纸基功能材料的开发与应用

纸基功能材料是特种纸和纸板制造的关键材料。研究表明：生物质基功能材料纳米纤维素通过复配共用技术可以提高纸张干、湿强度和氧气阻隔性能;功能性淀粉能明显提高再生纸质量。解决常规淀粉表面施胶留着率低的技术难题,经酯化、醚化、阳离子化复合变性技术可制备环保型涂布胶粘剂;采用多孔材料制备的热升华转印纸具有良好的转印效果和油墨转移率：多孔材料与植物抗菌剂制备水果保鲜纸具有良好的保鲜效果;多孔光降解材料对室内甲醛去除具有明显效果。     

二氧化氯缓释保鲜纸保鲜涂液配方优化

研究二氧化氯缓释保鲜纸保鲜涂液配方,为木质纤维类绿色保鲜材料的研发提供技术支持。保鲜涂液由氧化淀粉胶、氢氧化钠、亚氯酸钠等在一定工艺条件下复配制得,以纸基为载体,以亚氯酸钠为二氧化氯的前驱体,通过控制酸活化剂的量与作用时间,达到控制二氧化氯缓释的目的。以氧化淀粉胶含量、亚氯酸钠质量分数、氢氧化钠含量和酒石酸质量分数为影响因素,通过正交试验,确定保鲜纸基中亚氯酸钠留存率及保鲜体系中二氧化氯释放规律。采用回归分析的方法对结果进行拟合,利用SPSS分析软件进行处理,得到保鲜涂液各因素对保鲜纸基中亚氯酸钠留存率半衰期T0.5、保鲜体系中二氧化氯最大释放速率Kmax、二氧化氯最大释放速率所在时间tmax和二氧化氯释放总量Z总等指标的影响。通过所建立的目标方程,确定保鲜涂液的最佳配方为：氧化淀粉胶含量0.7 g/张、亚氯酸钠质量分数15%、氢氧化钠含量0.3 g/张、酒石酸质量分数15%。     

保鲜纸处理改善采后火龙果的贮藏品质

以红心火龙果为试材,在(20±0.5) ℃贮藏条件下,采用800 mg/L纳他霉素和800 mg/L ε-聚赖氨酸制成的保鲜纸处理,以蒸馏水制成的保鲜纸作为对照。研究纳他霉素和ε-聚赖氨酸保鲜纸处理对火龙果采后贮藏品质的影响。结果表明,与对照组相比,纳他霉素和ε-聚赖氨酸保鲜纸处理均能较好地降低采后火龙果贮藏期的呼吸强度,抑制果实腐烂率、失重率、丙二醛、霉菌及酵母菌和鳞片黄化率的增加,保持果实可溶性固性物、可滴定酸、Vc、甜菜素和鳞片叶绿素的含量。在贮藏末期8 d,纳他霉素保鲜纸处理组的腐烂率为8.30%,失重率为1.50%,丙二醛为4.30 μmol/g,均低于ε-聚赖氨酸保鲜纸处理组;Vc含量为15.53 mg/100 g,甜菜素含量为14.47 mg/100 g,均高于ε-聚赖氨酸保鲜纸处理组。因此,纳他霉素保鲜纸处理组的保鲜效果好于ε-聚赖氨酸保鲜纸处理。综上表明,纳他霉素保鲜纸可以有效地保持火龙果贮藏品质,延长其货架期。     

保鲜纸处理改善采后火龙果贮藏品质的研究

为提高火龙果贮藏品质,笔者在阅读大量文献资料的基础上结合实践,探索不同保鲜纸对火龙果贮藏品质的影响。通过试验发现,在一定贮藏条件下,纳他霉素和ε-聚赖氨酸保鲜纸处理对贮藏期火龙果的呼吸有较强的抑制作用,火龙果的腐烂率、鳞片黄化率、失重率、丙二醛含量等指标均有明显下降,还可有效抑制霉菌和酵母菌总数增长,果实的可溶性固性物、维生素C、甜菜素等含量仅出现少量流失,鳞片出现轻微黄化。贮藏周期设定为8 d,分别检测纳他霉素和ε-聚赖氨酸保鲜纸处理组火龙果的各项指标,纳他霉素保鲜纸处理组各项数据均优于ε-聚赖氨酸保鲜纸处理组。由此可确定,纳他霉素保鲜纸的保鲜效果明显高于ε-聚赖氨酸保鲜纸。试验结果表明,在火龙果贮藏期内采用纳他霉素保鲜纸可有效保持火龙果的品质,有助于延长火龙果的保鲜期、货架期。     

