二氧化硫脲漂白废纸脱墨浆的工艺优化

用二氧化硫脲(FAS)漂白混合废纸脱墨浆,探讨FAS用量、NaOH与FAS的碱比、浆浓、漂白温度和漂白时间对漂后纸浆白度的影响。结果表明,浆浓8%,FAS用量0.6%,温度80℃,时间60min时,NaOH与FAS的碱比0.5∶1最佳,浆的白度可达82.8%ISO,白度增值为5.4%ISO;延长漂白时间到65min,碱比调整为0.4:1或0.45:1,浆白度可达82.4%ISO,白度增值为5.0%ISO。     

红麻全秆亚硫酸氢镁浆HMP漂白

对红麻亚硫酸氢镁浆HMP三段漂白进行了研究。结果表明,采用金城纸业常规的单段次氯酸盐漂白条件,当有效氯用量为2%时,白度可由46.2%ISO提高到53.2%ISO;采用H加P两段漂白,白度可以进一步提高到72.4%ISO,但还未达到高白度80%ISO要求。在HP漂序中间添加M段预处理形成HMP三段漂白,在预处理条件为pH值3.0、浆浓8%、时间60min、温度40℃、M助剂用量为2%时,可以将红麻浆白度提高到80.97%ISO。实验表明,用HMP三段漂白红麻亚硫酸氢镁浆,在适宜的工艺条件下可以使浆料白度提高到80%ISO以上,满足高白度文化用纸的要求,并且大幅度降低单段次氯酸盐漂白带来的污染物。     

二氧化氯活化对麦草生物化机浆过氧化氢漂白的作用

研究了麦草生物化机浆二氧化氯(ClO2)活化条件以及ClO2活化与H2O2的组合漂白.结果表明:麦草生物化机浆ClO2活化适宜条件为:0.8%ClO2、20min、室温.经DP3P3a和DP5P5a漂白,麦草生物化机浆白度分别可达60.7%ISO和71.2%ISO.     

芦苇浆无元素氯漂白特性研究

进行芦苇浆无元素氯漂白的研究,并与常规的CEH漂白结果作比较。研究结果表明,芦苇浆经D0Ep D1流程漂白,当二氧化氯的有效氯用量为6.5%,H2O2用量为0.2%时,在优化条件下可达到84.42%ISO的白度。与CEH漂白浆相比,D0Ep D1漂白浆的白度稳定性较好,粘度高,漂白废水的污染负荷比CEH漂白废水低很多。     

麦草乙醇浆臭氧漂白后过氧化氢补充漂白

麦草浆常规漂白工艺污染较大,故采用QZP短序TCF工艺漂白乙醇麦草浆。本文对麦草乙醇浆臭氧漂白后H2O2补充漂白进行了研究。高锰酸钾值18.2,白度26.4%ISO,黏度1135mL.g-1。经臭氧漂白后(臭氧用量为1.2%时),麦草乙醇浆高锰酸钾值4.0,白度增加到60%ISO,黏度为966mL.g-1。研究结果表明,在纸浆浓度12%,柠檬酸三钠用量1.0%情况下,H2O2补充漂白最佳条件为:H2O2用量3.0%,NaOH用量1.8%,漂白温度70℃,漂白时间120min,漂后浆的高锰酸钾值2.0,白度84%ISO,黏度908mL.g-1。     

四羟甲基磷酸膦用于马尾松热磨机械浆漂白

采用四羟甲基磷酸膦(THPS)漂白马尾松热磨机械浆,探讨THPS用量、初始pH值、漂白时间和漂白温度对漂后纸浆白度的影响。研究结果表明,THPS漂白马尾松热磨机械浆的适宜条件是:浆浓10%,THPS用量2.0%,初始pH5.0,漂白时间2h,温度90℃时,漂后纸浆白度达到63.07%ISO,白度增值为7.07%ISO。通过比较连二亚硫酸盐(Y)漂白和THPS漂白的效果,当THPS用量为0.1%,Y用量为1.0%时,漂后纸浆的白度达到61.12%SO,比未漂浆的白度提高了5.12%ISO。     

二氰二胺用于马尾松硫酸盐浆的漂白

通过正交试验研究二氰二胺在马尾松硫酸盐浆漂白中的应用。结果表明:在过氧化氢漂白段影响纸浆白度的主要因素是二氰二胺用量,其次是漂白时间和氢氧化钠用量,而温度对漂白的效果影响最小。过氧化氢漂白段的适宜工艺条件为:过氧化氢用量3%,浆浓10%,二氰二胺用量1.6%,漂白时间60min,氢氧化钠用量3%,漂白温度70℃,硫酸镁用量0.5%,硅酸钠用量3%。在上述适宜条件下,漂后纸浆白度可达90.57%ISO,较未添加二氰二胺的漂后纸浆白度提高5.57%ISO。     

硫酸盐竹浆DEpP与CEH程序漂白的比较

通过分析研究不同时间、温度、二氧化氯用量对硫酸盐竹浆二氧化氯漂后卡伯值、白度、p H、黏度和得率的影响,来确定二氧化氯漂白的最佳工艺。将此工艺应用在DEp P中,比较分析相同有效氯条件下DEp P和CEH各漂段白度、卡伯值、返黄值、漂白浆的强度性能及漂白废水污染指标,来评价二氧化氯在多段漂白中的漂白效果及ECF和CEH对环境污染的程度。结果表明,硫酸盐竹浆最佳二氧化氯漂白工艺:70℃、2h、二氧化氯用量3.0%。打浆后发现,这两种漂白竹浆的强度性能都较好,其中DEp P漂白竹浆的各项强度性能更佳。DEp P漂终白度达81.8%ISO,比CEH高3%ISO且DEp P漂白废水的污染负荷比CEH漂白废水低得多,其中AOX(可吸附有机氯化物)含量为CEH的1/7,说明ECF不仅可以满足实际生产中对纸张白度和强度的要求,而且大幅度减轻对环境的污染,具有很好的环境友好性。     

祭祀纸生产用浆漂白工艺研究

通过单因素实验探讨了全竹浆生产祭祀纸的H2O2漂白的工艺参数,找出了H2O2漂白的适宜工艺条件。在H2O2用量9%,温度80℃,时间120min,浆浓10%,NaOH1.5%,Na2SiO33%,漂白助剂0.2%的条件下,漂后浆白度为29.1%ISO,比原浆白度提高了13.8%ISO。且原浆经过氧化氢—连二亚硫酸钠两段漂白后白度达到36.2%ISO,与原浆(白度15.3%ISO)相比白度提高了21个百分点,达到并超过生产厂家对漂白浆的要求。     

芦苇硫酸盐浆OpP漂白的研究

研究了芦苇硫酸盐浆H2O2强化氧脱木素及H2O2补充漂白。芦苇KP浆未漂浆卡伯值27.5,白度29.9%ISO,黏度1036mL/g,H2O2强化氧脱木素条件为:用碱量5%、氧压0.6MPa、H2O2用量2%、温度80℃、漂白时间60min,反应后纸浆卡伯值为4.1、白度63.0%ISO、黏度为864mL/g。随后再用H2O2进行补充漂白,所得纸浆卡伯值为3.2,白度81.0%ISO,黏度822mL/g。     

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.