相比,在达到相同成纸表面强度的条件下,能降低胶黏剂用量.     

羧甲基改性纳米纤维素对颜料分散与涂料性能的影响

对纸浆纤维进行羧甲基化学改性并结合高压均质处理,制得羧甲基改性纳米纤维素（NFC）,探究了羧甲基改性NFC的性能及其对颜料分散稳定性、低固含量涂料流变性的影响。结果表明,随着羧甲基取代度提高,改性NFC尺寸减小、电负性增强;其溶液具有“剪切稀化”特征,即浓度越高、黏度系数越大。颜料分散性研究结果表明,颜料分散液的黏度随羧甲基改性NFC添加量增加而增大、随羧甲基取代度提高而下降;提高NFC的羧甲基取代度及增加其添加量可提高颜料分散液的悬浮体积百分比,改善颜料分散液的稳定性。对涂料性能的研究发现,提高NFC的羧甲基取代度,涂料的假塑性逐步减弱、黏度也随之降低,在一定程度上对涂料的流变起到了调节作用。另外,当NFC的羧甲基取代度为0.4时,涂料保水值下降幅度达67.8%,保水性能得到极大改善。     

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.     

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.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the