涂布法水果保鲜纸的研究

以白硅石粉、高锰酸钾和肉桂醛为主要保鲜剂,制备涂布法保鲜纸,以草莓为保鲜对象,研究保鲜纸对其保鲜效果。结果表明:涂布法保鲜纸对草莓有较好的保鲜效果,可以减少草莓的水分流失和降低细胞膜透性;保鲜纸的最佳涂料配方为:白硅石的用量为100份,高锰酸钾的用量为0.095%,肉桂醛的用量为0.07%,此用量下的草莓平均失重率为14.2%     

集美大学枇杷保鲜技术达国内领先水平

<正>2007年6月5日,集美大学的"枇杷果实采后新型保鲜剂的研制"项目通过鉴定。鉴定会由厦门市科技局主持。该项目在国内首次研制开发了枇杷专用固态新型保鲜剂(保鲜纸及袋装粉剂),克服了传统液态水果保鲜剂使用程序复杂的缺点,经4年度贮藏保鲜试验表明,在低温(2～5℃)下,贮藏60d的枇杷果实腐烂率3.5%～4.8%,比对照降低3～4倍,果实品质也比对照明显提高,保鲜枇杷符合国家水果相关标准。鉴定委员会认为该项成果达国内领先水平,具有较高的学术意义和应用价值。     

生物保鲜纸处理对百香果采后贮藏品质的影响

为探究不同生物保鲜纸对采后百香果贮藏品质的影响。以百香果为研究材料,用不同处理的保鲜纸(800 mg/L纳他霉素、800 mg/Lε-聚赖氨酸)放入装有百香果的保鲜袋中,在(20±0.5)℃条件下贮藏,研究不同保鲜纸处理对采后百香果贮藏期果实品质的影响。结果表明,纳他霉素和ε-聚赖氨酸保鲜纸均能够抑制失重率、皱缩指数、相对电导率和丙二醛含量的增加,能有效维持果实的好果率、可溶性固形物(total soluble solids, TSS)含量、可滴定酸(titratable acid, TA)含量、维生素C含量、可溶性蛋白(soluble protein, SP)含量,且显著增强果实的超氧化物歧化酶(superoxide, SOD)活性,有效抑制果实霉菌及酵母菌的生长,较好地保持了百香果的贮藏品质。其中,在贮藏期20 d时,对照组、纳他霉素和ε-聚赖氨酸的百香果好果率分别为83%、90%、86%,纳他霉素的保鲜纸处理比ε-聚赖氨酸的保鲜纸效果更好,因此,800 mg/L纳他霉素保鲜纸更适宜百香果采后保鲜,能有效地保持百香果采后贮藏品质,并延长贮藏期。     

碳纤维/芳纶纸基复合材料的制备及其电磁参数调控技术研究

本研究采用芳纶纤维和碳纤维作为原料,通过斜网成形技术制备了一种电磁参数可以灵活设计的纸基复合材料。通过浆网速比调控碳纤维的分布,实现对纸基复合材料纵向和横向的电磁参数的调控。结果表明,浆网速比为0.5时,纸基复合材料的抗张指数纵横向比为2.2,8～12 GHz频率下纸基复合材料的介电常数实部纵横向比为2.1～2.2;浆网速比为1.2时,纸基复合材料的抗张指数纵横向比为1.5,8～12 GHz频率下纸基复合材料的介电常数实部纵横向比为1.5～1.6。仿真计算和工程化实验结果表明,控制浆网速比是调控碳纤维/芳纶纸基复合材料电磁参数的重要方法。     

新型复合保鲜纸的制备及在油桃保鲜中的应用

为提高油桃果实的保鲜效果,制备了一种以PVA涂层为阻隔层,以牛至精油和1-甲基环丙烯(1-MCP)为保鲜剂,既能抑菌又能抑制乙烯活性、延缓呼吸越变进程的新型复合保鲜纸。并采用GC-MS对精油抑菌成分和1-MCP的释放规律进行了研究;以油桃为供试水果,通过测定呼吸强度和腐烂指数,考察自制复合保鲜纸的实际保鲜效果。结果表明,这种新型的复合保鲜纸的保鲜效果明显优于单独使用牛至精油或1-MCP,可以明显降低油桃的腐烂指数。这种新型复合保鲜纸对呼吸跃变型的油桃具有良好的保鲜效果,为这类果蔬的保鲜提供了一种有效方法。     

复合材料在汽车上的应用

概述了纤维增强树脂基复合材料、金属基复合材料、陶瓷基复合材料等在汽车上的应用现状,并对复合材料在汽车上的应用前景进行了展望。国内外现状表明,复合材料在汽车上将有广阔的应用前景,同时,也有很多问题有待解决。     

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.